Revert "NAT: VPP-1531 api cleanup & update"

This reverts commit bed1421b9f1b3643d93384084972337b596aec73.

/vpp/master3/src/plugins/nat/nat_api.c: In function ‘send_nat_worker_details’:
/vpp/master3/src/vppinfra/clib.h:62:33: error: division ‘sizeof (u8 * {aka unsigned char *}) / sizeof (u8 {aka unsigned char})’ does not compute the number of array elements [-Werror=sizeof-pointer-div]
 #define ARRAY_LEN(x) (sizeof (x)/sizeof (x[0]))
                                 ^
/vpp/master3/src/plugins/nat/nat_api.c:205:43: note: in expansion of macro ‘ARRAY_LEN’
   rmp = vl_msg_api_alloc (sizeof (*rmp) + ARRAY_LEN (w->name) - 1);
                                           ^~~~~~~~~

Change-Id: Ie82672c145fb2f6580827f95e535435307bc7a23
Signed-off-by: Ole Troan <ot@cisco.com>

11 files changed, 1211 insertions, 1381 deletions

diff --git a/extras/vom/vom/nat_binding.cpp b/extras/vom/vom/nat_binding.cpp
index a3fdee77be4..3c3d8261d67 100644
--- a/extras/vom/vom/nat_binding.cpp
+++ b/extras/vom/vom/nat_binding.cpp
@@ -225,7 +225,7 @@ nat_binding::event_handler::handle_populate(const client_db::key_t& key)
 
     if (itf) {
       nat_binding nb(*itf, direction_t::INPUT, l3_proto_t::IPV4,
-                     zone_t::from_vpp(payload.flags & NAT_IS_INSIDE));
+                     zone_t::from_vpp(payload.is_inside));
       OM::commit(key, nb);
     } else {
       VOM_LOG(log_level_t::ERROR) << "nat-binding-input-44 no sw_if_index: "
@@ -245,7 +245,7 @@ nat_binding::event_handler::handle_populate(const client_db::key_t& key)
     std::shared_ptr<interface> itf = interface::find(payload.sw_if_index);
     if (itf) {
       nat_binding nb(*itf, direction_t::OUTPUT, l3_proto_t::IPV4,
-                     zone_t::from_vpp(payload.flags & NAT_IS_INSIDE));
+                     zone_t::from_vpp(payload.is_inside));
       OM::commit(key, nb);
     } else {
       VOM_LOG(log_level_t::ERROR) << "nat-binding-output-44 no sw_if_index: "
@@ -265,7 +265,7 @@ nat_binding::event_handler::handle_populate(const client_db::key_t& key)
     std::shared_ptr<interface> itf = interface::find(payload.sw_if_index);
     if (itf) {
       nat_binding nb(*itf, direction_t::INPUT, l3_proto_t::IPV6,
-                     zone_t::from_vpp(payload.flags & NAT_IS_INSIDE));
+                     zone_t::from_vpp(payload.is_inside));
       OM::commit(key, nb);
     } else {
       VOM_LOG(log_level_t::ERROR) << "nat-binding-input-66 no sw_if_index: "
diff --git a/extras/vom/vom/nat_binding_cmds.cpp b/extras/vom/vom/nat_binding_cmds.cpp
index 4e69a67f2af..d67a0828003 100644
--- a/extras/vom/vom/nat_binding_cmds.cpp
+++ b/extras/vom/vom/nat_binding_cmds.cpp
@@ -39,8 +39,7 @@ bind_44_input_cmd::issue(connection& con)
 
   auto& payload = req.get_request().get_payload();
   payload.is_add = 1;
-  payload.flags = (vapi_enum_nat_config_flags)(
-    nat_binding::zone_t::INSIDE == m_zone ? NAT_IS_INSIDE : 0);
+  payload.is_inside = (nat_binding::zone_t::INSIDE == m_zone ? 1 : 0);
   payload.sw_if_index = m_itf.value();
 
   VAPI_CALL(req.execute());
@@ -80,8 +79,7 @@ unbind_44_input_cmd::issue(connection& con)
 
   auto& payload = req.get_request().get_payload();
   payload.is_add = 0;
-  payload.flags = (vapi_enum_nat_config_flags)(
-    nat_binding::zone_t::INSIDE == m_zone ? NAT_IS_INSIDE : 0);
+  payload.is_inside = (nat_binding::zone_t::INSIDE == m_zone ? 1 : 0);
   payload.sw_if_index = m_itf.value();
 
   VAPI_CALL(req.execute());
@@ -121,8 +119,7 @@ bind_44_output_cmd::issue(connection& con)
 
   auto& payload = req.get_request().get_payload();
   payload.is_add = 1;
-  payload.flags = (vapi_enum_nat_config_flags)(
-    nat_binding::zone_t::INSIDE == m_zone ? NAT_IS_INSIDE : 0);
+  payload.is_inside = (nat_binding::zone_t::INSIDE == m_zone ? 1 : 0);
   payload.sw_if_index = m_itf.value();
 
   VAPI_CALL(req.execute());
@@ -162,8 +159,7 @@ unbind_44_output_cmd::issue(connection& con)
 
   auto& payload = req.get_request().get_payload();
   payload.is_add = 0;
-  payload.flags = (vapi_enum_nat_config_flags)(
-    nat_binding::zone_t::INSIDE == m_zone ? NAT_IS_INSIDE : 0);
+  payload.is_inside = (nat_binding::zone_t::INSIDE == m_zone ? 1 : 0);
   payload.sw_if_index = m_itf.value();
 
   VAPI_CALL(req.execute());
@@ -267,8 +263,7 @@ bind_66_input_cmd::issue(connection& con)
 
   auto& payload = req.get_request().get_payload();
   payload.is_add = 1;
-  payload.flags = (vapi_enum_nat_config_flags)(
-    nat_binding::zone_t::INSIDE == m_zone ? NAT_IS_INSIDE : 0);
+  payload.is_inside = (nat_binding::zone_t::INSIDE == m_zone ? 1 : 0);
   payload.sw_if_index = m_itf.value();
 
   VAPI_CALL(req.execute());
@@ -310,8 +305,7 @@ unbind_66_input_cmd::issue(connection& con)
 
   auto& payload = req.get_request().get_payload();
   payload.is_add = 0;
-  payload.flags = (vapi_enum_nat_config_flags)(
-    nat_binding::zone_t::INSIDE == m_zone ? NAT_IS_INSIDE : 0);
+  payload.is_inside = (nat_binding::zone_t::INSIDE == m_zone ? 1 : 0);
   payload.sw_if_index = m_itf.value();
 
   VAPI_CALL(req.execute());
diff --git a/extras/vom/vom/nat_static_cmds.cpp b/extras/vom/vom/nat_static_cmds.cpp
index 0c4d7283ea6..299f2f5f328 100644
--- a/extras/vom/vom/nat_static_cmds.cpp
+++ b/extras/vom/vom/nat_static_cmds.cpp
@@ -45,7 +45,7 @@ create_44_cmd::issue(connection& con)
 
   auto& payload = req.get_request().get_payload();
   payload.is_add = 1;
-  payload.flags = NAT_IS_ADDR_ONLY;
+  payload.addr_only = 1;
   payload.local_port = 0;
   payload.external_port = 0;
   payload.vrf_id = m_id;
@@ -94,7 +94,7 @@ delete_44_cmd::issue(connection& con)
 
   auto& payload = req.get_request().get_payload();
   payload.is_add = 0;
-  payload.flags = NAT_IS_ADDR_ONLY;
+  payload.addr_only = 1;
   payload.local_port = 0;
   payload.external_port = 0;
   payload.vrf_id = m_id;
diff --git a/src/plugins/nat/nat.api b/src/plugins/nat/nat.api
index 80a70a7e995..7f9fe3f8e7b 100644
--- a/src/plugins/nat/nat.api
+++ b/src/plugins/nat/nat.api
@@ -13,9 +13,8 @@
  * limitations under the License.
  */
 
-option version = "5.0.0";
+option version = "4.1.0";
 import "vnet/ip/ip_types.api";
-import "vnet/interface_types.api";
 
 /**
  * @file nat.api
@@ -29,18 +28,6 @@ import "vnet/interface_types.api";
  * Common NAT plugin APIs
  */
 
-enum nat_config_flags : u8
-{
-  NAT_IS_TWICE_NAT = 0x01,
-  NAT_IS_SELF_TWICE_NAT = 0x02,
-  NAT_IS_OUT2IN_ONLY = 0x04,
-  NAT_IS_ADDR_ONLY = 0x08,
-  NAT_IS_OUTSIDE = 0x10,
-  NAT_IS_INSIDE = 0x20,
-  NAT_IS_STATIC = 0x40,
-  NAT_IS_EXT_HOST_VALID = 0x80,
-};
-
 /** \brief Control ping from client to api server request
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
@@ -78,12 +65,11 @@ define nat_show_config
 /** \brief Show NAT plugin startup config reply
     @param context - sender context, to match reply w/ request
     @param retval - return code for the request
-    @param static_mapping_only - if true dynamic translations disabled
-    @param static_mapping_connection_tracking - if true create session data
-    @param deterministic - if true deterministic mapping
-    @param endpoint_dependent - if true endpoint-dependent mode
-    @param out2in_dpo - if true out2in dpo mode
-    @param dslite_ce - if true DS-Lite is CE/B4 element, if false AFTR elemet
+    @param static_mapping_only - if 1 dynamic translations disabled
+    @param static_mapping_connection_tracking - if 1 create session data
+    @param deterministic - if 1 deterministic mapping
+    @param endpoint_dependent - if 1 endpoint-dependent mode
+    @param out2in_dpo - if 1 out2in dpo mode
     @param translation_buckets - number of translation hash buckets
     @param translation_memory_size - translation hash memory size
     @param user_buckets - number of user hash buckets
@@ -91,6 +77,7 @@ define nat_show_config
     @param max_translations_per_user - maximum number of translations per user
     @param outside_vrf_id - outside VRF id
     @param inside_vrf_id - default inside VRF id
+    @param dslite_ce - if DS-Lite is CE/B4 element, if 0 AFTR elemet
     @param nat64_bib_buckets - number of NAT64 BIB hash buckets
     @param nat64_bib_memory_size - memory size of NAT64 BIB hash
     @param nat64_st_buckets - number of NAT64 session table hash buckets
@@ -100,12 +87,11 @@ define nat_show_config_reply
 {
   u32 context;
   i32 retval;
-  bool static_mapping_only;
-  bool static_mapping_connection_tracking;
-  bool deterministic;
-  bool endpoint_dependent;
-  bool out2in_dpo;
-  bool dslite_ce;
+  u8 static_mapping_only;
+  u8 static_mapping_connection_tracking;
+  u8 deterministic;
+  u8 endpoint_dependent;
+  u8 out2in_dpo;
   u32 translation_buckets;
   u32 translation_memory_size;
   u32 user_buckets;
@@ -113,6 +99,7 @@ define nat_show_config_reply
   u32 max_translations_per_user;
   u32 outside_vrf_id;
   u32 inside_vrf_id;
+  u8 dslite_ce;
   u32 nat64_bib_buckets;
   u32 nat64_bib_memory_size;
   u32 nat64_st_buckets;
@@ -149,7 +136,7 @@ define nat_worker_details {
   u32 context;
   u32 worker_index;
   u32 lcore_id;
-  string name;
+  u8 name[64];
 };
 
 /** \brief Enable/disable NAT IPFIX logging
@@ -157,14 +144,14 @@ define nat_worker_details {
     @param context - sender context, to match reply w/ request
     @param domain_id - observation domain ID
     @param src_port - source port number
-    @param enable - true if enable, false if disable
+    @param enable - 1 if enable, 0 if disable
 */
 autoreply define nat_ipfix_enable_disable {
   u32 client_index;
   u32 context;
   u32 domain_id;
   u16 src_port;
-  bool enable;
+  u8 enable;
 };
 
 /** \brief Set NAT virtual fragmentation reassembly
@@ -174,7 +161,7 @@ autoreply define nat_ipfix_enable_disable {
     @param max_reass - maximum number of concurrent reassemblies
     @param max_frag - maximum number of fragmets per reassembly
     @param drop_frag - if 0 translate fragments, otherwise drop fragments
-    @param is_ip6 - true if IPv6, false if IPv4
+    @param is_ip6 - 1 if IPv6, 0 if IPv4
 */
 autoreply define nat_set_reass {
   u32 client_index;
@@ -183,7 +170,7 @@ autoreply define nat_set_reass {
   u16 max_reass;
   u8  max_frag;
   u8  drop_frag;
-  bool  is_ip6;
+  u8  is_ip6;
 };
 
 /** \brief Get NAT virtual fragmentation reassembly configuration
@@ -231,16 +218,18 @@ define nat_reass_dump {
 
 /** \brief NAT virtual fragmentation reassemblies response
     @param context - sender context, to match reply w/ request
-    @param src_addr - source IPv4 address
-    @param dst_addr - destination IPv4 address
+    @param is_ip4 - 1 if address type is IPv4
+    @param src_addr - source IP address
+    @param dst_addr - destination IP address
     @param frag_id - fragment ID
     @param proto - protocol
     @param frag_n - number of cached fragments
 */
 define nat_reass_details {
   u32 context;
-  vl_api_address_t src_addr;
-  vl_api_address_t dst_addr;
+  u8 is_ip4;
+  u8 src_addr[16];
+  u8 dst_addr[16];
   u32 frag_id;
   u8 proto;
   u8 frag_n;
@@ -348,13 +337,13 @@ define nat_get_addr_and_port_alloc_alg_reply {
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
     @param mss_value - MSS value to be used for MSS rewriting
-    @param enable - if true enable MSS rewriting feature else disable
+    @param enable - disable(0)/enable(1) MSS rewriting feature
 */
 autoreply define nat_set_mss_clamping {
   u32 client_index;
   u32 context;
   u16 mss_value;
-  bool enable;
+  u8 enable;
 };
 
 /** \brief Get TCP MSS rewriting configuration
@@ -370,13 +359,13 @@ define nat_get_mss_clamping {
     @param context - sender context, to match reply w/ request
     @param retval - return code
     @param mss_value - MSS value to be used for MSS rewriting
-    @param enable - if true enable MSS rewriting feature else disable
+    @param enable - disable(0)/enable(1) MSS rewriting feature
 */
 define nat_get_mss_clamping_reply {
   u32 context;
   i32 retval;
   u16 mss_value;
-  bool enable;
+  u8 enable;
 };
 
 /** \brief Set HA listener (local settings)
@@ -469,8 +458,8 @@ autoreply define nat_ha_flush {
 };
 
 /** \brief Resync HA (resend existing sessions to new failover)
-    @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
+    @param retval - return code
     @param want_resync_event - resync completed event sent to the sender via
                                nat_ha_resync_completed_event API message if
                                non-zero
@@ -510,18 +499,17 @@ service {
     @param first_ip_address - first IPv4 address
     @param last_ip_address - last IPv4 address
     @param vrf_id - VRF id of tenant, ~0 means independent of VRF
-    @param is_add - true if add, false if delete
-    @param flags - flag NAT_IS_TWICE_NAT if NAT address range for external hosts
-
+    @param twice_nat - twice NAT address range for extenal hosts
+    @param is_add - 1 if add, 0 if delete
 */
 autoreply define nat44_add_del_address_range {
   u32 client_index;
   u32 context;
-  vl_api_ip4_address_t first_ip_address;
-  vl_api_ip4_address_t last_ip_address;
+  u8 first_ip_address[4];
+  u8 last_ip_address[4];
   u32 vrf_id;
-  bool is_add;
-  vl_api_nat_config_flags_t flags;
+  u8 twice_nat;
+  u8 is_add;
 };
 
 /** \brief Dump NAT44 addresses
@@ -536,30 +524,29 @@ define nat44_address_dump {
 /** \brief NAT44 address details response
     @param context - sender context, to match reply w/ request
     @param ip_address - IPv4 address
-    @param flags - flag NAT_IS_TWICE_NAT if NAT address range for external hosts
+    @param twice_nat - twice NAT address range for extenal hosts
     @param vrf_id - VRF id of tenant, ~0 means independent of VRF
 */
 define nat44_address_details {
   u32 context;
-  vl_api_ip4_address_t ip_address;
-  vl_api_nat_config_flags_t flags;
+  u8 ip_address[4];
+  u8 twice_nat;
   u32 vrf_id;
 };
 
 /** \brief Enable/disable NAT44 feature on the interface
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param is_add - true if add, false if delete
-    @param flags - flag NAT_IS_INSIDE if interface is inside else
-                   interface is outside
+    @param is_add - 1 if add, 0 if delete
+    @param is_inside - 1 if inside, 0 if outside
     @param sw_if_index - software index of the interface
 */
 autoreply define nat44_interface_add_del_feature {
   u32 client_index;
   u32 context;
-  bool is_add;
-  vl_api_nat_config_flags_t flags;
-  vl_api_interface_index_t sw_if_index;
+  u8 is_add;
+  u8 is_inside;
+  u32 sw_if_index;
 };
 
 /** \brief Dump interfaces with NAT44 feature
@@ -573,33 +560,29 @@ define nat44_interface_dump {
 
 /** \brief NAT44 interface details response
     @param context - sender context, to match reply w/ request
+    @param is_inside - 1 if inside, 0 if outside, 2 if inside and outside
     @param sw_if_index - software index of the interface
-    @param flags - flag NAT_IS_INSIDE if interface is inside,
-                   flag NAT_IS_OUTSIDE if interface is outside
-                   and if both flags are set the interface is
-                   both inside and outside
 */
 define nat44_interface_details {
   u32 context;
-  vl_api_nat_config_flags_t flags;
-  vl_api_interface_index_t sw_if_index;
+  u8 is_inside;
+  u32 sw_if_index;
 };
 
 /** \brief Enable/disbale NAT44 as an interface output feature (postrouting
            in2out translation)
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param is_add - true if add, false if delete
-    @param flags - flag NAT_IS_INSIDE if interface is inside else
-                   interface is outside
+    @param is_add - 1 if add, 0 if delete
+    @param is_inside - 1 if inside, 0 if outside
     @param sw_if_index - software index of the interface
 */
 autoreply define nat44_interface_add_del_output_feature {
   u32 client_index;
   u32 context;
-  bool is_add;
-  vl_api_nat_config_flags_t flags;
-  vl_api_interface_index_t sw_if_index;
+  u8 is_add;
+  u8 is_inside;
+  u32 sw_if_index;
 };
 
 /** \brief Dump interfaces with NAT44 output feature
@@ -613,26 +596,20 @@ define nat44_interface_output_feature_dump {
 
 /** \brief NAT44 interface with output feature details response
     @param context - sender context, to match reply w/ request
-    @param flags - flag NAT_IS_INSIDE if interface is inside else
-                   interface is outside
+    @param is_inside - 1 if inside, 0 if outside
     @param sw_if_index - software index of the interface
 */
 define nat44_interface_output_feature_details {
   u32 context;
-  vl_api_nat_config_flags_t flags;
-  vl_api_interface_index_t sw_if_index;
+  u8 is_inside;
+  u32 sw_if_index;
 };
 
 /** \brief Add/delete NAT44 static mapping
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param is_add - true if add, false if delete
-    @param flags - flag NAT_IS_ADDR_ONLY if address only mapping,
-                   flag nat_is_twice_nat if nat address range for external hosts,
-                   flag NAT_IS_SELF_TWICE_NAT if translate external host address
-                   and port whenever external host address equals local
-                   address of internal host,
-                   flag NAT_IS_OUT2IN_ONLY if rule match only out2in direction
+    @param is_add - 1 if add, 0 if delete
+    @param addr_only - 1 if address only mapping
     @param local_ip_address - local IPv4 address
     @param external_ip_address - external IPv4 address
     @param protocol - IP protocol, used only if addr_only=0
@@ -642,21 +619,30 @@ define nat44_interface_output_feature_details {
                                   external_ip_address is ignored, ~0 means not
                                   used)
     @param vfr_id - VRF ID
+    @param twice_nat - if 1 translate external host address and port, only for
+                       1:1 NAPT (addr_only must be 0)
+    @param self_twice_nat - if 1 translate external host address and port
+                            whenever external host address equals
+                            local address of internal host
+    @param out2in_only - if 1 rule match only out2in direction
     @param tag - opaque string tag
 */
 autoreply define nat44_add_del_static_mapping {
   u32 client_index;
   u32 context;
-  bool is_add;
-  vl_api_nat_config_flags_t flags;
-  vl_api_ip4_address_t local_ip_address;
-  vl_api_ip4_address_t external_ip_address;
+  u8 is_add;
+  u8 addr_only;
+  u8 local_ip_address[4];
+  u8 external_ip_address[4];
   u8 protocol;
   u16 local_port;
   u16 external_port;
-  vl_api_interface_index_t external_sw_if_index;
+  u32 external_sw_if_index;
   u32 vrf_id;
-  string tag;
+  u8 twice_nat;
+  u8 self_twice_nat;
+  u8 out2in_only;
+  u8 tag[64];
 };
 
 /** \brief Dump NAT44 static mappings
@@ -670,39 +656,42 @@ define nat44_static_mapping_dump {
 
 /** \brief NAT44 static mapping details response
     @param context - sender context, to match reply w/ request
-    @param flags - flag NAT_ADDR_ONLY if address only mapping,
-                   flag NAT_TWICE_NAT if NAT address range for external hosts,
-                   flag NAT_SELF_TWICE_NAT if translate external host address
-                   and port whenever external host address equals local
-                   address of internal host,
-                   flag NAT_OUT2IN_ONLY if rule match only out2in direction
+    @param addr_only - 1 if address only mapping
     @param local_ip_address - local IPv4 address
     @param external_ip_address - external IPv4 address
-    @param protocol - IP protocol, valid only if no NAT_ADDR_ONLY flag
-    @param local_port - local port number, valid only if no NAT_ADDR_ONLY flag
-    @param external_port - external port number, valid only if no NAT_ADDR_ONLY flag
+    @param protocol - IP protocol, valid only if addr_only=0
+    @param local_port - local port number, valid only if addr_only=0
+    @param external_port - external port number, valid only if addr_only=0
     @param external_sw_if_index - external interface
     @param vfr_id - VRF ID
+    @param twice_nat - if 1 translate external host address and port
+    @param self_twice_nat - if 1 translate external host address and port
+                            whenever external host address equals
+                            local address of internal host
+    @param out2in_only - if 1 rule match only out2in direction
     @param tag - opaque string tag
 */
 define nat44_static_mapping_details {
   u32 context;
-  vl_api_nat_config_flags_t flags;
-  vl_api_ip4_address_t local_ip_address;
-  vl_api_ip4_address_t external_ip_address;
+  u8 addr_only;
+  u8 local_ip_address[4];
+  u8 external_ip_address[4];
   u8 protocol;
   u16 local_port;
   u16 external_port;
-  vl_api_interface_index_t external_sw_if_index;
+  u32 external_sw_if_index;
   u32 vrf_id;
-  string tag;
+  u8 twice_nat;
+  u8 self_twice_nat;
+  u8 out2in_only;
+  u8 tag[64];
 };
 
 /** \brief Add/delete NAT44 identity mapping
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param is_add - true if add, false if delete
-    @param flags - flag NAT_ADDR_ONLY if address only mapping
+    @param is_add - 1 if add, 0 if delete
+    @param addr_only - 1 if address only mapping
     @param ip_address - IPv4 address
     @param protocol - IP protocol
     @param port - port number
@@ -714,14 +703,14 @@ define nat44_static_mapping_details {
 autoreply define nat44_add_del_identity_mapping {
   u32 client_index;
   u32 context;
-  bool is_add;
-  vl_api_nat_config_flags_t flags;
-  vl_api_ip4_address_t ip_address;
+  u8 is_add;
+  u8 addr_only;
+  u8 ip_address[4];
   u8 protocol;
   u16 port;
-  vl_api_interface_index_t sw_if_index;
+  u32 sw_if_index;
   u32 vrf_id;
-  string tag;
+  u8 tag[64];
 };
 
 /** \brief Dump NAT44 identity mappings
@@ -735,7 +724,7 @@ define nat44_identity_mapping_dump {
 
 /** \brief NAT44 identity mapping details response
     @param context - sender context, to match reply w/ request
-    @param flags - flag NAT_ADDR_ONLY if address only mapping
+    @param addr_only - 1 if address only mapping
     @param ip_address - IPv4 address
     @param protocol - IP protocol
     @param port - port number
@@ -745,28 +734,28 @@ define nat44_identity_mapping_dump {
 */
 define nat44_identity_mapping_details {
   u32 context;
-  vl_api_nat_config_flags_t flags;
-  vl_api_ip4_address_t ip_address;
+  u8 addr_only;
+  u8 ip_address[4];
   u8 protocol;
   u16 port;
-  vl_api_interface_index_t sw_if_index;
+  u32 sw_if_index;
   u32 vrf_id;
-  string tag;
+  u8 tag[64];
 };
 
 /** \brief Add/delete NAT44 pool address from specific interfce
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param is_add - true if add, false if delete
+    @param is_add - 1 if add, 0 if delete
+    @param twice_nat - twice NAT address for extenal hosts
     @param sw_if_index - software index of the interface
-    @param flags - flag NAT_TWICE_NAT if NAT address range for external hosts
 */
 autoreply define nat44_add_del_interface_addr {
   u32 client_index;
   u32 context;
-  bool is_add;
-  vl_api_interface_index_t sw_if_index;
-  vl_api_nat_config_flags_t flags;
+  u8 is_add;
+  u8 twice_nat;
+  u32 sw_if_index;
 };
 
 /** \brief Dump NAT44 pool addresses interfaces
@@ -781,13 +770,12 @@ define nat44_interface_addr_dump {
 /** \brief NAT44 pool addresses interfaces details response
     @param context - sender context, to match reply w/ request
     @param sw_if_index - software index of the interface
-    @param flags - flag NAT_TWICE_NAT if NAT address range for external hosts
-
+    @param twice_nat - twice NAT address for extenal hosts
 */
 define nat44_interface_addr_details {
   u32 context;
-  vl_api_interface_index_t sw_if_index;
-  vl_api_nat_config_flags_t flags;
+  u32 sw_if_index;
+  u8 twice_nat;
 };
 
 /** \brief Dump NAT44 users
@@ -802,14 +790,14 @@ define nat44_user_dump {
 /** \brief NAT44 users response
     @param context - sender context, to match reply w/ request
     @vrf_id - VRF ID
-    @param ip_address - IPv4 address
+    @param ip_adress - IPv4 address
     @param nsessions - number of dynamic sessions
     @param nstaticsessions - number of static sessions
 */
 define nat44_user_details {
   u32 context;
   u32 vrf_id;
-  vl_api_ip4_address_t ip_address;
+  u8 ip_address[4];
   u32 nsessions;
   u32 nstaticsessions;
 };
@@ -817,13 +805,14 @@ define nat44_user_details {
 /** \brief NAT44 user's sessions
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param ip_address - IPv4 address of the user to dump
+    @param is_ip4 - 1 if address type is IPv4
+    @param user_ip - IP address of the user to dump
     @param vrf_id - VRF_ID
 */
 define nat44_user_session_dump {
   u32 client_index;
   u32 context;
-  vl_api_ip4_address_t ip_address;
+  u8 ip_address[4];
   u32 vrf_id;
 };
 
