NAT: VPP-1531 api cleanup & update

Change-Id: I519d7efc8ee3c86381d96be2e2a46017cd948895
Signed-off-by: Filip Varga <fivarga@cisco.com>

11 files changed, 1381 insertions, 1211 deletions

diff --git a/extras/vom/vom/nat_binding.cpp b/extras/vom/vom/nat_binding.cpp
index 3c3d8261d67..a3fdee77be4 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.is_inside));
+                     zone_t::from_vpp(payload.flags & NAT_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.is_inside));
+                     zone_t::from_vpp(payload.flags & NAT_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.is_inside));
+                     zone_t::from_vpp(payload.flags & NAT_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 d67a0828003..4e69a67f2af 100644
--- a/extras/vom/vom/nat_binding_cmds.cpp
+++ b/extras/vom/vom/nat_binding_cmds.cpp
@@ -39,7 +39,8 @@ bind_44_input_cmd::issue(connection& con)
 
   auto& payload = req.get_request().get_payload();
   payload.is_add = 1;
-  payload.is_inside = (nat_binding::zone_t::INSIDE == m_zone ? 1 : 0);
+  payload.flags = (vapi_enum_nat_config_flags)(
+    nat_binding::zone_t::INSIDE == m_zone ? NAT_IS_INSIDE : 0);
   payload.sw_if_index = m_itf.value();
 
   VAPI_CALL(req.execute());
@@ -79,7 +80,8 @@ unbind_44_input_cmd::issue(connection& con)
 
   auto& payload = req.get_request().get_payload();
   payload.is_add = 0;
-  payload.is_inside = (nat_binding::zone_t::INSIDE == m_zone ? 1 : 0);
+  payload.flags = (vapi_enum_nat_config_flags)(
+    nat_binding::zone_t::INSIDE == m_zone ? NAT_IS_INSIDE : 0);
   payload.sw_if_index = m_itf.value();
 
   VAPI_CALL(req.execute());
@@ -119,7 +121,8 @@ bind_44_output_cmd::issue(connection& con)
 
   auto& payload = req.get_request().get_payload();
   payload.is_add = 1;
-  payload.is_inside = (nat_binding::zone_t::INSIDE == m_zone ? 1 : 0);
+  payload.flags = (vapi_enum_nat_config_flags)(
+    nat_binding::zone_t::INSIDE == m_zone ? NAT_IS_INSIDE : 0);
   payload.sw_if_index = m_itf.value();
 
   VAPI_CALL(req.execute());
@@ -159,7 +162,8 @@ unbind_44_output_cmd::issue(connection& con)
 
   auto& payload = req.get_request().get_payload();
   payload.is_add = 0;
-  payload.is_inside = (nat_binding::zone_t::INSIDE == m_zone ? 1 : 0);
+  payload.flags = (vapi_enum_nat_config_flags)(
+    nat_binding::zone_t::INSIDE == m_zone ? NAT_IS_INSIDE : 0);
   payload.sw_if_index = m_itf.value();
 
   VAPI_CALL(req.execute());
@@ -263,7 +267,8 @@ bind_66_input_cmd::issue(connection& con)
 
   auto& payload = req.get_request().get_payload();
   payload.is_add = 1;
-  payload.is_inside = (nat_binding::zone_t::INSIDE == m_zone ? 1 : 0);
+  payload.flags = (vapi_enum_nat_config_flags)(
+    nat_binding::zone_t::INSIDE == m_zone ? NAT_IS_INSIDE : 0);
   payload.sw_if_index = m_itf.value();
 
   VAPI_CALL(req.execute());
@@ -305,7 +310,8 @@ unbind_66_input_cmd::issue(connection& con)
 
   auto& payload = req.get_request().get_payload();
   payload.is_add = 0;
-  payload.is_inside = (nat_binding::zone_t::INSIDE == m_zone ? 1 : 0);
+  payload.flags = (vapi_enum_nat_config_flags)(
+    nat_binding::zone_t::INSIDE == m_zone ? NAT_IS_INSIDE : 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 299f2f5f328..0c4d7283ea6 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.addr_only = 1;
+  payload.flags = NAT_IS_ADDR_ONLY;
   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.addr_only = 1;
+  payload.flags = NAT_IS_ADDR_ONLY;
   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 7f9fe3f8e7b..80a70a7e995 100644
--- a/src/plugins/nat/nat.api
+++ b/src/plugins/nat/nat.api
@@ -13,8 +13,9 @@
  * limitations under the License.
  */
 
-option version = "4.1.0";
+option version = "5.0.0";
 import "vnet/ip/ip_types.api";
+import "vnet/interface_types.api";
 
 /**
  * @file nat.api
@@ -28,6 +29,18 @@ import "vnet/ip/ip_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
@@ -65,11 +78,12 @@ 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 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 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 translation_buckets - number of translation hash buckets
     @param translation_memory_size - translation hash memory size
     @param user_buckets - number of user hash buckets
@@ -77,7 +91,6 @@ 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
@@ -87,11 +100,12 @@ define nat_show_config_reply
 {
   u32 context;
   i32 retval;
-  u8 static_mapping_only;
-  u8 static_mapping_connection_tracking;
-  u8 deterministic;
-  u8 endpoint_dependent;
-  u8 out2in_dpo;
+  bool static_mapping_only;
+  bool static_mapping_connection_tracking;
+  bool deterministic;
+  bool endpoint_dependent;
+  bool out2in_dpo;
+  bool dslite_ce;
   u32 translation_buckets;
   u32 translation_memory_size;
   u32 user_buckets;
@@ -99,7 +113,6 @@ 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;
@@ -136,7 +149,7 @@ define nat_worker_details {
   u32 context;
   u32 worker_index;
   u32 lcore_id;
-  u8 name[64];
+  string name;
 };
 
 /** \brief Enable/disable NAT IPFIX logging
@@ -144,14 +157,14 @@ 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 - 1 if enable, 0 if disable
+    @param enable - true if enable, false if disable
 */
 autoreply define nat_ipfix_enable_disable {
   u32 client_index;
   u32 context;
   u32 domain_id;
   u16 src_port;
-  u8 enable;
+  bool enable;
 };
 
 /** \brief Set NAT virtual fragmentation reassembly
@@ -161,7 +174,7 @@ 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 - 1 if IPv6, 0 if IPv4
+    @param is_ip6 - true if IPv6, false if IPv4
 */
 autoreply define nat_set_reass {
   u32 client_index;
@@ -170,7 +183,7 @@ autoreply define nat_set_reass {
   u16 max_reass;
   u8  max_frag;
   u8  drop_frag;
-  u8  is_ip6;
+  bool  is_ip6;
 };
 
 /** \brief Get NAT virtual fragmentation reassembly configuration
@@ -218,18 +231,16 @@ define nat_reass_dump {
 
 /** \brief NAT virtual fragmentation reassemblies response
     @param context - sender context, to match reply w/ request
-    @param is_ip4 - 1 if address type is IPv4
-    @param src_addr - source IP address
-    @param dst_addr - destination IP address
+    @param src_addr - source IPv4 address
+    @param dst_addr - destination IPv4 address
     @param frag_id - fragment ID
     @param proto - protocol
     @param frag_n - number of cached fragments
 */
 define nat_reass_details {
   u32 context;
-  u8 is_ip4;
-  u8 src_addr[16];
-  u8 dst_addr[16];
+  vl_api_address_t src_addr;
+  vl_api_address_t dst_addr;
   u32 frag_id;
   u8 proto;
   u8 frag_n;
@@ -337,13 +348,13 @@ 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 - disable(0)/enable(1) MSS rewriting feature
+    @param enable - if true enable MSS rewriting feature else disable
 */
 autoreply define nat_set_mss_clamping {
   u32 client_index;
   u32 context;
   u16 mss_value;
-  u8 enable;
+  bool enable;
 };
 
 /** \brief Get TCP MSS rewriting configuration
@@ -359,13 +370,13 @@ 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 - disable(0)/enable(1) MSS rewriting feature
+    @param enable - if true enable MSS rewriting feature else disable
 */
 define nat_get_mss_clamping_reply {
   u32 context;
   i32 retval;
   u16 mss_value;
-  u8 enable;
+  bool enable;
 };
 
 /** \brief Set HA listener (local settings)
@@ -458,8 +469,8 @@ 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
@@ -499,17 +510,18 @@ 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 twice_nat - twice NAT address range for extenal hosts
-    @param is_add - 1 if add, 0 if delete
+    @param is_add - true if add, false if delete
+    @param flags - flag NAT_IS_TWICE_NAT if NAT address range for external hosts
+
 */
 autoreply define nat44_add_del_address_range {
   u32 client_index;
   u32 context;
-  u8 first_ip_address[4];
-  u8 last_ip_address[4];
+  vl_api_ip4_address_t first_ip_address;
+  vl_api_ip4_address_t last_ip_address;
   u32 vrf_id;
-  u8 twice_nat;
-  u8 is_add;
+  bool is_add;
+  vl_api_nat_config_flags_t flags;
 };
 
 /** \brief Dump NAT44 addresses
@@ -524,29 +536,30 @@ define nat44_address_dump {
 /** \brief NAT44 address details response
     @param context - sender context, to match reply w/ request
     @param ip_address - IPv4 address
-    @param twice_nat - twice NAT address range for extenal hosts
+    @param flags - flag NAT_IS_TWICE_NAT if NAT address range for external hosts
     @param vrf_id - VRF id of tenant, ~0 means independent of VRF
 */
 define nat44_address_details {
   u32 context;
-  u8 ip_address[4];
-  u8 twice_nat;
+  vl_api_ip4_address_t ip_address;
+  vl_api_nat_config_flags_t flags;
   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 - 1 if add, 0 if delete
-    @param is_inside - 1 if inside, 0 if outside
+    @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 - software index of the interface
 */
 autoreply define nat44_interface_add_del_feature {
   u32 client_index;
   u32 context;
-  u8 is_add;
-  u8 is_inside;
-  u32 sw_if_index;
+  bool is_add;
+  vl_api_nat_config_flags_t flags;
+  vl_api_interface_index_t sw_if_index;
 };
 
 /** \brief Dump interfaces with NAT44 feature
@@ -560,29 +573,33 @@ 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;
-  u8 is_inside;
-  u32 sw_if_index;
+  vl_api_nat_config_flags_t flags;
+  vl_api_interface_index_t 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 - 1 if add, 0 if delete
-    @param is_inside - 1 if inside, 0 if outside
+    @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 - software index of the interface
 */
 autoreply define nat44_interface_add_del_output_feature {
   u32 client_index;
   u32 context;
-  u8 is_add;
-  u8 is_inside;
-  u32 sw_if_index;
+  bool is_add;
+  vl_api_nat_config_flags_t flags;
+  vl_api_interface_index_t sw_if_index;
 };
 
 /** \brief Dump interfaces with NAT44 output feature
@@ -596,20 +613,26 @@ define nat44_interface_output_feature_dump {
 
 /** \brief NAT44 interface with output feature details response
     @param context - sender context, to match reply w/ request
-    @param is_inside - 1 if inside, 0 if outside
+    @param flags - flag NAT_IS_INSIDE if interface is inside else
+                   interface is outside
     @param sw_if_index - software index of the interface
 */
 define nat44_interface_output_feature_details {
   u32 context;
-  u8 is_inside;
-  u32 sw_if_index;
+  vl_api_nat_config_flags_t flags;
+  vl_api_interface_index_t 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 - 1 if add, 0 if delete
-    @param addr_only - 1 if address only mapping
+    @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 local_ip_address - local IPv4 address
     @param external_ip_address - external IPv4 address
     @param protocol - IP protocol, used only if addr_only=0
@@ -619,30 +642,21 @@ 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;
-  u8 is_add;
-  u8 addr_only;
-  u8 local_ip_address[4];
-  u8 external_ip_address[4];
+  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 protocol;
   u16 local_port;
   u16 external_port;
-  u32 external_sw_if_index;
+  vl_api_interface_index_t external_sw_if_index;
   u32 vrf_id;
-  u8 twice_nat;
-  u8 self_twice_nat;
-  u8 out2in_only;
-  u8 tag[64];
+  string tag;
 };
 
 /** \brief Dump NAT44 static mappings
@@ -656,42 +670,39 @@ define nat44_static_mapping_dump {
 
 /** \brief NAT44 static mapping details response
     @param context - sender context, to match reply w/ request
-    @param addr_only - 1 if address only mapping
+    @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 local_ip_address - local IPv4 address
     @param external_ip_address - external IPv4 address
-    @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 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 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;
-  u8 addr_only;
-  u8 local_ip_address[4];
-  u8 external_ip_address[4];
+  vl_api_nat_config_flags_t flags;
+  vl_api_ip4_address_t local_ip_address;
+  vl_api_ip4_address_t external_ip_address;
   u8 protocol;
   u16 local_port;
   u16 external_port;
-  u32 external_sw_if_index;
+  vl_api_interface_index_t external_sw_if_index;
   u32 vrf_id;
-  u8 twice_nat;
-  u8 self_twice_nat;
-  u8 out2in_only;
-  u8 tag[64];
+  string tag;
 };
 
 /** \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 - 1 if add, 0 if delete
-    @param addr_only - 1 if address only mapping
+    @param is_add - true if add, false if delete
+    @param flags - flag NAT_ADDR_ONLY if address only mapping
     @param ip_address - IPv4 address
     @param protocol - IP protocol
     @param port - port number
@@ -703,14 +714,14 @@ define nat44_static_mapping_details {
 autoreply define nat44_add_del_identity_mapping {
   u32 client_index;
   u32 context;
-  u8 is_add;
-  u8 addr_only;
-  u8 ip_address[4];
+  bool is_add;
+  vl_api_nat_config_flags_t flags;
+  vl_api_ip4_address_t ip_address;
   u8 protocol;
   u16 port;
-  u32 sw_if_index;
+  vl_api_interface_index_t sw_if_index;
   u32 vrf_id;
-  u8 tag[64];
+  string tag;
 };
 
 /** \brief Dump NAT44 identity mappings
@@ -724,7 +735,7 @@ define nat44_identity_mapping_dump {
 
 /** \brief NAT44 identity mapping details response
     @param context - sender context, to match reply w/ request
-    @param addr_only - 1 if address only mapping
+    @param flags - flag NAT_ADDR_ONLY if address only mapping
     @param ip_address - IPv4 address
     @param protocol - IP protocol
     @param port - port number
@@ -734,28 +745,28 @@ define nat44_identity_mapping_dump {
 */
 define nat44_identity_mapping_details {
   u32 context;
-  u8 addr_only;
-  u8 ip_address[4];
+  vl_api_nat_config_flags_t flags;
+  vl_api_ip4_address_t ip_address;
   u8 protocol;
   u16 port;
-  u32 sw_if_index;
+  vl_api_interface_index_t sw_if_index;
   u32 vrf_id;
-  u8 tag[64];
+  string tag;
 };
 
 /** \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 - 1 if add, 0 if delete
-    @param twice_nat - twice NAT address for extenal hosts
+    @param is_add - true if add, false if delete
     @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;
-  u8 is_add;
-  u8 twice_nat;
-  u32 sw_if_index;
+  bool is_add;
+  vl_api_interface_index_t sw_if_index;
+  vl_api_nat_config_flags_t flags;
 };
 
