nat: refactor and split fo EI/ED features p.2

Patch n. 2 aimed at moving EI features out of
NAT44 plugin & split of EI/ED functions.

Type: refactor

Change-Id: Ida20c1c084449b146344b6c3d8442f49efb6f3fa
Signed-off-by: Filip Varga <fivarga@cisco.com>

8 files changed, 1216 insertions, 351 deletions

diff --git a/src/plugins/nat/nat.c b/src/plugins/nat/nat.c
index 156b6ddf369..81af143ab2c 100644
--- a/src/plugins/nat/nat.c
+++ b/src/plugins/nat/nat.c
@@ -40,6 +40,39 @@
 
 snat_main_t snat_main;
 
+#define skip_if_disabled()                                                    \
+  do                                                                          \
+    {                                                                         \
+      snat_main_t *sm = &snat_main;                                           \
+      if (PREDICT_FALSE (!sm->enabled))                                       \
+	return;                                                               \
+    }                                                                         \
+  while (0)
+
+#define fail_if_enabled()                                                     \
+  do                                                                          \
+    {                                                                         \
+      snat_main_t *sm = &snat_main;                                           \
+      if (PREDICT_FALSE (sm->enabled))                                        \
+	{                                                                     \
+	  nat_log_err ("plugin enabled");                                     \
+	  return 1;                                                           \
+	}                                                                     \
+    }                                                                         \
+  while (0)
+
+#define fail_if_disabled()                                                    \
+  do                                                                          \
+    {                                                                         \
+      snat_main_t *sm = &snat_main;                                           \
+      if (PREDICT_FALSE (!sm->enabled))                                       \
+	{                                                                     \
+	  nat_log_err ("plugin disabled");                                    \
+	  return 1;                                                           \
+	}                                                                     \
+    }                                                                         \
+  while (0)
+
 /* *INDENT-OFF* */
 /* Hook up input features */
 VNET_FEATURE_INIT (nat_pre_in2out, static) = {
@@ -181,6 +214,11 @@ VLIB_PLUGIN_REGISTER () = {
 };
 /* *INDENT-ON* */
 
+static void nat44_ed_db_init (u32 translations, u32 translation_buckets,
+			      u32 user_buckets);
+
+static void nat44_ed_db_free ();
+
 static u32
 nat44_ed_get_worker_out2in_cb (vlib_buffer_t * b, ip4_header_t * ip,
 			       u32 rx_fib_index, u8 is_output);
@@ -189,7 +227,7 @@ static u32
 nat44_ed_get_worker_in2out_cb (ip4_header_t * ip, u32 rx_fib_index,
 			       u8 is_output);
 
-static u32 nat_calc_bihash_buckets (u32 n_elts);
+u32 nat_calc_bihash_buckets (u32 n_elts);
 
 u8 *
 format_session_kvp (u8 * s, va_list * args)
@@ -647,16 +685,11 @@ is_snat_address_used_in_static_mapping (snat_main_t * sm, ip4_address_t addr)
 }
 
 static void
-snat_add_static_mapping_when_resolved (snat_main_t * sm,
-				       ip4_address_t l_addr,
-				       u16 l_port,
-				       u32 sw_if_index,
-				       u16 e_port,
-				       u32 vrf_id,
-				       nat_protocol_t proto,
-				       int addr_only, int is_add, u8 * tag,
-				       int twice_nat, int out2in_only,
-				       int identity_nat,
+snat_add_static_mapping_when_resolved (snat_main_t *sm, ip4_address_t l_addr,
+				       u16 l_port, u32 sw_if_index, u16 e_port,
+				       u32 vrf_id, nat_protocol_t proto,
+				       int addr_only, u8 *tag, int twice_nat,
+				       int out2in_only, int identity_nat,
 				       ip4_address_t pool_addr, int exact)
 {
   snat_static_map_resolve_t *rp;
@@ -669,7 +702,6 @@ snat_add_static_mapping_when_resolved (snat_main_t * sm,
   rp->vrf_id = vrf_id;
   rp->proto = proto;
   rp->addr_only = addr_only;
-  rp->is_add = is_add;
   rp->twice_nat = twice_nat;
   rp->out2in_only = out2in_only;
   rp->identity_nat = identity_nat;
@@ -678,7 +710,7 @@ snat_add_static_mapping_when_resolved (snat_main_t * sm,
   rp->exact = exact;
 }
 
-static u32
+u32
 get_thread_idx_by_port (u16 e_port)
 {
   snat_main_t *sm = &snat_main;
@@ -738,12 +770,14 @@ nat_ed_static_mapping_del_sessions (snat_main_t * sm,
   vec_free (indexes_to_free);
 }
 