@@ -834,13 +823,12 @@ define nat44_user_session_dump {
     @param inside_ip_address - inside IPv4 address
     @param inside_port - inside port
     @param protocol - protocol
-    @param flags - flag NAT_IS_STATIC if session is static,
-                   flag NAT_IS_TWICE_NAT if session is twice-nat,
-                   flag NAT_IS_EXT_HOST_VALID if external host address
-                   and port are valid
+    @param is_static - 1 if session is static
     @param last_heard - last heard timer
     @param total_bytes - count of bytes sent through session
     @param total_pkts - count of pakets sent through session
+    @param is_twicenat - 1 if session is twice-nat
+    @param ext_host_valid - 1 if external host address and port are valid
     @param ext_host_address - external host IPv4 address
     @param ext_host_port - external host port
     @param ext_host_nat_address - post-NAT external host IPv4 address (valid
@@ -850,18 +838,20 @@ define nat44_user_session_dump {
 */
 define nat44_user_session_details {
   u32 context;
-  vl_api_ip4_address_t outside_ip_address;
+  u8 outside_ip_address[4];
   u16 outside_port;
-  vl_api_ip4_address_t inside_ip_address;
+  u8 inside_ip_address[4];
   u16 inside_port;
   u16 protocol;
-  vl_api_nat_config_flags_t flags;
+  u8 is_static;
   u64 last_heard;
   u64 total_bytes;
   u32 total_pkts;
-  vl_api_ip4_address_t ext_host_address;
+  u8 is_twicenat;
+  u8 ext_host_valid;
+  u8 ext_host_address[4];
   u16 ext_host_port;
-  vl_api_ip4_address_t ext_host_nat_address;
+  u8 ext_host_nat_address[4];
   u16 ext_host_nat_port;
 };
 
@@ -869,10 +859,9 @@ define nat44_user_session_details {
     @param addr - IPv4 address of the internal node
     @param port - L4 port number of the internal node
     @param probability - probability of the internal node to be randomly matched
-    @param vrf_id - VRF id
 */
 typeonly manual_endian define nat44_lb_addr_port {
-  vl_api_ip4_address_t addr;
+  u8 addr[4];
   u16 port;
   u8 probability;
   u32 vrf_id;
@@ -881,39 +870,41 @@ typeonly manual_endian define nat44_lb_addr_port {
 /** \brief Add/delete NAT44 load-balancing static mapping rule
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param is_add - true if add, false if delete
-    @param flags - flag NAT_TWICE_NAT if NAT address range for external hosts,
-                   flag NAT_SELF_TWICE_NAT if translate external host address
-                   and port whenever external host address equals local
-                   address of internal host,
-                   flag NAT_OUT2IN_ONLY if rule match only out2in direction
+    @param is_add - 1 if add, 0 if delete
     @param external_addr - external IPv4 address of the service
     @param external_port - external L4 port number of the service
     @param protocol - IP protocol number of the service
+    @param twice_nat - if 1 translate external host address and port
+    @param self_twice_nat - if 1 translate external host address and port
+                            whenever external host address equals
+                            local address of internal host
+    @param out2in_only - if 1 rule match only out2in direction
+    @param tag - opaque string tag
     @param affinity - if 0 disabled, otherwise client IP affinity sticky time
                       in seconds
     @param local_num - number of local network nodes
     @param locals - local network nodes
-    @param tag - opaque string tag
 */
 autoreply manual_endian define nat44_add_del_lb_static_mapping {
   u32 client_index;
   u32 context;
-  bool is_add;
-  vl_api_nat_config_flags_t flags;
-  vl_api_ip4_address_t external_addr;
+  u8 is_add;
+  u8 external_addr[4];
   u16 external_port;
   u8 protocol;
+  u8 twice_nat;
+  u8 self_twice_nat;
+  u8 out2in_only;
+  u8 tag[64];
   u32 affinity;
   u32 local_num;
   vl_api_nat44_lb_addr_port_t locals[local_num];
-  string tag;
 };
 
 /** \brief Add/delete NAT44 load-balancing static mapping rule backend
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param is_add - true if add, false if delete
+    @param is_add - 1 if add, 0 if delete
     @param external_addr - external IPv4 address of the service
     @param external_port - external L4 port number of the service
     @param protocol - IP protocol number of the service
@@ -922,8 +913,8 @@ autoreply manual_endian define nat44_add_del_lb_static_mapping {
 autoreply define nat44_lb_static_mapping_add_del_local {
   u32 client_index;
   u32 context;
-  bool is_add;
-  vl_api_ip4_address_t external_addr;
+  u8 is_add;
+  u8 external_addr[4];
   u16 external_port;
   u8 protocol;
   vl_api_nat44_lb_addr_port_t local;
@@ -940,55 +931,57 @@ define nat44_lb_static_mapping_dump {
 
 /** \brief NAT44 load-balancing static mapping rule details response
     @param context - sender context, to match reply w/ request
+    @param is_add - 1 if add, 0 if delete
     @param external_addr - external IPv4 address of the service
     @param external_port - external L4 port number of the service
     @param protocol - IP protocol number of the service
-    @param flags - flag NAT_TWICE_NAT if NAT address range for external hosts,
-                   flag NAT_SELF_TWICE_NAT if translate external host address
-                   and port whenever external host address equals local
-                   address of internal host,
-                   flag NAT_OUT2IN_ONLY if rule match only out2in direction
+    @param twice_nat - if 1 translate external host address and port
+    @param self_twice_nat - if 1 translate external host address and port
+                            whenever external host address equals
+                            local address of internal host
+    @param out2in_only - if 1 rule match only out2in direction
+    @param tag - opaque string tag
     @param affinity - if 0 disabled, otherwise client IP affinity sticky time
                       in seconds
     @param local_num - number of local network nodes
     @param locals - local network nodes
-    @param tag - opaque string tag
 */
 manual_endian define nat44_lb_static_mapping_details {
   u32 context;
-  vl_api_ip4_address_t external_addr;
+  u8 external_addr[4];
   u16 external_port;
   u8 protocol;
-  vl_api_nat_config_flags_t flags;
+  u8 twice_nat;
+  u8 self_twice_nat;
+  u8 out2in_only;
+  u8 tag[64];
   u32 affinity;
   u32 local_num;
   vl_api_nat44_lb_addr_port_t locals[local_num];
-  string tag;
 };
 
 /** \brief Delete NAT44 session
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
+    @param is_in - 1 if inside network address and port pair, 0 if outside
     @param ip_address - IPv4 address
     @param protocol - IP protocol
     @param port - port number
     @param vfr_id - VRF ID
-    @param flags - flag NAT_IS_INSIDE if interface is inside or
-                   interface is outside,
-                   flag NAT_IS_EXT_HOST_VALID if external host address and
-                   port are valid
+    @param ext_host_valid - 1 if external host address and port are valid
     @param ext_host_address - external host IPv4 address
     @param ext_host_port - external host port
 */
 autoreply define nat44_del_session {
   u32 client_index;
   u32 context;
-  vl_api_ip4_address_t address;
+  u8 is_in;
+  u8 address[4];
   u8 protocol;
   u16 port;
   u32 vrf_id;
-  vl_api_nat_config_flags_t flags;
-  vl_api_ip4_address_t ext_host_address;
+  u8 ext_host_valid;
+  u8 ext_host_address[4];
   u16 ext_host_port;
 };
 
@@ -997,12 +990,12 @@ autoreply define nat44_del_session {
     or static mapping instead of dropping them.
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param enable - true for enable, false for disable
+    @param enable - 0 for enable, 1 for disable
 */
 autoreply define nat44_forwarding_enable_disable {
   u32 client_index;
   u32 context;
-  bool enable;
+  u8 enable;
 };
 
 /** \brief Check if forwarding is enabled or disabled
@@ -1016,11 +1009,11 @@ define nat44_forwarding_is_enabled {
 
 /** \brief Response to check if forwarding is enabled or disabled
     @param context - sender context, to match reply w/ request
-    @param enabled - true if enabled, false if disabled
+    @param enabled - 1 if enabled, 0 if disabled
 */
 define nat44_forwarding_is_enabled_reply {
   u32 context;
-  bool enabled;
+  u8 enabled;
 };
 
 
@@ -1031,31 +1024,36 @@ define nat44_forwarding_is_enabled_reply {
 /** \brief Add/delete NAT deterministic mapping
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param is_add - true if add, false if delete
-    @param in_addr - inside IPv4 address
-    @param in_plen - inside IPv4 address prefix length
+    @param is_add - 1 if add, 0 if delete
+    @param is_nat44 - 1 if NAT44
+    @param in_addr - inside IP address
+    @param in_plen - inside IP address prefix length
     @param out_addr - outside IPv4 address
-    @param out_plen - outside IPv4 address prefix length
+    @param out_addr - outside IPv4 address prefix length
 */
 autoreply define nat_det_add_del_map {
   u32 client_index;
   u32 context;
-  bool is_add;
-  vl_api_ip4_address_t in_addr;
+  u8 is_add;
+  u8 is_nat44;
+  u8 addr_only;
+  u8 in_addr[16];
   u8 in_plen;
-  vl_api_ip4_address_t out_addr;
+  u8 out_addr[4];
   u8 out_plen;
 };
 
 /** \brief Get outside address and port range from inside address
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
+    @param is_nat44 - 1 if NAT44
     @param in_addr - inside IP address
 */
 define nat_det_forward {
   u32 client_index;
   u32 context;
-  vl_api_ip4_address_t in_addr;
+  u8 is_nat44;
+  u8 in_addr[16];
 };
 
 /** \brief Get outside address and port range from inside address
@@ -1070,7 +1068,7 @@ define nat_det_forward_reply {
   i32 retval;
   u16 out_port_lo;
   u16 out_port_hi;
-  vl_api_ip4_address_t out_addr;
+  u8 out_addr[4];
 };
 
 /** \brief Get inside address from outside address and port
@@ -1083,18 +1081,20 @@ define nat_det_reverse {
   u32 client_index;
   u32 context;
   u16 out_port;
-  vl_api_ip4_address_t out_addr;
+  u8 out_addr[4];
 };
 
 /** \brief Get inside address from outside address and port reply
     @param context - sender context, to match reply w/ request
     @param retval - return code
+    @param is_nat44 - 1 if NAT44
     @param in_addr - inside IP address
 */
 define nat_det_reverse_reply {
   u32 context;
   i32 retval;
-  vl_api_ip4_address_t in_addr;
+  u8 is_nat44;
+  u8 in_addr[16];
 };
 
 /** \brief Dump NAT deterministic mappings
@@ -1108,8 +1108,9 @@ define nat_det_map_dump {
 
 /** \brief NAT users response
     @param context - sender context, to match reply w/ request
-    @param in_addr - inside IPv4 address
-    @param in_plen - inside IPv4 address prefix length
+    @param is_nat44 - 1 if NAT44
+    @param in_addr - inside IP address
+    @param in_plen - inside IP address prefix length
     @param out_addr - outside IPv4 address
     @param out_plen - outside IPv4 address prefix length
     @param sharing_ratio - outside to inside address sharing ratio
@@ -1118,9 +1119,10 @@ define nat_det_map_dump {
 */
 define nat_det_map_details {
   u32 context;
-  vl_api_ip4_address_t in_addr;
+  u8 is_nat44;
+  u8 in_addr[16];
   u8 in_plen;
-  vl_api_ip4_address_t out_addr;
+  u8 out_addr[4];
   u8 out_plen;
   u32 sharing_ratio;
   u16 ports_per_host;
@@ -1138,15 +1140,16 @@ define nat_det_map_details {
 autoreply define nat_det_close_session_out {
   u32 client_index;
   u32 context;
-  vl_api_ip4_address_t out_addr;
+  u8 out_addr[4];
   u16 out_port;
-  vl_api_ip4_address_t ext_addr;
+  u8 ext_addr[4];
   u16 ext_port;
 };
 
 /** \brief Close deterministic NAT session by inside address and port
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
+    @param is_nat44 - 1 if NAT44
     @param in_addr - inside IP address
     @param in_port - inside port
     @param ext_addr - external host IP address
@@ -1155,27 +1158,30 @@ autoreply define nat_det_close_session_out {
 autoreply define nat_det_close_session_in {
   u32 client_index;
   u32 context;
-  vl_api_ip4_address_t in_addr;
+  u8 is_nat44;
+  u8 in_addr[16];
   u16 in_port;
-  vl_api_ip4_address_t ext_addr;
+  u8 ext_addr[16];
   u16 ext_port;
 };
 
 /** \brief Dump determinstic NAT sessions
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
+    @param is_nat44 - 1 if NAT44
     @param user_addr - address of an inside user whose sessions to dump
 */
 define nat_det_session_dump {
   u32 client_index;
   u32 context;
-  vl_api_ip4_address_t user_addr;
+  u8 is_nat44;
+  u8 user_addr[16];
 };
 
 /** \brief Deterministic NAT sessions reply
     @param context - sender context, to match reply w/ request
     @param in_port - inside port
-    @param ext_addr - external host IPv4 address
+    @param ext_addr - external host address
     @param ext_port - external host port
     @param out_port - outside NAT port
     @param state - session state
@@ -1184,7 +1190,7 @@ define nat_det_session_dump {
 define nat_det_session_details {
   u32 context;
   u16 in_port;
-  vl_api_ip4_address_t ext_addr;
+  u8 ext_addr[4];
   u16 ext_port;
   u16 out_port;
   u8 state;
@@ -1198,18 +1204,18 @@ define nat_det_session_details {
 /** \brief Add/delete address range to NAT64 pool
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param start_addr - start IPv4 address of the range
-    @param end_addr - end IPv4 address of the range
+    @param start_addr - start address of the range
+    @param end_addr - end address of the range
     @param vrf_id - VRF id of tenant, ~0 means independent of VRF
-    @param is_add - true if add, false if delete
+    @param is_add - 1 if add, 0 if delete
 */
 autoreply define nat64_add_del_pool_addr_range {
   u32 client_index;
   u32 context;
-  vl_api_ip4_address_t start_addr;
-  vl_api_ip4_address_t end_addr;
+  u8 start_addr[4];
+  u8 end_addr[4];
   u32 vrf_id;
-  bool is_add;
+  u8 is_add;
 };
 
 /** \brief Dump NAT64 pool addresses
@@ -1228,24 +1234,23 @@ define nat64_pool_addr_dump {
 */
 define nat64_pool_addr_details {
   u32 context;
-  vl_api_ip4_address_t address;
+  u8 address[4];
   u32 vrf_id;
 };
 
 /** \brief Enable/disable NAT64 feature on the interface
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param is_add - true if add, false if delete
-    @param flags - flag NAT_IS_INSIDE if interface is inside else
-                   interface is outside
     @param sw_if_index - index of the interface
+    @param is_inside - 1 if inside, 0 if outside
+    @param is_add - 1 if add, 0 if delete
 */
 autoreply define nat64_add_del_interface {
   u32 client_index;
   u32 context;
-  bool is_add;
-  vl_api_nat_config_flags_t flags;
-  vl_api_interface_index_t sw_if_index;
+  u32 sw_if_index;
+  u8 is_inside;
+  u8 is_add;
 };
 
 /** \brief Dump interfaces with NAT64 feature
@@ -1259,16 +1264,13 @@ define nat64_interface_dump {
 
 /** \brief NAT64 interface details response
     @param context - sender context, to match reply w/ request
-    @param flags - flag NAT_IS_INSIDE if interface is inside,
-                   flag NAT_IS_OUTSIDE if interface is outside
-                   and if both flags are set the interface is
-                   both inside and outside
+    @param is_inside - 1 if inside, 0 if outside
     @param sw_if_index - index of the interface
 */
 define nat64_interface_details {
   u32 context;
-  vl_api_nat_config_flags_t flags;
-  vl_api_interface_index_t sw_if_index;
+  u8 is_inside;
+  u32 sw_if_index;
 };
 
 /** \brief Add/delete NAT64 static BIB entry
@@ -1280,18 +1282,18 @@ define nat64_interface_details {
     @param o_port - outside port number
     @param vrf_id - VRF id of tenant
     @param proto - protocol number
-    @param is_add - true if add, false if delete
+    @param is_add - 1 if add, 0 if delete
 */
  autoreply define nat64_add_del_static_bib {
   u32 client_index;
   u32 context;
-  vl_api_ip6_address_t i_addr;
-  vl_api_ip4_address_t o_addr;
+  u8 i_addr[16];
+  u8 o_addr[4];
   u16 i_port;
   u16 o_port;
   u32 vrf_id;
   u8 proto;
-  bool is_add;
+  u8 is_add;
 };
 
 /** \brief Dump NAT64 BIB
@@ -1317,19 +1319,18 @@ define nat64_bib_dump {
     @param o_port - outside port number
     @param vrf_id - VRF id of tenant
     @param proto - protocol number
-    @param flags - flag NAT_IS_STATIC if BIB entry is static 
-                   or BIB entry is dynamic
+    @param is_static - 1 if static BIB entry, 0 if dynamic
     @param ses_num - number of sessions associated with the BIB entry
 */
 define nat64_bib_details {
   u32 context;
-  vl_api_ip6_address_t i_addr;
-  vl_api_ip4_address_t o_addr;
+  u8 i_addr[16];
+  u8 o_addr[4];
   u16 i_port;
   u16 o_port;
   u32 vrf_id;
   u8 proto;
-  vl_api_nat_config_flags_t flags;
+  u8 is_static;
   u32 ses_num;
 };
 
@@ -1354,20 +1355,20 @@ define nat64_st_dump {
     @param ol_addr - outside IPv4 address of the local host
     @param il_port - inside port number id of the local host/inside ICMP id
     @param ol_port - outside port number of the local host/outside ICMP id
-    @param ir_addr - inside IPv6 address of the remote host
-    @param or_addr - outside IPv4 address of the remote host
-    @param r_port - port number of the remote host (not used for ICMP)
+    @param il_addr - inside IPv6 address of the remote host
+    @param ol_addr - outside IPv4 address of the remote host
+    @param l_port - port number of the remote host (not used for ICMP)
     @param vrf_id - VRF id of tenant
     @param proto - protocol number
 */
 define nat64_st_details {
   u32 context;
-  vl_api_ip6_address_t il_addr;
-  vl_api_ip4_address_t ol_addr;
+  u8 il_addr[16];
+  u8 ol_addr[4];
   u16 il_port;
   u16 ol_port;
-  vl_api_ip6_address_t ir_addr;
-  vl_api_ip4_address_t or_addr;
+  u8 ir_addr[16];
+  u8 or_addr[4];
   u16 r_port;
   u32 vrf_id;
   u8 proto;
@@ -1377,15 +1378,17 @@ define nat64_st_details {
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
     @param prefix - NAT64 prefix
+    @param prefix - NAT64 prefix length
     @param vrf_id - VRF id of tenant
-    @param is_add - true if add, false if delete
+    @param is_add - 1 if add, 0 if delete
 */
 autoreply define nat64_add_del_prefix {
   u32 client_index;
   u32 context;
-  vl_api_ip6_prefix_t prefix;
+  u8 prefix[16];
+  u8 prefix_len;
   u32 vrf_id;
-  bool is_add;
+  u8 is_add;
 };
 
 /** \brief Dump NAT64 prefix
@@ -1400,27 +1403,31 @@ define nat64_prefix_dump {
 /** \brief Dump NAT64 prefix details response
     @param context - sender context, to match reply w/ request
     @param prefix - NAT64 prefix
+    @param prefix - NAT64 prefix length
     @param vrf_id - VRF id of tenant
 */
 define nat64_prefix_details {
   u32 context;
-  vl_api_ip6_prefix_t prefix;
+  u8 prefix[16];
+  u8 prefix_len;
   u32 vrf_id;
 };
 
 /** \brief Add/delete NAT64 pool address from specific interfce
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param is_add - true if add, false if delete
+    @param is_add - 1 if add, 0 if delete
     @param sw_if_index - software index of the interface
 */
 autoreply define nat64_add_del_interface_addr {
   u32 client_index;
   u32 context;
-  bool is_add;
-  vl_api_interface_index_t sw_if_index;
+  u8 is_add;
+  u8 is_inside;
+  u32 sw_if_index;
 };
 
+
 /*
  * DS-Lite APIs
  */
@@ -1428,16 +1435,16 @@ autoreply define nat64_add_del_interface_addr {
 /** \brief Add/delete address range to DS-Lite pool
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param start_addr - start IPv4 address of the range
-    @param end_addr - end IPv4 address of the range
-    @param is_add - true if add, false if delete
+    @param start_addr - start address of the range
+    @param end_addr - end address of the range
+    @param is_add - 1 if add, 0 if delete
 */
 autoreply define dslite_add_del_pool_addr_range {
   u32 client_index;
   u32 context;
-  vl_api_ip4_address_t start_addr;
-  vl_api_ip4_address_t end_addr;
-  bool is_add;
+  u8 start_addr[4];
+  u8 end_addr[4];
+  u8 is_add;
 };
 
 /** \brief Dump DS-Lite addresses
@@ -1455,20 +1462,20 @@ define dslite_address_dump {
 */
 define dslite_address_details {
   u32 context;
-  vl_api_ip4_address_t ip_address;
+  u8 ip_address[4];
 };
 
 /** \brief Set AFTR IPv6 and IPv4 addresses
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
     @param ip4_addr - IPv4 address
-    @param ip6_addr - IPv6 address
+    @param ip6_addr - IP64 address
 */
 autoreply define dslite_set_aftr_addr {
   u32 client_index;
   u32 context;
-  vl_api_ip4_address_t ip4_addr;
-  vl_api_ip6_address_t ip6_addr;
+  u8 ip4_addr[4];
+  u8 ip6_addr[16];
 };
 
 /** \brief Get AFTR IPv6 and IPv4 addresses
@@ -1484,26 +1491,26 @@ define dslite_get_aftr_addr {
     @param context - sender context, to match reply w/ request
     @param retval - return code
     @param ip4_addr - IPv4 address
-    @param ip6_addr - IPv6 address
+    @param ip6_addr - IP64 address
 */
 define dslite_get_aftr_addr_reply {
   u32 context;
   i32 retval;
-  vl_api_ip4_address_t ip4_addr;
-  vl_api_ip6_address_t ip6_addr;
+  u8 ip4_addr[4];
+  u8 ip6_addr[16];
 };
 
 /** \brief Set B4 IPv6 and IPv4 addresses
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
     @param ip4_addr - IPv4 address
-    @param ip6_addr - IPv6 address
+    @param ip6_addr - IP64 address
 */
 autoreply define dslite_set_b4_addr {
   u32 client_index;
   u32 context;
-  vl_api_ip4_address_t ip4_addr;
-  vl_api_ip6_address_t ip6_addr;
+  u8 ip4_addr[4];
+  u8 ip6_addr[16];
 };
 
 /** \brief Get B4 IPv6 and IPv4 addresses
@@ -1519,13 +1526,13 @@ define dslite_get_b4_addr {
     @param context - sender context, to match reply w/ request
     @param retval - return code
     @param ip4_addr - IPv4 address
-    @param ip6_addr - IPv6 address
+    @param ip6_addr - IP64 address
 */
 define dslite_get_b4_addr_reply {
   u32 context;
   i32 retval;
-  vl_api_ip4_address_t ip4_addr;
-  vl_api_ip6_address_t ip6_addr;
+  u8 ip4_addr[4];
+  u8 ip6_addr[16];
 };
 
 /*
@@ -1534,17 +1541,16 @@ define dslite_get_b4_addr_reply {
 /** \brief Enable/disable NAT66 feature on the interface
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param is_add - true if add, false if delete
-    @param flags - flag NAT_IS_INSIDE if interface is inside or
-                   interface is outside,
+    @param is_add - 1 if add, 0 if delete
+    @param is_inside - 1 if inside, 0 if outside
     @param sw_if_index - software index of the interface
 */
 autoreply define nat66_add_del_interface {
   u32 client_index;
   u32 context;
-  bool is_add;
-  vl_api_nat_config_flags_t flags;
-  vl_api_interface_index_t sw_if_index;
+  u8 is_add;
+  u8 is_inside;
+  u32 sw_if_index;
 };
 
 /** \brief Dump interfaces with NAT66 feature
@@ -1558,20 +1564,19 @@ define nat66_interface_dump {
 
 /** \brief NAT66 interface details response
     @param context - sender context, to match reply w/ request
-    @param flags - flag NAT_IS_INSIDE if interface is inside or
-                   interface is outside,
+    @param is_inside - 1 if inside, 0 if outside
     @param sw_if_index - software index of the interface
 */
 define nat66_interface_details {
   u32 context;
-  vl_api_nat_config_flags_t flags;
-  vl_api_interface_index_t sw_if_index;
+  u8 is_inside;
+  u32 sw_if_index;
 };
 
 /** \brief Add/delete 1:1 NAT66
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
-    @param is_add - true if add, false if delete
+    @param is_add - 1 if add, 0 if delete
     @param local_ip_address - local IPv6 address
     @param external_ip_address - external IPv6 address
     @param vrf_id - VRF id of tenant
@@ -1579,9 +1584,9 @@ define nat66_interface_details {
 autoreply define nat66_add_del_static_mapping {
   u32 client_index;
   u32 context;
-  bool is_add;
-  vl_api_ip6_address_t local_ip_address;
-  vl_api_ip6_address_t external_ip_address;
+  u8 is_add;
+  u8 local_ip_address[16];
+  u8 external_ip_address[16];
   u32 vrf_id;
 };
 
@@ -1604,8 +1609,8 @@ define nat66_static_mapping_dump {
 */
 define nat66_static_mapping_details {
   u32 context;
-  vl_api_ip6_address_t local_ip_address;
-  vl_api_ip6_address_t external_ip_address;
+  u8 local_ip_address[16];
+  u8 external_ip_address[16];
   u32 vrf_id;
   u64 total_bytes;
   u64 total_pkts;
diff --git a/src/plugins/nat/nat.h b/src/plugins/nat/nat.h
index 237d945a724..ca2d1fcf1bf 100644
--- a/src/plugins/nat/nat.h
+++ b/src/plugins/nat/nat.h
@@ -110,24 +110,6 @@ typedef struct
   u8 cached;
 } nat44_reass_trace_t;
 
-/* NAT API Configuration flags */
-#define foreach_nat_config_flag \
-  _(0x01, IS_TWICE_NAT)         \
-  _(0x02, IS_SELF_TWICE_NAT)    \
-  _(0x04, IS_OUT2IN_ONLY)       \
-  _(0x08, IS_ADDR_ONLY)         \
-  _(0x10, IS_OUTSIDE)           \
-  _(0x20, IS_INSIDE)            \
-  _(0x40, IS_STATIC)            \
-  _(0x80, IS_EXT_HOST_VALID)    \
-
-typedef enum nat_config_flags_t_
-{
-#define _(n,f) NAT_API_##f = n,
-  foreach_nat_config_flag
-#undef _
-} nat_config_flags_t;
-
 /* External address and port allocation modes */
 #define foreach_nat_addr_and_port_alloc_alg \
   _(0, DEFAULT, "default")         \
diff --git a/src/plugins/nat/nat_api.c b/src/plugins/nat/nat_api.c
index fce557fa8bf..21b2cd44880 100644
--- a/src/plugins/nat/nat_api.c
+++ b/src/plugins/nat/nat_api.c
@@ -31,7 +31,6 @@
 
 #include <nat/nat_msg_enum.h>
 #include <vnet/fib/fib_table.h>
-#include <vnet/ip/ip_types_api.h>
 
 #define vl_api_nat44_lb_addr_port_t_endian vl_noop_handler
 #define vl_api_nat44_add_del_lb_static_mapping_t_endian vl_noop_handler
@@ -64,6 +63,7 @@
     vec_free (s);                               \
     return handle;
 
+
 /******************************/
 /*** Common NAT plugin APIs ***/
 /******************************/
@@ -202,15 +202,13 @@ send_nat_worker_details (u32 worker_index, vl_api_registration_t * reg,
   vlib_worker_thread_t *w =
     vlib_worker_threads + worker_index + sm->first_worker_index;
 