 /** \brief Dump NAT44 pool addresses interfaces
@@ -770,12 +781,13 @@ 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 twice_nat - twice NAT address for extenal hosts
+    @param flags - flag NAT_TWICE_NAT if NAT address range for external hosts
+
 */
 define nat44_interface_addr_details {
   u32 context;
-  u32 sw_if_index;
-  u8 twice_nat;
+  vl_api_interface_index_t sw_if_index;
+  vl_api_nat_config_flags_t flags;
 };
 
 /** \brief Dump NAT44 users
@@ -790,14 +802,14 @@ define nat44_user_dump {
 /** \brief NAT44 users response
     @param context - sender context, to match reply w/ request
     @vrf_id - VRF ID
-    @param ip_adress - IPv4 address
+    @param ip_address - IPv4 address
     @param nsessions - number of dynamic sessions
     @param nstaticsessions - number of static sessions
 */
 define nat44_user_details {
   u32 context;
   u32 vrf_id;
-  u8 ip_address[4];
+  vl_api_ip4_address_t ip_address;
   u32 nsessions;
   u32 nstaticsessions;
 };
@@ -805,14 +817,13 @@ 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 is_ip4 - 1 if address type is IPv4
-    @param user_ip - IP address of the user to dump
+    @param ip_address - IPv4 address of the user to dump
     @param vrf_id - VRF_ID
 */
 define nat44_user_session_dump {
   u32 client_index;
   u32 context;
-  u8 ip_address[4];
+  vl_api_ip4_address_t ip_address;
   u32 vrf_id;
 };
 
@@ -823,12 +834,13 @@ define nat44_user_session_dump {
     @param inside_ip_address - inside IPv4 address
     @param inside_port - inside port
     @param protocol - protocol
-    @param is_static - 1 if session is static
+    @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 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
@@ -838,20 +850,18 @@ define nat44_user_session_dump {
 */
 define nat44_user_session_details {
   u32 context;
-  u8 outside_ip_address[4];
+  vl_api_ip4_address_t outside_ip_address;
   u16 outside_port;
-  u8 inside_ip_address[4];
+  vl_api_ip4_address_t inside_ip_address;
   u16 inside_port;
   u16 protocol;
-  u8 is_static;
+  vl_api_nat_config_flags_t flags;
   u64 last_heard;
   u64 total_bytes;
   u32 total_pkts;
-  u8 is_twicenat;
-  u8 ext_host_valid;
-  u8 ext_host_address[4];
+  vl_api_ip4_address_t ext_host_address;
   u16 ext_host_port;
-  u8 ext_host_nat_address[4];
+  vl_api_ip4_address_t ext_host_nat_address;
   u16 ext_host_nat_port;
 };
 
@@ -859,9 +869,10 @@ 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 {
-  u8 addr[4];
+  vl_api_ip4_address_t addr;
   u16 port;
   u8 probability;
   u32 vrf_id;
@@ -870,41 +881,39 @@ 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 - 1 if add, 0 if delete
+    @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 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;
-  u8 is_add;
-  u8 external_addr[4];
+  bool is_add;
+  vl_api_nat_config_flags_t flags;
+  vl_api_ip4_address_t external_addr;
   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 - 1 if add, 0 if delete
+    @param is_add - true if add, false 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
@@ -913,8 +922,8 @@ autoreply manual_endian define nat44_add_del_lb_static_mapping {
 autoreply define nat44_lb_static_mapping_add_del_local {
   u32 client_index;
   u32 context;
-  u8 is_add;
-  u8 external_addr[4];
+  bool is_add;
+  vl_api_ip4_address_t external_addr;
   u16 external_port;
   u8 protocol;
   vl_api_nat44_lb_addr_port_t local;
@@ -931,57 +940,55 @@ 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 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 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 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;
-  u8 external_addr[4];
+  vl_api_ip4_address_t external_addr;
   u16 external_port;
   u8 protocol;
-  u8 twice_nat;
-  u8 self_twice_nat;
-  u8 out2in_only;
-  u8 tag[64];
+  vl_api_nat_config_flags_t flags;
   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 ext_host_valid - 1 if external host address and port are valid
+    @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_address - external host IPv4 address
     @param ext_host_port - external host port
 */
 autoreply define nat44_del_session {
   u32 client_index;
   u32 context;
-  u8 is_in;
-  u8 address[4];
+  vl_api_ip4_address_t address;
   u8 protocol;
   u16 port;
   u32 vrf_id;
-  u8 ext_host_valid;
-  u8 ext_host_address[4];
+  vl_api_nat_config_flags_t flags;
+  vl_api_ip4_address_t ext_host_address;
   u16 ext_host_port;
 };
 
@@ -990,12 +997,12 @@ 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 - 0 for enable, 1 for disable
+    @param enable - true for enable, false for disable
 */
 autoreply define nat44_forwarding_enable_disable {
   u32 client_index;
   u32 context;
-  u8 enable;
+  bool enable;
 };
 
 /** \brief Check if forwarding is enabled or disabled
@@ -1009,11 +1016,11 @@ 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 - 1 if enabled, 0 if disabled
+    @param enabled - true if enabled, false if disabled
 */
 define nat44_forwarding_is_enabled_reply {
   u32 context;
-  u8 enabled;
+  bool enabled;
 };
 
 
@@ -1024,36 +1031,31 @@ 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 - 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 is_add - true if add, false if delete
+    @param in_addr - inside IPv4 address
+    @param in_plen - inside IPv4 address prefix length
     @param out_addr - outside IPv4 address
-    @param out_addr - outside IPv4 address prefix length
+    @param out_plen - outside IPv4 address prefix length
 */
 autoreply define nat_det_add_del_map {
   u32 client_index;
   u32 context;
-  u8 is_add;
-  u8 is_nat44;
-  u8 addr_only;
-  u8 in_addr[16];
+  bool is_add;
+  vl_api_ip4_address_t in_addr;
   u8 in_plen;
-  u8 out_addr[4];
+  vl_api_ip4_address_t out_addr;
   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;
-  u8 is_nat44;
-  u8 in_addr[16];
+  vl_api_ip4_address_t in_addr;
 };
 
 /** \brief Get outside address and port range from inside address
@@ -1068,7 +1070,7 @@ define nat_det_forward_reply {
   i32 retval;
   u16 out_port_lo;
   u16 out_port_hi;
-  u8 out_addr[4];
+  vl_api_ip4_address_t out_addr;
 };
 
 /** \brief Get inside address from outside address and port
@@ -1081,20 +1083,18 @@ define nat_det_reverse {
   u32 client_index;
   u32 context;
   u16 out_port;
-  u8 out_addr[4];
+  vl_api_ip4_address_t out_addr;
 };
 
 /** \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;
-  u8 is_nat44;
-  u8 in_addr[16];
+  vl_api_ip4_address_t in_addr;
 };
 
 /** \brief Dump NAT deterministic mappings
@@ -1108,9 +1108,8 @@ define nat_det_map_dump {
 
 /** \brief NAT users response
     @param context - sender context, to match reply w/ request
-    @param is_nat44 - 1 if NAT44
-    @param in_addr - inside IP address
-    @param in_plen - inside IP address prefix length
+    @param in_addr - inside IPv4 address
+    @param in_plen - inside IPv4 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
@@ -1119,10 +1118,9 @@ define nat_det_map_dump {
 */
 define nat_det_map_details {
   u32 context;
-  u8 is_nat44;
-  u8 in_addr[16];
+  vl_api_ip4_address_t in_addr;
   u8 in_plen;
-  u8 out_addr[4];
+  vl_api_ip4_address_t out_addr;
   u8 out_plen;
   u32 sharing_ratio;
   u16 ports_per_host;
@@ -1140,16 +1138,15 @@ define nat_det_map_details {
 autoreply define nat_det_close_session_out {
   u32 client_index;
   u32 context;
-  u8 out_addr[4];
+  vl_api_ip4_address_t out_addr;
   u16 out_port;
-  u8 ext_addr[4];
+  vl_api_ip4_address_t ext_addr;
   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
@@ -1158,30 +1155,27 @@ autoreply define nat_det_close_session_out {
 autoreply define nat_det_close_session_in {
   u32 client_index;
   u32 context;
-  u8 is_nat44;
-  u8 in_addr[16];
+  vl_api_ip4_address_t in_addr;
   u16 in_port;
-  u8 ext_addr[16];
+  vl_api_ip4_address_t ext_addr;
   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;
-  u8 is_nat44;
-  u8 user_addr[16];
+  vl_api_ip4_address_t user_addr;
 };
 
 /** \brief Deterministic NAT sessions reply
     @param context - sender context, to match reply w/ request
     @param in_port - inside port
-    @param ext_addr - external host address
+    @param ext_addr - external host IPv4 address
     @param ext_port - external host port
     @param out_port - outside NAT port
     @param state - session state
@@ -1190,7 +1184,7 @@ define nat_det_session_dump {
 define nat_det_session_details {
   u32 context;
   u16 in_port;
-  u8 ext_addr[4];
+  vl_api_ip4_address_t ext_addr;
   u16 ext_port;
   u16 out_port;
   u8 state;
@@ -1204,18 +1198,18 @@ 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 address of the range
-    @param end_addr - end address of the range
+    @param start_addr - start IPv4 address of the range
+    @param end_addr - end IPv4 address of the range
     @param vrf_id - VRF id of tenant, ~0 means independent of VRF
-    @param is_add - 1 if add, 0 if delete
+    @param is_add - true if add, false if delete
 */
 autoreply define nat64_add_del_pool_addr_range {
   u32 client_index;
   u32 context;
-  u8 start_addr[4];
-  u8 end_addr[4];
+  vl_api_ip4_address_t start_addr;
+  vl_api_ip4_address_t end_addr;
   u32 vrf_id;
-  u8 is_add;
+  bool is_add;
 };
 
 /** \brief Dump NAT64 pool addresses
@@ -1234,23 +1228,24 @@ define nat64_pool_addr_dump {
 */
 define nat64_pool_addr_details {
   u32 context;
-  u8 address[4];
+  vl_api_ip4_address_t address;
   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;
-  u32 sw_if_index;
-  u8 is_inside;
-  u8 is_add;
+  bool is_add;
+  vl_api_nat_config_flags_t flags;
+  vl_api_interface_index_t sw_if_index;
 };
 
 /** \brief Dump interfaces with NAT64 feature
@@ -1264,13 +1259,16 @@ define nat64_interface_dump {
 
 /** \brief NAT64 interface details response
     @param context - sender context, to match reply w/ request
-    @param is_inside - 1 if inside, 0 if outside
+    @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 sw_if_index - index of the interface
 */
 define nat64_interface_details {
   u32 context;
-  u8 is_inside;
-  u32 sw_if_index;
+  vl_api_nat_config_flags_t flags;
+  vl_api_interface_index_t sw_if_index;
 };
 
 /** \brief Add/delete NAT64 static BIB entry
@@ -1282,18 +1280,18 @@ define nat64_interface_details {
     @param o_port - outside port number
     @param vrf_id - VRF id of tenant
     @param proto - protocol number
-    @param is_add - 1 if add, 0 if delete
+    @param is_add - true if add, false if delete
 */
  autoreply define nat64_add_del_static_bib {
   u32 client_index;
   u32 context;
-  u8 i_addr[16];
-  u8 o_addr[4];
+  vl_api_ip6_address_t i_addr;
+  vl_api_ip4_address_t o_addr;
   u16 i_port;
   u16 o_port;
   u32 vrf_id;
   u8 proto;
-  u8 is_add;
+  bool is_add;
 };
 
 /** \brief Dump NAT64 BIB
@@ -1319,18 +1317,19 @@ define nat64_bib_dump {
     @param o_port - outside port number
     @param vrf_id - VRF id of tenant
     @param proto - protocol number
-    @param is_static - 1 if static BIB entry, 0 if dynamic
+    @param flags - flag NAT_IS_STATIC if BIB entry is static 
+                   or BIB entry is dynamic
     @param ses_num - number of sessions associated with the BIB entry
 */
 define nat64_bib_details {
   u32 context;
-  u8 i_addr[16];
-  u8 o_addr[4];
+  vl_api_ip6_address_t i_addr;
+  vl_api_ip4_address_t o_addr;
   u16 i_port;
   u16 o_port;
   u32 vrf_id;
   u8 proto;
-  u8 is_static;
+  vl_api_nat_config_flags_t flags;
   u32 ses_num;
 };
 
@@ -1355,20 +1354,20 @@ 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 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 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 vrf_id - VRF id of tenant
     @param proto - protocol number
 */
 define nat64_st_details {
   u32 context;
-  u8 il_addr[16];
-  u8 ol_addr[4];
+  vl_api_ip6_address_t il_addr;
+  vl_api_ip4_address_t ol_addr;
   u16 il_port;
   u16 ol_port;
-  u8 ir_addr[16];
-  u8 or_addr[4];
+  vl_api_ip6_address_t ir_addr;
+  vl_api_ip4_address_t or_addr;
   u16 r_port;
   u32 vrf_id;
   u8 proto;
@@ -1378,17 +1377,15 @@ 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 - 1 if add, 0 if delete
+    @param is_add - true if add, false if delete
 */
 autoreply define nat64_add_del_prefix {
   u32 client_index;
   u32 context;
-  u8 prefix[16];
-  u8 prefix_len;
+  vl_api_ip6_prefix_t prefix;
   u32 vrf_id;
-  u8 is_add;
+  bool is_add;
 };
 
 /** \brief Dump NAT64 prefix
@@ -1403,31 +1400,27 @@ 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;
-  u8 prefix[16];
-  u8 prefix_len;
+  vl_api_ip6_prefix_t prefix;
   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 - 1 if add, 0 if delete
+    @param is_add - true if add, false if delete
     @param sw_if_index - software index of the interface
 */
 autoreply define nat64_add_del_interface_addr {
   u32 client_index;
   u32 context;
-  u8 is_add;
-  u8 is_inside;
-  u32 sw_if_index;
+  bool is_add;
+  vl_api_interface_index_t sw_if_index;
 };
 
-
 /*
  * DS-Lite APIs
  */
@@ -1435,16 +1428,16 @@ 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 address of the range
-    @param end_addr - end address of the range
-    @param is_add - 1 if add, 0 if delete
+    @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
 */
 autoreply define dslite_add_del_pool_addr_range {
   u32 client_index;
   u32 context;
-  u8 start_addr[4];
-  u8 end_addr[4];
-  u8 is_add;
+  vl_api_ip4_address_t start_addr;
+  vl_api_ip4_address_t end_addr;
+  bool is_add;
 };
 
 /** \brief Dump DS-Lite addresses
@@ -1462,20 +1455,20 @@ define dslite_address_dump {
 */
 define dslite_address_details {
   u32 context;
-  u8 ip_address[4];
+  vl_api_ip4_address_t ip_address;
 };
 
 /** \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 - IP64 address
+    @param ip6_addr - IPv6 address
 */
 autoreply define dslite_set_aftr_addr {
   u32 client_index;
   u32 context;
-  u8 ip4_addr[4];
-  u8 ip6_addr[16];
+  vl_api_ip4_address_t ip4_addr;
+  vl_api_ip6_address_t ip6_addr;
 };
 
 /** \brief Get AFTR IPv6 and IPv4 addresses
@@ -1491,26 +1484,26 @@ 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 - IP64 address
+    @param ip6_addr - IPv6 address
 */
 define dslite_get_aftr_addr_reply {
   u32 context;
   i32 retval;
-  u8 ip4_addr[4];
-  u8 ip6_addr[16];
+  vl_api_ip4_address_t ip4_addr;
+  vl_api_ip6_address_t ip6_addr;
 };
 