-int
-snat_add_static_mapping (ip4_address_t l_addr, ip4_address_t e_addr,
-			 u16 l_port, u16 e_port, u32 vrf_id, int addr_only,
-			 u32 sw_if_index, nat_protocol_t proto, int is_add,
-			 twice_nat_type_t twice_nat, u8 out2in_only, u8 * tag,
-			 u8 identity_nat, ip4_address_t pool_addr, int exact)
+static_always_inline int
+nat44_ed_add_del_static_mapping (ip4_address_t l_addr, ip4_address_t e_addr,
+				 u16 l_port, u16 e_port, u32 vrf_id,
+				 int addr_only, u32 sw_if_index,
+				 nat_protocol_t proto, int is_add,
+				 twice_nat_type_t twice_nat, u8 out2in_only,
+				 u8 *tag, u8 identity_nat,
+				 ip4_address_t pool_addr, int exact)
 {
   snat_main_t *sm = &snat_main;
   snat_static_mapping_t *m;
@@ -803,10 +837,9 @@ snat_add_static_mapping (ip4_address_t l_addr, ip4_address_t e_addr,
 	  if (rp_match)
 	    return VNET_API_ERROR_VALUE_EXIST;
 
-	  snat_add_static_mapping_when_resolved
-	    (sm, l_addr, l_port, sw_if_index, e_port, vrf_id, proto,
-	     addr_only, is_add, tag, twice_nat, out2in_only,
-	     identity_nat, pool_addr, exact);
+	  snat_add_static_mapping_when_resolved (
+	    sm, l_addr, l_port, sw_if_index, e_port, vrf_id, proto, addr_only,
+	    tag, twice_nat, out2in_only, identity_nat, pool_addr, exact);
 
 	  /* DHCP resolution required? */
 	  if (first_int_addr == 0)
@@ -1002,10 +1035,12 @@ snat_add_static_mapping (ip4_address_t l_addr, ip4_address_t e_addr,
       else
 	tsm = vec_elt_at_index (sm->per_thread_data, sm->num_workers);
 
-      init_nat_kv (&kv, m->local_addr, m->local_port, fib_index, m->proto,
-		   m - sm->static_mappings);
       if (!out2in_only)
-	clib_bihash_add_del_8_8 (&sm->static_mapping_by_local, &kv, 1);
+	{
+	  init_nat_kv (&kv, m->local_addr, m->local_port, fib_index, m->proto,
+		       m - sm->static_mappings);
+	  clib_bihash_add_del_8_8 (&sm->static_mapping_by_local, &kv, 1);
+	}
 
       init_nat_kv (&kv, m->external_addr, m->external_port, 0, m->proto,
 		   m - sm->static_mappings);
@@ -1184,6 +1219,31 @@ snat_add_static_mapping (ip4_address_t l_addr, ip4_address_t e_addr,
 }
 
 int
+snat_add_static_mapping (ip4_address_t l_addr, ip4_address_t e_addr,
+			 u16 l_port, u16 e_port, u32 vrf_id, int addr_only,
+			 u32 sw_if_index, nat_protocol_t proto, int is_add,
+			 twice_nat_type_t twice_nat, u8 out2in_only, u8 *tag,
+			 u8 identity_nat, ip4_address_t pool_addr, int exact)
+{
+  snat_main_t *sm = &snat_main;
+  int rv;
+
+  if (sm->endpoint_dependent)
+    {
+      rv = nat44_ed_add_del_static_mapping (
+	l_addr, e_addr, l_port, e_port, vrf_id, addr_only, sw_if_index, proto,
+	is_add, twice_nat, out2in_only, tag, identity_nat, pool_addr, exact);
+    }
+  else
+    {
+      rv = nat44_ei_add_del_static_mapping (
+	l_addr, e_addr, l_port, e_port, proto, sw_if_index, vrf_id, addr_only,
+	identity_nat, tag, is_add);
+    }
+  return rv;
+}
+
+int
 nat44_add_del_lb_static_mapping (ip4_address_t e_addr, u16 e_port,
 				 nat_protocol_t proto,
 				 nat44_lb_addr_port_t * locals, u8 is_add,
@@ -2655,51 +2715,34 @@ nat_init (vlib_main_t * vm)
 
 VLIB_INIT_FUNCTION (nat_init);
 
-int
-nat44_plugin_enable (nat44_config_t c)
+static int
+nat44_ed_plugin_enable (nat44_config_t c)
 {
   snat_main_t *sm = &snat_main;
-  u32 static_mapping_buckets = 1024;
-  u32 static_mapping_memory_size = 64 << 20;
 