-  rmp = vl_msg_api_alloc (sizeof (*rmp) + ARRAY_LEN (w->name) - 1);
-  clib_memset (rmp, 0, sizeof (*rmp) + ARRAY_LEN (w->name) - 1);
+  rmp = vl_msg_api_alloc (sizeof (*rmp));
+  clib_memset (rmp, 0, sizeof (*rmp));
   rmp->_vl_msg_id = ntohs (VL_API_NAT_WORKER_DETAILS + sm->msg_id_base);
   rmp->context = context;
   rmp->worker_index = htonl (worker_index);
   rmp->lcore_id = htonl (w->cpu_id);
-
-  vl_api_to_api_string (ARRAY_LEN (w->name) - 1, (char *) w->name,
-			&rmp->name);
+  strncpy ((char *) rmp->name, (char *) w->name, ARRAY_LEN (rmp->name) - 1);
 
   vl_api_send_msg (reg, (u8 *) rmp);
 }
@@ -351,22 +349,17 @@ nat_ip4_reass_walk_api (nat_reass_ip4_t * reass, void *arg)
   vl_api_nat_reass_details_t *rmp;
   snat_main_t *sm = &snat_main;
   nat_api_walk_ctx_t *ctx = arg;
-  ip46_address_t ip_address;
 
   rmp = vl_msg_api_alloc (sizeof (*rmp));
   clib_memset (rmp, 0, sizeof (*rmp));
   rmp->_vl_msg_id = ntohs (VL_API_NAT_REASS_DETAILS + sm->msg_id_base);
   rmp->context = ctx->context;
-
-  clib_memcpy (&ip_address.ip4, &reass->key.src, 4);
-  ip_address_encode (&ip_address, IP46_TYPE_IP4, &rmp->src_addr);
-
-  clib_memcpy (&ip_address.ip4, &reass->key.dst, 4);
-  ip_address_encode (&ip_address, IP46_TYPE_IP4, &rmp->dst_addr);
-
+  clib_memcpy (rmp->src_addr, &(reass->key.src), 4);
+  clib_memcpy (rmp->dst_addr, &(reass->key.dst), 4);
   rmp->proto = reass->key.proto;
   rmp->frag_id = ntohl (reass->key.frag_id);
   rmp->frag_n = reass->frag_n;
+  rmp->is_ip4 = 1;
 
   vl_api_send_msg (ctx->reg, (u8 *) rmp);
 
@@ -379,22 +372,17 @@ nat_ip6_reass_walk_api (nat_reass_ip6_t * reass, void *arg)
   vl_api_nat_reass_details_t *rmp;
   snat_main_t *sm = &snat_main;
   nat_api_walk_ctx_t *ctx = arg;
-  ip46_address_t ip_address;
 
   rmp = vl_msg_api_alloc (sizeof (*rmp));
   clib_memset (rmp, 0, sizeof (*rmp));
   rmp->_vl_msg_id = ntohs (VL_API_NAT_REASS_DETAILS + sm->msg_id_base);
   rmp->context = ctx->context;
-
-  clib_memcpy (&ip_address.ip6, &reass->key.src, 16);
-  ip_address_encode (&ip_address, IP46_TYPE_IP6, &rmp->src_addr);
-
-  clib_memcpy (&ip_address.ip6, &reass->key.dst, 16);
-  ip_address_encode (&ip_address, IP46_TYPE_IP6, &rmp->dst_addr);
-
+  clib_memcpy (rmp->src_addr, &(reass->key.src), 16);
+  clib_memcpy (rmp->dst_addr, &(reass->key.dst), 16);
   rmp->proto = reass->key.proto;
   rmp->frag_id = ntohl (reass->key.frag_id);
   rmp->frag_n = reass->frag_n;
+  rmp->is_ip4 = 0;
 
   vl_api_send_msg (ctx->reg, (u8 *) rmp);
 
@@ -850,7 +838,6 @@ static void
   snat_main_t *sm = &snat_main;
   vl_api_nat44_add_del_address_range_reply_t *rmp;
   ip4_address_t this_addr;
-  u8 is_add, twice_nat;
   u32 start_host_order, end_host_order;
   u32 vrf_id;
   int i, count;
@@ -869,9 +856,6 @@ static void
       goto send_reply;
     }
 
-  is_add = mp->is_add;
-  twice_nat = mp->flags & NAT_API_IS_TWICE_NAT;
-
   tmp = (u32 *) mp->first_ip_address;
   start_host_order = clib_host_to_net_u32 (tmp[0]);
   tmp = (u32 *) mp->last_ip_address;
@@ -890,16 +874,16 @@ static void
 
   for (i = 0; i < count; i++)
     {
-      if (is_add)
-	rv = snat_add_address (sm, &this_addr, vrf_id, twice_nat);
+      if (mp->is_add)
+	rv = snat_add_address (sm, &this_addr, vrf_id, mp->twice_nat);
       else
-	rv = snat_del_address (sm, this_addr, 0, twice_nat);
+	rv = snat_del_address (sm, this_addr, 0, mp->twice_nat);
 
       if (rv)
 	goto send_reply;
 
       if (sm->out2in_dpo)
-	nat44_add_del_address_dpo (this_addr, is_add);
+	nat44_add_del_address_dpo (this_addr, mp->is_add);
 
       increment_v4_address (&this_addr);
     }
@@ -919,7 +903,7 @@ static void *vl_api_nat44_add_del_address_range_t_print
     {
       s = format (s, " - %U ", format_ip4_address, mp->last_ip_address);
     }
-  s = format (s, "twice_nat %d ", mp->flags & NAT_API_IS_TWICE_NAT);
+  s = format (s, "twice_nat %d ", mp->twice_nat);
   FINISH;
 }
 
@@ -942,8 +926,7 @@ send_nat44_address_details (snat_address_t * a,
     }
   else
     rmp->vrf_id = ~0;
-  if (twice_nat)
-    rmp->flags |= NAT_API_IS_TWICE_NAT;
+  rmp->twice_nat = twice_nat;
   rmp->context = context;
 
   vl_api_send_msg (reg, (u8 *) rmp);
@@ -988,17 +971,13 @@ static void
 {
   snat_main_t *sm = &snat_main;
   vl_api_nat44_interface_add_del_feature_reply_t *rmp;
+  u8 is_del = mp->is_add == 0;
   u32 sw_if_index = ntohl (mp->sw_if_index);
-  u8 is_del;
   int rv = 0;
 
-  is_del = !mp->is_add;
-
   VALIDATE_SW_IF_INDEX (mp);
 
-  rv =
-    snat_interface_add_del (sw_if_index, mp->flags & NAT_API_IS_INSIDE,
-			    is_del);
+  rv = snat_interface_add_del (sw_if_index, mp->is_inside, is_del);
 
   BAD_SW_IF_INDEX_LABEL;
 
@@ -1013,8 +992,7 @@ static void *vl_api_nat44_interface_add_del_feature_t_print
   s = format (0, "SCRIPT: nat44_interface_add_del_feature ");
   s = format (s, "sw_if_index %d %s %s",
 	      clib_host_to_net_u32 (mp->sw_if_index),
-	      mp->flags & NAT_API_IS_INSIDE ? "in" : "out",
-	      mp->is_add ? "" : "del");
+	      mp->is_inside ? "in" : "out", mp->is_add ? "" : "del");
 
   FINISH;
 }
@@ -1030,12 +1008,9 @@ send_nat44_interface_details (snat_interface_t * i,
   clib_memset (rmp, 0, sizeof (*rmp));
   rmp->_vl_msg_id = ntohs (VL_API_NAT44_INTERFACE_DETAILS + sm->msg_id_base);
   rmp->sw_if_index = ntohl (i->sw_if_index);
-
-  if (nat_interface_is_inside (i))
-    rmp->flags |= NAT_API_IS_INSIDE;
-  if (nat_interface_is_outside (i))
-    rmp->flags |= NAT_API_IS_OUTSIDE;
-
+  rmp->is_inside = (nat_interface_is_inside (i)
+		    && nat_interface_is_outside (i)) ? 2 :
+    nat_interface_is_inside (i);
   rmp->context = context;
 
   vl_api_send_msg (reg, (u8 *) rmp);
@@ -1077,6 +1052,7 @@ static void
 {
   snat_main_t *sm = &snat_main;
   vl_api_nat44_interface_add_del_output_feature_reply_t *rmp;
+  u8 is_del = mp->is_add == 0;
   u32 sw_if_index = ntohl (mp->sw_if_index);
   int rv = 0;
 
@@ -1088,9 +1064,8 @@ static void
 
   VALIDATE_SW_IF_INDEX (mp);
 
-  rv = snat_interface_add_del_output_feature (sw_if_index,
-					      mp->flags & NAT_API_IS_INSIDE,
-					      !mp->is_add);
+  rv = snat_interface_add_del_output_feature (sw_if_index, mp->is_inside,
+					      is_del);
 
   BAD_SW_IF_INDEX_LABEL;
 send_reply:
@@ -1105,8 +1080,7 @@ static void *vl_api_nat44_interface_add_del_output_feature_t_print
   s = format (0, "SCRIPT: nat44_interface_add_del_output_feature ");
   s = format (s, "sw_if_index %d %s %s",
 	      clib_host_to_net_u32 (mp->sw_if_index),
-	      mp->flags & NAT_API_IS_INSIDE ? "in" : "out",
-	      mp->is_add ? "" : "del");
+	      mp->is_inside ? "in" : "out", mp->is_add ? "" : "del");
 
   FINISH;
 }
@@ -1125,9 +1099,7 @@ send_nat44_interface_output_feature_details (snat_interface_t * i,
     ntohs (VL_API_NAT44_INTERFACE_OUTPUT_FEATURE_DETAILS + sm->msg_id_base);
   rmp->sw_if_index = ntohl (i->sw_if_index);
   rmp->context = context;
-
-  if (nat_interface_is_inside (i))
-    rmp->flags |= NAT_API_IS_INSIDE;
+  rmp->is_inside = nat_interface_is_inside (i);
 
   vl_api_send_msg (reg, (u8 *) rmp);
 }
@@ -1178,7 +1150,6 @@ static void
   int rv = 0;
   snat_protocol_t proto;
   u8 *tag = 0;
-  u32 len = 0;
 
   if (sm->deterministic)
     {
@@ -1188,34 +1159,27 @@ static void
 
   memcpy (&local_addr.as_u8, mp->local_ip_address, 4);
   memcpy (&external_addr.as_u8, mp->external_ip_address, 4);
-
-  if (!(mp->flags & NAT_API_IS_ADDR_ONLY))
+  if (mp->addr_only == 0)
     {
       local_port = clib_net_to_host_u16 (mp->local_port);
       external_port = clib_net_to_host_u16 (mp->external_port);
     }
-
   vrf_id = clib_net_to_host_u32 (mp->vrf_id);
   external_sw_if_index = clib_net_to_host_u32 (mp->external_sw_if_index);
   proto = ip_proto_to_snat_proto (mp->protocol);
-
-  if (mp->flags & NAT_API_IS_TWICE_NAT)
+  if (mp->twice_nat)
     twice_nat = TWICE_NAT;
-  else if (mp->flags & NAT_API_IS_SELF_TWICE_NAT)
+  else if (mp->self_twice_nat)
     twice_nat = TWICE_NAT_SELF;
-
-  len = vl_api_string_len (&mp->tag);
-
-  tag = vec_new (u8, len);
-  memcpy (tag, mp->tag.buf, len);
+  mp->tag[sizeof (mp->tag) - 1] = 0;
+  tag = format (0, "%s", mp->tag);
   vec_terminate_c_string (tag);
 
   rv = snat_add_static_mapping (local_addr, external_addr, local_port,
-				external_port, vrf_id,
-				mp->flags & NAT_API_IS_ADDR_ONLY,
-				external_sw_if_index, proto,
-				mp->is_add, twice_nat,
-				mp->flags & NAT_API_IS_OUT2IN_ONLY, tag, 0);
+				external_port, vrf_id, mp->addr_only,
+				external_sw_if_index, proto, mp->is_add,
+				twice_nat, mp->out2in_only, tag, 0);
+
   vec_free (tag);
 
 send_reply:
@@ -1233,14 +1197,13 @@ static void *vl_api_nat44_add_del_static_mapping_t_print
 	      format_ip4_address, mp->local_ip_address,
 	      format_ip4_address, mp->external_ip_address);
 
-  if (!(mp->flags & NAT_API_IS_ADDR_ONLY))
+  if (mp->addr_only == 0)
     s = format (s, "local_port %d external_port %d ",
 		clib_net_to_host_u16 (mp->local_port),
 		clib_net_to_host_u16 (mp->external_port));
 
   s = format (s, "twice_nat %d out2in_only %d ",
-	      mp->flags & NAT_API_IS_TWICE_NAT,
-	      mp->flags & NAT_API_IS_OUT2IN_ONLY);
+	      mp->twice_nat, mp->out2in_only);
 
   if (mp->vrf_id != ~0)
     s = format (s, "vrf %d", clib_net_to_host_u32 (mp->vrf_id));
@@ -1257,48 +1220,30 @@ send_nat44_static_mapping_details (snat_static_mapping_t * m,
 {
   vl_api_nat44_static_mapping_details_t *rmp;
   snat_main_t *sm = &snat_main;
-  u32 len = sizeof (*rmp);
-
-  if (m->tag)
-    {
-      len += vec_len (m->tag);
-      rmp = vl_msg_api_alloc (len);
-      clib_memset (rmp, 0, len);
-      vl_api_to_api_string (vec_len (m->tag), (char *) m->tag, &rmp->tag);
-    }
-  else
-    {
-      rmp = vl_msg_api_alloc (len);
-      clib_memset (rmp, 0, len);
-    }
 
+  rmp = vl_msg_api_alloc (sizeof (*rmp));
+  clib_memset (rmp, 0, sizeof (*rmp));
   rmp->_vl_msg_id =
     ntohs (VL_API_NAT44_STATIC_MAPPING_DETAILS + sm->msg_id_base);
-
+  rmp->addr_only = is_addr_only_static_mapping (m);
   clib_memcpy (rmp->local_ip_address, &(m->local_addr), 4);
   clib_memcpy (rmp->external_ip_address, &(m->external_addr), 4);
   rmp->external_sw_if_index = ~0;
   rmp->vrf_id = htonl (m->vrf_id);
   rmp->context = context;
-
   if (m->twice_nat == TWICE_NAT)
-    rmp->flags |= NAT_API_IS_TWICE_NAT;
+    rmp->twice_nat = 1;
   else if (m->twice_nat == TWICE_NAT_SELF)
-    rmp->flags |= NAT_API_IS_SELF_TWICE_NAT;
-
-  if (is_out2in_only_static_mapping (m))
-    rmp->flags |= NAT_API_IS_OUT2IN_ONLY;
-
-  if (is_addr_only_static_mapping (m))
-    {
-      rmp->flags |= NAT_API_IS_ADDR_ONLY;
-    }
-  else
+    rmp->self_twice_nat = 1;
+  rmp->out2in_only = is_out2in_only_static_mapping (m);
+  if (rmp->addr_only == 0)
     {
       rmp->protocol = snat_proto_to_ip_proto (m->proto);
       rmp->external_port = htons (m->external_port);
       rmp->local_port = htons (m->local_port);
     }
+  if (m->tag)
+    strncpy ((char *) rmp->tag, (char *) m->tag, vec_len (m->tag));
 
   vl_api_send_msg (reg, (u8 *) rmp);
 }
@@ -1310,41 +1255,25 @@ send_nat44_static_map_resolve_details (snat_static_map_resolve_t * m,
 {
   vl_api_nat44_static_mapping_details_t *rmp;
   snat_main_t *sm = &snat_main;
-  u32 len = sizeof (*rmp);
-
-  if (m->tag)
-    {
-      len += vec_len (m->tag);
-      rmp = vl_msg_api_alloc (len);
-      clib_memset (rmp, 0, len);
-      vl_api_to_api_string (vec_len (m->tag), (char *) m->tag, &rmp->tag);
-    }
-  else
-    {
-      rmp = vl_msg_api_alloc (len);
-      clib_memset (rmp, 0, len);
-    }
 
+  rmp = vl_msg_api_alloc (sizeof (*rmp));
+  clib_memset (rmp, 0, sizeof (*rmp));
   rmp->_vl_msg_id =
     ntohs (VL_API_NAT44_STATIC_MAPPING_DETAILS + sm->msg_id_base);
+  rmp->addr_only = m->addr_only;
   clib_memcpy (rmp->local_ip_address, &(m->l_addr), 4);
   rmp->external_sw_if_index = htonl (m->sw_if_index);
   rmp->vrf_id = htonl (m->vrf_id);
   rmp->context = context;
-
-  if (m->twice_nat)
-    rmp->flags |= NAT_API_IS_TWICE_NAT;
-
-  if (m->addr_only)
-    {
-      rmp->flags |= NAT_API_IS_ADDR_ONLY;
-    }
-  else
+  rmp->twice_nat = m->twice_nat;
+  if (m->addr_only == 0)
     {
       rmp->protocol = snat_proto_to_ip_proto (m->proto);
       rmp->external_port = htons (m->e_port);
       rmp->local_port = htons (m->l_port);
     }
+  if (m->tag)
+    strncpy ((char *) rmp->tag, (char *) m->tag, vec_len (m->tag));
 
   vl_api_send_msg (reg, (u8 *) rmp);
 }
@@ -1405,7 +1334,6 @@ static void
   int rv = 0;
   snat_protocol_t proto = ~0;
   u8 *tag = 0;
-  u32 len = 0;
 
   if (sm->deterministic)
     {
@@ -1413,7 +1341,7 @@ static void
       goto send_reply;
     }
 
-  if (!(mp->flags & NAT_API_IS_ADDR_ONLY))
+  if (mp->addr_only == 0)
     {
       port = clib_net_to_host_u16 (mp->port);
       proto = ip_proto_to_snat_proto (mp->protocol);
@@ -1424,17 +1352,14 @@ static void
     addr.as_u32 = 0;
   else
     memcpy (&addr.as_u8, mp->ip_address, 4);
-
-  len = vl_api_string_len (&mp->tag);
-
-  tag = vec_new (u8, len);
-  memcpy (tag, mp->tag.buf, len);
+  mp->tag[sizeof (mp->tag) - 1] = 0;
+  tag = format (0, "%s", mp->tag);
   vec_terminate_c_string (tag);
 
   rv =
-    snat_add_static_mapping (addr, addr, port, port, vrf_id,
-			     mp->flags & NAT_API_IS_ADDR_ONLY, sw_if_index,
-			     proto, mp->is_add, 0, 0, tag, 1);
+    snat_add_static_mapping (addr, addr, port, port, vrf_id, mp->addr_only,
+			     sw_if_index, proto, mp->is_add, 0, 0, tag, 1);
+
   vec_free (tag);
 
 send_reply:
@@ -1452,7 +1377,7 @@ static void *vl_api_nat44_add_del_identity_mapping_t_print
   else
     s = format (s, "addr %U", format_ip4_address, mp->ip_address);
 
-  if (!(mp->flags & NAT_API_IS_ADDR_ONLY))
+  if (mp->addr_only == 0)
     s =
       format (s, " protocol %d port %d", mp->protocol,
 	      clib_net_to_host_u16 (mp->port));
@@ -1470,33 +1395,20 @@ send_nat44_identity_mapping_details (snat_static_mapping_t * m, int index,
   vl_api_nat44_identity_mapping_details_t *rmp;
   snat_main_t *sm = &snat_main;
   nat44_lb_addr_port_t *local = pool_elt_at_index (m->locals, index);
-  u32 len = sizeof (*rmp);
-
-  if (m->tag)
-    {
-      len += vec_len (m->tag);
-      rmp = vl_msg_api_alloc (len);
-      clib_memset (rmp, 0, len);
-      vl_api_to_api_string (vec_len (m->tag), (char *) m->tag, &rmp->tag);
-    }
-  else
-    {
-      rmp = vl_msg_api_alloc (len);
-      clib_memset (rmp, 0, len);
-    }
 
+  rmp = vl_msg_api_alloc (sizeof (*rmp));
+  clib_memset (rmp, 0, sizeof (*rmp));
   rmp->_vl_msg_id =
     ntohs (VL_API_NAT44_IDENTITY_MAPPING_DETAILS + sm->msg_id_base);
-
-  if (is_addr_only_static_mapping (m))
-    rmp->flags |= NAT_API_IS_ADDR_ONLY;
-
+  rmp->addr_only = is_addr_only_static_mapping (m);
   clib_memcpy (rmp->ip_address, &(m->local_addr), 4);
   rmp->port = htons (m->local_port);
   rmp->sw_if_index = ~0;
   rmp->vrf_id = htonl (local->vrf_id);
   rmp->protocol = snat_proto_to_ip_proto (m->proto);
   rmp->context = context;
+  if (m->tag)
+    strncpy ((char *) rmp->tag, (char *) m->tag, vec_len (m->tag));
 
   vl_api_send_msg (reg, (u8 *) rmp);
 }
@@ -1508,32 +1420,19 @@ send_nat44_identity_map_resolve_details (snat_static_map_resolve_t * m,
 {
   vl_api_nat44_identity_mapping_details_t *rmp;
   snat_main_t *sm = &snat_main;
-  u32 len = sizeof (*rmp);
-
-  if (m->tag)
-    {
-      len += vec_len (m->tag);
-      rmp = vl_msg_api_alloc (len);
-      clib_memset (rmp, 0, len);
-      vl_api_to_api_string (vec_len (m->tag), (char *) m->tag, &rmp->tag);
-    }
-  else
-    {
-      rmp = vl_msg_api_alloc (len);
-      clib_memset (rmp, 0, len);
-    }
 
+  rmp = vl_msg_api_alloc (sizeof (*rmp));
+  clib_memset (rmp, 0, sizeof (*rmp));
   rmp->_vl_msg_id =
     ntohs (VL_API_NAT44_IDENTITY_MAPPING_DETAILS + sm->msg_id_base);
-
-  if (m->addr_only)
-    rmp->flags = (vl_api_nat_config_flags_t) NAT_API_IS_ADDR_ONLY;
-
+  rmp->addr_only = m->addr_only;
   rmp->port = htons (m->l_port);
   rmp->sw_if_index = htonl (m->sw_if_index);
   rmp->vrf_id = htonl (m->vrf_id);
   rmp->protocol = snat_proto_to_ip_proto (m->proto);
   rmp->context = context;
+  if (m->tag)
+    strncpy ((char *) rmp->tag, (char *) m->tag, vec_len (m->tag));
 
   vl_api_send_msg (reg, (u8 *) rmp);
 }
@@ -1592,9 +1491,9 @@ static void
 {
   snat_main_t *sm = &snat_main;
   vl_api_nat44_add_del_interface_addr_reply_t *rmp;
+  u8 is_del = mp->is_add == 0;
   u32 sw_if_index = ntohl (mp->sw_if_index);
   int rv = 0;
-  u8 is_del;
 
   if (sm->deterministic)
     {
@@ -1602,12 +1501,9 @@ static void
       goto send_reply;
     }
 
-  is_del = !mp->is_add;
-
   VALIDATE_SW_IF_INDEX (mp);
 
-  rv = snat_add_interface_address (sm, sw_if_index, is_del,
-				   mp->flags & NAT_API_IS_TWICE_NAT);
+  rv = snat_add_interface_address (sm, sw_if_index, is_del, mp->twice_nat);
 
   BAD_SW_IF_INDEX_LABEL;
 send_reply:
@@ -1622,7 +1518,7 @@ static void *vl_api_nat44_add_del_interface_addr_t_print
   s = format (0, "SCRIPT: nat44_add_del_interface_addr ");
   s = format (s, "sw_if_index %d twice_nat %d %s",
 	      clib_host_to_net_u32 (mp->sw_if_index),
-	      mp->flags & NAT_API_IS_TWICE_NAT, mp->is_add ? "" : "del");
+	      mp->twice_nat, mp->is_add ? "" : "del");
 
   FINISH;
 }
@@ -1640,9 +1536,7 @@ send_nat44_interface_addr_details (u32 sw_if_index,
   rmp->_vl_msg_id =
     ntohs (VL_API_NAT44_INTERFACE_ADDR_DETAILS + sm->msg_id_base);
   rmp->sw_if_index = ntohl (sw_if_index);
-
-  if (twice_nat)
-    rmp->flags = (vl_api_nat_config_flags_t) NAT_API_IS_TWICE_NAT;
+  rmp->twice_nat = twice_nat;
   rmp->context = context;
 
   vl_api_send_msg (reg, (u8 *) rmp);
@@ -1757,16 +1651,10 @@ send_nat44_user_session_details (snat_session_t * s,
     ntohs (VL_API_NAT44_USER_SESSION_DETAILS + sm->msg_id_base);
   clib_memcpy (rmp->outside_ip_address, (&s->out2in.addr), 4);
   clib_memcpy (rmp->inside_ip_address, (&s->in2out.addr), 4);
-
-  if (snat_is_session_static (s))
-    rmp->flags |= NAT_API_IS_STATIC;
-
-  if (is_twice_nat_session (s))
-    rmp->flags |= NAT_API_IS_TWICE_NAT;
-
-  if (is_ed_session (s) || is_fwd_bypass_session (s))
-    rmp->flags |= NAT_API_IS_EXT_HOST_VALID;
-
+  rmp->is_static = snat_is_session_static (s) ? 1 : 0;
+  rmp->is_twicenat = is_twice_nat_session (s) ? 1 : 0;
+  rmp->ext_host_valid = is_ed_session (s)
+    || is_fwd_bypass_session (s) ? 1 : 0;
   rmp->last_heard = clib_host_to_net_u64 ((u64) s->last_heard);
   rmp->total_bytes = clib_host_to_net_u64 (s->total_bytes);
   rmp->total_pkts = ntohl (s->total_pkts);
@@ -1899,9 +1787,7 @@ static void
   nat44_lb_addr_port_t *locals = 0;
   ip4_address_t e_addr;
   snat_protocol_t proto;
-  vl_api_string_t *sp;
   u8 *tag = 0;
-  u32 len = 0;
 
   if (!sm->endpoint_dependent)
     {
@@ -1914,28 +1800,19 @@ static void
 				 clib_net_to_host_u32 (mp->local_num));
   clib_memcpy (&e_addr, mp->external_addr, 4);
   proto = ip_proto_to_snat_proto (mp->protocol);
-
-  if (mp->flags & NAT_API_IS_TWICE_NAT)
+  if (mp->twice_nat)
     twice_nat = TWICE_NAT;
-  else if (mp->flags & NAT_API_IS_SELF_TWICE_NAT)
+  else if (mp->self_twice_nat)
     twice_nat = TWICE_NAT_SELF;
-
-  sp = (void *) &mp->locals +
-    sizeof (vl_api_nat44_lb_addr_port_t) *
-    clib_net_to_host_u32 (mp->local_num);
-
-  len = vl_api_string_len (sp);
-
-  tag = vec_new (u8, len);
-  memcpy (tag, sp->buf, len);
+  mp->tag[sizeof (mp->tag) - 1] = 0;
+  tag = format (0, "%s", mp->tag);
   vec_terminate_c_string (tag);
 
   rv =
     nat44_add_del_lb_static_mapping (e_addr,
 				     clib_net_to_host_u16 (mp->external_port),
-				     proto, locals, mp->is_add,
-				     twice_nat,
-				     mp->flags & NAT_API_IS_OUT2IN_ONLY, tag,
+				     proto, locals, mp->is_add, twice_nat,
+				     mp->out2in_only, tag,
 				     clib_net_to_host_u32 (mp->affinity));
 
   vec_free (locals);
@@ -1952,9 +1829,7 @@ static void *vl_api_nat44_add_del_lb_static_mapping_t_print
 
   s = format (0, "SCRIPT: nat44_add_del_lb_static_mapping ");
   s = format (s, "is_add %d twice_nat %d out2in_only %d ",
-	      mp->is_add,
-	      mp->flags & NAT_API_IS_TWICE_NAT,
-	      mp->flags & NAT_API_IS_OUT2IN_ONLY);
+	      mp->is_add, mp->twice_nat, mp->out2in_only);
 
   FINISH;
 }
@@ -2014,28 +1889,13 @@ send_nat44_lb_static_mapping_details (snat_static_mapping_t * m,
   snat_main_t *sm = &snat_main;
   nat44_lb_addr_port_t *ap;
   vl_api_nat44_lb_addr_port_t *locals;
-  vl_api_string_t *sp;
   u32 local_num = 0;
-  u32 len = sizeof (*rmp);
-
-  if (m->tag)
-    {
-      len += pool_elts (m->locals) *
-	sizeof (nat44_lb_addr_port_t) + vec_len (m->tag);
-      rmp = vl_msg_api_alloc (len);
-      clib_memset (rmp, 0, len);
-
-      sp = (void *) &m->locals +
-	sizeof (vl_api_nat44_lb_addr_port_t) * pool_elts (m->locals);
-      vl_api_to_api_string (vec_len (m->tag), (char *) m->tag, sp);
-    }
-  else
-    {
-      len += pool_elts (m->locals) * sizeof (nat44_lb_addr_port_t);
-      rmp = vl_msg_api_alloc (len);
-      clib_memset (rmp, 0, len);
-    }
 