 /** \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 - IP64 address
+    @param ip6_addr - IPv6 address
 */
 autoreply define dslite_set_b4_addr {
   u32 client_index;
   u32 context;
-  u8 ip4_addr[4];
-  u8 ip6_addr[16];
+  vl_api_ip4_address_t ip4_addr;
+  vl_api_ip6_address_t ip6_addr;
 };
 
 /** \brief Get B4 IPv6 and IPv4 addresses
@@ -1526,13 +1519,13 @@ 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 - IP64 address
+    @param ip6_addr - IPv6 address
 */
 define dslite_get_b4_addr_reply {
   u32 context;
   i32 retval;
-  u8 ip4_addr[4];
-  u8 ip6_addr[16];
+  vl_api_ip4_address_t ip4_addr;
+  vl_api_ip6_address_t ip6_addr;
 };
 
 /*
@@ -1541,16 +1534,17 @@ 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 - 1 if add, 0 if delete
-    @param is_inside - 1 if inside, 0 if outside
+    @param is_add - true if add, false if delete
+    @param flags - flag NAT_IS_INSIDE if interface is inside or
+                   interface is outside,
     @param sw_if_index - software index of the interface
 */
 autoreply define nat66_add_del_interface {
   u32 client_index;
   u32 context;
-  u8 is_add;
-  u8 is_inside;
-  u32 sw_if_index;
+  bool is_add;
+  vl_api_nat_config_flags_t flags;
+  vl_api_interface_index_t sw_if_index;
 };
 
 /** \brief Dump interfaces with NAT66 feature
@@ -1564,19 +1558,20 @@ define nat66_interface_dump {
 
 /** \brief NAT66 interface details response
     @param context - sender context, to match reply w/ request
-    @param is_inside - 1 if inside, 0 if outside
+    @param flags - flag NAT_IS_INSIDE if interface is inside or
+                   interface is outside,
     @param sw_if_index - software index of the interface
 */
 define nat66_interface_details {
   u32 context;
-  u8 is_inside;
-  u32 sw_if_index;
+  vl_api_nat_config_flags_t flags;
+  vl_api_interface_index_t 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 - 1 if add, 0 if delete
+    @param is_add - true if add, false if delete
     @param local_ip_address - local IPv6 address
     @param external_ip_address - external IPv6 address
     @param vrf_id - VRF id of tenant
@@ -1584,9 +1579,9 @@ define nat66_interface_details {
 autoreply define nat66_add_del_static_mapping {
   u32 client_index;
   u32 context;
-  u8 is_add;
-  u8 local_ip_address[16];
-  u8 external_ip_address[16];
+  bool is_add;
+  vl_api_ip6_address_t local_ip_address;
+  vl_api_ip6_address_t external_ip_address;
   u32 vrf_id;
 };
 
@@ -1609,8 +1604,8 @@ define nat66_static_mapping_dump {
 */
 define nat66_static_mapping_details {
   u32 context;
-  u8 local_ip_address[16];
-  u8 external_ip_address[16];
+  vl_api_ip6_address_t local_ip_address;
+  vl_api_ip6_address_t external_ip_address;
   u32 vrf_id;
   u64 total_bytes;
   u64 total_pkts;
diff --git a/src/plugins/nat/nat.h b/src/plugins/nat/nat.h
index ca2d1fcf1bf..237d945a724 100644
--- a/src/plugins/nat/nat.h
+++ b/src/plugins/nat/nat.h
@@ -110,6 +110,24 @@ 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 21b2cd44880..fce557fa8bf 100644
--- a/src/plugins/nat/nat_api.c
+++ b/src/plugins/nat/nat_api.c
@@ -31,6 +31,7 @@
 
 #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
@@ -63,7 +64,6 @@
     vec_free (s);                               \
     return handle;
 
-
 /******************************/
 /*** Common NAT plugin APIs ***/
 /******************************/
@@ -202,13 +202,15 @@ 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));
-  clib_memset (rmp, 0, sizeof (*rmp));
+  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_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);
-  strncpy ((char *) rmp->name, (char *) w->name, ARRAY_LEN (rmp->name) - 1);
+
+  vl_api_to_api_string (ARRAY_LEN (w->name) - 1, (char *) w->name,
+			&rmp->name);
 
   vl_api_send_msg (reg, (u8 *) rmp);
 }
@@ -349,17 +351,22 @@ 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 (rmp->src_addr, &(reass->key.src), 4);
-  clib_memcpy (rmp->dst_addr, &(reass->key.dst), 4);
+
+  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);
+
   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);
 
@@ -372,17 +379,22 @@ 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 (rmp->src_addr, &(reass->key.src), 16);
-  clib_memcpy (rmp->dst_addr, &(reass->key.dst), 16);
+
+  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);
+
   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);
 
@@ -838,6 +850,7 @@ 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;
@@ -856,6 +869,9 @@ 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;
@@ -874,16 +890,16 @@ static void
 
   for (i = 0; i < count; i++)
     {
-      if (mp->is_add)
-	rv = snat_add_address (sm, &this_addr, vrf_id, mp->twice_nat);
+      if (is_add)
+	rv = snat_add_address (sm, &this_addr, vrf_id, twice_nat);
       else
-	rv = snat_del_address (sm, this_addr, 0, mp->twice_nat);
+	rv = snat_del_address (sm, this_addr, 0, twice_nat);
 
       if (rv)
 	goto send_reply;
 
       if (sm->out2in_dpo)
-	nat44_add_del_address_dpo (this_addr, mp->is_add);
+	nat44_add_del_address_dpo (this_addr, is_add);
 
       increment_v4_address (&this_addr);
     }
@@ -903,7 +919,7 @@ 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->twice_nat);
+  s = format (s, "twice_nat %d ", mp->flags & NAT_API_IS_TWICE_NAT);
   FINISH;
 }
 
@@ -926,7 +942,8 @@ send_nat44_address_details (snat_address_t * a,
     }
   else
     rmp->vrf_id = ~0;
-  rmp->twice_nat = twice_nat;
+  if (twice_nat)
+    rmp->flags |= NAT_API_IS_TWICE_NAT;
   rmp->context = context;
 
   vl_api_send_msg (reg, (u8 *) rmp);
@@ -971,13 +988,17 @@ 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->is_inside, is_del);
+  rv =
+    snat_interface_add_del (sw_if_index, mp->flags & NAT_API_IS_INSIDE,
+			    is_del);
 
   BAD_SW_IF_INDEX_LABEL;
 
@@ -992,7 +1013,8 @@ 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->is_inside ? "in" : "out", mp->is_add ? "" : "del");
+	      mp->flags & NAT_API_IS_INSIDE ? "in" : "out",
+	      mp->is_add ? "" : "del");
 
   FINISH;
 }
@@ -1008,9 +1030,12 @@ 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);
-  rmp->is_inside = (nat_interface_is_inside (i)
-		    && nat_interface_is_outside (i)) ? 2 :
-    nat_interface_is_inside (i);
+
+  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->context = context;
 
   vl_api_send_msg (reg, (u8 *) rmp);
@@ -1052,7 +1077,6 @@ 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;
 
@@ -1064,8 +1088,9 @@ static void
 
   VALIDATE_SW_IF_INDEX (mp);
 
-  rv = snat_interface_add_del_output_feature (sw_if_index, mp->is_inside,
-					      is_del);
+  rv = snat_interface_add_del_output_feature (sw_if_index,
+					      mp->flags & NAT_API_IS_INSIDE,
+					      !mp->is_add);
 
   BAD_SW_IF_INDEX_LABEL;
 send_reply:
@@ -1080,7 +1105,8 @@ 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->is_inside ? "in" : "out", mp->is_add ? "" : "del");
+	      mp->flags & NAT_API_IS_INSIDE ? "in" : "out",
+	      mp->is_add ? "" : "del");
 
   FINISH;
 }
@@ -1099,7 +1125,9 @@ 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;
-  rmp->is_inside = nat_interface_is_inside (i);
+
+  if (nat_interface_is_inside (i))
+    rmp->flags |= NAT_API_IS_INSIDE;
 
   vl_api_send_msg (reg, (u8 *) rmp);
 }
@@ -1150,6 +1178,7 @@ static void
   int rv = 0;
   snat_protocol_t proto;
   u8 *tag = 0;
+  u32 len = 0;
 
   if (sm->deterministic)
     {
@@ -1159,27 +1188,34 @@ static void
 
   memcpy (&local_addr.as_u8, mp->local_ip_address, 4);
   memcpy (&external_addr.as_u8, mp->external_ip_address, 4);
-  if (mp->addr_only == 0)
+
+  if (!(mp->flags & NAT_API_IS_ADDR_ONLY))
     {
       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->twice_nat)
+
+  if (mp->flags & NAT_API_IS_TWICE_NAT)
     twice_nat = TWICE_NAT;
-  else if (mp->self_twice_nat)
+  else if (mp->flags & NAT_API_IS_SELF_TWICE_NAT)
     twice_nat = TWICE_NAT_SELF;
-  mp->tag[sizeof (mp->tag) - 1] = 0;
-  tag = format (0, "%s", mp->tag);
+
+  len = vl_api_string_len (&mp->tag);
+
+  tag = vec_new (u8, len);
+  memcpy (tag, mp->tag.buf, len);
   vec_terminate_c_string (tag);
 
   rv = snat_add_static_mapping (local_addr, external_addr, local_port,
-				external_port, vrf_id, mp->addr_only,
-				external_sw_if_index, proto, mp->is_add,
-				twice_nat, mp->out2in_only, tag, 0);
-
+				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);
   vec_free (tag);
 
 send_reply:
@@ -1197,13 +1233,14 @@ 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->addr_only == 0)
+  if (!(mp->flags & NAT_API_IS_ADDR_ONLY))
     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->twice_nat, mp->out2in_only);
+	      mp->flags & NAT_API_IS_TWICE_NAT,
+	      mp->flags & NAT_API_IS_OUT2IN_ONLY);
 
   if (mp->vrf_id != ~0)
     s = format (s, "vrf %d", clib_net_to_host_u32 (mp->vrf_id));
@@ -1220,30 +1257,48 @@ 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->twice_nat = 1;
+    rmp->flags |= NAT_API_IS_TWICE_NAT;
   else if (m->twice_nat == TWICE_NAT_SELF)
-    rmp->self_twice_nat = 1;
-  rmp->out2in_only = is_out2in_only_static_mapping (m);
-  if (rmp->addr_only == 0)
+    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->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);
 }
@@ -1255,25 +1310,41 @@ 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;
-  rmp->twice_nat = m->twice_nat;
-  if (m->addr_only == 0)
+
+  if (m->twice_nat)
+    rmp->flags |= NAT_API_IS_TWICE_NAT;
+
+  if (m->addr_only)
+    {
+      rmp->flags |= NAT_API_IS_ADDR_ONLY;
+    }
+  else
     {
       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);
 }
@@ -1334,6 +1405,7 @@ static void
   int rv = 0;
   snat_protocol_t proto = ~0;
   u8 *tag = 0;
+  u32 len = 0;
 
   if (sm->deterministic)
     {
@@ -1341,7 +1413,7 @@ static void
       goto send_reply;
     }
 
-  if (mp->addr_only == 0)
+  if (!(mp->flags & NAT_API_IS_ADDR_ONLY))
     {
       port = clib_net_to_host_u16 (mp->port);
       proto = ip_proto_to_snat_proto (mp->protocol);
@@ -1352,14 +1424,17 @@ static void
     addr.as_u32 = 0;
   else
     memcpy (&addr.as_u8, mp->ip_address, 4);
-  mp->tag[sizeof (mp->tag) - 1] = 0;
-  tag = format (0, "%s", mp->tag);
+
+  len = vl_api_string_len (&mp->tag);
+
+  tag = vec_new (u8, len);
+  memcpy (tag, mp->tag.buf, len);
   vec_terminate_c_string (tag);
 
   rv =
-    snat_add_static_mapping (addr, addr, port, port, vrf_id, mp->addr_only,
-			     sw_if_index, proto, mp->is_add, 0, 0, tag, 1);
-
+    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);
   vec_free (tag);
 
 send_reply:
@@ -1377,7 +1452,7 @@ 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->addr_only == 0)
+  if (!(mp->flags & NAT_API_IS_ADDR_ONLY))
     s =
       format (s, " protocol %d port %d", mp->protocol,
 	      clib_net_to_host_u16 (mp->port));
@@ -1395,20 +1470,33 @@ 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);
-  rmp->addr_only = is_addr_only_static_mapping (m);
+
+  if (is_addr_only_static_mapping (m))
+    rmp->flags |= NAT_API_IS_ADDR_ONLY;
+
   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);
 }
@@ -1420,19 +1508,32 @@ 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);
-  rmp->addr_only = m->addr_only;
+
+  if (m->addr_only)
+    rmp->flags = (vl_api_nat_config_flags_t) NAT_API_IS_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);
 }
@@ -1491,9 +1592,9 @@ 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)
     {
@@ -1501,9 +1602,12 @@ 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->twice_nat);
+  rv = snat_add_interface_address (sm, sw_if_index, is_del,
+				   mp->flags & NAT_API_IS_TWICE_NAT);
 
   BAD_SW_IF_INDEX_LABEL;
 send_reply:
@@ -1518,7 +1622,7 @@ 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->twice_nat, mp->is_add ? "" : "del");
+	      mp->flags & NAT_API_IS_TWICE_NAT, mp->is_add ? "" : "del");
 
   FINISH;
 }
@@ -1536,7 +1640,9 @@ 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);
-  rmp->twice_nat = twice_nat;
+
+  if (twice_nat)
+    rmp->flags = (vl_api_nat_config_flags_t) NAT_API_IS_TWICE_NAT;
   rmp->context = context;
 
   vl_api_send_msg (reg, (u8 *) rmp);
@@ -1651,10 +1757,16 @@ 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);
-  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;
+
+  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->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);
@@ -1787,7 +1899,9 @@ 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)
     {
@@ -1800,19 +1914,28 @@ 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->twice_nat)
+
+  if (mp->flags & NAT_API_IS_TWICE_NAT)
     twice_nat = TWICE_NAT;
-  else if (mp->self_twice_nat)
+  else if (mp->flags & NAT_API_IS_SELF_TWICE_NAT)
     twice_nat = TWICE_NAT_SELF;
-  mp->tag[sizeof (mp->tag) - 1] = 0;
-  tag = format (0, "%s", mp->tag);
+
+  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);
   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->out2in_only, tag,
+				     proto, locals, mp->is_add,
+				     twice_nat,
+				     mp->flags & NAT_API_IS_OUT2IN_ONLY, tag,
 				     clib_net_to_host_u32 (mp->affinity));
 
   vec_free (locals);
@@ -1829,7 +1952,9 @@ 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->twice_nat, mp->out2in_only);
+	      mp->is_add,
+	      mp->flags & NAT_API_IS_TWICE_NAT,
+	      mp->flags & NAT_API_IS_OUT2IN_ONLY);
 
   FINISH;
 }
@@ -1889,13 +2014,28 @@ 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);
 