-  if (sm->enabled)
+  if (c.static_mapping_only && !c.connection_tracking)
     {
-      nat_log_err ("nat44 is enabled");
+      nat_log_err ("unsupported combination of configuration");
       return 1;
     }
 
-  // c.static_mapping_only + c.connection_tracking
-  //  - supported in NAT EI & NAT ED
-  // c.out2in_dpo, c.static_mapping_only
-  //  - supported in NAT EI
-
-  if (c.endpoint_dependent)
-    {
-      if ((c.static_mapping_only && !c.connection_tracking) || c.out2in_dpo)
-	{
-	  nat_log_err ("unsupported combination of configuration");
-	  return 1;
-	}
-      if (c.users || c.user_sessions)
-	{
-	  nat_log_err ("unsupported combination of configuration");
-	  return 1;
-	}
-    }
-
-  nat_reset_timeouts (&sm->timeouts);
-
   // nat44 feature configuration
   sm->endpoint_dependent = c.endpoint_dependent;
   sm->static_mapping_only = c.static_mapping_only;
   sm->static_mapping_connection_tracking = c.connection_tracking;
+
+  // EI only feature (could break ED)
   sm->out2in_dpo = c.out2in_dpo;
+
   sm->forwarding_enabled = 0;
   sm->mss_clamping = 0;
+  sm->pat = (!c.static_mapping_only ||
+	     (c.static_mapping_only && c.connection_tracking));
 
   if (!c.users)
     c.users = 1024;
 
+  // EI only feature (could break ED)
   sm->max_users_per_thread = c.users;
   sm->user_buckets = nat_calc_bihash_buckets (c.users);
 
@@ -2709,65 +2752,34 @@ nat44_plugin_enable (nat44_config_t c)
   sm->max_translations_per_thread = c.sessions;
   sm->translation_buckets = nat_calc_bihash_buckets (c.sessions);
 
+  // ED only feature
   vec_add1 (sm->max_translations_per_fib, sm->max_translations_per_thread);
+
+  // EI only feature (could break ED)
   sm->max_translations_per_user
     = c.user_sessions ? c.user_sessions : sm->max_translations_per_thread;
 
-  sm->outside_vrf_id = c.outside_vrf;
-  sm->outside_fib_index =
-    fib_table_find_or_create_and_lock
-    (FIB_PROTOCOL_IP4, c.outside_vrf, sm->fib_src_hi);
-
   sm->inside_vrf_id = c.inside_vrf;
   sm->inside_fib_index =
     fib_table_find_or_create_and_lock
     (FIB_PROTOCOL_IP4, c.inside_vrf, sm->fib_src_hi);
 
-  if (c.endpoint_dependent)
-    {
-      sm->worker_out2in_cb = nat44_ed_get_worker_out2in_cb;
-      sm->worker_in2out_cb = nat44_ed_get_worker_in2out_cb;
-      sm->out2in_node_index = sm->ed_out2in_node_index;
-      sm->in2out_node_index = sm->ed_in2out_node_index;
-      sm->in2out_output_node_index = sm->ed_in2out_output_node_index;
-      sm->icmp_match_out2in_cb = icmp_match_out2in_ed;
-      sm->icmp_match_in2out_cb = icmp_match_in2out_ed;
-
-      // try to move it into nat44_db_init,
-      // consider static mapping requirements
-      clib_bihash_init_16_8 (&sm->out2in_ed, "out2in-ed",
-			     sm->translation_buckets, 0);
-      clib_bihash_set_kvp_format_fn_16_8 (&sm->out2in_ed,
-					  format_ed_session_kvp);
+  sm->outside_vrf_id = c.outside_vrf;
+  sm->outside_fib_index = fib_table_find_or_create_and_lock (
+    FIB_PROTOCOL_IP4, c.outside_vrf, sm->fib_src_hi);
 
-      nat_affinity_enable ();
-    }
-  else
-    {
-      sm->worker_out2in_cb = nat44_ei_get_out2in_worker_index;
-      sm->worker_in2out_cb = nat44_ei_get_in2out_worker_index;
+  sm->worker_in2out_cb = nat44_ed_get_worker_in2out_cb;
+  sm->worker_out2in_cb = nat44_ed_get_worker_out2in_cb;
 
-      sm->out2in_node_index = sm->ei_out2in_node_index;
-      sm->in2out_node_index = sm->ei_in2out_node_index;
-      sm->in2out_output_node_index = sm->ei_in2out_output_node_index;
-      sm->icmp_match_out2in_cb = icmp_match_out2in_slow;
-      sm->icmp_match_in2out_cb = icmp_match_in2out_slow;
+  sm->in2out_node_index = sm->ed_in2out_node_index;
+  sm->out2in_node_index = sm->ed_out2in_node_index;
 