+  rmp =
+    vl_msg_api_alloc (sizeof (*rmp) +
+		      (pool_elts (m->locals) *
+		       sizeof (nat44_lb_addr_port_t)));
+  clib_memset (rmp, 0, sizeof (*rmp));
   rmp->_vl_msg_id =
     ntohs (VL_API_NAT44_LB_STATIC_MAPPING_DETAILS + sm->msg_id_base);
 
@@ -2043,13 +1903,13 @@ send_nat44_lb_static_mapping_details (snat_static_mapping_t * m,
   rmp->external_port = ntohs (m->external_port);
   rmp->protocol = snat_proto_to_ip_proto (m->proto);
   rmp->context = context;
-
   if (m->twice_nat == TWICE_NAT)
-    rmp->flags |= NAT_API_IS_TWICE_NAT;
+    rmp->twice_nat = 1;
   else if (m->twice_nat == TWICE_NAT_SELF)
-    rmp->flags |= NAT_API_IS_SELF_TWICE_NAT;
-  if (is_out2in_only_static_mapping (m))
-    rmp->flags |= NAT_API_IS_OUT2IN_ONLY;
+    rmp->self_twice_nat = 1;
+  rmp->out2in_only = is_out2in_only_static_mapping (m);
+  if (m->tag)
+    strncpy ((char *) rmp->tag, (char *) m->tag, vec_len (m->tag));
 
   locals = (vl_api_nat44_lb_addr_port_t *) rmp->locals;
   /* *INDENT-OFF* */
@@ -2111,7 +1971,6 @@ vl_api_nat44_del_session_t_handler (vl_api_nat44_del_session_t * mp)
   u16 port, eh_port;
   u32 vrf_id;
   int rv = 0;
-  u8 is_in;
   snat_protocol_t proto;
 
   if (sm->deterministic)
@@ -2127,14 +1986,12 @@ vl_api_nat44_del_session_t_handler (vl_api_nat44_del_session_t * mp)
   memcpy (&eh_addr.as_u8, mp->ext_host_address, 4);
   eh_port = clib_net_to_host_u16 (mp->ext_host_port);
 
-  is_in = mp->flags & NAT_API_IS_INSIDE;
-
-  if (mp->flags & NAT_API_IS_EXT_HOST_VALID)
+  if (mp->ext_host_valid)
     rv =
       nat44_del_ed_session (sm, &addr, port, &eh_addr, eh_port, mp->protocol,
-			    vrf_id, is_in);
+			    vrf_id, mp->is_in);
   else
-    rv = nat44_del_session (sm, &addr, port, proto, vrf_id, is_in);
+    rv = nat44_del_session (sm, &addr, port, proto, vrf_id, mp->is_in);
 
 send_reply:
   REPLY_MACRO (VL_API_NAT44_DEL_SESSION_REPLY);
@@ -2150,9 +2007,8 @@ vl_api_nat44_del_session_t_print (vl_api_nat44_del_session_t * mp,
   s = format (s, "addr %U port %d protocol %d vrf_id %d is_in %d",
 	      format_ip4_address, mp->address,
 	      clib_net_to_host_u16 (mp->port),
-	      mp->protocol, clib_net_to_host_u32 (mp->vrf_id),
-	      mp->flags & NAT_API_IS_INSIDE);
-  if (mp->flags & NAT_API_IS_EXT_HOST_VALID)
+	      mp->protocol, clib_net_to_host_u32 (mp->vrf_id), mp->is_in);
+  if (mp->ext_host_valid)
     s = format (s, "ext_host_address %U ext_host_port %d",
 		format_ip4_address, mp->ext_host_address,
 		clib_net_to_host_u16 (mp->ext_host_port));
@@ -2261,6 +2117,12 @@ vl_api_nat_det_add_del_map_t_handler (vl_api_nat_det_add_del_map_t * mp)
       goto send_reply;
     }
 
+  if (!mp->is_nat44)
+    {
+      rv = VNET_API_ERROR_UNIMPLEMENTED;
+      goto send_reply;
+    }
+
   clib_memcpy (&in_addr, mp->in_addr, 4);
   clib_memcpy (&out_addr, mp->out_addr, 4);
   rv = snat_det_add_map (sm, &in_addr, mp->in_plen, &out_addr,
@@ -2301,6 +2163,13 @@ vl_api_nat_det_forward_t_handler (vl_api_nat_det_forward_t * mp)
       return;
     }
 
+  if (!mp->is_nat44)
+    {
+      out_addr.as_u32 = 0;
+      rv = VNET_API_ERROR_UNIMPLEMENTED;
+      goto send_reply;
+    }
+
   out_addr.as_u32 = 0;
   clib_memcpy (&in_addr, mp->in_addr, 4);
   dm = snat_det_map_by_user (sm, &in_addr);
@@ -2366,6 +2235,8 @@ send_reply:
   /* *INDENT-OFF* */
   REPLY_MACRO2 (VL_API_NAT_DET_REVERSE_REPLY,
   ({
+    rmp->is_nat44 = 1;
+    clib_memset (rmp->in_addr, 0, 16);
     clib_memcpy (rmp->in_addr, &in_addr, 4);
   }))
   /* *INDENT-ON* */
@@ -2393,6 +2264,7 @@ sent_nat_det_map_details (snat_det_map_t * m, vl_api_registration_t * reg,
   rmp = vl_msg_api_alloc (sizeof (*rmp));
   clib_memset (rmp, 0, sizeof (*rmp));
   rmp->_vl_msg_id = ntohs (VL_API_NAT_DET_MAP_DETAILS + sm->msg_id_base);
+  rmp->is_nat44 = 1;
   clib_memcpy (rmp->in_addr, &m->in_addr, 4);
   rmp->in_plen = m->in_plen;
   clib_memcpy (rmp->out_addr, &m->out_addr, 4);
@@ -2511,6 +2383,12 @@ vl_api_nat_det_close_session_in_t_handler (vl_api_nat_det_close_session_in_t *
       goto send_reply;
     }
 
+  if (!mp->is_nat44)
+    {
+      rv = VNET_API_ERROR_UNIMPLEMENTED;
+      goto send_reply;
+    }
+
   clib_memcpy (&in_addr, mp->in_addr, 4);
   clib_memcpy (&ext_addr, mp->ext_addr, 4);
 
@@ -2584,6 +2462,8 @@ vl_api_nat_det_session_dump_t_handler (vl_api_nat_det_session_dump_t * mp)
   reg = vl_api_client_index_to_registration (mp->client_index);
   if (!reg)
     return;
+  if (!mp->is_nat44)
+    return;
 
   clib_memset (&empty_ses, 0, sizeof (empty_ses));
   clib_memcpy (&user_addr, mp->user_addr, 4);
@@ -2739,8 +2619,8 @@ vl_api_nat64_add_del_interface_t_handler (vl_api_nat64_add_del_interface_t *
   VALIDATE_SW_IF_INDEX (mp);
 
   rv =
-    nat64_add_del_interface (ntohl (mp->sw_if_index),
-			     mp->flags & NAT_API_IS_INSIDE, mp->is_add);
+    nat64_add_del_interface (ntohl (mp->sw_if_index), mp->is_inside,
+			     mp->is_add);
 
   BAD_SW_IF_INDEX_LABEL;
 
@@ -2756,8 +2636,7 @@ vl_api_nat64_add_del_interface_t_print (vl_api_nat64_add_del_interface_t * mp,
   s = format (0, "SCRIPT: nat64_add_del_interface ");
   s = format (s, "sw_if_index %d %s %s",
 	      clib_host_to_net_u32 (mp->sw_if_index),
-	      mp->flags & NAT_API_IS_INSIDE ? "in" : "out",
-	      mp->is_add ? "" : "del");
+	      mp->is_inside ? "in" : "out", mp->is_add ? "" : "del");
 
   FINISH;
 }
@@ -2773,12 +2652,9 @@ nat64_api_interface_walk (snat_interface_t * i, void *arg)
   clib_memset (rmp, 0, sizeof (*rmp));
   rmp->_vl_msg_id = ntohs (VL_API_NAT64_INTERFACE_DETAILS + sm->msg_id_base);
   rmp->sw_if_index = ntohl (i->sw_if_index);
-
-  if (nat_interface_is_inside (i))
-    rmp->flags |= NAT_API_IS_INSIDE;
-  if (nat_interface_is_outside (i))
-    rmp->flags |= NAT_API_IS_OUTSIDE;
-
+  rmp->is_inside = (nat_interface_is_inside (i)
+		    && nat_interface_is_outside (i)) ? 2 :
+    nat_interface_is_inside (i);
   rmp->context = ctx->context;
 
   vl_api_send_msg (ctx->reg, (u8 *) rmp);
@@ -2876,8 +2752,7 @@ nat64_api_bib_walk (nat64_db_bib_entry_t * bibe, void *arg)
   rmp->o_port = bibe->out_port;
   rmp->vrf_id = ntohl (fib->ft_table_id);
   rmp->proto = bibe->proto;
-  if (bibe->is_static)
-    rmp->flags |= NAT_API_IS_STATIC;
+  rmp->is_static = bibe->is_static;
   rmp->ses_num = ntohl (bibe->ses_num);
 
   vl_api_send_msg (ctx->reg, (u8 *) rmp);
@@ -2996,10 +2871,10 @@ vl_api_nat64_add_del_prefix_t_handler (vl_api_nat64_add_del_prefix_t * mp)
   ip6_address_t prefix;
   int rv = 0;
 
-  memcpy (&prefix.as_u8, mp->prefix.prefix, 16);
+  memcpy (&prefix.as_u8, mp->prefix, 16);
 
   rv =
-    nat64_add_del_prefix (&prefix, mp->prefix.len,
+    nat64_add_del_prefix (&prefix, mp->prefix_len,
 			  clib_net_to_host_u32 (mp->vrf_id), mp->is_add);
   REPLY_MACRO (VL_API_NAT64_ADD_DEL_PREFIX_REPLY);
 }
@@ -3011,7 +2886,7 @@ vl_api_nat64_add_del_prefix_t_print (vl_api_nat64_add_del_prefix_t * mp,
   u8 *s;
 
   s = format (0, "SCRIPT: nat64_add_del_prefix %U/%u vrf_id %u %s\n",
-	      format_ip6_address, mp->prefix.prefix, mp->prefix.len,
+	      format_ip6_address, mp->prefix, mp->prefix_len,
 	      ntohl (mp->vrf_id), mp->is_add ? "" : "del");
 
   FINISH;
@@ -3027,8 +2902,8 @@ nat64_api_prefix_walk (nat64_prefix_t * p, void *arg)
   rmp = vl_msg_api_alloc (sizeof (*rmp));
   clib_memset (rmp, 0, sizeof (*rmp));
   rmp->_vl_msg_id = ntohs (VL_API_NAT64_PREFIX_DETAILS + sm->msg_id_base);
-  clib_memcpy (rmp->prefix.prefix, &(p->prefix), 16);
-  rmp->prefix.len = p->plen;
+  clib_memcpy (rmp->prefix, &(p->prefix), 16);
+  rmp->prefix_len = p->plen;
   rmp->vrf_id = ntohl (p->vrf_id);
   rmp->context = ctx->context;
 
@@ -3334,8 +3209,8 @@ vl_api_nat66_add_del_interface_t_handler (vl_api_nat66_add_del_interface_t *
   VALIDATE_SW_IF_INDEX (mp);
 
   rv =
-    nat66_interface_add_del (ntohl (mp->sw_if_index),
-			     mp->flags & NAT_API_IS_INSIDE, mp->is_add);
+    nat66_interface_add_del (ntohl (mp->sw_if_index), mp->is_inside,
+			     mp->is_add);
 
   BAD_SW_IF_INDEX_LABEL;
 
@@ -3351,8 +3226,7 @@ vl_api_nat66_add_del_interface_t_print (vl_api_nat66_add_del_interface_t * mp,
   s = format (0, "SCRIPT: nat66_add_del_interface ");
   s = format (s, "sw_if_index %d %s %s",
 	      clib_host_to_net_u32 (mp->sw_if_index),
-	      mp->flags & NAT_API_IS_INSIDE ? "in" : "out",
-	      mp->is_add ? "" : "del");
+	      mp->is_inside ? "in" : "out", mp->is_add ? "" : "del");
 
   FINISH;
 }
@@ -3408,8 +3282,7 @@ nat66_api_interface_walk (snat_interface_t * i, void *arg)
   clib_memset (rmp, 0, sizeof (*rmp));
   rmp->_vl_msg_id = ntohs (VL_API_NAT66_INTERFACE_DETAILS + sm->msg_id_base);
   rmp->sw_if_index = ntohl (i->sw_if_index);
-  if (nat_interface_is_inside (i))
-    rmp->flags |= NAT_API_IS_INSIDE;
+  rmp->is_inside = nat_interface_is_inside (i);
   rmp->context = ctx->context;
 
   vl_api_send_msg (ctx->rp, (u8 *) rmp);
diff --git a/src/plugins/nat/nat_test.c b/src/plugins/nat/nat_test.c
index 0371ec48553..b1de5340b9d 100644
--- a/src/plugins/nat/nat_test.c
+++ b/src/plugins/nat/nat_test.c
@@ -221,8 +221,7 @@ static int api_nat44_interface_add_del_feature (vat_main_t * vam)
   M(NAT44_INTERFACE_ADD_DEL_FEATURE, mp);
   mp->sw_if_index = ntohl(sw_if_index);
   mp->is_add = is_add;
-  if (is_inside)
-    mp->flags |= NAT_API_IS_INSIDE;
+  mp->is_inside = is_inside;
 
   S(mp);
   W (ret);
@@ -292,11 +291,8 @@ static int api_nat44_add_del_static_mapping(vat_main_t * vam)
     }
 
   M(NAT44_ADD_DEL_STATIC_MAPPING, mp);
-
   mp->is_add = is_add;
-  if (addr_only)
-    mp->flags |= NAT_API_IS_ADDR_ONLY;
-
+  mp->addr_only = addr_only;
   mp->local_port = ntohs ((u16) local_port);
   mp->external_port = ntohs ((u16) external_port);
   mp->external_sw_if_index = ntohl (sw_if_index);
@@ -331,21 +327,20 @@ static void vl_api_nat44_static_mapping_details_t_handler
 {
   snat_test_main_t * sm = &snat_test_main;
   vat_main_t *vam = sm->vat_main;
-  nat_config_flags_t flags = (nat_config_flags_t) mp->flags;
 
-  if (flags & NAT_API_IS_ADDR_ONLY && mp->external_sw_if_index != ~0)
+  if (mp->addr_only && mp->external_sw_if_index != ~0)
       fformat (vam->ofp, "%15U%6s%15d%6s%11d%6d\n",
                format_ip4_address, &mp->local_ip_address, "",
                ntohl (mp->external_sw_if_index), "",
                ntohl (mp->vrf_id),
                mp->protocol);
-  else if (flags & NAT_API_IS_ADDR_ONLY && mp->external_sw_if_index == ~0)
+  else if (mp->addr_only && mp->external_sw_if_index == ~0)
       fformat (vam->ofp, "%15U%6s%15U%6s%11d%6d\n",
                format_ip4_address, &mp->local_ip_address, "",
                format_ip4_address, &mp->external_ip_address, "",
                ntohl (mp->vrf_id),
                mp->protocol);
-  else if (!(flags & NAT_API_IS_ADDR_ONLY) && mp->external_sw_if_index != ~0)
+  else if (!mp->addr_only && mp->external_sw_if_index != ~0)
       fformat (vam->ofp, "%15U%6d%15d%6d%11d%6d\n",
                format_ip4_address, &mp->local_ip_address,
                ntohs (mp->local_port),
@@ -474,19 +469,11 @@ static int api_nat44_address_dump(vat_main_t * vam)
 static void vl_api_nat44_interface_details_t_handler
   (vl_api_nat44_interface_details_t *mp)
 {
-  nat_config_flags_t flags = (nat_config_flags_t) mp->flags;
   snat_test_main_t * sm = &snat_test_main;
   vat_main_t *vam = sm->vat_main;
 
-  if ((flags & NAT_API_IS_INSIDE) && (flags & NAT_API_IS_OUTSIDE))
-    {
-      fformat (vam->ofp, "sw_if_index %d in & out\n", ntohl (mp->sw_if_index));
-    }
-  else
-    {
-      fformat (vam->ofp, "sw_if_index %d %s\n", ntohl (mp->sw_if_index),
-               flags & NAT_API_IS_INSIDE ? "in" : "out");
-    }
+  fformat (vam->ofp, "sw_if_index %d %s\n", ntohl (mp->sw_if_index),
+           mp->is_inside ? "in" : "out");
 }
 
 static int api_nat44_interface_dump(vat_main_t * vam)
@@ -603,7 +590,6 @@ static int api_nat44_add_del_interface_addr (vat_main_t * vam)
 
   M(NAT44_ADD_DEL_INTERFACE_ADDR, mp);
   mp->sw_if_index = ntohl(sw_if_index);
-
   mp->is_add = is_add;
 
   S(mp);
@@ -685,7 +671,7 @@ static void vl_api_nat44_user_session_details_t_handler
 
   fformat(vam->ofp, "%s session %U:%d to %U:%d protocol id %d "
                     "total packets %d total bytes %lld\n",
-          mp->flags & NAT_API_IS_STATIC ? "static" : "dynamic",
+          mp->is_static ? "static" : "dynamic",
           format_ip4_address, mp->inside_ip_address, ntohs(mp->inside_port),
           format_ip4_address, mp->outside_ip_address, ntohs(mp->outside_port),
           ntohs(mp->protocol), ntohl(mp->total_pkts),
diff --git a/src/vpp-api/vapi/vapi_json_parser.py b/src/vpp-api/vapi/vapi_json_parser.py
index fda3f75d9c1..2c08b90a93b 100644
--- a/src/vpp-api/vapi/vapi_json_parser.py
+++ b/src/vpp-api/vapi/vapi_json_parser.py
@@ -298,7 +298,7 @@ class JsonParser(object):
             x: simple_type_class(x) for x in [
                 'i8', 'i16', 'i32', 'i64',
                 'u8', 'u16', 'u32', 'u64',
-                'f64', 'bool'
+                'f64'
             ]
         }
 
diff --git a/test/test_gbp.py b/test/test_gbp.py
index cc38bc9c1ce..44a9b396730 100644
--- a/test/test_gbp.py
+++ b/test/test_gbp.py
@@ -575,10 +575,6 @@ class VppGbpAcl(VppObject):
 class TestGBP(VppTestCase):
     """ GBP Test Case """
 
-    @property
-    def config_flags(self):
-        return VppEnum.vl_api_nat_config_flags_t
-
     @classmethod
     def setUpClass(cls):
         super(TestGBP, cls).setUpClass()
@@ -799,11 +795,12 @@ class TestGBP(VppTestCase):
                     self.router_mac.packed)
 
                 # The BVIs are NAT inside interfaces
-                flags = self.config_flags.NAT_IS_INSIDE
                 self.vapi.nat44_interface_add_del_feature(epg.bvi.sw_if_index,
-                                                          flags=flags)
+                                                          is_inside=1,
+                                                          is_add=1)
                 self.vapi.nat66_add_del_interface(epg.bvi.sw_if_index,
-                                                  flags=flags)
+                                                  is_inside=1,
+                                                  is_add=1)
 
             if_ip4 = VppIpInterfaceAddress(self, epg.bvi, epg.bvi_ip4, 32)
             if_ip6 = VppIpInterfaceAddress(self, epg.bvi, epg.bvi_ip6, 128)
@@ -835,9 +832,13 @@ class TestGBP(VppTestCase):
                                recirc.epg.rd.t6).add_vpp_config()
 
             self.vapi.nat44_interface_add_del_feature(
-                recirc.recirc.sw_if_index)
+                recirc.recirc.sw_if_index,
+                is_inside=0,
+                is_add=1)
             self.vapi.nat66_add_del_interface(
-                recirc.recirc.sw_if_index)
+                recirc.recirc.sw_if_index,
+                is_inside=0,
+                is_add=1)
 
             recirc.add_vpp_config()
 
@@ -857,11 +858,10 @@ class TestGBP(VppTestCase):
             for (ip, fip) in zip(ep.ips, ep.fips):
                 # Add static mappings for each EP from the 10/8 to 11/8 network
                 if ip.af == AF_INET:
-                    flags = self.config_flags.NAT_IS_ADDR_ONLY
                     self.vapi.nat44_add_del_static_mapping(ip.bytes,
                                                            fip.bytes,
                                                            vrf_id=0,
-                                                           flags=flags)
+                                                           addr_only=1)
                 else:
                     self.vapi.nat66_add_del_static_mapping(ip.bytes,
                                                            fip.bytes,
@@ -1404,12 +1404,11 @@ class TestGBP(VppTestCase):
         #
         for ep in eps:
             # del static mappings for each EP from the 10/8 to 11/8 network
-            flags = self.config_flags.NAT_IS_ADDR_ONLY
             self.vapi.nat44_add_del_static_mapping(ep.ip4.bytes,
                                                    ep.fip4.bytes,
                                                    vrf_id=0,
-                                                   is_add=0,
-                                                   flags=flags)
+                                                   addr_only=1,
+                                                   is_add=0)
             self.vapi.nat66_add_del_static_mapping(ep.ip6.bytes,
                                                    ep.fip6.bytes,
                                                    vrf_id=0,
@@ -1418,20 +1417,21 @@ class TestGBP(VppTestCase):
         for epg in epgs:
             # IP config on the BVI interfaces
             if epg != epgs[0] and epg != epgs[3]:
-                flags = self.config_flags.NAT_IS_INSIDE
                 self.vapi.nat44_interface_add_del_feature(epg.bvi.sw_if_index,
-                                                          flags=flags,
+                                                          is_inside=1,
                                                           is_add=0)
                 self.vapi.nat66_add_del_interface(epg.bvi.sw_if_index,
-                                                  flags=flags,
+                                                  is_inside=1,
                                                   is_add=0)
 
         for recirc in recircs:
             self.vapi.nat44_interface_add_del_feature(
                 recirc.recirc.sw_if_index,
+                is_inside=0,
                 is_add=0)
             self.vapi.nat66_add_del_interface(
                 recirc.recirc.sw_if_index,
+                is_inside=0,
                 is_add=0)
 
     def wait_for_ep_timeout(self, sw_if_index=None, ip=None, mac=None,
diff --git a/test/test_nat.py b/test/test_nat.py
index c88981b48b4..29d747d0932 100644
--- a/test/test_nat.py
+++ b/test/test_nat.py
@@ -29,7 +29,6 @@ from vpp_papi import VppEnum
 from scapy.all import bind_layers, Packet, ByteEnumField, ShortField, \
     IPField, IntField, LongField, XByteField, FlagsField, FieldLenField, \
     PacketListField
-from ipaddress import IPv6Network
 
 
 # NAT HA protocol event data
@@ -71,10 +70,6 @@ class HANATStateSync(Packet):
 class MethodHolder(VppTestCase):
     """ NAT create capture and verify method holder """
 
-    @property
-    def config_flags(self):
-        return VppEnum.vl_api_nat_config_flags_t
-
     def clear_nat44(self):
         """
         Clear NAT44 configuration.
@@ -111,7 +106,7 @@ class MethodHolder(VppTestCase):
         interfaces = self.vapi.nat44_interface_addr_dump()
         for intf in interfaces:
             self.vapi.nat44_add_del_interface_addr(intf.sw_if_index,
-                                                   flags=intf.flags,
+                                                   twice_nat=intf.twice_nat,
                                                    is_add=0)
 
         self.vapi.nat_ipfix_enable_disable(enable=0,
@@ -127,32 +122,36 @@ class MethodHolder(VppTestCase):
 
         interfaces = self.vapi.nat44_interface_dump()
         for intf in interfaces:
-            if intf.flags & self.config_flags.NAT_IS_INSIDE and \
-                 intf.flags & self.config_flags.NAT_IS_OUTSIDE:
+            if intf.is_inside > 1:
                 self.vapi.nat44_interface_add_del_feature(intf.sw_if_index,
+                                                          0,
                                                           is_add=0)
             self.vapi.nat44_interface_add_del_feature(intf.sw_if_index,
-                                                      is_add=0,
-                                                      flags=intf.flags)
+                                                      intf.is_inside,
+                                                      is_add=0)
 
         interfaces = self.vapi.nat44_interface_output_feature_dump()
         for intf in interfaces:
             self.vapi.nat44_interface_add_del_output_feature(intf.sw_if_index,
-                                                             is_add=0,
-                                                             flags=intf.flags)
+                                                             intf.is_inside,
+                                                             is_add=0)
+
         static_mappings = self.vapi.nat44_static_mapping_dump()
         for sm in static_mappings:
             self.vapi.nat44_add_del_static_mapping(
                 sm.local_ip_address,
                 sm.external_ip_address,
-                sm.external_sw_if_index,
-                sm.local_port,
-                sm.external_port,
-                sm.vrf_id,
-                sm.protocol,
-                is_add=0,
-                flags=sm.flags,
-                tag=sm.tag)
+                local_port=sm.local_port,
+                external_port=sm.external_port,
+                addr_only=sm.addr_only,
+                vrf_id=sm.vrf_id,
+                protocol=sm.protocol,
+                twice_nat=sm.twice_nat,
+                self_twice_nat=sm.self_twice_nat,
+                out2in_only=sm.out2in_only,
+                tag=sm.tag,
+                external_sw_if_index=sm.external_sw_if_index,
+                is_add=0)
 
         lb_static_mappings = self.vapi.nat44_lb_static_mapping_dump()
         for lb_sm in lb_static_mappings:
@@ -160,16 +159,18 @@ class MethodHolder(VppTestCase):
                 lb_sm.external_addr,
                 lb_sm.external_port,
                 lb_sm.protocol,
+                twice_nat=lb_sm.twice_nat,
+                self_twice_nat=lb_sm.self_twice_nat,
+                out2in_only=lb_sm.out2in_only,
                 tag=lb_sm.tag,
                 is_add=0,
                 local_num=0,
-                locals=[],
-                flags=lb_sm.flags)
+                locals=[])
 
         identity_mappings = self.vapi.nat44_identity_mapping_dump()
         for id_m in identity_mappings:
             self.vapi.nat44_add_del_identity_mapping(
-                flags=id_m.flags,
+                addr_only=id_m.addr_only,
                 ip=id_m.ip_address,
                 port=id_m.port,
                 sw_if_index=id_m.sw_if_index,
@@ -181,8 +182,8 @@ class MethodHolder(VppTestCase):
         for addr in addresses:
             self.vapi.nat44_add_del_address_range(addr.ip_address,
                                                   addr.ip_address,
-                                                  is_add=0,
-                                                  flags=addr.flags)
+                                                  twice_nat=addr.twice_nat,
+                                                  is_add=0)
 
         self.vapi.nat_set_reass()
         self.vapi.nat_set_reass(is_ip6=1)
@@ -194,7 +195,8 @@ class MethodHolder(VppTestCase):
     def nat44_add_static_mapping(self, local_ip, external_ip='0.0.0.0',
                                  local_port=0, external_port=0, vrf_id=0,
                                  is_add=1, external_sw_if_index=0xFFFFFFFF,
-                                 proto=0, tag="", flags=0):
+                                 proto=0, twice_nat=0, self_twice_nat=0,
+                                 out2in_only=0, tag=""):
         """
         Add/delete NAT44 static mapping
 