@@ -1903,13 +2043,13 @@ 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->twice_nat = 1;
+    rmp->flags |= NAT_API_IS_TWICE_NAT;
   else if (m->twice_nat == TWICE_NAT_SELF)
-    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));
+    rmp->flags |= NAT_API_IS_SELF_TWICE_NAT;
+  if (is_out2in_only_static_mapping (m))
+    rmp->flags |= NAT_API_IS_OUT2IN_ONLY;
 
   locals = (vl_api_nat44_lb_addr_port_t *) rmp->locals;
   /* *INDENT-OFF* */
@@ -1971,6 +2111,7 @@ 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)
@@ -1986,12 +2127,14 @@ 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);
 
-  if (mp->ext_host_valid)
+  is_in = mp->flags & NAT_API_IS_INSIDE;
+
+  if (mp->flags & NAT_API_IS_EXT_HOST_VALID)
     rv =
       nat44_del_ed_session (sm, &addr, port, &eh_addr, eh_port, mp->protocol,
-			    vrf_id, mp->is_in);
+			    vrf_id, is_in);
   else
-    rv = nat44_del_session (sm, &addr, port, proto, vrf_id, mp->is_in);
+    rv = nat44_del_session (sm, &addr, port, proto, vrf_id, is_in);
 
 send_reply:
   REPLY_MACRO (VL_API_NAT44_DEL_SESSION_REPLY);
@@ -2007,8 +2150,9 @@ 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->is_in);
-  if (mp->ext_host_valid)
+	      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)
     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));
@@ -2117,12 +2261,6 @@ 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,
@@ -2163,13 +2301,6 @@ 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);
@@ -2235,8 +2366,6 @@ 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* */
@@ -2264,7 +2393,6 @@ 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);
@@ -2383,12 +2511,6 @@ 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);
 
@@ -2462,8 +2584,6 @@ 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);
@@ -2619,8 +2739,8 @@ 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->is_inside,
-			     mp->is_add);
+    nat64_add_del_interface (ntohl (mp->sw_if_index),
+			     mp->flags & NAT_API_IS_INSIDE, mp->is_add);
 
   BAD_SW_IF_INDEX_LABEL;
 
@@ -2636,7 +2756,8 @@ 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->is_inside ? "in" : "out", mp->is_add ? "" : "del");
+	      mp->flags & NAT_API_IS_INSIDE ? "in" : "out",
+	      mp->is_add ? "" : "del");
 
   FINISH;
 }
@@ -2652,9 +2773,12 @@ 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);
-  rmp->is_inside = (nat_interface_is_inside (i)
-		    && nat_interface_is_outside (i)) ? 2 :
-    nat_interface_is_inside (i);
+
+  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->context = ctx->context;
 
   vl_api_send_msg (ctx->reg, (u8 *) rmp);
@@ -2752,7 +2876,8 @@ 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;
-  rmp->is_static = bibe->is_static;
+  if (bibe->is_static)
+    rmp->flags |= NAT_API_IS_STATIC;
   rmp->ses_num = ntohl (bibe->ses_num);
 
   vl_api_send_msg (ctx->reg, (u8 *) rmp);
@@ -2871,10 +2996,10 @@ 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, 16);
+  memcpy (&prefix.as_u8, mp->prefix.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);
 }
@@ -2886,7 +3011,7 @@ 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, mp->prefix_len,
+	      format_ip6_address, mp->prefix.prefix, mp->prefix.len,
 	      ntohl (mp->vrf_id), mp->is_add ? "" : "del");
 
   FINISH;
@@ -2902,8 +3027,8 @@ 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, &(p->prefix), 16);
-  rmp->prefix_len = p->plen;
+  clib_memcpy (rmp->prefix.prefix, &(p->prefix), 16);
+  rmp->prefix.len = p->plen;
   rmp->vrf_id = ntohl (p->vrf_id);
   rmp->context = ctx->context;
 
@@ -3209,8 +3334,8 @@ 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->is_inside,
-			     mp->is_add);
+    nat66_interface_add_del (ntohl (mp->sw_if_index),
+			     mp->flags & NAT_API_IS_INSIDE, mp->is_add);
 
   BAD_SW_IF_INDEX_LABEL;
 
@@ -3226,7 +3351,8 @@ 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->is_inside ? "in" : "out", mp->is_add ? "" : "del");
+	      mp->flags & NAT_API_IS_INSIDE ? "in" : "out",
+	      mp->is_add ? "" : "del");
 
   FINISH;
 }
@@ -3282,7 +3408,8 @@ 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);
-  rmp->is_inside = nat_interface_is_inside (i);
+  if (nat_interface_is_inside (i))
+    rmp->flags |= NAT_API_IS_INSIDE;
   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 b1de5340b9d..0371ec48553 100644
--- a/src/plugins/nat/nat_test.c
+++ b/src/plugins/nat/nat_test.c
@@ -221,7 +221,8 @@ 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;
-  mp->is_inside = is_inside;
+  if (is_inside)
+    mp->flags |= NAT_API_IS_INSIDE;
 
   S(mp);
   W (ret);
@@ -291,8 +292,11 @@ static int api_nat44_add_del_static_mapping(vat_main_t * vam)
     }
 
   M(NAT44_ADD_DEL_STATIC_MAPPING, mp);
+
   mp->is_add = is_add;
-  mp->addr_only = addr_only;
+  if (addr_only)
+    mp->flags |= NAT_API_IS_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);
@@ -327,20 +331,21 @@ 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 (mp->addr_only && mp->external_sw_if_index != ~0)
+  if (flags & NAT_API_IS_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 (mp->addr_only && mp->external_sw_if_index == ~0)
+  else if (flags & NAT_API_IS_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 (!mp->addr_only && mp->external_sw_if_index != ~0)
+  else if (!(flags & NAT_API_IS_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),
@@ -469,11 +474,19 @@ 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;
 
-  fformat (vam->ofp, "sw_if_index %d %s\n", ntohl (mp->sw_if_index),
-           mp->is_inside ? "in" : "out");
+  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");
+    }
 }
 
 static int api_nat44_interface_dump(vat_main_t * vam)
@@ -590,6 +603,7 @@ 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);
@@ -671,7 +685,7 @@ 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->is_static ? "static" : "dynamic",
+          mp->flags & NAT_API_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 2c08b90a93b..fda3f75d9c1 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'
+                'f64', 'bool'
             ]
         }
 
diff --git a/test/test_gbp.py b/test/test_gbp.py
index 44a9b396730..cc38bc9c1ce 100644
--- a/test/test_gbp.py
+++ b/test/test_gbp.py
@@ -575,6 +575,10 @@ 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()
@@ -795,12 +799,11 @@ 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,
-                                                          is_inside=1,
-                                                          is_add=1)
+                                                          flags=flags)
                 self.vapi.nat66_add_del_interface(epg.bvi.sw_if_index,
-                                                  is_inside=1,
-                                                  is_add=1)
+                                                  flags=flags)
 
             if_ip4 = VppIpInterfaceAddress(self, epg.bvi, epg.bvi_ip4, 32)
             if_ip6 = VppIpInterfaceAddress(self, epg.bvi, epg.bvi_ip6, 128)
@@ -832,13 +835,9 @@ class TestGBP(VppTestCase):
                                recirc.epg.rd.t6).add_vpp_config()
 
             self.vapi.nat44_interface_add_del_feature(
-                recirc.recirc.sw_if_index,
-                is_inside=0,
-                is_add=1)
+                recirc.recirc.sw_if_index)
             self.vapi.nat66_add_del_interface(
-                recirc.recirc.sw_if_index,
-                is_inside=0,
-                is_add=1)
+                recirc.recirc.sw_if_index)
 
             recirc.add_vpp_config()
 
@@ -858,10 +857,11 @@ 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,
-                                                           addr_only=1)
+                                                           flags=flags)
                 else:
                     self.vapi.nat66_add_del_static_mapping(ip.bytes,
                                                            fip.bytes,
@@ -1404,11 +1404,12 @@ 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,
-                                                   addr_only=1,
-                                                   is_add=0)
+                                                   is_add=0,
+                                                   flags=flags)
             self.vapi.nat66_add_del_static_mapping(ep.ip6.bytes,
                                                    ep.fip6.bytes,
                                                    vrf_id=0,
@@ -1417,21 +1418,20 @@ 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,
-                                                          is_inside=1,
+                                                          flags=flags,
                                                           is_add=0)
                 self.vapi.nat66_add_del_interface(epg.bvi.sw_if_index,
-                                                  is_inside=1,
+                                                  flags=flags,
                                                   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 29d747d0932..c88981b48b4 100644
--- a/test/test_nat.py
+++ b/test/test_nat.py
@@ -29,6 +29,7 @@ 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
@@ -70,6 +71,10 @@ 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.
@@ -106,7 +111,7 @@ 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,
-                                                   twice_nat=intf.twice_nat,
+                                                   flags=intf.flags,
                                                    is_add=0)
 
         self.vapi.nat_ipfix_enable_disable(enable=0,
@@ -122,36 +127,32 @@ class MethodHolder(VppTestCase):
 
         interfaces = self.vapi.nat44_interface_dump()
         for intf in interfaces:
-            if intf.is_inside > 1:
+            if intf.flags & self.config_flags.NAT_IS_INSIDE and \
+                 intf.flags & self.config_flags.NAT_IS_OUTSIDE:
                 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,
-                                                      intf.is_inside,
-                                                      is_add=0)
+                                                      is_add=0,
+                                                      flags=intf.flags)
 
         interfaces = self.vapi.nat44_interface_output_feature_dump()
         for intf in interfaces:
             self.vapi.nat44_interface_add_del_output_feature(intf.sw_if_index,
-                                                             intf.is_inside,
-                                                             is_add=0)
-
+                                                             is_add=0,
+                                                             flags=intf.flags)
         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,
-                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)
+                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)
 
         lb_static_mappings = self.vapi.nat44_lb_static_mapping_dump()
         for lb_sm in lb_static_mappings:
@@ -159,18 +160,16 @@ 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=[])
+                locals=[],
+                flags=lb_sm.flags)
 
         identity_mappings = self.vapi.nat44_identity_mapping_dump()
         for id_m in identity_mappings:
             self.vapi.nat44_add_del_identity_mapping(
-                addr_only=id_m.addr_only,
+                flags=id_m.flags,
                 ip=id_m.ip_address,
                 port=id_m.port,
                 sw_if_index=id_m.sw_if_index,
@@ -182,8 +181,8 @@ class MethodHolder(VppTestCase):
         for addr in addresses:
             self.vapi.nat44_add_del_address_range(addr.ip_address,
                                                   addr.ip_address,
-                                                  twice_nat=addr.twice_nat,
-                                                  is_add=0)
+                                                  is_add=0,
+                                                  flags=addr.flags)
 
         self.vapi.nat_set_reass()
         self.vapi.nat_set_reass(is_ip6=1)
@@ -195,8 +194,7 @@ 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, twice_nat=0, self_twice_nat=0,
-                                 out2in_only=0, tag=""):
+                                 proto=0, tag="", flags=0):
         """
         Add/delete NAT44 static mapping
 
@@ -208,32 +206,24 @@ 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
         """
-        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)
+
+        if not (local_port and external_port):
+            flags |= self.config_flags.NAT_IS_ADDR_ONLY
+
         self.vapi.nat44_add_del_static_mapping(
-            l_ip,
-            e_ip,
+            local_ip,
+            external_ip,
             external_sw_if_index,
             local_port,
             external_port,
-            addr_only,
             vrf_id,
             proto,
-            twice_nat,
-            self_twice_nat,
-            out2in_only,
-            tag,
-            is_add)
+            is_add,
+            flags,
+            tag)
 
     def nat44_add_address(self, ip, is_add=1, vrf_id=0xFFFFFFFF, twice_nat=0):
         """
@@ -243,10 +233,10 @@ class MethodHolder(VppTestCase):
         :param is_add: 1 if add, 0 if delete (Default add)
         :param twice_nat: twice NAT address for external hosts
         """
-        nat_addr = socket.inet_pton(socket.AF_INET, ip)
-        self.vapi.nat44_add_del_address_range(nat_addr, nat_addr, is_add,
+        flags = self.config_flags.NAT_IS_TWICE_NAT if twice_nat else 0
+        self.vapi.nat44_add_del_address_range(ip, ip, is_add,
                                               vrf_id=vrf_id,
-                                              twice_nat=twice_nat)
+                                              flags=flags)
 
     def create_stream_in(self, in_if, out_if, dst_ip=None, ttl=64):
         """
@@ -1502,7 +1492,6 @@ 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
@@ -1569,9 +1558,10 @@ class TestNAT44(MethodHolder):
     def test_dynamic(self):
         """ NAT44 dynamic translation test """
         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_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        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)
 
         # in2out
         tcpn = self.statistics.get_counter(
@@ -1636,9 +1626,10 @@ class TestNAT44(MethodHolder):
         """ NAT44 handling of client packets with TTL=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_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        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)
 
         # Client side - generate traffic
         pkts = self.create_stream_in(self.pg0, self.pg1, ttl=1)
@@ -1654,9 +1645,10 @@ class TestNAT44(MethodHolder):
         """ NAT44 handling of server packets with TTL=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_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        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)
 
         # Client side - create sessions
         pkts = self.create_stream_in(self.pg0, self.pg1)
@@ -1681,9 +1673,10 @@ class TestNAT44(MethodHolder):
         """ NAT44 handling of error responses to client packets with TTL=2 """
 
         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_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        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)
 
         # Client side - generate traffic
         pkts = self.create_stream_in(self.pg0, self.pg1, ttl=2)
@@ -1708,9 +1701,10 @@ class TestNAT44(MethodHolder):
         """ NAT44 handling of error responses to server packets with TTL=2 """
 
         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_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        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)
 
         # Client side - create sessions
         pkts = self.create_stream_in(self.pg0, self.pg1)
@@ -1743,9 +1737,10 @@ class TestNAT44(MethodHolder):
         """ Ping NAT44 out interface from outside network """
 
         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_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        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)
 
         p = (Ether(dst=self.pg1.local_mac, src=self.pg1.remote_mac) /
              IP(src=self.pg1.remote_ip4, dst=self.pg1.local_ip4) /
@@ -1770,9 +1765,10 @@ class TestNAT44(MethodHolder):
         """ Ping internal host from outside network """
 
         self.nat44_add_static_mapping(self.pg0.remote_ip4, self.nat_addr)
-        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)
+        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)
 
         # out2in
         pkt = (Ether(dst=self.pg1.local_mac, src=self.pg1.remote_mac) /
@@ -1799,15 +1795,18 @@ class TestNAT44(MethodHolder):
     def test_forwarding(self):
         """ NAT44 forwarding test """
 
-        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)
+        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_forwarding_enable_disable(1)
 
         real_ip = self.pg0.remote_ip4n
-        alias_ip = self.nat_addr_n
+        alias_ip = self.nat_addr
+        flags = self.config_flags.NAT_IS_ADDR_ONLY
         self.vapi.nat44_add_del_static_mapping(local_ip=real_ip,
-                                               external_ip=alias_ip)
+                                               external_ip=alias_ip,
+                                               flags=flags)
 
         try:
             # static mapping match
@@ -1852,9 +1851,10 @@ 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)
+                                                   is_add=0, flags=flags)
 
     def test_static_in(self):
         """ 1:1 NAT initialized from inside network """
@@ -1865,9 +1865,10 @@ class TestNAT44(MethodHolder):
         self.icmp_id_out = 6305
 
         self.nat44_add_static_mapping(self.pg0.remote_ip4, nat_ip)
-        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)
+        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)
         sm = self.vapi.nat44_static_mapping_dump()
         self.assertEqual(len(sm), 1)
         self.assertEqual((sm[0].tag).split(b'\0', 1)[0], b'')
@@ -1901,9 +1902,10 @@ class TestNAT44(MethodHolder):
         tag = b"testTAG"
 
         self.nat44_add_static_mapping(self.pg0.remote_ip4, nat_ip, tag=tag)
-        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)
+        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)
         sm = self.vapi.nat44_static_mapping_dump()
         self.assertEqual(len(sm), 1)
         self.assertEqual((sm[0].tag).split(b'\0', 1)[0], tag)
@@ -1941,9 +1943,10 @@ 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)
-        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)
+        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)
 