-      nat44_ei_plugin_enable ();
-    }
+  sm->in2out_output_node_index = sm->ed_in2out_output_node_index;
 
-  // c.static_mapping & c.connection_tracking require
-  // session database
-  if (!c.static_mapping_only
-      || (c.static_mapping_only && c.connection_tracking))
+  if (sm->pat)
     {
-      snat_main_per_thread_data_t *tsm;
-      /* *INDENT-OFF* */
-      vec_foreach (tsm, sm->per_thread_data)
-        {
-          nat44_db_init (tsm);
-        }
-      /* *INDENT-ON* */
+      sm->icmp_match_in2out_cb = icmp_match_in2out_ed;
+      sm->icmp_match_out2in_cb = icmp_match_out2in_ed;
     }
   else
     {
@@ -2775,19 +2787,14 @@ nat44_plugin_enable (nat44_config_t c)
       sm->icmp_match_out2in_cb = icmp_match_out2in_fast;
     }
 
-  clib_bihash_init_8_8 (&sm->static_mapping_by_local,
-			"static_mapping_by_local", static_mapping_buckets,
-			static_mapping_memory_size);
-  clib_bihash_set_kvp_format_fn_8_8 (&sm->static_mapping_by_local,
-				     format_static_mapping_kvp);
+  nat44_ed_db_init (sm->max_translations_per_thread, sm->translation_buckets,
+		    sm->user_buckets);
 
-  clib_bihash_init_8_8 (&sm->static_mapping_by_external,
-			"static_mapping_by_external",
-			static_mapping_buckets, static_mapping_memory_size);
-  clib_bihash_set_kvp_format_fn_8_8 (&sm->static_mapping_by_external,
-				     format_static_mapping_kvp);
+  nat_affinity_enable ();
+
+  nat_reset_timeouts (&sm->timeouts);
 
-  // last: reset counters
+  // TODO: function for reset counters
   vlib_zero_simple_counter (&sm->total_users, 0);
   vlib_zero_simple_counter (&sm->total_sessions, 0);
   vlib_zero_simple_counter (&sm->user_limit_reached, 0);
@@ -2798,6 +2805,43 @@ nat44_plugin_enable (nat44_config_t c)
   return 0;
 }
 
+int
+nat44_plugin_enable (nat44_config_t c)
+{
+  fail_if_enabled ();
+
+  // c.static_mapping_only + c.connection_tracking
+  //  - supported in NAT EI & NAT ED
+  // c.out2in_dpo, c.static_mapping_only
+  //  - supported in NAT EI
+
+  if (c.endpoint_dependent)
+    {
+      if (c.out2in_dpo || c.users || c.user_sessions)
+	{
+	  nat_log_err ("unsupported combination of configuration");
+	  return 1;
+	}
+      return nat44_ed_plugin_enable (c);
+    }
+
+  // separation:
+  // for now just copy variables
+
+  nat44_ei_config_t ei_c = {
+    .inside_vrf = c.inside_vrf,
+    .outside_vrf = c.outside_vrf,
+    .users = c.users,
+    .sessions = c.sessions,
+    .user_sessions = c.user_sessions,
+    .out2in_dpo = c.out2in_dpo,
+    .static_mapping_only = c.static_mapping_only,
+    .connection_tracking = c.connection_tracking,
+  };
+
+  return nat44_ei_plugin_enable (ei_c);
+}
+
 void
 nat44_addresses_free (snat_address_t ** addresses)
 {
@@ -2815,24 +2859,13 @@ nat44_addresses_free (snat_address_t ** addresses)
   *addresses = 0;
 }
 
-int
-nat44_plugin_disable ()
+static int
+nat44_ed_plugin_disable ()
 {
   snat_main_t *sm = &snat_main;
   snat_interface_t *i, *vec;
   int error = 0;
 
-  if (!sm->enabled)
-    {
-      nat_log_err ("nat44 is disabled");
-      return 1;
-    }
-
-  if (!sm->endpoint_dependent)
-    {
-      nat44_ei_plugin_disable ();
-    }
-
   // first unregister all nodes from interfaces
   vec = vec_dup (sm->interfaces);
   /* *INDENT-OFF* */
@@ -2874,28 +2907,9 @@ nat44_plugin_disable ()
 
   vec_free (sm->max_translations_per_fib);
 