@@ -206,24 +208,32 @@ class MethodHolder(VppTestCase):
         :param is_add: 1 if add, 0 if delete (Default add)
         :param external_sw_if_index: External interface instead of IP address
         :param proto: IP protocol (Mandatory if port specified)
+        :param twice_nat: 1 if translate external host address and port
+        :param self_twice_nat: 1 if translate external host address and port
+                               whenever external host address equals
+                               local address of internal host
+        :param out2in_only: if 1 rule is matching only out2in direction
         :param tag: Opaque string tag
-        :param flags: NAT configuration flags
         """
-
-        if not (local_port and external_port):
-            flags |= self.config_flags.NAT_IS_ADDR_ONLY
-
+        addr_only = 1
+        if local_port and external_port:
+            addr_only = 0
+        l_ip = socket.inet_pton(socket.AF_INET, local_ip)
+        e_ip = socket.inet_pton(socket.AF_INET, external_ip)
         self.vapi.nat44_add_del_static_mapping(
-            local_ip,
-            external_ip,
+            l_ip,
+            e_ip,
             external_sw_if_index,
             local_port,
             external_port,
+            addr_only,
             vrf_id,
             proto,
-            is_add,
-            flags,
-            tag)
+            twice_nat,
+            self_twice_nat,
+            out2in_only,
+            tag,
+            is_add)
 
     def nat44_add_address(self, ip, is_add=1, vrf_id=0xFFFFFFFF, twice_nat=0):
         """
@@ -233,10 +243,10 @@ class MethodHolder(VppTestCase):
         :param is_add: 1 if add, 0 if delete (Default add)
         :param twice_nat: twice NAT address for external hosts
         """
-        flags = self.config_flags.NAT_IS_TWICE_NAT if twice_nat else 0
-        self.vapi.nat44_add_del_address_range(ip, ip, is_add,
+        nat_addr = socket.inet_pton(socket.AF_INET, ip)
+        self.vapi.nat44_add_del_address_range(nat_addr, nat_addr, is_add,
                                               vrf_id=vrf_id,
-                                              flags=flags)
+                                              twice_nat=twice_nat)
 
     def create_stream_in(self, in_if, out_if, dst_ip=None, ttl=64):
         """
@@ -1492,6 +1502,7 @@ class TestNAT44(MethodHolder):
             cls.icmp_id_in = 6305
             cls.icmp_id_out = 6305
             cls.nat_addr = '10.0.0.3'
+            cls.nat_addr_n = socket.inet_pton(socket.AF_INET, cls.nat_addr)
             cls.ipfix_src_port = 4739
             cls.ipfix_domain_id = 1
             cls.tcp_external_port = 80
@@ -1558,10 +1569,9 @@ class TestNAT44(MethodHolder):
     def test_dynamic(self):
         """ NAT44 dynamic translation test """
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         # in2out
         tcpn = self.statistics.get_counter(
@@ -1626,10 +1636,9 @@ class TestNAT44(MethodHolder):
         """ NAT44 handling of client packets with TTL=1 """
 
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         # Client side - generate traffic
         pkts = self.create_stream_in(self.pg0, self.pg1, ttl=1)
@@ -1645,10 +1654,9 @@ class TestNAT44(MethodHolder):
         """ NAT44 handling of server packets with TTL=1 """
 
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         # Client side - create sessions
         pkts = self.create_stream_in(self.pg0, self.pg1)
@@ -1673,10 +1681,9 @@ class TestNAT44(MethodHolder):
         """ NAT44 handling of error responses to client packets with TTL=2 """
 
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         # Client side - generate traffic
         pkts = self.create_stream_in(self.pg0, self.pg1, ttl=2)
@@ -1701,10 +1708,9 @@ class TestNAT44(MethodHolder):
         """ NAT44 handling of error responses to server packets with TTL=2 """
 
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         # Client side - create sessions
         pkts = self.create_stream_in(self.pg0, self.pg1)
@@ -1737,10 +1743,9 @@ class TestNAT44(MethodHolder):
         """ Ping NAT44 out interface from outside network """
 
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         p = (Ether(dst=self.pg1.local_mac, src=self.pg1.remote_mac) /
              IP(src=self.pg1.remote_ip4, dst=self.pg1.local_ip4) /
@@ -1765,10 +1770,9 @@ class TestNAT44(MethodHolder):
         """ Ping internal host from outside network """
 
         self.nat44_add_static_mapping(self.pg0.remote_ip4, self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         # out2in
         pkt = (Ether(dst=self.pg1.local_mac, src=self.pg1.remote_mac) /
@@ -1795,18 +1799,15 @@ class TestNAT44(MethodHolder):
     def test_forwarding(self):
         """ NAT44 forwarding test """
 
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
         self.vapi.nat44_forwarding_enable_disable(1)
 
         real_ip = self.pg0.remote_ip4n
-        alias_ip = self.nat_addr
-        flags = self.config_flags.NAT_IS_ADDR_ONLY
+        alias_ip = self.nat_addr_n
         self.vapi.nat44_add_del_static_mapping(local_ip=real_ip,
-                                               external_ip=alias_ip,
-                                               flags=flags)
+                                               external_ip=alias_ip)
 
         try:
             # static mapping match
@@ -1851,10 +1852,9 @@ class TestNAT44(MethodHolder):
 
         finally:
             self.vapi.nat44_forwarding_enable_disable(0)
-            flags = self.config_flags.NAT_IS_ADDR_ONLY
             self.vapi.nat44_add_del_static_mapping(local_ip=real_ip,
                                                    external_ip=alias_ip,
-                                                   is_add=0, flags=flags)
+                                                   is_add=0)
 
     def test_static_in(self):
         """ 1:1 NAT initialized from inside network """
@@ -1865,10 +1865,9 @@ class TestNAT44(MethodHolder):
         self.icmp_id_out = 6305
 
         self.nat44_add_static_mapping(self.pg0.remote_ip4, nat_ip)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
         sm = self.vapi.nat44_static_mapping_dump()
         self.assertEqual(len(sm), 1)
         self.assertEqual((sm[0].tag).split(b'\0', 1)[0], b'')
@@ -1902,10 +1901,9 @@ class TestNAT44(MethodHolder):
         tag = b"testTAG"
 
         self.nat44_add_static_mapping(self.pg0.remote_ip4, nat_ip, tag=tag)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
         sm = self.vapi.nat44_static_mapping_dump()
         self.assertEqual(len(sm), 1)
         self.assertEqual((sm[0].tag).split(b'\0', 1)[0], tag)
@@ -1943,10 +1941,9 @@ class TestNAT44(MethodHolder):
         self.nat44_add_static_mapping(self.pg0.remote_ip4, self.nat_addr,
                                       self.icmp_id_in, self.icmp_id_out,
                                       proto=IP_PROTOS.icmp)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         # in2out
         pkts = self.create_stream_in(self.pg0, self.pg1)
@@ -1981,10 +1978,9 @@ class TestNAT44(MethodHolder):
         self.nat44_add_static_mapping(self.pg0.remote_ip4, self.nat_addr,
                                       self.icmp_id_in, self.icmp_id_out,
                                       proto=IP_PROTOS.icmp)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         # out2in
         pkts = self.create_stream_out(self.pg1)
@@ -2015,12 +2011,10 @@ class TestNAT44(MethodHolder):
                                       vrf_id=10)
         self.nat44_add_static_mapping(self.pg0.remote_ip4, nat_ip2,
                                       vrf_id=10)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg3.sw_if_index)
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg4.sw_if_index,
-                                                  flags=flags)
+        self.vapi.nat44_interface_add_del_feature(self.pg3.sw_if_index,
+                                                  is_inside=0)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg4.sw_if_index)
 
         # inside interface VRF match NAT44 static mapping VRF
         pkts = self.create_stream_in(self.pg4, self.pg3)
@@ -2046,10 +2040,9 @@ class TestNAT44(MethodHolder):
         self.icmp_id_out = 6305
 
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         # dynamic
         pkts = self.create_stream_in(self.pg0, self.pg1)
@@ -2072,13 +2065,11 @@ class TestNAT44(MethodHolder):
 
     def test_identity_nat(self):
         """ Identity NAT """
-        flags = self.config_flags.NAT_IS_ADDR_ONLY
-        self.vapi.nat44_add_del_identity_mapping(ip=self.pg0.remote_ip4n,
-                                                 flags=flags)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+
+        self.vapi.nat44_add_del_identity_mapping(ip=self.pg0.remote_ip4n)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
              IP(src=self.pg1.remote_ip4, dst=self.pg0.remote_ip4) /
@@ -2102,9 +2093,8 @@ class TestNAT44(MethodHolder):
 
         sessions = self.vapi.nat44_user_session_dump(self.pg0.remote_ip4n, 0)
         self.assertEqual(len(sessions), 0)
-        flags = self.config_flags.NAT_IS_ADDR_ONLY
         self.vapi.nat44_add_del_identity_mapping(ip=self.pg0.remote_ip4n,
-                                                 flags=flags, vrf_id=1)
+                                                 vrf_id=1)
         identity_mappings = self.vapi.nat44_identity_mapping_dump()
         self.assertEqual(len(identity_mappings), 2)
 
@@ -2112,12 +2102,10 @@ class TestNAT44(MethodHolder):
         """ NAT44 multiple non-overlapping address space inside interfaces """
 
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg3.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg3.sw_if_index,
+                                                  is_inside=0)
 
         # between two NAT44 inside interfaces (no translation)
         pkts = self.create_stream_in(self.pg0, self.pg1)
@@ -2172,14 +2160,11 @@ class TestNAT44(MethodHolder):
 
         static_nat_ip = "10.0.0.10"
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg3.sw_if_index)
-        self.vapi.nat44_interface_add_del_feature(self.pg4.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg5.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg6.sw_if_index,
-                                                  flags=flags)
+        self.vapi.nat44_interface_add_del_feature(self.pg3.sw_if_index,
+                                                  is_inside=0)
+        self.vapi.nat44_interface_add_del_feature(self.pg4.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg5.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg6.sw_if_index)
         self.nat44_add_static_mapping(self.pg6.remote_ip4, static_nat_ip,
                                       vrf_id=20)
 
@@ -2249,9 +2234,9 @@ class TestNAT44(MethodHolder):
         sessions = self.vapi.nat44_user_session_dump(self.pg5.remote_ip4n, 10)
         self.assertEqual(len(sessions), 3)
         for session in sessions:
-            self.assertFalse(session.flags & self.config_flags.NAT_IS_STATIC)
-            self.assertEqual(str(session.inside_ip_address),
-                             self.pg5.remote_ip4)
+            self.assertFalse(session.is_static)
+            self.assertEqual(session.inside_ip_address[0:4],
+                             self.pg5.remote_ip4n)
             self.assertEqual(session.outside_ip_address,
                              addresses[0].ip_address)
         self.assertEqual(sessions[0].protocol, IP_PROTOS.tcp)
@@ -2294,16 +2279,15 @@ class TestNAT44(MethodHolder):
                 self.assertTrue(session.protocol in
                                 [IP_PROTOS.tcp, IP_PROTOS.udp,
                                  IP_PROTOS.icmp])
-                self.assertFalse(session.flags &
-                                 self.config_flags.NAT_IS_EXT_HOST_VALID)
+                self.assertFalse(session.ext_host_valid)
 
         # pg4 session dump
         sessions = self.vapi.nat44_user_session_dump(self.pg4.remote_ip4n, 10)
         self.assertGreaterEqual(len(sessions), 4)
         for session in sessions:
-            self.assertFalse(session.flags & self.config_flags.NAT_IS_STATIC)
-            self.assertEqual(str(session.inside_ip_address),
-                             self.pg4.remote_ip4)
+            self.assertFalse(session.is_static)
+            self.assertEqual(session.inside_ip_address[0:4],
+                             self.pg4.remote_ip4n)
             self.assertEqual(session.outside_ip_address,
                              addresses[0].ip_address)
 
@@ -2311,11 +2295,11 @@ class TestNAT44(MethodHolder):
         sessions = self.vapi.nat44_user_session_dump(self.pg6.remote_ip4n, 20)
         self.assertGreaterEqual(len(sessions), 3)
         for session in sessions:
-            self.assertTrue(session.flags & self.config_flags.NAT_IS_STATIC)
-            self.assertEqual(str(session.inside_ip_address),
-                             self.pg6.remote_ip4)
-            self.assertEqual(str(session.outside_ip_address),
-                             static_nat_ip)
+            self.assertTrue(session.is_static)
+            self.assertEqual(session.inside_ip_address[0:4],
+                             self.pg6.remote_ip4n)
+            self.assertEqual(session.outside_ip_address,
+                             socket.inet_pton(socket.AF_INET, static_nat_ip))
             self.assertTrue(session.inside_port in
                             [self.tcp_port_in, self.udp_port_in,
                              self.icmp_id_in])
@@ -2331,11 +2315,9 @@ class TestNAT44(MethodHolder):
         server_out_port = 8765
 
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
-
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
         # add static mapping for server
         self.nat44_add_static_mapping(server.ip4, self.nat_addr,
                                       server_in_port, server_out_port,
@@ -2396,10 +2378,9 @@ class TestNAT44(MethodHolder):
         server_udp_port = 20
 
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         # add static mapping for servers
         self.nat44_add_static_mapping(server1.ip4, server1_nat_ip)
@@ -2555,10 +2536,9 @@ class TestNAT44(MethodHolder):
         """ MAX translations per user - recycle the least recently used """
 
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         # get maximum number of translations per user
         nat44_config = self.vapi.nat_show_config()
@@ -2615,7 +2595,7 @@ class TestNAT44(MethodHolder):
         self.pg7.config_ip4()
         addresses = self.vapi.nat44_address_dump()
         self.assertEqual(1, len(addresses))
-        self.assertEqual(str(addresses[0].ip_address), self.pg7.local_ip4)
+        self.assertEqual(addresses[0].ip_address[0:4], self.pg7.local_ip4n)
 
         # remove interface address and check NAT address pool
         self.pg7.unconfig_ip4()
@@ -2646,8 +2626,8 @@ class TestNAT44(MethodHolder):
         resolved = False
         for sm in static_mappings:
             if sm.external_sw_if_index == 0xFFFFFFFF:
-                self.assertEqual(str(sm.external_ip_address),
-                                 self.pg7.local_ip4)
+                self.assertEqual(sm.external_ip_address[0:4],
+                                 self.pg7.local_ip4n)
                 self.assertEqual((sm.tag).split(b'\0', 1)[0], tag)
                 resolved = True
         self.assertTrue(resolved)
@@ -2667,8 +2647,8 @@ class TestNAT44(MethodHolder):
         resolved = False
         for sm in static_mappings:
             if sm.external_sw_if_index == 0xFFFFFFFF:
-                self.assertEqual(str(sm.external_ip_address),
-                                 self.pg7.local_ip4)
+                self.assertEqual(sm.external_ip_address[0:4],
+                                 self.pg7.local_ip4n)
                 self.assertEqual((sm.tag).split(b'\0', 1)[0], tag)
                 resolved = True
         self.assertTrue(resolved)
@@ -2690,7 +2670,8 @@ class TestNAT44(MethodHolder):
         self.vapi.nat44_add_del_identity_mapping(
             sw_if_index=self.pg7.sw_if_index,
             port=port,
-            protocol=IP_PROTOS.tcp)
+            protocol=IP_PROTOS.tcp,
+            addr_only=0)
 
         # identity mappings with external interface
         identity_mappings = self.vapi.nat44_identity_mapping_dump()
@@ -2705,8 +2686,8 @@ class TestNAT44(MethodHolder):
         self.assertEqual(2, len(identity_mappings))
         for sm in identity_mappings:
             if sm.sw_if_index == 0xFFFFFFFF:
-                self.assertEqual(str(identity_mappings[0].ip_address),
-                                 self.pg7.local_ip4)
+                self.assertEqual(identity_mappings[0].ip_address,
+                                 self.pg7.local_ip4n)
                 self.assertEqual(port, identity_mappings[0].port)
                 self.assertEqual(IP_PROTOS.tcp, identity_mappings[0].protocol)
                 resolved = True
@@ -2726,10 +2707,9 @@ class TestNAT44(MethodHolder):
         collector_port = 30303
         bind_layers(UDP, IPFIX, dport=30303)
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
         self.vapi.set_ipfix_exporter(collector_address=self.pg3.remote_ip4n,
                                      src_address=self.pg3.local_ip4n,
                                      path_mtu=512,
@@ -2767,10 +2747,9 @@ class TestNAT44(MethodHolder):
 
     def test_ipfix_addr_exhausted(self):
         """ IPFIX logging NAT addresses exhausted """
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
         self.vapi.set_ipfix_exporter(collector_address=self.pg3.remote_ip4n,
                                      src_address=self.pg3.local_ip4n,
                                      path_mtu=512,
@@ -2810,10 +2789,9 @@ class TestNAT44(MethodHolder):
     def test_ipfix_max_sessions(self):
         """ IPFIX logging maximum session entries exceeded """
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         nat44_config = self.vapi.nat_show_config()
         max_sessions = 10 * nat44_config.translation_buckets
@@ -2870,10 +2848,9 @@ class TestNAT44(MethodHolder):
         self.vapi.syslog_set_filter(SYSLOG_SEVERITY.INFO)
         self.vapi.syslog_set_sender(self.pg3.local_ip4n, self.pg3.remote_ip4n)
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
              IP(src=self.pg0.remote_ip4, dst=self.pg1.remote_ip4) /
@@ -2896,10 +2873,9 @@ class TestNAT44(MethodHolder):
         """ NAT44 add pool addresses to FIB """
         static_addr = '10.0.0.10'
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
         self.nat44_add_static_mapping(self.pg0.remote_ip4, static_addr)
 
         # NAT44 address
@@ -2975,12 +2951,10 @@ class TestNAT44(MethodHolder):
 
         self.nat44_add_address(nat_ip1, vrf_id=vrf_id1)
         self.nat44_add_address(nat_ip2, vrf_id=vrf_id2)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg2.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg2.sw_if_index,
+                                                  is_inside=0)
 
         try:
             # first VRF
@@ -3019,12 +2993,10 @@ class TestNAT44(MethodHolder):
 
         self.nat44_add_address(nat_ip1)
         self.nat44_add_address(nat_ip2, vrf_id=99)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg2.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg2.sw_if_index,
+                                                  is_inside=0)
 
         # first VRF
         pkts = self.create_stream_in(self.pg0, self.pg2)
@@ -3068,10 +3040,9 @@ class TestNAT44(MethodHolder):
                                    next_hop_sw_if_index=self.pg8.sw_if_index)
 
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg7.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg8.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg7.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg8.sw_if_index,
+                                                  is_inside=0)
 
         # in2out
         pkts = self.create_stream_in(self.pg7, self.pg8)
@@ -3115,10 +3086,9 @@ class TestNAT44(MethodHolder):
                                    next_hop_sw_if_index=self.pg8.sw_if_index)
 
         self.nat44_add_static_mapping(self.pg7.remote_ip4, self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg7.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg8.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg7.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg8.sw_if_index,
+                                                  is_inside=0)
 
         # out2in
         pkts = self.create_stream_out(self.pg8)
@@ -3175,10 +3145,9 @@ class TestNAT44(MethodHolder):
         self.nat44_add_static_mapping(self.pg7.remote_ip4, self.nat_addr,
                                       self.icmp_id_in, self.icmp_id_out,
                                       proto=IP_PROTOS.icmp)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg7.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg8.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg7.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg8.sw_if_index,
+                                                  is_inside=0)
 
         # out2in
         pkts = self.create_stream_out(self.pg8)
@@ -3200,10 +3169,9 @@ class TestNAT44(MethodHolder):
         """ 1:1 NAT translate packet with unknown protocol """
         nat_ip = "10.0.0.10"
         self.nat44_add_static_mapping(self.pg0.remote_ip4, nat_ip)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         # in2out
         p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
@@ -3256,10 +3224,9 @@ class TestNAT44(MethodHolder):
 
         self.nat44_add_static_mapping(host.ip4, host_nat_ip)
         self.nat44_add_static_mapping(server.ip4, server_nat_ip)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         # host to server
         p = (Ether(dst=self.pg0.local_mac, src=host.mac) /
@@ -3304,12 +3271,10 @@ class TestNAT44(MethodHolder):
     def test_output_feature(self):
         """ NAT44 interface output feature (in2out postrouting) """
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_output_feature(self.pg0.sw_if_index,
-                                                         flags=flags)
-        self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index,
-                                                         flags=flags)
-        self.vapi.nat44_interface_add_del_output_feature(self.pg3.sw_if_index)
+        self.vapi.nat44_interface_add_del_output_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_output_feature(self.pg3.sw_if_index,
+                                                         is_inside=0)
 
         # in2out
         pkts = self.create_stream_in(self.pg0, self.pg3)
@@ -3353,12 +3318,10 @@ class TestNAT44(MethodHolder):
 
         self.nat44_add_address(nat_ip_vrf10, vrf_id=10)
         self.nat44_add_address(nat_ip_vrf20, vrf_id=20)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_output_feature(self.pg4.sw_if_index,
-                                                         flags=flags)
-        self.vapi.nat44_interface_add_del_output_feature(self.pg6.sw_if_index,
-                                                         flags=flags)
-        self.vapi.nat44_interface_add_del_output_feature(self.pg3.sw_if_index)
+        self.vapi.nat44_interface_add_del_output_feature(self.pg4.sw_if_index)
+        self.vapi.nat44_interface_add_del_output_feature(self.pg6.sw_if_index)
+        self.vapi.nat44_interface_add_del_output_feature(self.pg3.sw_if_index,
+                                                         is_inside=0)
 
         # in2out VRF 10
         pkts = self.create_stream_in(self.pg4, self.pg3)
@@ -3402,10 +3365,9 @@ class TestNAT44(MethodHolder):
         server_out_port = 8765
 
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_output_feature(self.pg0.sw_if_index,
-                                                         flags=flags)
-        self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_output_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index,
+                                                         is_inside=0)
 
         # add static mapping for server
         self.nat44_add_static_mapping(server.ip4, self.nat_addr,
@@ -3462,10 +3424,9 @@ class TestNAT44(MethodHolder):
         external_port = 0
 
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
         self.vapi.nat44_interface_add_del_feature(self.pg9.sw_if_index)
         self.vapi.nat44_interface_add_del_feature(self.pg9.sw_if_index,
-                                                  flags=flags)
+                                                  is_inside=0)
 
         # in2out
         p = (Ether(src=self.pg9.remote_mac, dst=self.pg9.local_mac) /
@@ -3518,10 +3479,9 @@ class TestNAT44(MethodHolder):
     def test_del_session(self):
         """ Delete NAT44 session """
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         pkts = self.create_stream_in(self.pg0, self.pg1)
         self.pg0.add_stream(pkts)
@@ -3534,19 +3494,18 @@ class TestNAT44(MethodHolder):
 
         self.vapi.nat44_del_session(sessions[0].inside_ip_address,
                                     sessions[0].inside_port,
-                                    sessions[0].protocol,
-                                    flags=self.config_flags.NAT_IS_INSIDE)
+                                    sessions[0].protocol)
         self.vapi.nat44_del_session(sessions[1].outside_ip_address,
                                     sessions[1].outside_port,
-                                    sessions[1].protocol)
+                                    sessions[1].protocol,
+                                    is_in=0)
 
         sessions = self.vapi.nat44_user_session_dump(self.pg0.remote_ip4n, 0)
         self.assertEqual(nsessions - len(sessions), 2)
 
         self.vapi.nat44_del_session(sessions[0].inside_ip_address,
                                     sessions[0].inside_port,
-                                    sessions[0].protocol,
-                                    flags=self.config_flags.NAT_IS_INSIDE)
+                                    sessions[0].protocol)
 
         self.verify_no_nat44_user()
 
@@ -3571,10 +3530,9 @@ class TestNAT44(MethodHolder):
         """ NAT44 translate fragments arriving in order """
 
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         self.frag_in_order(proto=IP_PROTOS.tcp)
         self.frag_in_order(proto=IP_PROTOS.udp)
@@ -3583,10 +3541,9 @@ class TestNAT44(MethodHolder):
     def test_frag_forwarding(self):
         """ NAT44 forwarding fragment test """
         self.vapi.nat44_add_del_interface_addr(self.pg1.sw_if_index)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
         self.vapi.nat44_forwarding_enable_disable(1)
 
         data = b"A" * 16 + b"B" * 16 + b"C" * 3
@@ -3616,10 +3573,9 @@ class TestNAT44(MethodHolder):
         self.server_out_port = random.randint(1025, 65535)
 
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
         # add static mapping for server
         self.nat44_add_static_mapping(self.server.ip4, self.nat_addr,
                                       self.server_in_port,
@@ -3639,10 +3595,9 @@ class TestNAT44(MethodHolder):
         """ NAT44 translate fragments arriving out of order """
 
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         self.frag_out_of_order(proto=IP_PROTOS.tcp)
         self.frag_out_of_order(proto=IP_PROTOS.udp)
@@ -3651,10 +3606,9 @@ class TestNAT44(MethodHolder):
     def test_port_restricted(self):
         """ Port restricted NAT44 (MAP-E CE) """
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
         self.vapi.nat_set_addr_and_port_alloc_alg(alg=1,
                                                   psid_offset=6,
                                                   psid_length=6,
@@ -3684,10 +3638,9 @@ class TestNAT44(MethodHolder):
     def test_port_range(self):
         """ External address port range """
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
         self.vapi.nat_set_addr_and_port_alloc_alg(alg=2,
                                                   start_port=1025,
                                                   end_port=1027)
@@ -3710,10 +3663,9 @@ class TestNAT44(MethodHolder):
     def test_ipfix_max_frags(self):
         """ IPFIX logging maximum fragments pending reassembly exceeded """
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
         self.vapi.nat_set_reass(max_frag=1)
         self.vapi.set_ipfix_exporter(collector_address=self.pg3.remote_ip4n,
                                      src_address=self.pg3.local_ip4n,
@@ -3773,11 +3725,11 @@ class TestNAT44(MethodHolder):
         self.pg2.resolve_arp()
 
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
-        self.vapi.nat44_interface_add_del_feature(self.pg2.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
+        self.vapi.nat44_interface_add_del_feature(self.pg2.sw_if_index,
+                                                  is_inside=0)
 
         try:
             # first VRF
@@ -3828,10 +3780,9 @@ class TestNAT44(MethodHolder):
     def test_session_timeout(self):
         """ NAT44 session timeouts """
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
         self.vapi.nat_set_timeouts(udp=5)
 
         max_sessions = 1000
@@ -3870,10 +3821,9 @@ class TestNAT44(MethodHolder):
     def test_mss_clamping(self):
         """ TCP MSS clamping """
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         p = (Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac) /
              IP(src=self.pg0.remote_ip4, dst=self.pg1.remote_ip4) /
@@ -3908,10 +3858,9 @@ class TestNAT44(MethodHolder):
     def test_ha_send(self):
         """ Send HA session synchronization events (active) """
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
         self.vapi.nat_ha_set_listener(self.pg3.local_ip4, port=12345)
         self.vapi.nat_ha_set_failover(self.pg3.remote_ip4, port=12346)
         bind_layers(UDP, HANATStateSync, sport=12345)
@@ -3964,10 +3913,8 @@ class TestNAT44(MethodHolder):
 
         # delete one session
         self.pg_enable_capture(self.pg_interfaces)
-        self.vapi.nat44_del_session(self.pg0.remote_ip4n,
-                                    self.tcp_port_in,
-                                    IP_PROTOS.tcp,
-                                    flags=self.config_flags.NAT_IS_INSIDE)
+        self.vapi.nat44_del_session(self.pg0.remote_ip4n, self.tcp_port_in,
+                                    IP_PROTOS.tcp)
         self.vapi.nat_ha_flush()
         stats = self.statistics.get_counter('/nat44/ha/del-event-send')
         self.assertEqual(stats[0][0], 1)
@@ -4038,10 +3985,9 @@ class TestNAT44(MethodHolder):
     def test_ha_recv(self):
         """ Receive HA session synchronization events (passive) """
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
         self.vapi.nat_ha_set_listener(self.pg3.local_ip4, port=12345)
         bind_layers(UDP, HANATStateSync, sport=12345)
 