         # in2out
         pkts = self.create_stream_in(self.pg0, self.pg1)
@@ -1978,9 +1981,10 @@ 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)
-        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)
+        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)
 
         # out2in
         pkts = self.create_stream_out(self.pg1)
@@ -2011,10 +2015,12 @@ class TestNAT44(MethodHolder):
                                       vrf_id=10)
         self.nat44_add_static_mapping(self.pg0.remote_ip4, nat_ip2,
                                       vrf_id=10)
-        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)
+        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)
 
         # inside interface VRF match NAT44 static mapping VRF
         pkts = self.create_stream_in(self.pg4, self.pg3)
@@ -2040,9 +2046,10 @@ class TestNAT44(MethodHolder):
         self.icmp_id_out = 6305
 
         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_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        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)
 
         # dynamic
         pkts = self.create_stream_in(self.pg0, self.pg1)
@@ -2065,11 +2072,13 @@ class TestNAT44(MethodHolder):
 
     def test_identity_nat(self):
         """ Identity NAT """
-
-        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)
+        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)
 
         p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
              IP(src=self.pg1.remote_ip4, dst=self.pg0.remote_ip4) /
@@ -2093,8 +2102,9 @@ 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,
-                                                 vrf_id=1)
+                                                 flags=flags, vrf_id=1)
         identity_mappings = self.vapi.nat44_identity_mapping_dump()
         self.assertEqual(len(identity_mappings), 2)
 
@@ -2102,10 +2112,12 @@ class TestNAT44(MethodHolder):
         """ NAT44 multiple non-overlapping address space inside interfaces """
 
         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_feature(self.pg1.sw_if_index)
-        self.vapi.nat44_interface_add_del_feature(self.pg3.sw_if_index,
-                                                  is_inside=0)
+        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)
 
         # between two NAT44 inside interfaces (no translation)
         pkts = self.create_stream_in(self.pg0, self.pg1)
@@ -2160,11 +2172,14 @@ class TestNAT44(MethodHolder):
 
         static_nat_ip = "10.0.0.10"
         self.nat44_add_address(self.nat_addr)
-        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)
+        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.nat44_add_static_mapping(self.pg6.remote_ip4, static_nat_ip,
                                       vrf_id=20)
 
@@ -2234,9 +2249,9 @@ 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.is_static)
-            self.assertEqual(session.inside_ip_address[0:4],
-                             self.pg5.remote_ip4n)
+            self.assertFalse(session.flags & self.config_flags.NAT_IS_STATIC)
+            self.assertEqual(str(session.inside_ip_address),
+                             self.pg5.remote_ip4)
             self.assertEqual(session.outside_ip_address,
                              addresses[0].ip_address)
         self.assertEqual(sessions[0].protocol, IP_PROTOS.tcp)
@@ -2279,15 +2294,16 @@ class TestNAT44(MethodHolder):
                 self.assertTrue(session.protocol in
                                 [IP_PROTOS.tcp, IP_PROTOS.udp,
                                  IP_PROTOS.icmp])
-                self.assertFalse(session.ext_host_valid)
+                self.assertFalse(session.flags &
+                                 self.config_flags.NAT_IS_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.is_static)
-            self.assertEqual(session.inside_ip_address[0:4],
-                             self.pg4.remote_ip4n)
+            self.assertFalse(session.flags & self.config_flags.NAT_IS_STATIC)
+            self.assertEqual(str(session.inside_ip_address),
+                             self.pg4.remote_ip4)
             self.assertEqual(session.outside_ip_address,
                              addresses[0].ip_address)
 
@@ -2295,11 +2311,11 @@ 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.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.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.inside_port in
                             [self.tcp_port_in, self.udp_port_in,
                              self.icmp_id_in])
@@ -2315,9 +2331,11 @@ class TestNAT44(MethodHolder):
         server_out_port = 8765
 
         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_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        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)
+
         # add static mapping for server
         self.nat44_add_static_mapping(server.ip4, self.nat_addr,
                                       server_in_port, server_out_port,
@@ -2378,9 +2396,10 @@ class TestNAT44(MethodHolder):
         server_udp_port = 20
 
         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_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        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)
 
         # add static mapping for servers
         self.nat44_add_static_mapping(server1.ip4, server1_nat_ip)
@@ -2536,9 +2555,10 @@ class TestNAT44(MethodHolder):
         """ MAX translations per user - recycle the least recently used """
 
         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_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        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)
 
         # get maximum number of translations per user
         nat44_config = self.vapi.nat_show_config()
@@ -2595,7 +2615,7 @@ class TestNAT44(MethodHolder):
         self.pg7.config_ip4()
         addresses = self.vapi.nat44_address_dump()
         self.assertEqual(1, len(addresses))
-        self.assertEqual(addresses[0].ip_address[0:4], self.pg7.local_ip4n)
+        self.assertEqual(str(addresses[0].ip_address), self.pg7.local_ip4)
 
         # remove interface address and check NAT address pool
         self.pg7.unconfig_ip4()
@@ -2626,8 +2646,8 @@ class TestNAT44(MethodHolder):
         resolved = False
         for sm in static_mappings:
             if sm.external_sw_if_index == 0xFFFFFFFF:
-                self.assertEqual(sm.external_ip_address[0:4],
-                                 self.pg7.local_ip4n)
+                self.assertEqual(str(sm.external_ip_address),
+                                 self.pg7.local_ip4)
                 self.assertEqual((sm.tag).split(b'\0', 1)[0], tag)
                 resolved = True
         self.assertTrue(resolved)
@@ -2647,8 +2667,8 @@ class TestNAT44(MethodHolder):
         resolved = False
         for sm in static_mappings:
             if sm.external_sw_if_index == 0xFFFFFFFF:
-                self.assertEqual(sm.external_ip_address[0:4],
-                                 self.pg7.local_ip4n)
+                self.assertEqual(str(sm.external_ip_address),
+                                 self.pg7.local_ip4)
                 self.assertEqual((sm.tag).split(b'\0', 1)[0], tag)
                 resolved = True
         self.assertTrue(resolved)
@@ -2670,8 +2690,7 @@ class TestNAT44(MethodHolder):
         self.vapi.nat44_add_del_identity_mapping(
             sw_if_index=self.pg7.sw_if_index,
             port=port,
-            protocol=IP_PROTOS.tcp,
-            addr_only=0)
+            protocol=IP_PROTOS.tcp)
 
         # identity mappings with external interface
         identity_mappings = self.vapi.nat44_identity_mapping_dump()
@@ -2686,8 +2705,8 @@ class TestNAT44(MethodHolder):
         self.assertEqual(2, len(identity_mappings))
         for sm in identity_mappings:
             if sm.sw_if_index == 0xFFFFFFFF:
-                self.assertEqual(identity_mappings[0].ip_address,
-                                 self.pg7.local_ip4n)
+                self.assertEqual(str(identity_mappings[0].ip_address),
+                                 self.pg7.local_ip4)
                 self.assertEqual(port, identity_mappings[0].port)
                 self.assertEqual(IP_PROTOS.tcp, identity_mappings[0].protocol)
                 resolved = True
@@ -2707,9 +2726,10 @@ class TestNAT44(MethodHolder):
         collector_port = 30303
         bind_layers(UDP, IPFIX, dport=30303)
         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_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        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.set_ipfix_exporter(collector_address=self.pg3.remote_ip4n,
                                      src_address=self.pg3.local_ip4n,
                                      path_mtu=512,
@@ -2747,9 +2767,10 @@ class TestNAT44(MethodHolder):
 
     def test_ipfix_addr_exhausted(self):
         """ IPFIX logging NAT addresses exhausted """
-        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)
+        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.set_ipfix_exporter(collector_address=self.pg3.remote_ip4n,
                                      src_address=self.pg3.local_ip4n,
                                      path_mtu=512,
@@ -2789,9 +2810,10 @@ class TestNAT44(MethodHolder):
     def test_ipfix_max_sessions(self):
         """ IPFIX logging maximum session entries exceeded """
         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_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        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)
 
         nat44_config = self.vapi.nat_show_config()
         max_sessions = 10 * nat44_config.translation_buckets
@@ -2848,9 +2870,10 @@ 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)
-        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)
+        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)
 
         p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
              IP(src=self.pg0.remote_ip4, dst=self.pg1.remote_ip4) /
@@ -2873,9 +2896,10 @@ class TestNAT44(MethodHolder):
         """ NAT44 add pool addresses to FIB """
         static_addr = '10.0.0.10'
         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_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        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.nat44_add_static_mapping(self.pg0.remote_ip4, static_addr)
 
         # NAT44 address
@@ -2951,10 +2975,12 @@ class TestNAT44(MethodHolder):
 
         self.nat44_add_address(nat_ip1, vrf_id=vrf_id1)
         self.nat44_add_address(nat_ip2, vrf_id=vrf_id2)
-        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)
+        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)
 
         try:
             # first VRF
@@ -2993,10 +3019,12 @@ class TestNAT44(MethodHolder):
 
         self.nat44_add_address(nat_ip1)
         self.nat44_add_address(nat_ip2, vrf_id=99)
-        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)
+        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)
 
         # first VRF
         pkts = self.create_stream_in(self.pg0, self.pg2)
@@ -3040,9 +3068,10 @@ class TestNAT44(MethodHolder):
                                    next_hop_sw_if_index=self.pg8.sw_if_index)
 
         self.nat44_add_address(self.nat_addr)
-        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)
+        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)
 
         # in2out
         pkts = self.create_stream_in(self.pg7, self.pg8)
@@ -3086,9 +3115,10 @@ 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)
-        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)
+        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)
 
         # out2in
         pkts = self.create_stream_out(self.pg8)
@@ -3145,9 +3175,10 @@ 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)
-        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)
+        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)
 
         # out2in
         pkts = self.create_stream_out(self.pg8)
@@ -3169,9 +3200,10 @@ 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)
-        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)
+        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)
 
         # in2out
         p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
@@ -3224,9 +3256,10 @@ class TestNAT44(MethodHolder):
 
         self.nat44_add_static_mapping(host.ip4, host_nat_ip)
         self.nat44_add_static_mapping(server.ip4, server_nat_ip)
-        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)
+        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)
 
         # host to server
         p = (Ether(dst=self.pg0.local_mac, src=host.mac) /
@@ -3271,10 +3304,12 @@ class TestNAT44(MethodHolder):
     def test_output_feature(self):
         """ NAT44 interface output feature (in2out postrouting) """
         self.nat44_add_address(self.nat_addr)
-        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)
+        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)
 
         # in2out
         pkts = self.create_stream_in(self.pg0, self.pg3)
@@ -3318,10 +3353,12 @@ class TestNAT44(MethodHolder):
 
         self.nat44_add_address(nat_ip_vrf10, vrf_id=10)
         self.nat44_add_address(nat_ip_vrf20, vrf_id=20)
-        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)
+        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)
 
         # in2out VRF 10
         pkts = self.create_stream_in(self.pg4, self.pg3)
@@ -3365,9 +3402,10 @@ class TestNAT44(MethodHolder):
         server_out_port = 8765
 
         self.nat44_add_address(self.nat_addr)
-        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)
+        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)
 
         # add static mapping for server
         self.nat44_add_static_mapping(server.ip4, self.nat_addr,
@@ -3424,9 +3462,10 @@ 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,
-                                                  is_inside=0)
+                                                  flags=flags)
 
         # in2out
         p = (Ether(src=self.pg9.remote_mac, dst=self.pg9.local_mac) /
@@ -3479,9 +3518,10 @@ class TestNAT44(MethodHolder):
     def test_del_session(self):
         """ Delete NAT44 session """
         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_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        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)
 
         pkts = self.create_stream_in(self.pg0, self.pg1)
         self.pg0.add_stream(pkts)
@@ -3494,18 +3534,19 @@ class TestNAT44(MethodHolder):
 
         self.vapi.nat44_del_session(sessions[0].inside_ip_address,
                                     sessions[0].inside_port,
-                                    sessions[0].protocol)
+                                    sessions[0].protocol,
+                                    flags=self.config_flags.NAT_IS_INSIDE)
         self.vapi.nat44_del_session(sessions[1].outside_ip_address,
                                     sessions[1].outside_port,
-                                    sessions[1].protocol,
-                                    is_in=0)
+                                    sessions[1].protocol)
 
         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)
+                                    sessions[0].protocol,
+                                    flags=self.config_flags.NAT_IS_INSIDE)
 
         self.verify_no_nat44_user()
 
@@ -3530,9 +3571,10 @@ class TestNAT44(MethodHolder):
         """ NAT44 translate fragments arriving in order """
 
         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_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        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.frag_in_order(proto=IP_PROTOS.tcp)
         self.frag_in_order(proto=IP_PROTOS.udp)
@@ -3541,9 +3583,10 @@ class TestNAT44(MethodHolder):
     def test_frag_forwarding(self):
         """ NAT44 forwarding fragment test """
         self.vapi.nat44_add_del_interface_addr(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)
+        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_forwarding_enable_disable(1)
 
         data = b"A" * 16 + b"B" * 16 + b"C" * 3
@@ -3573,9 +3616,10 @@ class TestNAT44(MethodHolder):
         self.server_out_port = random.randint(1025, 65535)
 
         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_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        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)
         # add static mapping for server
         self.nat44_add_static_mapping(self.server.ip4, self.nat_addr,
                                       self.server_in_port,
@@ -3595,9 +3639,10 @@ class TestNAT44(MethodHolder):
         """ NAT44 translate fragments arriving out of order """
 
         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_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        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.frag_out_of_order(proto=IP_PROTOS.tcp)
         self.frag_out_of_order(proto=IP_PROTOS.udp)
@@ -3606,9 +3651,10 @@ class TestNAT44(MethodHolder):
     def test_port_restricted(self):
         """ Port restricted NAT44 (MAP-E CE) """
         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_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        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.nat_set_addr_and_port_alloc_alg(alg=1,
                                                   psid_offset=6,
                                                   psid_length=6,
@@ -3638,9 +3684,10 @@ class TestNAT44(MethodHolder):
     def test_port_range(self):
         """ External address port range """
         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_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        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.nat_set_addr_and_port_alloc_alg(alg=2,
                                                   start_port=1025,
                                                   end_port=1027)
@@ -3663,9 +3710,10 @@ class TestNAT44(MethodHolder):
     def test_ipfix_max_frags(self):
         """ IPFIX logging maximum fragments pending reassembly exceeded """
         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_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        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.nat_set_reass(max_frag=1)
         self.vapi.set_ipfix_exporter(collector_address=self.pg3.remote_ip4n,
                                      src_address=self.pg3.local_ip4n,
@@ -3725,11 +3773,11 @@ class TestNAT44(MethodHolder):
         self.pg2.resolve_arp()
 