-  if (sm->endpoint_dependent)
-    {
-      nat_affinity_disable ();
-      clib_bihash_free_16_8 (&sm->out2in_ed);
-    }
-
-  clib_bihash_free_8_8 (&sm->static_mapping_by_local);
-  clib_bihash_free_8_8 (&sm->static_mapping_by_external);
-
-  if (!sm->static_mapping_only ||
-      (sm->static_mapping_only && sm->static_mapping_connection_tracking))
-    {
-      snat_main_per_thread_data_t *tsm;
-     /* *INDENT-OFF* */
-      vec_foreach (tsm, sm->per_thread_data)
-        {
-          nat44_db_free (tsm);
-        }
-      /* *INDENT-ON* */
-    }
+  nat_affinity_disable ();
 
-  pool_free (sm->static_mappings);
+  nat44_ed_db_free ();
 
   nat44_addresses_free (&sm->addresses);
   nat44_addresses_free (&sm->twice_nat_addresses);
@@ -2917,10 +2931,21 @@ nat44_plugin_disable ()
   return 0;
 }
 
+int
+nat44_plugin_disable ()
+{
+  snat_main_t *sm = &snat_main;
+
+  fail_if_disabled ();
+
+  if (sm->endpoint_dependent)
+    return nat44_ed_plugin_disable ();
+  return nat44_ei_plugin_disable ();
+}
+
 void
-snat_free_outside_address_and_port (snat_address_t * addresses,
-				    u32 thread_index,
-				    ip4_address_t * addr,
+snat_free_outside_address_and_port (snat_address_t *addresses,
+				    u32 thread_index, ip4_address_t *addr,
 				    u16 port, nat_protocol_t protocol)
 {
   snat_address_t *a;
@@ -3177,7 +3202,7 @@ nat44_add_del_address_dpo (ip4_address_t addr, u8 is_add)
 }
 
 static u32
-nat44_ed_get_worker_in2out_cb (ip4_header_t * ip, u32 rx_fib_index,
+nat44_ed_get_worker_in2out_cb (ip4_header_t *ip, u32 rx_fib_index,
 			       u8 is_output)
 {
   snat_main_t *sm = &snat_main;
@@ -3435,7 +3460,7 @@ done:
   return next_worker_index;
 }
 
-static u32
+u32
 nat_calc_bihash_buckets (u32 n_elts)
 {
   n_elts = n_elts / 2.5;
@@ -3504,16 +3529,15 @@ nat44_update_session_limit (u32 session_limit, u32 vrf_id)
   return 0;
 }
 
-void
-nat44_db_init (snat_main_per_thread_data_t * tsm)
+static void
+nat44_ed_worker_db_init (snat_main_per_thread_data_t *tsm, u32 translations,
+			 u32 translation_buckets, u32 user_buckets)
 {
-  snat_main_t *sm = &snat_main;
-
-  pool_alloc (tsm->sessions, sm->max_translations_per_thread);
-  pool_alloc (tsm->lru_pool, sm->max_translations_per_thread);
-
   dlist_elt_t *head;
 
+  pool_alloc (tsm->sessions, translations);
+  pool_alloc (tsm->lru_pool, translations);
+
   pool_get (tsm->lru_pool, head);
   tsm->tcp_trans_lru_head_index = head - tsm->lru_pool;
   clib_dlist_init (tsm->lru_pool, tsm->tcp_trans_lru_head_index);
@@ -3534,87 +3558,122 @@ nat44_db_init (snat_main_per_thread_data_t * tsm)
   tsm->unk_proto_lru_head_index = head - tsm->lru_pool;
   clib_dlist_init (tsm->lru_pool, tsm->unk_proto_lru_head_index);
 
-  if (sm->endpoint_dependent)
-    {
-      clib_bihash_init_16_8 (&tsm->in2out_ed, "in2out-ed",
-			     sm->translation_buckets, 0);
-      clib_bihash_set_kvp_format_fn_16_8 (&tsm->in2out_ed,
-					  format_ed_session_kvp);
-      /*
-         clib_bihash_init_16_8 (&sm->out2in_ed, "out2in-ed",
-         sm->translation_buckets, 0);
-         clib_bihash_set_kvp_format_fn_16_8 (&sm->out2in_ed,
-         format_ed_session_kvp); */
-    }
-  else
-    {
-      clib_bihash_init_8_8 (&tsm->in2out, "in2out", sm->translation_buckets,
-			    0);
-      clib_bihash_set_kvp_format_fn_8_8 (&tsm->in2out, format_session_kvp);
-      clib_bihash_init_8_8 (&tsm->out2in, "out2in", sm->translation_buckets,
-			    0);
-      clib_bihash_set_kvp_format_fn_8_8 (&tsm->out2in, format_session_kvp);
-    }
+  clib_bihash_init_16_8 (&tsm->in2out_ed, "in2out-ed", translation_buckets, 0);
+  clib_bihash_set_kvp_format_fn_16_8 (&tsm->in2out_ed, format_ed_session_kvp);
 