@@ -4094,17 +4040,14 @@ class TestNAT44(MethodHolder):
         self.assertEqual(sessions[0][0], 2)
         users = self.vapi.nat44_user_dump()
         self.assertEqual(len(users), 1)
-        self.assertEqual(str(users[0].ip_address),
-                         self.pg0.remote_ip4)
+        self.assertEqual(users[0].ip_address, self.pg0.remote_ip4n)
         # there should be 2 sessions created by HA
         sessions = self.vapi.nat44_user_session_dump(users[0].ip_address,
                                                      users[0].vrf_id)
         self.assertEqual(len(sessions), 2)
         for session in sessions:
-            self.assertEqual(str(session.inside_ip_address),
-                             self.pg0.remote_ip4)
-            self.assertEqual(str(session.outside_ip_address),
-                             self.nat_addr)
+            self.assertEqual(session.inside_ip_address, self.pg0.remote_ip4n)
+            self.assertEqual(session.outside_ip_address, self.nat_addr_n)
             self.assertIn(session.inside_port,
                           [self.tcp_port_in, self.udp_port_in])
             self.assertIn(session.outside_port,
@@ -4141,8 +4084,7 @@ class TestNAT44(MethodHolder):
             self.assertEqual(hanat.version, 1)
         users = self.vapi.nat44_user_dump()
         self.assertEqual(len(users), 1)
-        self.assertEqual(str(users[0].ip_address),
-                         self.pg0.remote_ip4)
+        self.assertEqual(users[0].ip_address, self.pg0.remote_ip4n)
         # now we should have only 1 session, 1 deleted by HA
         sessions = self.vapi.nat44_user_session_dump(users[0].ip_address,
                                                      users[0].vrf_id)
@@ -4183,8 +4125,7 @@ class TestNAT44(MethodHolder):
             self.assertEqual(hanat.version, 1)
         users = self.vapi.nat44_user_dump()
         self.assertEqual(len(users), 1)
-        self.assertEqual(str(users[0].ip_address),
-                         self.pg0.remote_ip4)
+        self.assertEqual(users[0].ip_address, self.pg0.remote_ip4n)
         sessions = self.vapi.nat44_user_session_dump(users[0].ip_address,
                                                      users[0].vrf_id)
         self.assertEqual(len(sessions), 1)
@@ -4257,6 +4198,7 @@ class TestNAT44EndpointDependent(MethodHolder):
             cls.icmp_id_in = 6305
             cls.icmp_id_out = 6305
             cls.nat_addr = '10.0.0.3'
+            cls.nat_addr_n = socket.inet_pton(socket.AF_INET, cls.nat_addr)
             cls.ipfix_src_port = 4739
             cls.ipfix_domain_id = 1
             cls.tcp_external_port = 80
@@ -4346,52 +4288,47 @@ class TestNAT44EndpointDependent(MethodHolder):
     def test_frag_in_order(self):
         """ NAT44 translate fragments arriving in order """
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
         self.frag_in_order(proto=IP_PROTOS.tcp)
         self.frag_in_order(proto=IP_PROTOS.udp)
         self.frag_in_order(proto=IP_PROTOS.icmp)
 
     def test_frag_in_order_dont_translate(self):
         """ NAT44 don't translate fragments arriving in order """
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
         self.vapi.nat44_forwarding_enable_disable(enable=True)
         self.frag_in_order(proto=IP_PROTOS.tcp, dont_translate=True)
 
     def test_frag_out_of_order(self):
         """ NAT44 translate fragments arriving out of order """
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
         self.frag_out_of_order(proto=IP_PROTOS.tcp)
         self.frag_out_of_order(proto=IP_PROTOS.udp)
         self.frag_out_of_order(proto=IP_PROTOS.icmp)
 
     def test_frag_out_of_order_dont_translate(self):
         """ NAT44 don't translate fragments arriving out of order """
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
         self.vapi.nat44_forwarding_enable_disable(enable=True)
         self.frag_out_of_order(proto=IP_PROTOS.tcp, dont_translate=True)
 
     def test_frag_in_order_in_plus_out(self):
         """ in+out interface fragments in order """
-        flags = self.config_flags.NAT_IS_INSIDE
         self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
         self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
+                                                  is_inside=0)
         self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
         self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
-                                                  flags=flags)
+                                                  is_inside=0)
 
         self.server = self.pg1.remote_hosts[0]
 
@@ -4425,13 +4362,12 @@ class TestNAT44EndpointDependent(MethodHolder):
 
     def test_frag_out_of_order_in_plus_out(self):
         """ in+out interface fragments out of order """
-        flags = self.config_flags.NAT_IS_INSIDE
         self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
         self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
+                                                  is_inside=0)
         self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
         self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
-                                                  flags=flags)
+                                                  is_inside=0)
 
         self.server = self.pg1.remote_hosts[0]
 
@@ -4471,10 +4407,9 @@ class TestNAT44EndpointDependent(MethodHolder):
         self.server_out_port = random.randint(1025, 65535)
 
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
         # add static mapping for server
         self.nat44_add_static_mapping(self.server.ip4, self.nat_addr,
                                       self.server_in_port,
@@ -4494,10 +4429,9 @@ class TestNAT44EndpointDependent(MethodHolder):
         """ NAT44 dynamic translation test """
 
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         nat_config = self.vapi.nat_show_config()
         self.assertEqual(1, nat_config.endpoint_dependent)
@@ -4566,18 +4500,15 @@ class TestNAT44EndpointDependent(MethodHolder):
     def test_forwarding(self):
         """ NAT44 forwarding test """
 
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
         self.vapi.nat44_forwarding_enable_disable(1)
 
-        real_ip = self.pg0.remote_ip4
-        alias_ip = self.nat_addr
-        flags = self.config_flags.NAT_IS_ADDR_ONLY
+        real_ip = self.pg0.remote_ip4n
+        alias_ip = self.nat_addr_n
         self.vapi.nat44_add_del_static_mapping(local_ip=real_ip,
-                                               external_ip=alias_ip,
-                                               flags=flags)
+                                               external_ip=alias_ip)
 
         try:
             # in2out - static mapping match
@@ -4623,14 +4554,11 @@ class TestNAT44EndpointDependent(MethodHolder):
             user = self.pg0.remote_hosts[1]
             sessions = self.vapi.nat44_user_session_dump(user.ip4n, 0)
             self.assertEqual(len(sessions), 3)
-            self.assertTrue(sessions[0].flags &
-                            self.config_flags.NAT_IS_EXT_HOST_VALID)
+            self.assertTrue(sessions[0].ext_host_valid)
             self.vapi.nat44_del_session(
                 sessions[0].inside_ip_address,
                 sessions[0].inside_port,
                 sessions[0].protocol,
-                flags=(self.config_flags.NAT_IS_INSIDE |
-                       self.config_flags.NAT_IS_EXT_HOST_VALID),
                 ext_host_address=sessions[0].ext_host_address,
                 ext_host_port=sessions[0].ext_host_port)
             sessions = self.vapi.nat44_user_session_dump(user.ip4n, 0)
@@ -4638,14 +4566,13 @@ class TestNAT44EndpointDependent(MethodHolder):
 
         finally:
             self.vapi.nat44_forwarding_enable_disable(0)
-            flags = self.config_flags.NAT_IS_ADDR_ONLY
             self.vapi.nat44_add_del_static_mapping(local_ip=real_ip,
                                                    external_ip=alias_ip,
-                                                   is_add=0, flags=flags)
+                                                   is_add=0)
 
     def test_static_lb(self):
         """ NAT44 local service load balancing """
-        external_addr_n = self.nat_addr
+        external_addr_n = socket.inet_pton(socket.AF_INET, self.nat_addr)
         external_port = 80
         local_port = 8080
         server1 = self.pg0.remote_hosts[0]
@@ -4666,10 +4593,9 @@ class TestNAT44EndpointDependent(MethodHolder):
                                                   IP_PROTOS.tcp,
                                                   local_num=len(locals),
                                                   locals=locals)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         # from client to service
         p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
@@ -4716,14 +4642,11 @@ class TestNAT44EndpointDependent(MethodHolder):
 
         sessions = self.vapi.nat44_user_session_dump(server.ip4n, 0)
         self.assertEqual(len(sessions), 1)
-        self.assertTrue(sessions[0].flags &
-                        self.config_flags.NAT_IS_EXT_HOST_VALID)
+        self.assertTrue(sessions[0].ext_host_valid)
         self.vapi.nat44_del_session(
             sessions[0].inside_ip_address,
             sessions[0].inside_port,
             sessions[0].protocol,
-            flags=(self.config_flags.NAT_IS_INSIDE |
-                   self.config_flags.NAT_IS_EXT_HOST_VALID),
             ext_host_address=sessions[0].ext_host_address,
             ext_host_port=sessions[0].ext_host_port)
         sessions = self.vapi.nat44_user_session_dump(server.ip4n, 0)
@@ -4733,7 +4656,7 @@ class TestNAT44EndpointDependent(MethodHolder):
     def test_static_lb_multi_clients(self):
         """ NAT44 local service load balancing - multiple clients"""
 
-        external_addr = self.nat_addr
+        external_addr_n = socket.inet_pton(socket.AF_INET, self.nat_addr)
         external_port = 80
         local_port = 8080
         server1 = self.pg0.remote_hosts[0]
@@ -4750,15 +4673,14 @@ class TestNAT44EndpointDependent(MethodHolder):
                    'vrf_id': 0}]
 
         self.nat44_add_address(self.nat_addr)
-        self.vapi.nat44_add_del_lb_static_mapping(external_addr,
+        self.vapi.nat44_add_del_lb_static_mapping(external_addr_n,
                                                   external_port,
                                                   IP_PROTOS.tcp,
                                                   local_num=len(locals),
                                                   locals=locals)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         server1_n = 0
         server2_n = 0
@@ -4781,7 +4703,7 @@ class TestNAT44EndpointDependent(MethodHolder):
         self.assertGreater(server1_n, server2_n)
 
         # add new back-end
-        self.vapi.nat44_lb_static_mapping_add_del_local(external_addr,
+        self.vapi.nat44_lb_static_mapping_add_del_local(external_addr_n,
                                                         external_port,
                                                         server3.ip4n,
                                                         local_port,
@@ -4814,7 +4736,7 @@ class TestNAT44EndpointDependent(MethodHolder):
         self.assertGreater(server3_n, 0)
 
         # remove one back-end
-        self.vapi.nat44_lb_static_mapping_add_del_local(external_addr,
+        self.vapi.nat44_lb_static_mapping_add_del_local(external_addr_n,
                                                         external_port,
                                                         server2.ip4n,
                                                         local_port,
@@ -4841,7 +4763,7 @@ class TestNAT44EndpointDependent(MethodHolder):
 
     def test_static_lb_2(self):
         """ NAT44 local service load balancing (asymmetrical rule) """
-        external_addr = self.nat_addr
+        external_addr_n = socket.inet_pton(socket.AF_INET, self.nat_addr)
         external_port = 80
         local_port = 8080
         server1 = self.pg0.remote_hosts[0]
@@ -4857,17 +4779,15 @@ class TestNAT44EndpointDependent(MethodHolder):
                    'vrf_id': 0}]
 
         self.vapi.nat44_forwarding_enable_disable(1)
-        flags = self.config_flags.NAT_IS_OUT2IN_ONLY
-        self.vapi.nat44_add_del_lb_static_mapping(external_addr,
+        self.vapi.nat44_add_del_lb_static_mapping(external_addr_n,
                                                   external_port,
                                                   IP_PROTOS.tcp,
+                                                  out2in_only=1,
                                                   local_num=len(locals),
-                                                  locals=locals,
-                                                  flags=flags)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+                                                  locals=locals)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         # from client to service
         p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
@@ -4953,7 +4873,7 @@ class TestNAT44EndpointDependent(MethodHolder):
 
     def test_lb_affinity(self):
         """ NAT44 local service load balancing affinity """
-        external_addr = self.nat_addr
+        external_addr_n = socket.inet_pton(socket.AF_INET, self.nat_addr)
         external_port = 80
         local_port = 8080
         server1 = self.pg0.remote_hosts[0]
@@ -4969,16 +4889,15 @@ class TestNAT44EndpointDependent(MethodHolder):
                    'vrf_id': 0}]
 
         self.nat44_add_address(self.nat_addr)
-        self.vapi.nat44_add_del_lb_static_mapping(external_addr,
+        self.vapi.nat44_add_del_lb_static_mapping(external_addr_n,
                                                   external_port,
                                                   IP_PROTOS.tcp,
                                                   affinity=10800,
                                                   local_num=len(locals),
                                                   locals=locals)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         p = (Ether(dst=self.pg1.local_mac, src=self.pg1.remote_mac) /
              IP(src=self.pg1.remote_ip4, dst=self.nat_addr) /
@@ -4989,16 +4908,14 @@ class TestNAT44EndpointDependent(MethodHolder):
         capture = self.pg0.get_capture(1)
         backend = capture[0][IP].dst
 
-        sessions = self.vapi.nat44_user_session_dump(backend, 0)
+        sessions = self.vapi.nat44_user_session_dump(
+            socket.inet_pton(socket.AF_INET, backend), 0)
         self.assertEqual(len(sessions), 1)
-        self.assertTrue(sessions[0].flags &
-                        self.config_flags.NAT_IS_EXT_HOST_VALID)
+        self.assertTrue(sessions[0].ext_host_valid)
         self.vapi.nat44_del_session(
             sessions[0].inside_ip_address,
             sessions[0].inside_port,
             sessions[0].protocol,
-            flags=(self.config_flags.NAT_IS_INSIDE |
-                   self.config_flags.NAT_IS_EXT_HOST_VALID),
             ext_host_address=sessions[0].ext_host_address,
             ext_host_port=sessions[0].ext_host_port)
 
@@ -5018,10 +4935,9 @@ class TestNAT44EndpointDependent(MethodHolder):
     def test_unknown_proto(self):
         """ NAT44 translate packet with unknown protocol """
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         # in2out
         p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
@@ -5080,10 +4996,9 @@ class TestNAT44EndpointDependent(MethodHolder):
         server_nat_ip = "10.0.0.11"
 
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         # add static mapping for server
         self.nat44_add_static_mapping(server.ip4, server_nat_ip)
@@ -5144,18 +5059,15 @@ class TestNAT44EndpointDependent(MethodHolder):
 
         self.vapi.nat44_forwarding_enable_disable(1)
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_ADDR_ONLY
-        self.vapi.nat44_add_del_identity_mapping(ip=self.pg1.remote_ip4n,
-                                                 flags=flags)
-        flags = self.config_flags.NAT_IS_OUT2IN_ONLY
+        self.vapi.nat44_add_del_identity_mapping(ip=self.pg1.remote_ip4n)
         self.nat44_add_static_mapping(self.pg0.remote_ip4, external_addr,
                                       local_port, external_port,
-                                      proto=IP_PROTOS.tcp, flags=flags)
-        flags = self.config_flags.NAT_IS_INSIDE
+                                      proto=IP_PROTOS.tcp, out2in_only=1)
         self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
         self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index)
+                                                  is_inside=0)
+        self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index,
+                                                         is_inside=0)
 
         # from client to service
         p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
@@ -5221,7 +5133,8 @@ class TestNAT44EndpointDependent(MethodHolder):
         """ NAT44 interface output feature and service host direct access """
         self.vapi.nat44_forwarding_enable_disable(1)
         self.nat44_add_address(self.nat_addr)
-        self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index,
+                                                         is_inside=0)
 
         # session initiated from service host - translate
         pkts = self.create_stream_in(self.pg0, self.pg1)
@@ -5267,15 +5180,14 @@ class TestNAT44EndpointDependent(MethodHolder):
 
         self.vapi.nat44_forwarding_enable_disable(1)
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_OUT2IN_ONLY
         self.nat44_add_static_mapping(self.pg1.remote_ip4, external_addr,
                                       local_port, external_port,
-                                      proto=IP_PROTOS.tcp, flags=flags)
-        flags = self.config_flags.NAT_IS_INSIDE
+                                      proto=IP_PROTOS.tcp, out2in_only=1)
         self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
         self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index)
+                                                  is_inside=0)
+        self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index,
+                                                         is_inside=0)
 
         p = (Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac) /
              IP(src=self.pg0.remote_ip4, dst=external_addr) /
@@ -5326,13 +5238,12 @@ class TestNAT44EndpointDependent(MethodHolder):
 
         self.vapi.nat44_forwarding_enable_disable(1)
         self.nat44_add_address(twice_nat_addr, twice_nat=1)
-        flags = (self.config_flags.NAT_IS_OUT2IN_ONLY |
-                 self.config_flags.NAT_IS_SELF_TWICE_NAT)
         self.nat44_add_static_mapping(self.pg6.remote_ip4, self.pg1.remote_ip4,
                                       local_port, external_port,
-                                      proto=IP_PROTOS.tcp, vrf_id=1,
-                                      flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg6.sw_if_index)
+                                      proto=IP_PROTOS.tcp, out2in_only=1,
+                                      self_twice_nat=1, vrf_id=1)
+        self.vapi.nat44_interface_add_del_feature(self.pg6.sw_if_index,
+                                                  is_inside=0)
 
         p = (Ether(src=self.pg6.remote_mac, dst=self.pg6.local_mac) /
              IP(src=self.pg6.remote_ip4, dst=self.pg1.remote_ip4) /
@@ -5409,18 +5320,12 @@ class TestNAT44EndpointDependent(MethodHolder):
 
         self.nat44_add_address(self.nat_addr)
         self.nat44_add_address(twice_nat_addr, twice_nat=1)
-
-        flags = 0
-        if self_twice_nat:
-            flags |= self.config_flags.NAT_IS_SELF_TWICE_NAT
-        else:
-            flags |= self.config_flags.NAT_IS_TWICE_NAT
-
         if not lb:
             self.nat44_add_static_mapping(pg0.remote_ip4, self.nat_addr,
                                           port_in, port_out,
                                           proto=IP_PROTOS.tcp,
-                                          flags=flags)
+                                          twice_nat=int(not self_twice_nat),
+                                          self_twice_nat=int(self_twice_nat))
         else:
             locals = [{'addr': server1.ip4n,
                        'port': port_in1,
@@ -5430,18 +5335,19 @@ class TestNAT44EndpointDependent(MethodHolder):
                        'port': port_in2,
                        'probability': 50,
                        'vrf_id': 0}]
-            out_addr = self.nat_addr
-
-            self.vapi.nat44_add_del_lb_static_mapping(out_addr,
+            out_addr_n = socket.inet_pton(socket.AF_INET, self.nat_addr)
+            self.vapi.nat44_add_del_lb_static_mapping(out_addr_n,
                                                       port_out,
                                                       IP_PROTOS.tcp,
+                                                      twice_nat=int(
+                                                          not self_twice_nat),
+                                                      self_twice_nat=int(
+                                                          self_twice_nat),
                                                       local_num=len(locals),
-                                                      locals=locals,
-                                                      flags=flags)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(pg1.sw_if_index)
+                                                      locals=locals)
+        self.vapi.nat44_interface_add_del_feature(pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(pg1.sw_if_index,
+                                                  is_inside=0)
 
         if same_pg:
             if not lb:
@@ -5514,17 +5420,12 @@ class TestNAT44EndpointDependent(MethodHolder):
         if eh_translate:
             sessions = self.vapi.nat44_user_session_dump(server.ip4n, 0)
             self.assertEqual(len(sessions), 1)
-            self.assertTrue(sessions[0].flags &
-                            self.config_flags.NAT_IS_EXT_HOST_VALID)
-            self.assertTrue(sessions[0].flags &
-                            self.config_flags.NAT_IS_TWICE_NAT)
-            self.logger.error(self.vapi.cli("show nat44 sessions detail"))
+            self.assertTrue(sessions[0].ext_host_valid)
+            self.assertTrue(sessions[0].is_twicenat)
             self.vapi.nat44_del_session(
                 sessions[0].inside_ip_address,
                 sessions[0].inside_port,
                 sessions[0].protocol,
-                flags=(self.config_flags.NAT_IS_INSIDE |
-                       self.config_flags.NAT_IS_EXT_HOST_VALID),
                 ext_host_address=sessions[0].ext_host_nat_address,
                 ext_host_port=sessions[0].ext_host_nat_port)
             sessions = self.vapi.nat44_user_session_dump(server.ip4n, 0)
@@ -5558,9 +5459,8 @@ class TestNAT44EndpointDependent(MethodHolder):
 
     def test_twice_nat_interface_addr(self):
         """ Acquire twice NAT44 addresses from interface """
-        flags = self.config_flags.NAT_IS_TWICE_NAT
         self.vapi.nat44_add_del_interface_addr(self.pg3.sw_if_index,
-                                               flags=flags)
+                                               twice_nat=1)
 
         # no address in NAT pool
         adresses = self.vapi.nat44_address_dump()
@@ -5570,9 +5470,8 @@ class TestNAT44EndpointDependent(MethodHolder):
         self.pg3.config_ip4()
         adresses = self.vapi.nat44_address_dump()
         self.assertEqual(1, len(adresses))
-        self.assertEqual(str(adresses[0].ip_address),
-                         self.pg3.local_ip4)
-        self.assertEqual(adresses[0].flags, flags)
+        self.assertEqual(adresses[0].ip_address[0:4], self.pg3.local_ip4n)
+        self.assertEqual(adresses[0].twice_nat, 1)
 
         # remove interface address and check NAT address pool
         self.pg3.unconfig_ip4()
@@ -5586,19 +5485,18 @@ class TestNAT44EndpointDependent(MethodHolder):
         twice_nat_addr = '10.0.1.3'
         service_ip = '192.168.16.150'
         self.nat44_add_address(twice_nat_addr, twice_nat=1)
-        flags = self.config_flags.NAT_IS_INSIDE
         self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
         self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index)
-        flags = (self.config_flags.NAT_IS_OUT2IN_ONLY |
-                 self.config_flags.NAT_IS_TWICE_NAT)
+                                                  is_inside=0)
+        self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index,
+                                                         is_inside=0)
         self.nat44_add_static_mapping(self.pg0.remote_ip4,
                                       service_ip,
                                       80,
                                       80,
                                       proto=IP_PROTOS.tcp,
-                                      flags=flags)
+                                      out2in_only=1,
+                                      twice_nat=1)
         sessions = self.vapi.nat44_user_session_dump(self.pg0.remote_ip4n, 0)
         start_sessnum = len(sessions)
 
@@ -5666,17 +5564,15 @@ class TestNAT44EndpointDependent(MethodHolder):
         """ Close TCP session from inside network """
         self.tcp_port_out = 10505
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_TWICE_NAT
         self.nat44_add_static_mapping(self.pg0.remote_ip4,
                                       self.nat_addr,
                                       self.tcp_port_in,
                                       self.tcp_port_out,
                                       proto=IP_PROTOS.tcp,
-                                      flags=flags)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+                                      twice_nat=1)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         sessions = self.vapi.nat44_user_session_dump(self.pg0.remote_ip4n, 0)
         start_sessnum = len(sessions)
@@ -5732,17 +5628,15 @@ class TestNAT44EndpointDependent(MethodHolder):
         """ Close TCP session from outside network """
         self.tcp_port_out = 10505
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_TWICE_NAT
         self.nat44_add_static_mapping(self.pg0.remote_ip4,
                                       self.nat_addr,
                                       self.tcp_port_in,
                                       self.tcp_port_out,
                                       proto=IP_PROTOS.tcp,
-                                      flags=flags)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+                                      twice_nat=1)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         sessions = self.vapi.nat44_user_session_dump(self.pg0.remote_ip4n, 0)
         start_sessnum = len(sessions)
@@ -5788,17 +5682,15 @@ class TestNAT44EndpointDependent(MethodHolder):
         """ Close TCP session from inside network """
         self.tcp_port_out = 10505
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_TWICE_NAT
         self.nat44_add_static_mapping(self.pg0.remote_ip4,
                                       self.nat_addr,
                                       self.tcp_port_in,
                                       self.tcp_port_out,
                                       proto=IP_PROTOS.tcp,
-                                      flags=flags)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+                                      twice_nat=1)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         sessions = self.vapi.nat44_user_session_dump(self.pg0.remote_ip4n, 0)
         start_sessnum = len(sessions)
@@ -5859,15 +5751,13 @@ class TestNAT44EndpointDependent(MethodHolder):
 
         self.vapi.nat44_forwarding_enable_disable(1)
         self.nat44_add_address(self.nat_addr, twice_nat=1)
-        flags = (self.config_flags.NAT_IS_OUT2IN_ONLY |
-                 self.config_flags.NAT_IS_TWICE_NAT)
         self.nat44_add_static_mapping(local_host.ip4, self.nat_addr,
                                       local_port, external_port,
-                                      proto=IP_PROTOS.tcp, flags=flags)
-        flags = self.config_flags.NAT_IS_INSIDE
+                                      proto=IP_PROTOS.tcp, out2in_only=1,
+                                      twice_nat=1)
         self.vapi.nat44_interface_add_del_feature(self.pg4.sw_if_index)
         self.vapi.nat44_interface_add_del_feature(self.pg4.sw_if_index,
-                                                  flags=flags)
+                                                  is_inside=0)
 
         # from client to service
         p = (Ether(src=self.pg4.remote_mac, dst=self.pg4.local_mac) /
@@ -5919,14 +5809,12 @@ class TestNAT44EndpointDependent(MethodHolder):
         local_port = 8080
 
         self.vapi.nat44_forwarding_enable_disable(1)
-        flags = self.config_flags.NAT_IS_OUT2IN_ONLY
         self.nat44_add_static_mapping(self.pg0.remote_ip4, self.nat_addr,
                                       local_port, external_port,
-                                      proto=IP_PROTOS.tcp, flags=flags)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+                                      proto=IP_PROTOS.tcp, out2in_only=1)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         # from client to service
         p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
@@ -6044,8 +5932,10 @@ class TestNAT44EndpointDependent(MethodHolder):
         """ NAT44 interface output feature (in2out postrouting) """
         self.vapi.nat44_forwarding_enable_disable(1)
         self.nat44_add_address(self.nat_addr)
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
-        self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
+                                                  is_inside=0)
+        self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index,
+                                                         is_inside=0)
 
         # in2out
         pkts = self.create_stream_in(self.pg0, self.pg1)
@@ -6072,28 +5962,23 @@ class TestNAT44EndpointDependent(MethodHolder):
 
         self.vapi.nat44_forwarding_enable_disable(1)
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
         self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
         self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index)
+                                                  is_inside=0)
+        self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index,
+                                                         is_inside=0)
         self.vapi.nat44_interface_add_del_feature(self.pg5.sw_if_index)
         self.vapi.nat44_interface_add_del_feature(self.pg5.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg6.sw_if_index)
-        flags = self.config_flags.NAT_IS_OUT2IN_ONLY
+                                                  is_inside=0)
+        self.vapi.nat44_interface_add_del_feature(self.pg6.sw_if_index,
+                                                  is_inside=0)
         self.nat44_add_static_mapping(self.pg5.remote_ip4, external_addr,
                                       local_port, external_port, vrf_id=1,
-                                      proto=IP_PROTOS.tcp, flags=flags)
+                                      proto=IP_PROTOS.tcp, out2in_only=1)
         self.nat44_add_static_mapping(
-                self.pg0.remote_ip4,
-                external_sw_if_index=self.pg0.sw_if_index,
-                local_port=local_port,
-                vrf_id=0,
-                external_port=external_port,
-                proto=IP_PROTOS.tcp,
-                flags=flags
-        )
+            self.pg0.remote_ip4, external_sw_if_index=self.pg0.sw_if_index,
+            local_port=local_port, vrf_id=0, external_port=external_port,
+            proto=IP_PROTOS.tcp, out2in_only=1)
 