         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_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
-        self.vapi.nat44_interface_add_del_feature(self.pg2.sw_if_index,
-                                                  is_inside=0)
+        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)
 
         try:
             # first VRF
@@ -3780,9 +3828,10 @@ class TestNAT44(MethodHolder):
     def test_session_timeout(self):
         """ NAT44 session timeouts """
         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_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        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.nat_set_timeouts(udp=5)
 
         max_sessions = 1000
@@ -3821,9 +3870,10 @@ class TestNAT44(MethodHolder):
     def test_mss_clamping(self):
         """ TCP MSS clamping """
         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_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        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)
 
         p = (Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac) /
              IP(src=self.pg0.remote_ip4, dst=self.pg1.remote_ip4) /
@@ -3858,9 +3908,10 @@ class TestNAT44(MethodHolder):
     def test_ha_send(self):
         """ Send HA session synchronization events (active) """
         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_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        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.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)
@@ -3913,8 +3964,10 @@ 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)
+        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.nat_ha_flush()
         stats = self.statistics.get_counter('/nat44/ha/del-event-send')
         self.assertEqual(stats[0][0], 1)
@@ -3985,9 +4038,10 @@ class TestNAT44(MethodHolder):
     def test_ha_recv(self):
         """ Receive HA session synchronization events (passive) """
         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_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        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.nat_ha_set_listener(self.pg3.local_ip4, port=12345)
         bind_layers(UDP, HANATStateSync, sport=12345)
 
@@ -4040,14 +4094,17 @@ class TestNAT44(MethodHolder):
         self.assertEqual(sessions[0][0], 2)
         users = self.vapi.nat44_user_dump()
         self.assertEqual(len(users), 1)
-        self.assertEqual(users[0].ip_address, self.pg0.remote_ip4n)
+        self.assertEqual(str(users[0].ip_address),
+                         self.pg0.remote_ip4)
         # 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(session.inside_ip_address, self.pg0.remote_ip4n)
-            self.assertEqual(session.outside_ip_address, self.nat_addr_n)
+            self.assertEqual(str(session.inside_ip_address),
+                             self.pg0.remote_ip4)
+            self.assertEqual(str(session.outside_ip_address),
+                             self.nat_addr)
             self.assertIn(session.inside_port,
                           [self.tcp_port_in, self.udp_port_in])
             self.assertIn(session.outside_port,
@@ -4084,7 +4141,8 @@ class TestNAT44(MethodHolder):
             self.assertEqual(hanat.version, 1)
         users = self.vapi.nat44_user_dump()
         self.assertEqual(len(users), 1)
-        self.assertEqual(users[0].ip_address, self.pg0.remote_ip4n)
+        self.assertEqual(str(users[0].ip_address),
+                         self.pg0.remote_ip4)
         # 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)
@@ -4125,7 +4183,8 @@ class TestNAT44(MethodHolder):
             self.assertEqual(hanat.version, 1)
         users = self.vapi.nat44_user_dump()
         self.assertEqual(len(users), 1)
-        self.assertEqual(users[0].ip_address, self.pg0.remote_ip4n)
+        self.assertEqual(str(users[0].ip_address),
+                         self.pg0.remote_ip4)
         sessions = self.vapi.nat44_user_session_dump(users[0].ip_address,
                                                      users[0].vrf_id)
         self.assertEqual(len(sessions), 1)
@@ -4198,7 +4257,6 @@ 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
@@ -4288,47 +4346,52 @@ class TestNAT44EndpointDependent(MethodHolder):
     def test_frag_in_order(self):
         """ NAT44 translate fragments arriving in order """
         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_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        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.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 """
-        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)
+        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_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)
-        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)
+        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.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 """
-        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)
+        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_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,
-                                                  is_inside=0)
+                                                  flags=flags)
         self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
         self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+                                                  flags=flags)
 
         self.server = self.pg1.remote_hosts[0]
 
@@ -4362,12 +4425,13 @@ 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,
-                                                  is_inside=0)
+                                                  flags=flags)
         self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
         self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+                                                  flags=flags)
 
         self.server = self.pg1.remote_hosts[0]
 
@@ -4407,9 +4471,10 @@ class TestNAT44EndpointDependent(MethodHolder):
         self.server_out_port = random.randint(1025, 65535)
 
         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_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        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)
         # add static mapping for server
         self.nat44_add_static_mapping(self.server.ip4, self.nat_addr,
                                       self.server_in_port,
@@ -4429,9 +4494,10 @@ class TestNAT44EndpointDependent(MethodHolder):
         """ NAT44 dynamic translation test """
 
         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_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        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)
 
         nat_config = self.vapi.nat_show_config()
         self.assertEqual(1, nat_config.endpoint_dependent)
@@ -4500,15 +4566,18 @@ class TestNAT44EndpointDependent(MethodHolder):
     def test_forwarding(self):
         """ NAT44 forwarding test """
 
-        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)
+        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_forwarding_enable_disable(1)
 
-        real_ip = self.pg0.remote_ip4n
-        alias_ip = self.nat_addr_n
+        real_ip = self.pg0.remote_ip4
+        alias_ip = self.nat_addr
+        flags = self.config_flags.NAT_IS_ADDR_ONLY
         self.vapi.nat44_add_del_static_mapping(local_ip=real_ip,
-                                               external_ip=alias_ip)
+                                               external_ip=alias_ip,
+                                               flags=flags)
 
         try:
             # in2out - static mapping match
@@ -4554,11 +4623,14 @@ 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].ext_host_valid)
+            self.assertTrue(sessions[0].flags &
+                            self.config_flags.NAT_IS_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)
@@ -4566,13 +4638,14 @@ 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)
+                                                   is_add=0, flags=flags)
 
     def test_static_lb(self):
         """ NAT44 local service load balancing """
-        external_addr_n = socket.inet_pton(socket.AF_INET, self.nat_addr)
+        external_addr_n = self.nat_addr
         external_port = 80
         local_port = 8080
         server1 = self.pg0.remote_hosts[0]
@@ -4593,9 +4666,10 @@ class TestNAT44EndpointDependent(MethodHolder):
                                                   IP_PROTOS.tcp,
                                                   local_num=len(locals),
                                                   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)
+        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)
 
         # from client to service
         p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
@@ -4642,11 +4716,14 @@ class TestNAT44EndpointDependent(MethodHolder):
 
         sessions = self.vapi.nat44_user_session_dump(server.ip4n, 0)
         self.assertEqual(len(sessions), 1)
-        self.assertTrue(sessions[0].ext_host_valid)
+        self.assertTrue(sessions[0].flags &
+                        self.config_flags.NAT_IS_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)
@@ -4656,7 +4733,7 @@ class TestNAT44EndpointDependent(MethodHolder):
     def test_static_lb_multi_clients(self):
         """ NAT44 local service load balancing - multiple clients"""
 
-        external_addr_n = socket.inet_pton(socket.AF_INET, self.nat_addr)
+        external_addr = self.nat_addr
         external_port = 80
         local_port = 8080
         server1 = self.pg0.remote_hosts[0]
@@ -4673,14 +4750,15 @@ class TestNAT44EndpointDependent(MethodHolder):
                    'vrf_id': 0}]
 
         self.nat44_add_address(self.nat_addr)
-        self.vapi.nat44_add_del_lb_static_mapping(external_addr_n,
+        self.vapi.nat44_add_del_lb_static_mapping(external_addr,
                                                   external_port,
                                                   IP_PROTOS.tcp,
                                                   local_num=len(locals),
                                                   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)
+        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)
 
         server1_n = 0
         server2_n = 0
@@ -4703,7 +4781,7 @@ class TestNAT44EndpointDependent(MethodHolder):
         self.assertGreater(server1_n, server2_n)
 
         # add new back-end
-        self.vapi.nat44_lb_static_mapping_add_del_local(external_addr_n,
+        self.vapi.nat44_lb_static_mapping_add_del_local(external_addr,
                                                         external_port,
                                                         server3.ip4n,
                                                         local_port,
@@ -4736,7 +4814,7 @@ class TestNAT44EndpointDependent(MethodHolder):
         self.assertGreater(server3_n, 0)
 
         # remove one back-end
-        self.vapi.nat44_lb_static_mapping_add_del_local(external_addr_n,
+        self.vapi.nat44_lb_static_mapping_add_del_local(external_addr,
                                                         external_port,
                                                         server2.ip4n,
                                                         local_port,
@@ -4763,7 +4841,7 @@ class TestNAT44EndpointDependent(MethodHolder):
 
     def test_static_lb_2(self):
         """ NAT44 local service load balancing (asymmetrical rule) """
-        external_addr_n = socket.inet_pton(socket.AF_INET, self.nat_addr)
+        external_addr = self.nat_addr
         external_port = 80
         local_port = 8080
         server1 = self.pg0.remote_hosts[0]
@@ -4779,15 +4857,17 @@ class TestNAT44EndpointDependent(MethodHolder):
                    'vrf_id': 0}]
 
         self.vapi.nat44_forwarding_enable_disable(1)
-        self.vapi.nat44_add_del_lb_static_mapping(external_addr_n,
+        flags = self.config_flags.NAT_IS_OUT2IN_ONLY
+        self.vapi.nat44_add_del_lb_static_mapping(external_addr,
                                                   external_port,
                                                   IP_PROTOS.tcp,
-                                                  out2in_only=1,
                                                   local_num=len(locals),
-                                                  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)
+                                                  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)
 
         # from client to service
         p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
@@ -4873,7 +4953,7 @@ class TestNAT44EndpointDependent(MethodHolder):
 
     def test_lb_affinity(self):
         """ NAT44 local service load balancing affinity """
-        external_addr_n = socket.inet_pton(socket.AF_INET, self.nat_addr)
+        external_addr = self.nat_addr
         external_port = 80
         local_port = 8080
         server1 = self.pg0.remote_hosts[0]
@@ -4889,15 +4969,16 @@ class TestNAT44EndpointDependent(MethodHolder):
                    'vrf_id': 0}]
 
         self.nat44_add_address(self.nat_addr)
-        self.vapi.nat44_add_del_lb_static_mapping(external_addr_n,
+        self.vapi.nat44_add_del_lb_static_mapping(external_addr,
                                                   external_port,
                                                   IP_PROTOS.tcp,
                                                   affinity=10800,
                                                   local_num=len(locals),
                                                   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)
+        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)
 
         p = (Ether(dst=self.pg1.local_mac, src=self.pg1.remote_mac) /
              IP(src=self.pg1.remote_ip4, dst=self.nat_addr) /
@@ -4908,14 +4989,16 @@ class TestNAT44EndpointDependent(MethodHolder):
         capture = self.pg0.get_capture(1)
         backend = capture[0][IP].dst
 
-        sessions = self.vapi.nat44_user_session_dump(
-            socket.inet_pton(socket.AF_INET, backend), 0)
+        sessions = self.vapi.nat44_user_session_dump(backend, 0)
         self.assertEqual(len(sessions), 1)
-        self.assertTrue(sessions[0].ext_host_valid)
+        self.assertTrue(sessions[0].flags &
+                        self.config_flags.NAT_IS_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)
 
@@ -4935,9 +5018,10 @@ class TestNAT44EndpointDependent(MethodHolder):
     def test_unknown_proto(self):
         """ NAT44 translate packet with unknown protocol """
         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_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        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)
 
         # in2out
         p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
@@ -4996,9 +5080,10 @@ class TestNAT44EndpointDependent(MethodHolder):
         server_nat_ip = "10.0.0.11"
 
         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_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        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)
 
         # add static mapping for server
         self.nat44_add_static_mapping(server.ip4, server_nat_ip)
@@ -5059,15 +5144,18 @@ class TestNAT44EndpointDependent(MethodHolder):
 
         self.vapi.nat44_forwarding_enable_disable(1)
         self.nat44_add_address(self.nat_addr)
-        self.vapi.nat44_add_del_identity_mapping(ip=self.pg1.remote_ip4n)
+        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.nat44_add_static_mapping(self.pg0.remote_ip4, external_addr,
                                       local_port, external_port,
-                                      proto=IP_PROTOS.tcp, out2in_only=1)
+                                      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)
         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)
+                                                  flags=flags)
+        self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index)
 
         # from client to service
         p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
@@ -5133,8 +5221,7 @@ 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,
-                                                         is_inside=0)
+        self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index)
 
         # session initiated from service host - translate
         pkts = self.create_stream_in(self.pg0, self.pg1)
@@ -5180,14 +5267,15 @@ 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, out2in_only=1)
+                                      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)
         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)
+                                                  flags=flags)
+        self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index)
 
         p = (Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac) /
              IP(src=self.pg0.remote_ip4, dst=external_addr) /
@@ -5238,12 +5326,13 @@ 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, 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)
+                                      proto=IP_PROTOS.tcp, vrf_id=1,
+                                      flags=flags)
+        self.vapi.nat44_interface_add_del_feature(self.pg6.sw_if_index)
 
         p = (Ether(src=self.pg6.remote_mac, dst=self.pg6.local_mac) /
              IP(src=self.pg6.remote_ip4, dst=self.pg1.remote_ip4) /
@@ -5320,12 +5409,18 @@ 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,
-                                          twice_nat=int(not self_twice_nat),
-                                          self_twice_nat=int(self_twice_nat))
+                                          flags=flags)
         else:
             locals = [{'addr': server1.ip4n,
                        'port': port_in1,
@@ -5335,19 +5430,18 @@ class TestNAT44EndpointDependent(MethodHolder):
                        'port': port_in2,
                        'probability': 50,
                        'vrf_id': 0}]
-            out_addr_n = socket.inet_pton(socket.AF_INET, self.nat_addr)
-            self.vapi.nat44_add_del_lb_static_mapping(out_addr_n,
+            out_addr = self.nat_addr
+
+            self.vapi.nat44_add_del_lb_static_mapping(out_addr,
                                                       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)
-        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)
+                                                      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)
 
         if same_pg:
             if not lb:
@@ -5420,12 +5514,17 @@ 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].ext_host_valid)
-            self.assertTrue(sessions[0].is_twicenat)
+            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.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)
@@ -5459,8 +5558,9 @@ 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,
-                                               twice_nat=1)
+                                               flags=flags)
 
         # no address in NAT pool
         adresses = self.vapi.nat44_address_dump()
@@ -5470,8 +5570,9 @@ class TestNAT44EndpointDependent(MethodHolder):
         self.pg3.config_ip4()
         adresses = self.vapi.nat44_address_dump()
         self.assertEqual(1, len(adresses))
-        self.assertEqual(adresses[0].ip_address[0:4], self.pg3.local_ip4n)
-        self.assertEqual(adresses[0].twice_nat, 1)
+        self.assertEqual(str(adresses[0].ip_address),
+                         self.pg3.local_ip4)
+        self.assertEqual(adresses[0].flags, flags)
 
         # remove interface address and check NAT address pool
         self.pg3.unconfig_ip4()
@@ -5485,18 +5586,19 @@ 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,
-                                                  is_inside=0)
-        self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index,
-                                                         is_inside=0)
+                                                  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)
         self.nat44_add_static_mapping(self.pg0.remote_ip4,
                                       service_ip,
                                       80,
                                       80,
                                       proto=IP_PROTOS.tcp,
-                                      out2in_only=1,
-                                      twice_nat=1)
+                                      flags=flags)
         sessions = self.vapi.nat44_user_session_dump(self.pg0.remote_ip4n, 0)
         start_sessnum = len(sessions)
 