   // TODO: ED nat is not using these
   // before removal large refactor required
-  pool_alloc (tsm->list_pool, sm->max_translations_per_thread);
-  clib_bihash_init_8_8 (&tsm->user_hash, "users", sm->user_buckets, 0);
+  pool_alloc (tsm->list_pool, translations);
+  clib_bihash_init_8_8 (&tsm->user_hash, "users", user_buckets, 0);
   clib_bihash_set_kvp_format_fn_8_8 (&tsm->user_hash, format_user_kvp);
 }
 
-void
-nat44_db_free (snat_main_per_thread_data_t * tsm)
+static void
+nat44_ed_db_init (u32 translations, u32 translation_buckets, u32 user_buckets)
 {
   snat_main_t *sm = &snat_main;
+  snat_main_per_thread_data_t *tsm;
+  u32 static_mapping_buckets = 1024;
+  u32 static_mapping_memory_size = 64 << 20;
 
-  pool_free (tsm->sessions);
-  pool_free (tsm->lru_pool);
+  clib_bihash_init_16_8 (&sm->out2in_ed, "out2in-ed", translation_buckets, 0);
+  clib_bihash_set_kvp_format_fn_16_8 (&sm->out2in_ed, format_ed_session_kvp);
 
-  if (sm->endpoint_dependent)
-    {
-      clib_bihash_free_16_8 (&tsm->in2out_ed);
-      vec_free (tsm->per_vrf_sessions_vec);
-    }
-  else
+  clib_bihash_init_8_8 (&sm->static_mapping_by_local,
+			"static_mapping_by_local", static_mapping_buckets,
+			static_mapping_memory_size);
+  clib_bihash_set_kvp_format_fn_8_8 (&sm->static_mapping_by_local,
+				     format_static_mapping_kvp);
+
+  clib_bihash_init_8_8 (&sm->static_mapping_by_external,
+			"static_mapping_by_external", static_mapping_buckets,
+			static_mapping_memory_size);
+  clib_bihash_set_kvp_format_fn_8_8 (&sm->static_mapping_by_external,
+				     format_static_mapping_kvp);
+
+  if (sm->pat)
     {
-      clib_bihash_free_8_8 (&tsm->in2out);
-      clib_bihash_free_8_8 (&tsm->out2in);
+      vec_foreach (tsm, sm->per_thread_data)
+	{
+	  nat44_ed_worker_db_init (tsm, sm->max_translations_per_thread,
+				   sm->translation_buckets, sm->user_buckets);
+	}
     }
+}
+
+static void
+nat44_ed_worker_db_free (snat_main_per_thread_data_t *tsm)
+{
+  pool_free (tsm->sessions);
+  pool_free (tsm->lru_pool);
+
+  clib_bihash_free_16_8 (&tsm->in2out_ed);
+  vec_free (tsm->per_vrf_sessions_vec);
 
   // TODO: resolve static mappings (put only to !ED)
-  pool_free (tsm->users);
   pool_free (tsm->list_pool);
+  pool_free (tsm->users);
   clib_bihash_free_8_8 (&tsm->user_hash);
 }
 
-void
-nat44_sessions_clear ()
+static void
+nat44_ed_db_free ()
 {
   snat_main_t *sm = &snat_main;
   snat_main_per_thread_data_t *tsm;
 
-  if (sm->endpoint_dependent)
+  pool_free (sm->static_mappings);
+  clib_bihash_free_16_8 (&sm->out2in_ed);
+  clib_bihash_free_8_8 (&sm->static_mapping_by_local);
+  clib_bihash_free_8_8 (&sm->static_mapping_by_external);
+
+  if (sm->pat)
     {
-      clib_bihash_free_16_8 (&sm->out2in_ed);
-      clib_bihash_init_16_8 (&sm->out2in_ed, "out2in-ed",
-			     clib_max (1,
-				       sm->num_workers) *
-			     sm->translation_buckets, 0);
-      clib_bihash_set_kvp_format_fn_16_8 (&sm->out2in_ed,
-					  format_ed_session_kvp);
+      vec_foreach (tsm, sm->per_thread_data)
+	{
+	  nat44_ed_worker_db_free (tsm);
+	}
     }
+}
 