         # from client to service (both VRF1)
         p = (Ether(src=self.pg6.remote_mac, dst=self.pg6.local_mac) /
@@ -6365,10 +6250,9 @@ class TestNAT44EndpointDependent(MethodHolder):
     def test_session_timeout(self):
         """ NAT44 session timeouts """
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
         self.vapi.nat_set_timeouts(icmp=5)
 
         max_sessions = 1000
@@ -6408,10 +6292,9 @@ class TestNAT44EndpointDependent(MethodHolder):
     def test_session_rst_timeout(self):
         """ NAT44 session RST timeouts """
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
         self.vapi.nat_set_timeouts(tcp_transitory=5)
 
         self.initiate_tcp_session(self.pg0, self.pg1)
@@ -6438,18 +6321,16 @@ class TestNAT44EndpointDependent(MethodHolder):
         nsessions = 0
         users = self.vapi.nat44_user_dump()
         self.assertEqual(len(users), 1)
-        self.assertEqual(str(users[0].ip_address),
-                         self.pg0.remote_ip4)
+        self.assertEqual(users[0].ip_address, self.pg0.remote_ip4n)
         self.assertEqual(users[0].nsessions, 1)
 
     @unittest.skipUnless(running_extended_tests, "part of extended tests")
     def test_session_limit_per_user(self):
         """ Maximum sessions per user limit """
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
         self.vapi.set_ipfix_exporter(collector_address=self.pg2.remote_ip4n,
                                      src_address=self.pg2.local_ip4n,
                                      path_mtu=512,
@@ -6515,10 +6396,9 @@ class TestNAT44EndpointDependent(MethodHolder):
         self.vapi.syslog_set_filter(SYSLOG_SEVERITY.INFO)
         self.vapi.syslog_set_sender(self.pg2.local_ip4n, self.pg2.remote_ip4n)
         self.nat44_add_address(self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
              IP(src=self.pg0.remote_ip4, dst=self.pg1.remote_ip4) /
@@ -6574,6 +6454,7 @@ class TestNAT44Out2InDPO(MethodHolder):
             cls.icmp_id_in = 6305
             cls.icmp_id_out = 6305
             cls.nat_addr = '10.0.0.3'
+            cls.nat_addr_n = socket.inet_pton(socket.AF_INET, cls.nat_addr)
             cls.dst_ip4 = '192.168.70.1'
 
             cls.create_pg_interfaces(range(2))
@@ -6622,9 +6503,7 @@ class TestNAT44Out2InDPO(MethodHolder):
 
         self.configure_xlat()
 
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
         self.vapi.nat44_add_del_address_range(self.nat_addr_n, self.nat_addr_n)
 
         out_src_ip6 = self.compose_ip6(self.dst_ip4, self.dst_ip6_pfx,
@@ -6650,7 +6529,7 @@ class TestNAT44Out2InDPO(MethodHolder):
             self.verify_capture_in(capture, self.pg0)
         finally:
             self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                      is_add=0, flags=flags)
+                                                      is_add=0)
             self.vapi.nat44_add_del_address_range(self.nat_addr_n,
                                                   self.nat_addr_n, is_add=0)
 
@@ -6810,26 +6689,28 @@ class TestDeterministicNAT(MethodHolder):
         in_addr = '172.16.255.0'
         out_addr = '172.17.255.50'
         in_addr_t = '172.16.255.20'
+        in_addr_n = socket.inet_aton(in_addr)
+        out_addr_n = socket.inet_aton(out_addr)
+        in_addr_t_n = socket.inet_aton(in_addr_t)
         in_plen = 24
         out_plen = 32
 
         nat_config = self.vapi.nat_show_config()
         self.assertEqual(1, nat_config.deterministic)
 
-        self.vapi.nat_det_add_del_map(1, in_addr, in_plen, out_addr, out_plen)
-
-        rep1 = self.vapi.nat_det_forward(in_addr_t)
-        self.assertEqual(str(rep1.out_addr), out_addr)
-        rep2 = self.vapi.nat_det_reverse(rep1.out_port_hi, out_addr)
+        self.vapi.nat_det_add_del_map(in_addr_n, in_plen, out_addr_n, out_plen)
 
-        self.assertEqual(str(rep2.in_addr), in_addr_t)
+        rep1 = self.vapi.nat_det_forward(in_addr_t_n)
+        self.assertEqual(rep1.out_addr[:4], out_addr_n)
+        rep2 = self.vapi.nat_det_reverse(out_addr_n, rep1.out_port_hi)
+        self.assertEqual(rep2.in_addr[:4], in_addr_t_n)
 
         deterministic_mappings = self.vapi.nat_det_map_dump()
         self.assertEqual(len(deterministic_mappings), 1)
         dsm = deterministic_mappings[0]
-        self.assertEqual(in_addr, str(dsm.in_addr))
+        self.assertEqual(in_addr_n, dsm.in_addr[:4])
         self.assertEqual(in_plen, dsm.in_plen)
-        self.assertEqual(out_addr, str(dsm.out_addr))
+        self.assertEqual(out_addr_n, dsm.out_addr[:4])
         self.assertEqual(out_plen, dsm.out_plen)
 
         self.clear_nat_det()
@@ -6859,16 +6740,13 @@ class TestDeterministicNAT(MethodHolder):
 
         nat_ip = "10.0.0.10"
 
-        self.vapi.nat_det_add_del_map(1,
-                                      self.pg0.remote_ip4n,
+        self.vapi.nat_det_add_del_map(self.pg0.remote_ip4n,
                                       32,
                                       socket.inet_aton(nat_ip),
                                       32)
-
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         # in2out
         pkts = self.create_stream_in(self.pg0, self.pg1)
@@ -6892,21 +6770,21 @@ class TestDeterministicNAT(MethodHolder):
 
         # TCP session
         s = sessions[0]
-        self.assertEqual(str(s.ext_addr), self.pg1.remote_ip4)
+        self.assertEqual(s.ext_addr[:4], self.pg1.remote_ip4n)
         self.assertEqual(s.in_port, self.tcp_port_in)
         self.assertEqual(s.out_port, self.tcp_port_out)
         self.assertEqual(s.ext_port, self.tcp_external_port)
 
         # UDP session
         s = sessions[1]
-        self.assertEqual(str(s.ext_addr), self.pg1.remote_ip4)
+        self.assertEqual(s.ext_addr[:4], self.pg1.remote_ip4n)
         self.assertEqual(s.in_port, self.udp_port_in)
         self.assertEqual(s.out_port, self.udp_port_out)
         self.assertEqual(s.ext_port, self.udp_external_port)
 
         # ICMP session
         s = sessions[2]
-        self.assertEqual(str(s.ext_addr), self.pg1.remote_ip4)
+        self.assertEqual(s.ext_addr[:4], self.pg1.remote_ip4n)
         self.assertEqual(s.in_port, self.icmp_id_in)
         self.assertEqual(s.out_port, self.icmp_external_id)
 
@@ -6920,15 +6798,13 @@ class TestDeterministicNAT(MethodHolder):
         host0 = self.pg0.remote_hosts[0]
         host1 = self.pg0.remote_hosts[1]
 
-        self.vapi.nat_det_add_del_map(1,
-                                      host0.ip4n,
+        self.vapi.nat_det_add_del_map(host0.ip4n,
                                       24,
                                       socket.inet_aton(nat_ip),
                                       32)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         # host0 to out
         p = (Ether(src=host0.mac, dst=self.pg0.local_mac) /
@@ -7031,15 +6907,13 @@ class TestDeterministicNAT(MethodHolder):
 
     def test_tcp_session_close_detection_in(self):
         """ Deterministic NAT TCP session close from inside network """
-        self.vapi.nat_det_add_del_map(1,
-                                      self.pg0.remote_ip4n,
+        self.vapi.nat_det_add_del_map(self.pg0.remote_ip4n,
                                       32,
                                       socket.inet_aton(self.nat_addr),
                                       32)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         self.initiate_tcp_session(self.pg0, self.pg1)
 
@@ -7095,15 +6969,13 @@ class TestDeterministicNAT(MethodHolder):
 
     def test_tcp_session_close_detection_out(self):
         """ Deterministic NAT TCP session close from outside network """
-        self.vapi.nat_det_add_del_map(1,
-                                      self.pg0.remote_ip4n,
+        self.vapi.nat_det_add_del_map(self.pg0.remote_ip4n,
                                       32,
                                       socket.inet_aton(self.nat_addr),
                                       32)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         self.initiate_tcp_session(self.pg0, self.pg1)
 
@@ -7160,15 +7032,13 @@ class TestDeterministicNAT(MethodHolder):
     @unittest.skipUnless(running_extended_tests, "part of extended tests")
     def test_session_timeout(self):
         """ Deterministic NAT session timeouts """
-        self.vapi.nat_det_add_del_map(1,
-                                      self.pg0.remote_ip4n,
+        self.vapi.nat_det_add_del_map(self.pg0.remote_ip4n,
                                       32,
                                       socket.inet_aton(self.nat_addr),
                                       32)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         self.initiate_tcp_session(self.pg0, self.pg1)
         self.vapi.nat_set_timeouts(5, 5, 5, 5)
@@ -7185,15 +7055,13 @@ class TestDeterministicNAT(MethodHolder):
     @unittest.skipUnless(running_extended_tests, "part of extended tests")
     def test_session_limit_per_user(self):
         """ Deterministic NAT maximum sessions per user limit """
-        self.vapi.nat_det_add_del_map(1,
-                                      self.pg0.remote_ip4n,
+        self.vapi.nat_det_add_del_map(self.pg0.remote_ip4n,
                                       32,
                                       socket.inet_aton(self.nat_addr),
                                       32)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
-                                                  flags=flags)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
         self.vapi.set_ipfix_exporter(collector_address=self.pg2.remote_ip4n,
                                      src_address=self.pg2.local_ip4n,
                                      path_mtu=512,
@@ -7262,17 +7130,17 @@ class TestDeterministicNAT(MethodHolder):
         self.vapi.nat_set_timeouts()
         deterministic_mappings = self.vapi.nat_det_map_dump()
         for dsm in deterministic_mappings:
-            self.vapi.nat_det_add_del_map(0,
-                                          dsm.in_addr,
+            self.vapi.nat_det_add_del_map(dsm.in_addr,
                                           dsm.in_plen,
                                           dsm.out_addr,
-                                          dsm.out_plen)
+                                          dsm.out_plen,
+                                          is_add=0)
 
         interfaces = self.vapi.nat44_interface_dump()
         for intf in interfaces:
             self.vapi.nat44_interface_add_del_feature(intf.sw_if_index,
-                                                      is_add=0,
-                                                      flags=intf.flags)
+                                                      intf.is_inside,
+                                                      is_add=0)
 
     def tearDown(self):
         super(TestDeterministicNAT, self).tearDown()
@@ -7313,6 +7181,8 @@ class TestNAT64(MethodHolder):
             cls.nat_addr_n = socket.inet_pton(socket.AF_INET, cls.nat_addr)
             cls.vrf1_id = 10
             cls.vrf1_nat_addr = '10.0.10.3'
+            cls.vrf1_nat_addr_n = socket.inet_pton(socket.AF_INET,
+                                                   cls.vrf1_nat_addr)
             cls.ipfix_src_port = 4739
             cls.ipfix_domain_id = 1
 
@@ -7358,8 +7228,7 @@ class TestNAT64(MethodHolder):
     def test_nat64_inside_interface_handles_neighbor_advertisement(self):
         """ NAT64 inside interface handles Neighbor Advertisement """
 
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat64_add_del_interface(1, flags, self.pg5.sw_if_index)
+        self.vapi.nat64_add_del_interface(self.pg5.sw_if_index)
 
         # Try to send ping
         ping = (Ether(dst=self.pg5.local_mac, src=self.pg5.remote_mac) /
@@ -7410,13 +7279,13 @@ class TestNAT64(MethodHolder):
 
     def test_pool(self):
         """ Add/delete address to NAT64 pool """
-        nat_addr = '1.2.3.4'
+        nat_addr = socket.inet_pton(socket.AF_INET, '1.2.3.4')
 
         self.vapi.nat64_add_del_pool_addr_range(nat_addr, nat_addr)
 
         addresses = self.vapi.nat64_pool_addr_dump()
         self.assertEqual(len(addresses), 1)
-        self.assertEqual(str(addresses[0].address), nat_addr)
+        self.assertEqual(addresses[0].address, nat_addr)
 
         self.vapi.nat64_add_del_pool_addr_range(nat_addr, nat_addr, is_add=0)
 
@@ -7425,9 +7294,8 @@ class TestNAT64(MethodHolder):
 
     def test_interface(self):
         """ Enable/disable NAT64 feature on the interface """
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat64_add_del_interface(1, flags, self.pg0.sw_if_index)
-        self.vapi.nat64_add_del_interface(1, 0, self.pg1.sw_if_index)
+        self.vapi.nat64_add_del_interface(self.pg0.sw_if_index)
+        self.vapi.nat64_add_del_interface(self.pg1.sw_if_index, is_inside=0)
 
         interfaces = self.vapi.nat64_interface_dump()
         self.assertEqual(len(interfaces), 2)
@@ -7435,10 +7303,10 @@ class TestNAT64(MethodHolder):
         pg1_found = False
         for intf in interfaces:
             if intf.sw_if_index == self.pg0.sw_if_index:
-                self.assertEqual(intf.flags, self.config_flags.NAT_IS_INSIDE)
+                self.assertEqual(intf.is_inside, 1)
                 pg0_found = True
             elif intf.sw_if_index == self.pg1.sw_if_index:
-                self.assertEqual(intf.flags, self.config_flags.NAT_IS_OUTSIDE)
+                self.assertEqual(intf.is_inside, 0)
                 pg1_found = True
         self.assertTrue(pg0_found)
         self.assertTrue(pg1_found)
@@ -7448,16 +7316,17 @@ class TestNAT64(MethodHolder):
         features = self.vapi.cli("show interface features pg1")
         self.assertIn('nat64-out2in', features)
 
-        self.vapi.nat64_add_del_interface(0, flags, self.pg0.sw_if_index)
-        self.vapi.nat64_add_del_interface(0, flags, self.pg1.sw_if_index)
+        self.vapi.nat64_add_del_interface(self.pg0.sw_if_index, is_add=0)
+        self.vapi.nat64_add_del_interface(self.pg1.sw_if_index, is_add=0)
 
         interfaces = self.vapi.nat64_interface_dump()
         self.assertEqual(len(interfaces), 0)
 
     def test_static_bib(self):
         """ Add/delete static BIB entry """
-        in_addr = '2001:db8:85a3::8a2e:370:7334'
-        out_addr = '10.1.1.3'
+        in_addr = socket.inet_pton(socket.AF_INET6,
+                                   '2001:db8:85a3::8a2e:370:7334')
+        out_addr = socket.inet_pton(socket.AF_INET, '10.1.1.3')
         in_port = 1234
         out_port = 5678
         proto = IP_PROTOS.tcp
@@ -7470,10 +7339,10 @@ class TestNAT64(MethodHolder):
         bib = self.vapi.nat64_bib_dump(IP_PROTOS.tcp)
         static_bib_num = 0
         for bibe in bib:
-            if bibe.flags & self.config_flags.NAT_IS_STATIC:
+            if bibe.is_static:
                 static_bib_num += 1
-                self.assertEqual(str(bibe.i_addr), in_addr)
-                self.assertEqual(str(bibe.o_addr), out_addr)
+                self.assertEqual(bibe.i_addr, in_addr)
+                self.assertEqual(bibe.o_addr, out_addr)
                 self.assertEqual(bibe.i_port, in_port)
                 self.assertEqual(bibe.o_port, out_port)
         self.assertEqual(static_bib_num, 1)
@@ -7489,7 +7358,7 @@ class TestNAT64(MethodHolder):
         bib = self.vapi.nat64_bib_dump(IP_PROTOS.tcp)
         static_bib_num = 0
         for bibe in bib:
-            if bibe.flags & self.config_flags.NAT_IS_STATIC:
+            if bibe.is_static:
                 static_bib_num += 1
         self.assertEqual(static_bib_num, 0)
         bibs = self.statistics.get_counter('/nat64/total-bibs')
@@ -7521,11 +7390,10 @@ class TestNAT64(MethodHolder):
 
         ses_num_start = self.nat64_get_ses_num()
 
-        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr,
-                                                self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat64_add_del_interface(1, flags, self.pg0.sw_if_index)
-        self.vapi.nat64_add_del_interface(1, 0, self.pg1.sw_if_index)
+        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr_n,
+                                                self.nat_addr_n)
+        self.vapi.nat64_add_del_interface(self.pg0.sw_if_index)
+        self.vapi.nat64_add_del_interface(self.pg1.sw_if_index, is_inside=0)
 
         # in2out
         tcpn = self.statistics.get_counter('/err/nat64-in2out/TCP packets')
@@ -7604,11 +7472,10 @@ class TestNAT64(MethodHolder):
         self.assertEqual(ses_num_end - ses_num_start, 3)
 
         # tenant with specific VRF
-        self.vapi.nat64_add_del_pool_addr_range(self.vrf1_nat_addr,
-                                                self.vrf1_nat_addr,
+        self.vapi.nat64_add_del_pool_addr_range(self.vrf1_nat_addr_n,
+                                                self.vrf1_nat_addr_n,
                                                 vrf_id=self.vrf1_id)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat64_add_del_interface(1, flags, self.pg2.sw_if_index)
+        self.vapi.nat64_add_del_interface(self.pg2.sw_if_index)
 
         pkts = self.create_stream_in_ip6(self.pg2, self.pg1)
         self.pg2.add_stream(pkts)
@@ -7636,24 +7503,23 @@ class TestNAT64(MethodHolder):
 
         ses_num_start = self.nat64_get_ses_num()
 
-        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr,
-                                                self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat64_add_del_interface(1, flags, self.pg0.sw_if_index)
-        self.vapi.nat64_add_del_interface(1, 0, self.pg1.sw_if_index)
+        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr_n,
+                                                self.nat_addr_n)
+        self.vapi.nat64_add_del_interface(self.pg0.sw_if_index)
+        self.vapi.nat64_add_del_interface(self.pg1.sw_if_index, is_inside=0)
 
         self.vapi.nat64_add_del_static_bib(self.pg0.remote_ip6n,
-                                           self.nat_addr,
+                                           self.nat_addr_n,
                                            self.tcp_port_in,
                                            self.tcp_port_out,
                                            IP_PROTOS.tcp)
         self.vapi.nat64_add_del_static_bib(self.pg0.remote_ip6n,
-                                           self.nat_addr,
+                                           self.nat_addr_n,
                                            self.udp_port_in,
                                            self.udp_port_out,
                                            IP_PROTOS.udp)
         self.vapi.nat64_add_del_static_bib(self.pg0.remote_ip6n,
-                                           self.nat_addr,
+                                           self.nat_addr_n,
                                            self.icmp_id_in,
                                            self.icmp_id_out,
                                            IP_PROTOS.icmp)
@@ -7684,11 +7550,10 @@ class TestNAT64(MethodHolder):
     def test_session_timeout(self):
         """ NAT64 session timeout """
         self.icmp_id_in = 1234
-        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr,
-                                                self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat64_add_del_interface(1, flags, self.pg0.sw_if_index)
-        self.vapi.nat64_add_del_interface(1, 0, self.pg1.sw_if_index)
+        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr_n,
+                                                self.nat_addr_n)
+        self.vapi.nat64_add_del_interface(self.pg0.sw_if_index)
+        self.vapi.nat64_add_del_interface(self.pg1.sw_if_index, is_inside=0)
         self.vapi.nat_set_timeouts(icmp=5, tcp_transitory=5, tcp_established=5)
 
         pkts = self.create_stream_in_ip6(self.pg0, self.pg1)
@@ -7711,11 +7576,10 @@ class TestNAT64(MethodHolder):
         self.udp_port_in = 6304
         self.icmp_id_in = 6305
 
-        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr,
-                                                self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat64_add_del_interface(1, flags, self.pg0.sw_if_index)
-        self.vapi.nat64_add_del_interface(1, 0, self.pg1.sw_if_index)
+        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr_n,
+                                                self.nat_addr_n)
+        self.vapi.nat64_add_del_interface(self.pg0.sw_if_index)
+        self.vapi.nat64_add_del_interface(self.pg1.sw_if_index, is_inside=0)
 
         # send some packets to create sessions
         pkts = self.create_stream_in_ip6(self.pg0, self.pg1)
@@ -7811,19 +7675,18 @@ class TestNAT64(MethodHolder):
         ip = IPv6(src=''.join(['64:ff9b::', self.nat_addr]))
         nat_addr_ip6 = ip.src
 
-        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr,
-                                                self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat64_add_del_interface(1, flags, self.pg0.sw_if_index)
-        self.vapi.nat64_add_del_interface(1, 0, self.pg1.sw_if_index)
+        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr_n,
+                                                self.nat_addr_n)
+        self.vapi.nat64_add_del_interface(self.pg0.sw_if_index)
+        self.vapi.nat64_add_del_interface(self.pg1.sw_if_index, is_inside=0)
 
         self.vapi.nat64_add_del_static_bib(server.ip6n,
-                                           self.nat_addr,
+                                           self.nat_addr_n,
                                            server_tcp_in_port,
                                            server_tcp_out_port,
                                            IP_PROTOS.tcp)
         self.vapi.nat64_add_del_static_bib(server.ip6n,
-                                           self.nat_addr,
+                                           self.nat_addr_n,
                                            server_udp_in_port,
                                            server_udp_out_port,
                                            IP_PROTOS.udp)
@@ -7923,34 +7786,34 @@ class TestNAT64(MethodHolder):
     def test_prefix(self):
         """ NAT64 Network-Specific Prefix """
 
-        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr,
-                                                self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat64_add_del_interface(1, flags, self.pg0.sw_if_index)
-        self.vapi.nat64_add_del_interface(1, 0, self.pg1.sw_if_index)
-        self.vapi.nat64_add_del_pool_addr_range(self.vrf1_nat_addr,
-                                                self.vrf1_nat_addr,
+        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr_n,
+                                                self.nat_addr_n)
+        self.vapi.nat64_add_del_interface(self.pg0.sw_if_index)
+        self.vapi.nat64_add_del_interface(self.pg1.sw_if_index, is_inside=0)
+        self.vapi.nat64_add_del_pool_addr_range(self.vrf1_nat_addr_n,
+                                                self.vrf1_nat_addr_n,
                                                 vrf_id=self.vrf1_id)
-        self.vapi.nat64_add_del_interface(1, flags, self.pg2.sw_if_index)
+        self.vapi.nat64_add_del_interface(self.pg2.sw_if_index)
 
         # Add global prefix
         global_pref64 = "2001:db8::"
+        global_pref64_n = socket.inet_pton(socket.AF_INET6, global_pref64)
         global_pref64_len = 32
-        global_pref64_str = "{}/{}".format(global_pref64, global_pref64_len)
-        self.vapi.nat64_add_del_prefix(global_pref64_str)
+        self.vapi.nat64_add_del_prefix(global_pref64_n, global_pref64_len)
 
         prefix = self.vapi.nat64_prefix_dump()
         self.assertEqual(len(prefix), 1)
-        self.assertEqual(prefix[0].prefix,
-                         IPv6Network(unicode(global_pref64_str)))
+        self.assertEqual(prefix[0].prefix, global_pref64_n)
+        self.assertEqual(prefix[0].prefix_len, global_pref64_len)
         self.assertEqual(prefix[0].vrf_id, 0)
 
         # Add tenant specific prefix
         vrf1_pref64 = "2001:db8:122:300::"
+        vrf1_pref64_n = socket.inet_pton(socket.AF_INET6, vrf1_pref64)
         vrf1_pref64_len = 56
-        vrf1_pref64_str = "{}/{}".format(vrf1_pref64, vrf1_pref64_len)
-        self.vapi.nat64_add_del_prefix(vrf1_pref64_str, vrf_id=self.vrf1_id)
-
+        self.vapi.nat64_add_del_prefix(vrf1_pref64_n,
+                                       vrf1_pref64_len,
+                                       vrf_id=self.vrf1_id)
         prefix = self.vapi.nat64_prefix_dump()
         self.assertEqual(len(prefix), 2)
 
@@ -8001,11 +7864,10 @@ class TestNAT64(MethodHolder):
     def test_unknown_proto(self):
         """ NAT64 translate packet with unknown protocol """
 
-        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr,
-                                                self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat64_add_del_interface(1, flags, self.pg0.sw_if_index)
-        self.vapi.nat64_add_del_interface(1, 0, self.pg1.sw_if_index)
+        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr_n,
+                                                self.nat_addr_n)
+        self.vapi.nat64_add_del_interface(self.pg0.sw_if_index)
+        self.vapi.nat64_add_del_interface(self.pg1.sw_if_index, is_inside=0)
         remote_ip6 = self.compose_ip6(self.pg1.remote_ip4, '64:ff9b::', 96)
 
         # in2out
@@ -8066,29 +7928,30 @@ class TestNAT64(MethodHolder):
         client_tcp_out_port = 1235
         server_nat_ip = "10.0.0.100"
         client_nat_ip = "10.0.0.110"
+        server_nat_ip_n = socket.inet_pton(socket.AF_INET, server_nat_ip)
+        client_nat_ip_n = socket.inet_pton(socket.AF_INET, client_nat_ip)
         server_nat_ip6 = self.compose_ip6(server_nat_ip, '64:ff9b::', 96)
         client_nat_ip6 = self.compose_ip6(client_nat_ip, '64:ff9b::', 96)
 
-        self.vapi.nat64_add_del_pool_addr_range(server_nat_ip,
-                                                client_nat_ip)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat64_add_del_interface(1, flags, self.pg0.sw_if_index)
-        self.vapi.nat64_add_del_interface(1, 0, self.pg1.sw_if_index)
+        self.vapi.nat64_add_del_pool_addr_range(server_nat_ip_n,
+                                                client_nat_ip_n)
+        self.vapi.nat64_add_del_interface(self.pg0.sw_if_index)
+        self.vapi.nat64_add_del_interface(self.pg1.sw_if_index, is_inside=0)
 
         self.vapi.nat64_add_del_static_bib(server.ip6n,
-                                           server_nat_ip,
+                                           server_nat_ip_n,
                                            server_tcp_in_port,
                                            server_tcp_out_port,
                                            IP_PROTOS.tcp)
 
         self.vapi.nat64_add_del_static_bib(server.ip6n,
-                                           server_nat_ip,
+                                           server_nat_ip_n,
                                            0,
                                            0,
                                            IP_PROTOS.gre)
 
         self.vapi.nat64_add_del_static_bib(client.ip6n,
-                                           client_nat_ip,
+                                           client_nat_ip_n,
                                            client_tcp_in_port,
                                            client_tcp_out_port,
                                            IP_PROTOS.tcp)
@@ -8146,11 +8009,10 @@ class TestNAT64(MethodHolder):
                                            '64:ff9b::',
                                            96)
 
-        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr,
-                                                self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat64_add_del_interface(1, flags, self.pg3.sw_if_index)
-        self.vapi.nat64_add_del_interface(1, 0, self.pg3.sw_if_index)
+        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr_n,
+                                                self.nat_addr_n)
+        self.vapi.nat64_add_del_interface(self.pg3.sw_if_index)
+        self.vapi.nat64_add_del_interface(self.pg3.sw_if_index, is_inside=0)
 
         # in2out
         p = (Ether(src=self.pg3.remote_mac, dst=self.pg3.local_mac) /
@@ -8199,11 +8061,10 @@ class TestNAT64(MethodHolder):
         """ NAT64 translate fragments arriving in order """
         self.tcp_port_in = random.randint(1025, 65535)
 
-        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr,
-                                                self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat64_add_del_interface(1, flags, self.pg0.sw_if_index)
-        self.vapi.nat64_add_del_interface(1, 0, self.pg1.sw_if_index)
+        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr_n,
+                                                self.nat_addr_n)
+        self.vapi.nat64_add_del_interface(self.pg0.sw_if_index)
+        self.vapi.nat64_add_del_interface(self.pg1.sw_if_index, is_inside=0)
 
         reass = self.vapi.nat_reass_dump()
         reass_n_start = len(reass)
@@ -8256,15 +8117,14 @@ class TestNAT64(MethodHolder):
         ip = IPv6(src=''.join(['64:ff9b::', self.nat_addr]))
         nat_addr_ip6 = ip.src
 