@@ -5564,15 +5666,17 @@ 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,
-                                      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)
+                                      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)
 
         sessions = self.vapi.nat44_user_session_dump(self.pg0.remote_ip4n, 0)
         start_sessnum = len(sessions)
@@ -5628,15 +5732,17 @@ 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,
-                                      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)
+                                      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)
 
         sessions = self.vapi.nat44_user_session_dump(self.pg0.remote_ip4n, 0)
         start_sessnum = len(sessions)
@@ -5682,15 +5788,17 @@ 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,
-                                      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)
+                                      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)
 
         sessions = self.vapi.nat44_user_session_dump(self.pg0.remote_ip4n, 0)
         start_sessnum = len(sessions)
@@ -5751,13 +5859,15 @@ 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, out2in_only=1,
-                                      twice_nat=1)
+                                      proto=IP_PROTOS.tcp, flags=flags)
+        flags = self.config_flags.NAT_IS_INSIDE
         self.vapi.nat44_interface_add_del_feature(self.pg4.sw_if_index)
         self.vapi.nat44_interface_add_del_feature(self.pg4.sw_if_index,
-                                                  is_inside=0)
+                                                  flags=flags)
 
         # from client to service
         p = (Ether(src=self.pg4.remote_mac, dst=self.pg4.local_mac) /
@@ -5809,12 +5919,14 @@ 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, 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)
+                                      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)
 
         # from client to service
         p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
@@ -5932,10 +6044,8 @@ 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,
-                                                  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.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index)
 
         # in2out
         pkts = self.create_stream_in(self.pg0, self.pg1)
@@ -5962,23 +6072,28 @@ 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,
-                                                  is_inside=0)
-        self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index,
-                                                         is_inside=0)
+                                                  flags=flags)
+        self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index)
         self.vapi.nat44_interface_add_del_feature(self.pg5.sw_if_index)
         self.vapi.nat44_interface_add_del_feature(self.pg5.sw_if_index,
-                                                  is_inside=0)
-        self.vapi.nat44_interface_add_del_feature(self.pg6.sw_if_index,
-                                                  is_inside=0)
+                                                  flags=flags)
+        self.vapi.nat44_interface_add_del_feature(self.pg6.sw_if_index)
+        flags = self.config_flags.NAT_IS_OUT2IN_ONLY
         self.nat44_add_static_mapping(self.pg5.remote_ip4, external_addr,
                                       local_port, external_port, vrf_id=1,
-                                      proto=IP_PROTOS.tcp, out2in_only=1)
+                                      proto=IP_PROTOS.tcp, flags=flags)
         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, out2in_only=1)
+                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
+        )
 
         # from client to service (both VRF1)
         p = (Ether(src=self.pg6.remote_mac, dst=self.pg6.local_mac) /
@@ -6250,9 +6365,10 @@ class TestNAT44EndpointDependent(MethodHolder):
     def test_session_timeout(self):
         """ NAT44 session timeouts """
         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_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        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.nat_set_timeouts(icmp=5)
 
         max_sessions = 1000
@@ -6292,9 +6408,10 @@ class TestNAT44EndpointDependent(MethodHolder):
     def test_session_rst_timeout(self):
         """ NAT44 session RST timeouts """
         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_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        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.nat_set_timeouts(tcp_transitory=5)
 
         self.initiate_tcp_session(self.pg0, self.pg1)
@@ -6321,16 +6438,18 @@ class TestNAT44EndpointDependent(MethodHolder):
         nsessions = 0
         users = self.vapi.nat44_user_dump()
         self.assertEqual(len(users), 1)
-        self.assertEqual(users[0].ip_address, self.pg0.remote_ip4n)
+        self.assertEqual(str(users[0].ip_address),
+                         self.pg0.remote_ip4)
         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)
-        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)
+        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.set_ipfix_exporter(collector_address=self.pg2.remote_ip4n,
                                      src_address=self.pg2.local_ip4n,
                                      path_mtu=512,
@@ -6396,9 +6515,10 @@ 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)
-        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)
+        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)
 
         p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
              IP(src=self.pg0.remote_ip4, dst=self.pg1.remote_ip4) /
@@ -6454,7 +6574,6 @@ 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))
@@ -6503,7 +6622,9 @@ class TestNAT44Out2InDPO(MethodHolder):
 
         self.configure_xlat()
 
-        self.vapi.nat44_interface_add_del_feature(self.pg0.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_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,
@@ -6529,7 +6650,7 @@ 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)
+                                                      is_add=0, flags=flags)
             self.vapi.nat44_add_del_address_range(self.nat_addr_n,
                                                   self.nat_addr_n, is_add=0)
 
@@ -6689,28 +6810,26 @@ 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(in_addr_n, in_plen, out_addr_n, out_plen)
+        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)
 
-        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)
+        self.assertEqual(str(rep2.in_addr), in_addr_t)
 
         deterministic_mappings = self.vapi.nat_det_map_dump()
         self.assertEqual(len(deterministic_mappings), 1)
         dsm = deterministic_mappings[0]
-        self.assertEqual(in_addr_n, dsm.in_addr[:4])
+        self.assertEqual(in_addr, str(dsm.in_addr))
         self.assertEqual(in_plen, dsm.in_plen)
-        self.assertEqual(out_addr_n, dsm.out_addr[:4])
+        self.assertEqual(out_addr, str(dsm.out_addr))
         self.assertEqual(out_plen, dsm.out_plen)
 
         self.clear_nat_det()
@@ -6740,13 +6859,16 @@ class TestDeterministicNAT(MethodHolder):
 
         nat_ip = "10.0.0.10"
 
-        self.vapi.nat_det_add_del_map(self.pg0.remote_ip4n,
+        self.vapi.nat_det_add_del_map(1,
+                                      self.pg0.remote_ip4n,
                                       32,
                                       socket.inet_aton(nat_ip),
                                       32)
-        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)
+
+        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)
 
         # in2out
         pkts = self.create_stream_in(self.pg0, self.pg1)
@@ -6770,21 +6892,21 @@ class TestDeterministicNAT(MethodHolder):
 
         # TCP session
         s = sessions[0]
-        self.assertEqual(s.ext_addr[:4], self.pg1.remote_ip4n)
+        self.assertEqual(str(s.ext_addr), self.pg1.remote_ip4)
         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(s.ext_addr[:4], self.pg1.remote_ip4n)
+        self.assertEqual(str(s.ext_addr), self.pg1.remote_ip4)
         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(s.ext_addr[:4], self.pg1.remote_ip4n)
+        self.assertEqual(str(s.ext_addr), self.pg1.remote_ip4)
         self.assertEqual(s.in_port, self.icmp_id_in)
         self.assertEqual(s.out_port, self.icmp_external_id)
 
@@ -6798,13 +6920,15 @@ class TestDeterministicNAT(MethodHolder):
         host0 = self.pg0.remote_hosts[0]
         host1 = self.pg0.remote_hosts[1]
 
-        self.vapi.nat_det_add_del_map(host0.ip4n,
+        self.vapi.nat_det_add_del_map(1,
+                                      host0.ip4n,
                                       24,
                                       socket.inet_aton(nat_ip),
                                       32)
-        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)
+        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)
 
         # host0 to out
         p = (Ether(src=host0.mac, dst=self.pg0.local_mac) /
@@ -6907,13 +7031,15 @@ 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(self.pg0.remote_ip4n,
+        self.vapi.nat_det_add_del_map(1,
+                                      self.pg0.remote_ip4n,
                                       32,
                                       socket.inet_aton(self.nat_addr),
                                       32)
-        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)
+        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.initiate_tcp_session(self.pg0, self.pg1)
 
@@ -6969,13 +7095,15 @@ 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(self.pg0.remote_ip4n,
+        self.vapi.nat_det_add_del_map(1,
+                                      self.pg0.remote_ip4n,
                                       32,
                                       socket.inet_aton(self.nat_addr),
                                       32)
-        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)
+        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.initiate_tcp_session(self.pg0, self.pg1)
 
@@ -7032,13 +7160,15 @@ 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(self.pg0.remote_ip4n,
+        self.vapi.nat_det_add_del_map(1,
+                                      self.pg0.remote_ip4n,
                                       32,
                                       socket.inet_aton(self.nat_addr),
                                       32)
-        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)
+        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.initiate_tcp_session(self.pg0, self.pg1)
         self.vapi.nat_set_timeouts(5, 5, 5, 5)
@@ -7055,13 +7185,15 @@ 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(self.pg0.remote_ip4n,
+        self.vapi.nat_det_add_del_map(1,
+                                      self.pg0.remote_ip4n,
                                       32,
                                       socket.inet_aton(self.nat_addr),
                                       32)
-        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)
+        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.set_ipfix_exporter(collector_address=self.pg2.remote_ip4n,
                                      src_address=self.pg2.local_ip4n,
                                      path_mtu=512,
@@ -7130,17 +7262,17 @@ 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(dsm.in_addr,
+            self.vapi.nat_det_add_del_map(0,
+                                          dsm.in_addr,
                                           dsm.in_plen,
                                           dsm.out_addr,
-                                          dsm.out_plen,
-                                          is_add=0)
+                                          dsm.out_plen)
 
         interfaces = self.vapi.nat44_interface_dump()
         for intf in interfaces:
             self.vapi.nat44_interface_add_del_feature(intf.sw_if_index,
-                                                      intf.is_inside,
-                                                      is_add=0)
+                                                      is_add=0,
+                                                      flags=intf.flags)
 
     def tearDown(self):
         super(TestDeterministicNAT, self).tearDown()
@@ -7181,8 +7313,6 @@ 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
 
@@ -7228,7 +7358,8 @@ class TestNAT64(MethodHolder):
     def test_nat64_inside_interface_handles_neighbor_advertisement(self):
         """ NAT64 inside interface handles Neighbor Advertisement """
 
-        self.vapi.nat64_add_del_interface(self.pg5.sw_if_index)
+        flags = self.config_flags.NAT_IS_INSIDE
+        self.vapi.nat64_add_del_interface(1, flags, self.pg5.sw_if_index)
 
         # Try to send ping
         ping = (Ether(dst=self.pg5.local_mac, src=self.pg5.remote_mac) /
@@ -7279,13 +7410,13 @@ class TestNAT64(MethodHolder):
 
     def test_pool(self):
         """ Add/delete address to NAT64 pool """
-        nat_addr = socket.inet_pton(socket.AF_INET, '1.2.3.4')
+        nat_addr = '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(addresses[0].address, nat_addr)
+        self.assertEqual(str(addresses[0].address), nat_addr)
 
         self.vapi.nat64_add_del_pool_addr_range(nat_addr, nat_addr, is_add=0)
 
@@ -7294,8 +7425,9 @@ class TestNAT64(MethodHolder):
 
     def test_interface(self):
         """ Enable/disable NAT64 feature on the interface """
-        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)
+        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)
 
         interfaces = self.vapi.nat64_interface_dump()
         self.assertEqual(len(interfaces), 2)
@@ -7303,10 +7435,10 @@ class TestNAT64(MethodHolder):
         pg1_found = False
         for intf in interfaces:
             if intf.sw_if_index == self.pg0.sw_if_index:
-                self.assertEqual(intf.is_inside, 1)
+                self.assertEqual(intf.flags, self.config_flags.NAT_IS_INSIDE)
                 pg0_found = True
             elif intf.sw_if_index == self.pg1.sw_if_index:
-                self.assertEqual(intf.is_inside, 0)
+                self.assertEqual(intf.flags, self.config_flags.NAT_IS_OUTSIDE)
                 pg1_found = True
         self.assertTrue(pg0_found)
         self.assertTrue(pg1_found)
@@ -7316,17 +7448,16 @@ class TestNAT64(MethodHolder):
         features = self.vapi.cli("show interface features pg1")
         self.assertIn('nat64-out2in', features)
 
-        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)
+        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)
 
         interfaces = self.vapi.nat64_interface_dump()
         self.assertEqual(len(interfaces), 0)
 
     def test_static_bib(self):
         """ Add/delete static BIB entry """
-        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_addr = '2001:db8:85a3::8a2e:370:7334'
+        out_addr = '10.1.1.3'
         in_port = 1234
         out_port = 5678
         proto = IP_PROTOS.tcp
@@ -7339,10 +7470,10 @@ class TestNAT64(MethodHolder):
         bib = self.vapi.nat64_bib_dump(IP_PROTOS.tcp)
         static_bib_num = 0
         for bibe in bib:
-            if bibe.is_static:
+            if bibe.flags & self.config_flags.NAT_IS_STATIC:
                 static_bib_num += 1
-                self.assertEqual(bibe.i_addr, in_addr)
-                self.assertEqual(bibe.o_addr, out_addr)
+                self.assertEqual(str(bibe.i_addr), in_addr)
+                self.assertEqual(str(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)
@@ -7358,7 +7489,7 @@ class TestNAT64(MethodHolder):
         bib = self.vapi.nat64_bib_dump(IP_PROTOS.tcp)
         static_bib_num = 0
         for bibe in bib:
-            if bibe.is_static:
+            if bibe.flags & self.config_flags.NAT_IS_STATIC:
                 static_bib_num += 1
         self.assertEqual(static_bib_num, 0)
         bibs = self.statistics.get_counter('/nat64/total-bibs')
@@ -7390,10 +7521,11 @@ class TestNAT64(MethodHolder):
 
         ses_num_start = self.nat64_get_ses_num()
 
-        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.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)
 
         # in2out
         tcpn = self.statistics.get_counter('/err/nat64-in2out/TCP packets')
@@ -7472,10 +7604,11 @@ 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_n,
-                                                self.vrf1_nat_addr_n,
+        self.vapi.nat64_add_del_pool_addr_range(self.vrf1_nat_addr,
+                                                self.vrf1_nat_addr,
                                                 vrf_id=self.vrf1_id)
-        self.vapi.nat64_add_del_interface(self.pg2.sw_if_index)
+        flags = self.config_flags.NAT_IS_INSIDE
+        self.vapi.nat64_add_del_interface(1, flags, self.pg2.sw_if_index)
 
         pkts = self.create_stream_in_ip6(self.pg2, self.pg1)
         self.pg2.add_stream(pkts)
@@ -7503,23 +7636,24 @@ class TestNAT64(MethodHolder):
 
         ses_num_start = self.nat64_get_ses_num()
 
-        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.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_static_bib(self.pg0.remote_ip6n,
-                                           self.nat_addr_n,
+                                           self.nat_addr,
                                            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_n,
+                                           self.nat_addr,
                                            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_n,
+                                           self.nat_addr,
                                            self.icmp_id_in,
                                            self.icmp_id_out,
                                            IP_PROTOS.icmp)
@@ -7550,10 +7684,11 @@ 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_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.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.nat_set_timeouts(icmp=5, tcp_transitory=5, tcp_established=5)
 
         pkts = self.create_stream_in_ip6(self.pg0, self.pg1)
@@ -7576,10 +7711,11 @@ class TestNAT64(MethodHolder):
         self.udp_port_in = 6304
         self.icmp_id_in = 6305
 
-        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.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)
 