-  /* *INDENT-OFF* */
-  vec_foreach (tsm, sm->per_thread_data)
+void
+nat44_ed_sessions_clear ()
+{
+  snat_main_t *sm = &snat_main;
+  snat_main_per_thread_data_t *tsm;
+
+  clib_bihash_free_16_8 (&sm->out2in_ed);
+  clib_bihash_init_16_8 (
+    &sm->out2in_ed, "out2in-ed",
+    clib_max (1, sm->num_workers) * sm->translation_buckets, 0);
+  clib_bihash_set_kvp_format_fn_16_8 (&sm->out2in_ed, format_ed_session_kvp);
+
+  if (sm->pat)
     {
-      nat44_db_free (tsm);
-      nat44_db_init (tsm);
+      vec_foreach (tsm, sm->per_thread_data)
+	{
+
+	  nat44_ed_worker_db_free (tsm);
+	  nat44_ed_worker_db_init (tsm, sm->max_translations_per_thread,
+				   sm->translation_buckets, sm->user_buckets);
+	}
     }
-  /* *INDENT-ON* */
 
+  // TODO: function for reset counters
   vlib_zero_simple_counter (&sm->total_users, 0);
   vlib_zero_simple_counter (&sm->total_sessions, 0);
+  vlib_zero_simple_counter (&sm->user_limit_reached, 0);
+}
+
+void
+nat44_sessions_clear ()
+{
+  snat_main_t *sm = &snat_main;
+
+  if (sm->endpoint_dependent)
+    nat44_ed_sessions_clear ();
+  else
+    nat44_ei_sessions_clear ();
 }
 
 static void
@@ -3744,18 +3803,11 @@ match:
 	      else
 		l_addr.as_u32 = rp->l_addr.as_u32;
 	      /* Add the static mapping */
-	      rv = snat_add_static_mapping (l_addr,
-					    address[0],
-					    rp->l_port,
-					    rp->e_port,
-					    rp->vrf_id,
-					    rp->addr_only,
-					    ~0 /* sw_if_index */ ,
-					    rp->proto,
-					    rp->is_add, rp->twice_nat,
-					    rp->out2in_only, rp->tag,
-					    rp->identity_nat,
-					    rp->pool_addr, rp->exact);
+	      rv = snat_add_static_mapping (
+		l_addr, address[0], rp->l_port, rp->e_port, rp->vrf_id,
+		rp->addr_only, ~0 /* sw_if_index */, rp->proto, 1,
+		rp->twice_nat, rp->out2in_only, rp->tag, rp->identity_nat,
+		rp->pool_addr, rp->exact);
 	      if (rv)
 		nat_elog_notice_X1 ("snat_add_static_mapping returned %d",
 				    "i4", rv);
@@ -3839,44 +3891,6 @@ snat_add_interface_address (snat_main_t * sm, u32 sw_if_index, int is_del,
 }
 
 int
-nat44_del_session (snat_main_t * sm, ip4_address_t * addr, u16 port,
-		   nat_protocol_t proto, u32 vrf_id, int is_in)
-{
-  snat_main_per_thread_data_t *tsm;
-  clib_bihash_kv_8_8_t kv, value;
-  ip4_header_t ip;
-  u32 fib_index = fib_table_find (FIB_PROTOCOL_IP4, vrf_id);
-  snat_session_t *s;
-  clib_bihash_8_8_t *t;
-
-  if (sm->endpoint_dependent)
-    return VNET_API_ERROR_UNSUPPORTED;
-
-  ip.dst_address.as_u32 = ip.src_address.as_u32 = addr->as_u32;
-  if (sm->num_workers > 1)
-    tsm =
-      vec_elt_at_index (sm->per_thread_data,
-			sm->worker_in2out_cb (&ip, fib_index, 0));
-  else
-    tsm = vec_elt_at_index (sm->per_thread_data, sm->num_workers);
-
-  init_nat_k (&kv, *addr, port, fib_index, proto);
-  t = is_in ? &tsm->in2out : &tsm->out2in;
-  if (!clib_bihash_search_8_8 (t, &kv, &value))
-    {
-      if (pool_is_free_index (tsm->sessions, value.value))
-	return VNET_API_ERROR_UNSPECIFIED;
-
-      s = pool_elt_at_index (tsm->sessions, value.value);
-      nat_free_session_data (sm, s, tsm - sm->per_thread_data, 0);
-      nat44_delete_session (sm, s, tsm - sm->per_thread_data);
-      return 0;
-    }
-
-  return VNET_API_ERROR_NO_SUCH_ENTRY;
-}
-
-int
 nat44_del_ed_session (snat_main_t * sm, ip4_address_t * addr, u16 port,
 		      ip4_address_t * eh_addr, u16 eh_port, u8 proto,
 		      u32 vrf_id, int is_in)
diff --git a/src/plugins/nat/nat.h b/src/plugins/nat/nat.h
index af40409d267..58883d491aa 100644
--- a/src/plugins/nat/nat.h
+++ b/src/plugins/nat/nat.h
@@ -427,7 +427,6 @@ typedef struct
   u32 flags;
   int addr_only;
   int twice_nat;
-  int is_add;
   int out2in_only;
   int identity_nat;
   int exact;
@@ -729,6 +728,9 @@ typedef struct snat_main_s
   fib_source_t fib_src_hi;
   fib_source_t fib_src_low;
 