-        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr,
-                                                self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat64_add_del_interface(1, flags, self.pg0.sw_if_index)
-        self.vapi.nat64_add_del_interface(1, 0, self.pg1.sw_if_index)
+        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr_n,
+                                                self.nat_addr_n)
+        self.vapi.nat64_add_del_interface(self.pg0.sw_if_index)
+        self.vapi.nat64_add_del_interface(self.pg1.sw_if_index, is_inside=0)
 
         # add static BIB entry for server
         self.vapi.nat64_add_del_static_bib(server.ip6n,
-                                           self.nat_addr,
+                                           self.nat_addr_n,
                                            server_in_port,
                                            server_out_port,
                                            IP_PROTOS.tcp)
@@ -8288,11 +8148,10 @@ class TestNAT64(MethodHolder):
         """ NAT64 translate fragments arriving out of order """
         self.tcp_port_in = random.randint(1025, 65535)
 
-        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr,
-                                                self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat64_add_del_interface(1, flags, self.pg0.sw_if_index)
-        self.vapi.nat64_add_del_interface(1, 0, self.pg1.sw_if_index)
+        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr_n,
+                                                self.nat_addr_n)
+        self.vapi.nat64_add_del_interface(self.pg0.sw_if_index)
+        self.vapi.nat64_add_del_interface(self.pg1.sw_if_index, is_inside=0)
 
         # in2out
         data = b'a' * 200
@@ -8341,9 +8200,7 @@ class TestNAT64(MethodHolder):
         self.pg4.config_ip4()
         addresses = self.vapi.nat64_pool_addr_dump()
         self.assertEqual(len(addresses), 1)
-
-        self.assertEqual(str(addresses[0].address),
-                         self.pg4.local_ip4)
+        self.assertEqual(addresses[0].address, self.pg4.local_ip4n)
 
         # remove interface address and check NAT64 address pool
         self.pg4.unconfig_ip4()
@@ -8359,11 +8216,10 @@ class TestNAT64(MethodHolder):
                                            '64:ff9b::',
                                            96)
 
-        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr,
-                                                self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat64_add_del_interface(1, flags, self.pg0.sw_if_index)
-        self.vapi.nat64_add_del_interface(1, 0, self.pg1.sw_if_index)
+        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr_n,
+                                                self.nat_addr_n)
+        self.vapi.nat64_add_del_interface(self.pg0.sw_if_index)
+        self.vapi.nat64_add_del_interface(self.pg1.sw_if_index, is_inside=0)
 
         pkts = []
         src = ""
@@ -8442,11 +8298,10 @@ class TestNAT64(MethodHolder):
 
     def test_ipfix_max_frags(self):
         """ IPFIX logging maximum fragments pending reassembly exceeded """
-        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr,
-                                                self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat64_add_del_interface(1, flags, self.pg0.sw_if_index)
-        self.vapi.nat64_add_del_interface(1, 0, self.pg1.sw_if_index)
+        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr_n,
+                                                self.nat_addr_n)
+        self.vapi.nat64_add_del_interface(self.pg0.sw_if_index)
+        self.vapi.nat64_add_del_interface(self.pg1.sw_if_index, is_inside=0)
         self.vapi.nat_set_reass(max_frag=1, is_ip6=1)
         self.vapi.set_ipfix_exporter(collector_address=self.pg3.remote_ip4n,
                                      src_address=self.pg3.local_ip4n,
@@ -8492,11 +8347,10 @@ class TestNAT64(MethodHolder):
                                            '64:ff9b::',
                                            96)
 
-        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr,
-                                                self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat64_add_del_interface(1, flags, self.pg0.sw_if_index)
-        self.vapi.nat64_add_del_interface(1, 0, self.pg1.sw_if_index)
+        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr_n,
+                                                self.nat_addr_n)
+        self.vapi.nat64_add_del_interface(self.pg0.sw_if_index)
+        self.vapi.nat64_add_del_interface(self.pg1.sw_if_index, is_inside=0)
         self.vapi.set_ipfix_exporter(collector_address=self.pg3.remote_ip4n,
                                      src_address=self.pg3.local_ip4n,
                                      path_mtu=512,
@@ -8544,8 +8398,8 @@ class TestNAT64(MethodHolder):
 
         # Delete
         self.pg_enable_capture(self.pg_interfaces)
-        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr,
-                                                self.nat_addr,
+        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr_n,
+                                                self.nat_addr_n,
                                                 is_add=0)
         self.vapi.cli("ipfix flush")  # FIXME this should be an API call
         capture = self.pg3.get_capture(2)
@@ -8578,11 +8432,10 @@ class TestNAT64(MethodHolder):
                                            '64:ff9b::',
                                            96)
 
-        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr,
-                                                self.nat_addr)
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat64_add_del_interface(1, flags, self.pg0.sw_if_index)
-        self.vapi.nat64_add_del_interface(1, 0, self.pg1.sw_if_index)
+        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr_n,
+                                                self.nat_addr_n)
+        self.vapi.nat64_add_del_interface(self.pg0.sw_if_index)
+        self.vapi.nat64_add_del_interface(self.pg1.sw_if_index, is_inside=0)
         self.vapi.syslog_set_filter(SYSLOG_SEVERITY.INFO)
         self.vapi.syslog_set_sender(self.pg3.local_ip4n, self.pg3.remote_ip4n)
 
@@ -8599,8 +8452,8 @@ class TestNAT64(MethodHolder):
 
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr,
-                                                self.nat_addr,
+        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr_n,
+                                                self.nat_addr_n,
                                                 is_add=0)
         capture = self.pg3.get_capture(1)
         self.verify_syslog_sess(capture[0][Raw].load, False, True)
@@ -8628,13 +8481,17 @@ class TestNAT64(MethodHolder):
 
         interfaces = self.vapi.nat64_interface_dump()
         for intf in interfaces:
-            self.vapi.nat64_add_del_interface(0,
-                                              intf.flags,
-                                              intf.sw_if_index)
+            if intf.is_inside > 1:
+                self.vapi.nat64_add_del_interface(intf.sw_if_index,
+                                                  0,
+                                                  is_add=0)
+            self.vapi.nat64_add_del_interface(intf.sw_if_index,
+                                              intf.is_inside,
+                                              is_add=0)
 
         bib = self.vapi.nat64_bib_dump(255)
         for bibe in bib:
-            if bibe.flags & self.config_flags.NAT_IS_STATIC:
+            if bibe.is_static:
                 self.vapi.nat64_add_del_static_bib(bibe.i_addr,
                                                    bibe.o_addr,
                                                    bibe.i_port,
@@ -8652,7 +8509,8 @@ class TestNAT64(MethodHolder):
 
         prefixes = self.vapi.nat64_prefix_dump()
         for prefix in prefixes:
-            self.vapi.nat64_add_del_prefix(str(prefix.prefix),
+            self.vapi.nat64_add_del_prefix(prefix.prefix,
+                                           prefix.prefix_len,
                                            vrf_id=prefix.vrf_id,
                                            is_add=0)
 
@@ -8684,6 +8542,7 @@ class TestDSlite(MethodHolder):
 
         try:
             cls.nat_addr = '10.0.0.3'
+            cls.nat_addr_n = socket.inet_pton(socket.AF_INET, cls.nat_addr)
 
             cls.create_pg_interfaces(range(3))
             cls.pg0.admin_up()
@@ -8733,11 +8592,13 @@ class TestDSlite(MethodHolder):
         nat_config = self.vapi.nat_show_config()
         self.assertEqual(0, nat_config.dslite_ce)
 
-        self.vapi.dslite_add_del_pool_addr_range(self.nat_addr,
-                                                 self.nat_addr)
+        self.vapi.dslite_add_del_pool_addr_range(self.nat_addr_n,
+                                                 self.nat_addr_n)
         aftr_ip4 = '192.0.0.1'
+        aftr_ip4_n = socket.inet_pton(socket.AF_INET, aftr_ip4)
         aftr_ip6 = '2001:db8:85a3::8a2e:370:1'
-        self.vapi.dslite_set_aftr_addr(aftr_ip6, aftr_ip4)
+        aftr_ip6_n = socket.inet_pton(socket.AF_INET6, aftr_ip6)
+        self.vapi.dslite_set_aftr_addr(aftr_ip6_n, aftr_ip4_n)
         self.vapi.syslog_set_sender(self.pg2.local_ip4n, self.pg2.remote_ip4n)
 
         # UDP
@@ -8909,13 +8770,16 @@ class TestDSliteCE(MethodHolder):
         self.assertEqual(1, nat_config.dslite_ce)
 
         b4_ip4 = '192.0.0.2'
+        b4_ip4_n = socket.inet_pton(socket.AF_INET, b4_ip4)
         b4_ip6 = '2001:db8:62aa::375e:f4c1:1'
-        self.vapi.dslite_set_b4_addr(b4_ip6, b4_ip4)
+        b4_ip6_n = socket.inet_pton(socket.AF_INET6, b4_ip6)
+        self.vapi.dslite_set_b4_addr(b4_ip6_n, b4_ip4_n)
 
         aftr_ip4 = '192.0.0.1'
+        aftr_ip4_n = socket.inet_pton(socket.AF_INET, aftr_ip4)
         aftr_ip6 = '2001:db8:85a3::8a2e:370:1'
         aftr_ip6_n = socket.inet_pton(socket.AF_INET6, aftr_ip6)
-        self.vapi.dslite_set_aftr_addr(aftr_ip6, aftr_ip4)
+        self.vapi.dslite_set_aftr_addr(aftr_ip6_n, aftr_ip4_n)
 
         self.vapi.ip_add_del_route(dst_address=aftr_ip6_n,
                                    dst_address_length=128,
@@ -8989,6 +8853,7 @@ class TestNAT66(MethodHolder):
 
         try:
             cls.nat_addr = 'fd01:ff::2'
+            cls.nat_addr_n = socket.inet_pton(socket.AF_INET6, cls.nat_addr)
 
             cls.create_pg_interfaces(range(2))
             cls.interfaces = list(cls.pg_interfaces)
@@ -9008,11 +8873,10 @@ class TestNAT66(MethodHolder):
 
     def test_static(self):
         """ 1:1 NAT66 test """
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat66_add_del_interface(self.pg0.sw_if_index, flags=flags)
-        self.vapi.nat66_add_del_interface(self.pg1.sw_if_index)
+        self.vapi.nat66_add_del_interface(self.pg0.sw_if_index)
+        self.vapi.nat66_add_del_interface(self.pg1.sw_if_index, is_inside=0)
         self.vapi.nat66_add_del_static_mapping(self.pg0.remote_ip6n,
-                                               self.nat_addr)
+                                               self.nat_addr_n)
 
         # in2out
         pkts = []
@@ -9082,11 +8946,10 @@ class TestNAT66(MethodHolder):
 
     def test_check_no_translate(self):
         """ NAT66 translate only when egress interface is outside interface """
-        flags = self.config_flags.NAT_IS_INSIDE
-        self.vapi.nat66_add_del_interface(self.pg0.sw_if_index, flags=flags)
-        self.vapi.nat66_add_del_interface(self.pg1.sw_if_index, flags=flags)
+        self.vapi.nat66_add_del_interface(self.pg0.sw_if_index)
+        self.vapi.nat66_add_del_interface(self.pg1.sw_if_index)
         self.vapi.nat66_add_del_static_mapping(self.pg0.remote_ip6n,
-                                               self.nat_addr)
+                                               self.nat_addr_n)
 
         # in2out
         p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
@@ -9111,8 +8974,8 @@ class TestNAT66(MethodHolder):
         interfaces = self.vapi.nat66_interface_dump()
         for intf in interfaces:
             self.vapi.nat66_add_del_interface(intf.sw_if_index,
-                                              is_add=0,
-                                              flags=intf.flags)
+                                              intf.is_inside,
+                                              is_add=0)
 
         static_mappings = self.vapi.nat66_static_mapping_dump()
         for sm in static_mappings:
diff --git a/test/vpp_papi_provider.py b/test/vpp_papi_provider.py
index bda1aea425c..62fc0aa42b3 100644
--- a/test/vpp_papi_provider.py
+++ b/test/vpp_papi_provider.py
@@ -122,22 +122,23 @@ defaultmapping = {
     'mpls_tunnel_dump': {'sw_if_index': 4294967295, },
     'nat44_add_del_address_range': {'is_add': 1, 'vrf_id': 4294967295, },
     'nat44_add_del_identity_mapping': {'ip': b'0', 'sw_if_index': 4294967295,
-                                       'is_add': 1, },
+                                       'addr_only': 1, 'is_add': 1, },
     'nat44_add_del_interface_addr': {'is_add': 1, },
     'nat44_add_del_lb_static_mapping': {'is_add': 1, },
     'nat44_add_del_static_mapping': {'external_sw_if_index': 4294967295,
-                                     'is_add': 1, },
-    'nat44_interface_add_del_feature': {'is_add': 1, },
-    'nat44_interface_add_del_output_feature': {'is_add': 1, },
+                                     'addr_only': 1, 'is_add': 1, },
+    'nat44_del_session': {'is_in': 1, },
+    'nat44_interface_add_del_feature': {'is_inside': 1, 'is_add': 1, },
+    'nat44_interface_add_del_output_feature': {'is_inside': 1, 'is_add': 1, },
     'nat44_lb_static_mapping_add_del_local': {'is_add': 1, },
-    'nat64_add_del_interface': {'is_add': 1, },
+    'nat64_add_del_interface': {'is_inside': 1, 'is_add': 1, },
     'nat64_add_del_interface_addr': {'is_add': 1, },
     'nat64_add_del_pool_addr_range': {'vrf_id': 4294967295, 'is_add': 1, },
     'nat64_add_del_prefix': {'is_add': 1, },
     'nat64_add_del_static_bib': {'is_add': 1, },
     'nat64_bib_dump': {'protocol': 255, },
     'nat64_st_dump': {'protocol': 255, },
-    'nat66_add_del_interface': {'is_add': 1, },
+    'nat66_add_del_interface': {'is_inside': 1, 'is_add': 1, },
     'nat66_add_del_static_mapping': {'is_add': 1, },
     'nat_det_add_del_map': {'is_add': 1, },
     'nat_ha_resync': {'want_resync_event': 1, },
@@ -754,35 +755,35 @@ class VppPapiProvider(object):
     def nat44_interface_add_del_feature(
             self,
             sw_if_index,
-            is_add=1,
-            flags=0):
+            is_inside=1,
+            is_add=1):
         """Enable/disable NAT44 feature on the interface
 
         :param sw_if_index: Software index of the interface
+        :param is_inside: 1 if inside, 0 if outside (Default value = 1)
         :param is_add: 1 if add, 0 if delete (Default value = 1)
-        :param flags: NAT_IS_INSIDE if inside else outside
         """
         return self.api(
             self.papi.nat44_interface_add_del_feature,
             {'is_add': is_add,
-             'flags': flags,
+             'is_inside': is_inside,
              'sw_if_index': sw_if_index})
 
     def nat44_interface_add_del_output_feature(
             self,
             sw_if_index,
-            is_add=1,
-            flags=0):
+            is_inside=1,
+            is_add=1):
         """Enable/disable NAT44 output feature on the interface
 
         :param sw_if_index: Software index of the interface
+        :param is_inside: 1 if inside, 0 if outside (Default value = 1)
         :param is_add: 1 if add, 0 if delete (Default value = 1)
-        :param flags: NAT_IS_INSIDE if inside else outside
         """
         return self.api(
             self.papi.nat44_interface_add_del_output_feature,
             {'is_add': is_add,
-             'flags': flags,
+             'is_inside': is_inside,
              'sw_if_index': sw_if_index})
 
     def nat44_add_del_static_mapping(
@@ -792,11 +793,14 @@ class VppPapiProvider(object):
             external_sw_if_index=0xFFFFFFFF,
             local_port=0,
             external_port=0,
+            addr_only=1,
             vrf_id=0,
             protocol=0,
-            is_add=1,
-            flags=0,
-            tag=""):
+            twice_nat=0,
+            self_twice_nat=0,
+            out2in_only=0,
+            tag="",
+            is_add=1):
         """Add/delete NAT44 static mapping
 
         :param local_ip: Local IP address
@@ -804,23 +808,31 @@ class VppPapiProvider(object):
         :param external_sw_if_index: External interface instead of IP address
         :param local_port: Local port number (Default value = 0)
         :param external_port: External port number (Default value = 0)
+        :param addr_only: 1 if address only mapping, 0 if address and port
         :param vrf_id: VRF ID
         :param protocol: IP protocol (Default value = 0)
-        :param flags: NAT configuration flags
-        :param is_add: 1 if add, 0 if delete (Default value = 1)
+        :param twice_nat: 1 if translate external host address and port
+        :param self_twice_nat: 1 if translate external host address and port
+                               whenever external host address equals
+                               local address of internal host
+        :param out2in_only: if 1 rule is matching only out2in direction
         :param tag: Opaque string tag
+        :param is_add: 1 if add, 0 if delete (Default value = 1)
         """
         return self.api(
             self.papi.nat44_add_del_static_mapping,
             {'is_add': is_add,
-             'flags': flags,
+             'addr_only': addr_only,
              'local_ip_address': local_ip,
              'external_ip_address': external_ip,
-             'protocol': protocol,
              'local_port': local_port,
              'external_port': external_port,
              'external_sw_if_index': external_sw_if_index,
              'vrf_id': vrf_id,
+             'protocol': protocol,
+             'twice_nat': twice_nat,
+             'self_twice_nat': self_twice_nat,
+             'out2in_only': out2in_only,
              'tag': tag})
 
     def nat44_add_del_identity_mapping(
@@ -828,7 +840,7 @@ class VppPapiProvider(object):
             ip=b'0',
             sw_if_index=0xFFFFFFFF,
             port=0,
-            flags=0,
+            addr_only=1,
             vrf_id=0,
             protocol=0,
             tag='',
@@ -838,7 +850,7 @@ class VppPapiProvider(object):
         :param ip: IP address (Default value = 0)
         :param sw_if_index: Interface instead of IP address
         :param port: Port number (Default value = 0)
-        :param flags: NAT configuration flags (NAT_IS_ADDR_ONLY)
+        :param addr_only: 1 if address only mapping, 0 if address and port
         :param vrf_id: VRF ID
         :param protocol: IP protocol (Default value = 0)
         :param tag: Opaque string tag
@@ -847,13 +859,13 @@ class VppPapiProvider(object):
         return self.api(
             self.papi.nat44_add_del_identity_mapping,
             {'is_add': is_add,
-             'flags': flags,
+             'addr_only': addr_only,
              'ip_address': ip,
-             'protocol': protocol,
              'port': port,
              'sw_if_index': sw_if_index,
              'vrf_id': vrf_id,
-             'tag': tag})
+             'tag': tag,
+             'protocol': protocol})
 
     def nat44_add_del_address_range(
             self,
@@ -861,69 +873,73 @@ class VppPapiProvider(object):
             last_ip_address,
             is_add=1,
             vrf_id=0xFFFFFFFF,
-            flags=0):
+            twice_nat=0):
         """Add/del NAT44 address range
 
         :param first_ip_address: First IP address
         :param last_ip_address: Last IP address
         :param vrf_id: VRF id for the address range
+        :param twice_nat: twice NAT address for extenral hosts
         :param is_add: 1 if add, 0 if delete (Default value = 1)
-        :param flags: NAT configuration flags (NAT_IS_TWICE_NAT)
         """
         return self.api(
             self.papi.nat44_add_del_address_range,
             {'first_ip_address': first_ip_address,
              'last_ip_address': last_ip_address,
              'vrf_id': vrf_id,
-             'is_add': is_add,
-             'flags': flags})
+             'twice_nat': twice_nat,
+             'is_add': is_add})
 
     def nat44_add_del_interface_addr(
             self,
             sw_if_index,
-            flags=0,
+            twice_nat=0,
             is_add=1):
         """Add/del NAT44 address from interface
 
         :param sw_if_index: Software index of the interface
-        :param flags: NAT configuration flags (NAT_IS_TWICE_NAT)
+        :param twice_nat: twice NAT address for external hosts
         :param is_add: 1 if add, 0 if delete (Default value = 1)
         """
         return self.api(
             self.papi.nat44_add_del_interface_addr,
             {'is_add': is_add,
              'sw_if_index': sw_if_index,
-             'flags': flags})
+             'twice_nat': twice_nat})
 
     def nat44_add_del_lb_static_mapping(
             self,
             external_addr,
             external_port,
             protocol,
+            twice_nat=0,
+            self_twice_nat=0,
+            out2in_only=0,
             tag='',
             affinity=0,
             local_num=0,
             locals=[],
-            flags=0,
             is_add=1):
         """Add/delete NAT44 load balancing static mapping
 
+        :param twice_nat: 1 if translate external host address and port
         :param tag: Opaque string tag
         :param affinity: if 0 disabled, otherwise client IP affinity timeout
-        :param flags: NAT configuration flags (NAT_IS_TWICE_NAT)
         :param is_add - 1 if add, 0 if delete
         """
         return self.api(
             self.papi.nat44_add_del_lb_static_mapping,
             {'is_add': is_add,
-             'flags': flags,
              'external_addr': external_addr,
              'external_port': external_port,
              'protocol': protocol,
+             'twice_nat': twice_nat,
+             'self_twice_nat': self_twice_nat,
+             'out2in_only': out2in_only,
+             'tag': tag,
              'affinity': affinity,
              'local_num': local_num,
-             'locals': locals,
-             'tag': tag})
+             'locals': locals})
 
     def nat44_lb_static_mapping_add_del_local(
             self,
@@ -964,7 +980,7 @@ class VppPapiProvider(object):
             port,
             protocol,
             vrf_id=0,
-            flags=0,
+            is_in=1,
             ext_host_address=None,
             ext_host_port=0):
         """Delete NAT44 session
@@ -973,19 +989,29 @@ class VppPapiProvider(object):
         :param por: port number
         :param protocol: IP protocol number
         :param vrf_id: VRF ID
-        :param flags: NAT configuration flags (NAT_IS_INSIDE)
+        :param is_in: 1 if inside network address and port pair, 0 if outside
         :param ext_host_address: external host IPv4 address
         :param ext_host_port: external host port
         """
-        return self.api(
-            self.papi.nat44_del_session,
-            {'address': addr,
-             'protocol': protocol,
-             'port': port,
-             'vrf_id': vrf_id,
-             'flags': flags,
-             'ext_host_address': ext_host_address,
-             'ext_host_port': ext_host_port})
+        if ext_host_address is None:
+            return self.api(
+                self.papi.nat44_del_session,
+                {'address': addr,
+                 'port': port,
+                 'protocol': protocol,
+                 'vrf_id': vrf_id,
+                 'is_in': is_in})
+        else:
+            return self.api(
+                self.papi.nat44_del_session,
+                {'address': addr,
+                 'port': port,
+                 'protocol': protocol,
+                 'vrf_id': vrf_id,
+                 'is_in': is_in,
+                 'ext_host_valid': 1,
+                 'ext_host_address': ext_host_address,
+                 'ext_host_port': ext_host_port})
 
     def nat44_forwarding_enable_disable(
             self,
@@ -998,6 +1024,56 @@ class VppPapiProvider(object):
             self.papi.nat44_forwarding_enable_disable,
             {'enable': enable})
 
+    def nat_det_add_del_map(
+            self,
+            in_addr,
+            in_plen,
+            out_addr,
+            out_plen,
+            is_add=1):
+        """Add/delete deterministic NAT mapping
+
+        :param is_add - 1 if add, 0 if delete
+        :param in_addr - inside IP address
+        :param in_plen - inside IP address prefix length
+        :param out_addr - outside IP address
+        :param out_plen - outside IP address prefix length
+        """
+        return self.api(
+            self.papi.nat_det_add_del_map,
+            {'is_add': is_add,
+             'is_nat44': 1,
+             'in_addr': in_addr,
+             'in_plen': in_plen,
+             'out_addr': out_addr,
+             'out_plen': out_plen})
+
+    def nat_det_forward(
+            self,
+            in_addr):
+        """Get outside address and port range from inside address
+
+        :param in_addr - inside IP address
+        """
+        return self.api(
+            self.papi.nat_det_forward,
+            {'in_addr': in_addr,
+             'is_nat44': 1})
+
+    def nat_det_reverse(
+            self,
+            out_addr,
+            out_port):
+        """Get inside address from outside address and port
+
+        :param out_addr - outside IP address
+        :param out_port - outside port
+        """
+        return self.api(
+            self.papi.nat_det_reverse,
+            {'out_addr': out_addr,
+             'out_port': out_port})
+
     def nat_det_map_dump(self):
         """Dump deterministic NAT mappings
 
@@ -1015,6 +1091,56 @@ class VppPapiProvider(object):
             self.papi.nat_set_mss_clamping,
             {'enable': enable, 'mss_value': mss_value})
 
+    def nat_det_close_session_in(
+            self,
+            in_addr,
+            in_port,
+            ext_addr,
+            ext_port):
+        """Close deterministic NAT session using inside address and port
+
+        :param in_addr - inside IP address
+        :param in_port - inside port
+        :param ext_addr - external host IP address
+        :param ext_port - external host port
+        """
+        return self.api(
+            self.papi.nat_det_close_session_in,
+            {'in_addr': in_addr,
+             'in_port': in_port,
+             'ext_addr': ext_addr,
+             'ext_port': ext_port,
+             'is_nat44': 1})
+
+    def nat_det_session_dump(
+            self,
+            user_addr):
+        """Dump deterministic NAT sessions belonging to a user
+
+        :param user_addr - inside IP address of the user
+        :return: Dictionary of deterministic NAT sessions
+        """
+        return self.api(
+            self.papi.nat_det_session_dump,
+            {'is_nat44': 1,
+             'user_addr': user_addr})
+
+    def nat64_add_del_interface(
+            self,
+            sw_if_index,
+            is_inside=1,
+            is_add=1):
+        """Enable/disable NAT64 feature on the interface
+           :param sw_if_index: Index of the interface
+           :param is_inside: 1 if inside, 0 if outside (Default value = 1)
+           :param is_add: 1 if add, 0 if delete (Default value = 1)
+        """
+        return self.api(
+            self.papi.nat64_add_del_interface,
+            {'sw_if_index': sw_if_index,
+             'is_inside': is_inside,
+             'is_add': is_add})
+
     def nat64_add_del_static_bib(
             self,
             in_ip,
@@ -1060,16 +1186,18 @@ class VppPapiProvider(object):
         """
         return self.api(self.papi.nat64_st_dump, {'proto': protocol})
 
-    def nat64_add_del_prefix(self, prefix, vrf_id=0, is_add=1):
+    def nat64_add_del_prefix(self, prefix, plen, vrf_id=0, is_add=1):
         """Add/del NAT64 prefix
 
         :param prefix: NAT64 prefix
+        :param plen: NAT64 prefix length
         :param vrf_id: VRF id of tenant (Default 0)
         :param is_add: 1 if add, 0 if delete (Default value = 1)
         """
         return self.api(
             self.papi.nat64_add_del_prefix,
             {'prefix': prefix,
+             'prefix_len': plen,
              'vrf_id': vrf_id,
              'is_add': is_add})
 
@@ -1110,19 +1238,18 @@ class VppPapiProvider(object):
     def nat66_add_del_interface(
             self,
             sw_if_index,
-            flags=0,
+            is_inside=1,
             is_add=1):
         """Enable/disable NAT66 feature on the interface
-
            :param sw_if_index: Index of the interface
-           :param flags: NAT configuration flags (NAT_IS_INSIDE)
+           :param is_inside: 1 if inside, 0 if outside (Default value = 1)
            :param is_add: 1 if add, 0 if delete (Default value = 1)
         """
         return self.api(
             self.papi.nat66_add_del_interface,
-            {'is_add': is_add,
-             'flags': flags,
-             'sw_if_index': sw_if_index})
+            {'sw_if_index': sw_if_index,
+             'is_inside': is_inside,
+             'is_add': is_add})
 
     def nat66_add_del_static_mapping(
             self,