         # send some packets to create sessions
         pkts = self.create_stream_in_ip6(self.pg0, self.pg1)
@@ -7675,18 +7811,19 @@ 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_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.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_static_bib(server.ip6n,
-                                           self.nat_addr_n,
+                                           self.nat_addr,
                                            server_tcp_in_port,
                                            server_tcp_out_port,
                                            IP_PROTOS.tcp)
         self.vapi.nat64_add_del_static_bib(server.ip6n,
-                                           self.nat_addr_n,
+                                           self.nat_addr,
                                            server_udp_in_port,
                                            server_udp_out_port,
                                            IP_PROTOS.udp)
@@ -7786,34 +7923,34 @@ class TestNAT64(MethodHolder):
     def test_prefix(self):
         """ NAT64 Network-Specific Prefix """
 
-        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,
+        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,
                                                 vrf_id=self.vrf1_id)
-        self.vapi.nat64_add_del_interface(self.pg2.sw_if_index)
+        self.vapi.nat64_add_del_interface(1, flags, 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
-        self.vapi.nat64_add_del_prefix(global_pref64_n, global_pref64_len)
+        global_pref64_str = "{}/{}".format(global_pref64, global_pref64_len)
+        self.vapi.nat64_add_del_prefix(global_pref64_str)
 
         prefix = self.vapi.nat64_prefix_dump()
         self.assertEqual(len(prefix), 1)
-        self.assertEqual(prefix[0].prefix, global_pref64_n)
-        self.assertEqual(prefix[0].prefix_len, global_pref64_len)
+        self.assertEqual(prefix[0].prefix,
+                         IPv6Network(unicode(global_pref64_str)))
         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
-        self.vapi.nat64_add_del_prefix(vrf1_pref64_n,
-                                       vrf1_pref64_len,
-                                       vrf_id=self.vrf1_id)
+        vrf1_pref64_str = "{}/{}".format(vrf1_pref64, vrf1_pref64_len)
+        self.vapi.nat64_add_del_prefix(vrf1_pref64_str, vrf_id=self.vrf1_id)
+
         prefix = self.vapi.nat64_prefix_dump()
         self.assertEqual(len(prefix), 2)
 
@@ -7864,10 +8001,11 @@ 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_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.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)
         remote_ip6 = self.compose_ip6(self.pg1.remote_ip4, '64:ff9b::', 96)
 
         # in2out
@@ -7928,30 +8066,29 @@ 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_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_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_static_bib(server.ip6n,
-                                           server_nat_ip_n,
+                                           server_nat_ip,
                                            server_tcp_in_port,
                                            server_tcp_out_port,
                                            IP_PROTOS.tcp)
 
         self.vapi.nat64_add_del_static_bib(server.ip6n,
-                                           server_nat_ip_n,
+                                           server_nat_ip,
                                            0,
                                            0,
                                            IP_PROTOS.gre)
 
         self.vapi.nat64_add_del_static_bib(client.ip6n,
-                                           client_nat_ip_n,
+                                           client_nat_ip,
                                            client_tcp_in_port,
                                            client_tcp_out_port,
                                            IP_PROTOS.tcp)
@@ -8009,10 +8146,11 @@ class TestNAT64(MethodHolder):
                                            '64:ff9b::',
                                            96)
 
-        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)
+        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)
 
         # in2out
         p = (Ether(src=self.pg3.remote_mac, dst=self.pg3.local_mac) /
@@ -8061,10 +8199,11 @@ 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_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.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)
 
         reass = self.vapi.nat_reass_dump()
         reass_n_start = len(reass)
@@ -8117,14 +8256,15 @@ 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_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.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)
 
         # add static BIB entry for server
         self.vapi.nat64_add_del_static_bib(server.ip6n,
-                                           self.nat_addr_n,
+                                           self.nat_addr,
                                            server_in_port,
                                            server_out_port,
                                            IP_PROTOS.tcp)
@@ -8148,10 +8288,11 @@ 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_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.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)
 
         # in2out
         data = b'a' * 200
@@ -8200,7 +8341,9 @@ class TestNAT64(MethodHolder):
         self.pg4.config_ip4()
         addresses = self.vapi.nat64_pool_addr_dump()
         self.assertEqual(len(addresses), 1)
-        self.assertEqual(addresses[0].address, self.pg4.local_ip4n)
+
+        self.assertEqual(str(addresses[0].address),
+                         self.pg4.local_ip4)
 
         # remove interface address and check NAT64 address pool
         self.pg4.unconfig_ip4()
@@ -8216,10 +8359,11 @@ class TestNAT64(MethodHolder):
                                            '64:ff9b::',
                                            96)
 
-        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.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)
 
         pkts = []
         src = ""
@@ -8298,10 +8442,11 @@ 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_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.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.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,
@@ -8347,10 +8492,11 @@ class TestNAT64(MethodHolder):
                                            '64:ff9b::',
                                            96)
 
-        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.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.set_ipfix_exporter(collector_address=self.pg3.remote_ip4n,
                                      src_address=self.pg3.local_ip4n,
                                      path_mtu=512,
@@ -8398,8 +8544,8 @@ class TestNAT64(MethodHolder):
 
         # Delete
         self.pg_enable_capture(self.pg_interfaces)
-        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr_n,
-                                                self.nat_addr_n,
+        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr,
+                                                self.nat_addr,
                                                 is_add=0)
         self.vapi.cli("ipfix flush")  # FIXME this should be an API call
         capture = self.pg3.get_capture(2)
@@ -8432,10 +8578,11 @@ class TestNAT64(MethodHolder):
                                            '64:ff9b::',
                                            96)
 
-        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.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.syslog_set_filter(SYSLOG_SEVERITY.INFO)
         self.vapi.syslog_set_sender(self.pg3.local_ip4n, self.pg3.remote_ip4n)
 
@@ -8452,8 +8599,8 @@ class TestNAT64(MethodHolder):
 
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr_n,
-                                                self.nat_addr_n,
+        self.vapi.nat64_add_del_pool_addr_range(self.nat_addr,
+                                                self.nat_addr,
                                                 is_add=0)
         capture = self.pg3.get_capture(1)
         self.verify_syslog_sess(capture[0][Raw].load, False, True)
@@ -8481,17 +8628,13 @@ class TestNAT64(MethodHolder):
 
         interfaces = self.vapi.nat64_interface_dump()
         for intf in interfaces:
-            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)
+            self.vapi.nat64_add_del_interface(0,
+                                              intf.flags,
+                                              intf.sw_if_index)
 
         bib = self.vapi.nat64_bib_dump(255)
         for bibe in bib:
-            if bibe.is_static:
+            if bibe.flags & self.config_flags.NAT_IS_STATIC:
                 self.vapi.nat64_add_del_static_bib(bibe.i_addr,
                                                    bibe.o_addr,
                                                    bibe.i_port,
@@ -8509,8 +8652,7 @@ class TestNAT64(MethodHolder):
 
         prefixes = self.vapi.nat64_prefix_dump()
         for prefix in prefixes:
-            self.vapi.nat64_add_del_prefix(prefix.prefix,
-                                           prefix.prefix_len,
+            self.vapi.nat64_add_del_prefix(str(prefix.prefix),
                                            vrf_id=prefix.vrf_id,
                                            is_add=0)
 
@@ -8542,7 +8684,6 @@ 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()
@@ -8592,13 +8733,11 @@ 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_n,
-                                                 self.nat_addr_n)
+        self.vapi.dslite_add_del_pool_addr_range(self.nat_addr,
+                                                 self.nat_addr)
         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_n, aftr_ip4_n)
+        self.vapi.dslite_set_aftr_addr(aftr_ip6, aftr_ip4)
         self.vapi.syslog_set_sender(self.pg2.local_ip4n, self.pg2.remote_ip4n)
 
         # UDP
@@ -8770,16 +8909,13 @@ 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'
-        b4_ip6_n = socket.inet_pton(socket.AF_INET6, b4_ip6)
-        self.vapi.dslite_set_b4_addr(b4_ip6_n, b4_ip4_n)
+        self.vapi.dslite_set_b4_addr(b4_ip6, b4_ip4)
 
         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_n, aftr_ip4_n)
+        self.vapi.dslite_set_aftr_addr(aftr_ip6, aftr_ip4)
 
         self.vapi.ip_add_del_route(dst_address=aftr_ip6_n,
                                    dst_address_length=128,
@@ -8853,7 +8989,6 @@ 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)
@@ -8873,10 +9008,11 @@ class TestNAT66(MethodHolder):
 
     def test_static(self):
         """ 1:1 NAT66 test """
-        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)
+        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_static_mapping(self.pg0.remote_ip6n,
-                                               self.nat_addr_n)
+                                               self.nat_addr)
 
         # in2out
         pkts = []
@@ -8946,10 +9082,11 @@ class TestNAT66(MethodHolder):
 
     def test_check_no_translate(self):
         """ NAT66 translate only when egress interface is outside interface """
-        self.vapi.nat66_add_del_interface(self.pg0.sw_if_index)
-        self.vapi.nat66_add_del_interface(self.pg1.sw_if_index)
+        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_static_mapping(self.pg0.remote_ip6n,
-                                               self.nat_addr_n)
+                                               self.nat_addr)
 
         # in2out
         p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
@@ -8974,8 +9111,8 @@ class TestNAT66(MethodHolder):
         interfaces = self.vapi.nat66_interface_dump()
         for intf in interfaces:
             self.vapi.nat66_add_del_interface(intf.sw_if_index,
-                                              intf.is_inside,
-                                              is_add=0)
+                                              is_add=0,
+                                              flags=intf.flags)
 
         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 62fc0aa42b3..bda1aea425c 100644
--- a/test/vpp_papi_provider.py
+++ b/test/vpp_papi_provider.py
@@ -122,23 +122,22 @@ 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,
-                                       'addr_only': 1, 'is_add': 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,
-                                     '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, },
+                                     'is_add': 1, },
+    'nat44_interface_add_del_feature': {'is_add': 1, },
+    'nat44_interface_add_del_output_feature': {'is_add': 1, },
     'nat44_lb_static_mapping_add_del_local': {'is_add': 1, },
-    'nat64_add_del_interface': {'is_inside': 1, 'is_add': 1, },
+    'nat64_add_del_interface': {'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_inside': 1, 'is_add': 1, },
+    'nat66_add_del_interface': {'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, },
@@ -755,35 +754,35 @@ class VppPapiProvider(object):
     def nat44_interface_add_del_feature(
             self,
             sw_if_index,
-            is_inside=1,
-            is_add=1):
+            is_add=1,
+            flags=0):
         """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,
-             'is_inside': is_inside,
+             'flags': flags,
              'sw_if_index': sw_if_index})
 
     def nat44_interface_add_del_output_feature(
             self,
             sw_if_index,
-            is_inside=1,
-            is_add=1):
+            is_add=1,
+            flags=0):
         """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,
-             'is_inside': is_inside,
+             'flags': flags,
              'sw_if_index': sw_if_index})
 
     def nat44_add_del_static_mapping(
@@ -793,14 +792,11 @@ class VppPapiProvider(object):
             external_sw_if_index=0xFFFFFFFF,
             local_port=0,
             external_port=0,
-            addr_only=1,
             vrf_id=0,
             protocol=0,
-            twice_nat=0,
-            self_twice_nat=0,
-            out2in_only=0,
-            tag="",
-            is_add=1):
+            is_add=1,
+            flags=0,
+            tag=""):
         """Add/delete NAT44 static mapping
 
         :param local_ip: Local IP address
@@ -808,31 +804,23 @@ 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 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
         :param is_add: 1 if add, 0 if delete (Default value = 1)
+        :param tag: Opaque string tag
         """
         return self.api(
             self.papi.nat44_add_del_static_mapping,
             {'is_add': is_add,
-             'addr_only': addr_only,
+             'flags': flags,
              '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(
@@ -840,7 +828,7 @@ class VppPapiProvider(object):
             ip=b'0',
             sw_if_index=0xFFFFFFFF,
             port=0,
-            addr_only=1,
+            flags=0,
             vrf_id=0,
             protocol=0,
             tag='',
@@ -850,7 +838,7 @@ 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 addr_only: 1 if address only mapping, 0 if address and port
+        :param flags: NAT configuration flags (NAT_IS_ADDR_ONLY)
         :param vrf_id: VRF ID
         :param protocol: IP protocol (Default value = 0)
         :param tag: Opaque string tag
@@ -859,13 +847,13 @@ class VppPapiProvider(object):
         return self.api(
             self.papi.nat44_add_del_identity_mapping,
             {'is_add': is_add,
-             'addr_only': addr_only,
+             'flags': flags,
              'ip_address': ip,
+             'protocol': protocol,
              'port': port,
              'sw_if_index': sw_if_index,
              'vrf_id': vrf_id,
-             'tag': tag,
-             'protocol': protocol})
+             'tag': tag})
 
     def nat44_add_del_address_range(
             self,
@@ -873,73 +861,69 @@ class VppPapiProvider(object):
             last_ip_address,
             is_add=1,
             vrf_id=0xFFFFFFFF,
-            twice_nat=0):
+            flags=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,
-             'twice_nat': twice_nat,
-             'is_add': is_add})
+             'is_add': is_add,
+             'flags': flags})
 
     def nat44_add_del_interface_addr(
             self,
             sw_if_index,
-            twice_nat=0,
+            flags=0,
             is_add=1):
         """Add/del NAT44 address from interface
 
         :param sw_if_index: Software index of the interface
-        :param twice_nat: twice NAT address for external hosts
+        :param flags: NAT configuration flags (NAT_IS_TWICE_NAT)
         :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,
-             'twice_nat': twice_nat})
+             'flags': flags})
 
     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})
+             'locals': locals,
+             'tag': tag})
 
     def nat44_lb_static_mapping_add_del_local(
             self,
@@ -980,7 +964,7 @@ class VppPapiProvider(object):
             port,
             protocol,
             vrf_id=0,
-            is_in=1,
+            flags=0,
             ext_host_address=None,
             ext_host_port=0):
         """Delete NAT44 session
@@ -989,29 +973,19 @@ class VppPapiProvider(object):
         :param por: port number
         :param protocol: IP protocol number
         :param vrf_id: VRF ID
-        :param is_in: 1 if inside network address and port pair, 0 if outside
+        :param flags: NAT configuration flags (NAT_IS_INSIDE)
         :param ext_host_address: external host IPv4 address
         :param ext_host_port: external 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})
+        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})
 
     def nat44_forwarding_enable_disable(
             self,
@@ -1024,56 +998,6 @@ 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
 
@@ -1091,56 +1015,6 @@ 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,
@@ -1186,18 +1060,16 @@ class VppPapiProvider(object):
         """
         return self.api(self.papi.nat64_st_dump, {'proto': protocol})
 
-    def nat64_add_del_prefix(self, prefix, plen, vrf_id=0, is_add=1):
+    def nat64_add_del_prefix(self, prefix, 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})
 
@@ -1238,18 +1110,19 @@ class VppPapiProvider(object):
     def nat66_add_del_interface(
             self,
             sw_if_index,
-            is_inside=1,
+            flags=0,
             is_add=1):
         """Enable/disable NAT66 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 flags: NAT configuration flags (NAT_IS_INSIDE)
            :param is_add: 1 if add, 0 if delete (Default value = 1)
         """
         return self.api(
             self.papi.nat66_add_del_interface,
-            {'sw_if_index': sw_if_index,
-             'is_inside': is_inside,
-             'is_add': is_add})
+            {'is_add': is_add,
+             'flags': flags,
+             'sw_if_index': sw_if_index})
 
     def nat66_add_del_static_mapping(
             self,