+  /* pat - dynamic mapping enabled or conneciton tracking */
+  u8 pat;
+
   /* nat44 plugin enabled */
   u8 enabled;
 
@@ -1298,20 +1300,6 @@ int snat_add_interface_address (snat_main_t * sm, u32 sw_if_index, int is_del,
 				u8 twice_nat);
 
 /**
- * @brief Delete NAT44 session
- *
- * @param addr   IPv4 address
- * @param port   L4 port number
- * @param proto  L4 protocol
- * @param vrf_id VRF ID
- * @param is_in  1 = inside network address and port pair, 0 = outside
- *
- * @return 0 on success, non-zero value otherwise
- */
-int nat44_del_session (snat_main_t * sm, ip4_address_t * addr, u16 port,
-		       nat_protocol_t proto, u32 vrf_id, int is_in);
-
-/**
  * @brief Delete NAT44 endpoint-dependent session
  *
  * @param sm     snat global configuration data
@@ -1357,20 +1345,6 @@ int nat44_set_session_limit (u32 session_limit, u32 vrf_id);
 int nat44_update_session_limit (u32 session_limit, u32 vrf_id);
 
 /**
- * @brief Initialize NAT44 data
- *
- * @param tsm          per thread data
- */
-void nat44_db_init (snat_main_per_thread_data_t * tsm);
-
-/**
- * @brief Free NAT44 data
- *
- * @param tsm          per thread data
- */
-void nat44_db_free (snat_main_per_thread_data_t * tsm);
-
-/**
  * @brief Free all NAT44 sessions
  */
 void nat44_sessions_clear ();
@@ -1510,6 +1484,18 @@ typedef struct
 
 u8 *format_user_kvp (u8 * s, va_list * args);
 
+u32 get_thread_idx_by_port (u16 e_port);
+
+u8 *format_static_mapping_kvp (u8 *s, va_list *args);
+
+u8 *format_session_kvp (u8 *s, va_list *args);
+
+u8 *format_user_kvp (u8 *s, va_list *args);
+
+u32 nat_calc_bihash_buckets (u32 n_elts);
+
+void nat44_addresses_free (snat_address_t **addresses);
+
 #endif /* __included_nat_h__ */
 /*
  * fd.io coding-style-patch-verification: ON
diff --git a/src/plugins/nat/nat44-ei/nat44_ei.c b/src/plugins/nat/nat44-ei/nat44_ei.c
index f50ccb9ba1b..00aa8e1b65b 100644
--- a/src/plugins/nat/nat44-ei/nat44_ei.c
+++ b/src/plugins/nat/nat44-ei/nat44_ei.c
@@ -36,18 +36,156 @@
 #include <nat/nat44-ei/nat44_ei_inlines.h>
 #include <nat/nat44-ei/nat44_ei.h>
 
+nat44_ei_main_t nat44_ei_main;
+
+static void nat44_ei_db_free ();
+
+static void nat44_ei_db_init (u32 translations, u32 translation_buckets,
+			      u32 user_buckets);
+
 int
-nat44_ei_plugin_enable ()
+nat44_ei_plugin_enable (nat44_ei_config_t c)
 {
+  nat44_ei_main_t *nm = &nat44_ei_main;
+  snat_main_t *sm = &snat_main;
+
+  clib_memset (nm, 0, sizeof (*nm));
+
+  if (!c.users)
+    c.users = 1024;
+
+  if (!c.sessions)
+    c.sessions = 10 * 1024;
+
+  nm->rconfig = c;
+
+  nm->translations = c.sessions;
+  nm->translation_buckets = nat_calc_bihash_buckets (c.sessions);
+  nm->user_buckets = nat_calc_bihash_buckets (c.users);
+
+  // OBSOLETE
+
+  sm->static_mapping_only = c.static_mapping_only;
+  sm->static_mapping_connection_tracking = c.connection_tracking;
+  sm->out2in_dpo = c.out2in_dpo;
+  sm->forwarding_enabled = 0;
+  sm->mss_clamping = 0;
+  sm->pat = (!c.static_mapping_only ||
+	     (c.static_mapping_only && c.connection_tracking));
+
+  sm->max_users_per_thread = c.users;
+  sm->max_translations_per_thread = c.sessions;
+  sm->translation_buckets = nat_calc_bihash_buckets (c.sessions);
+  sm->max_translations_per_user =
+    c.user_sessions ? c.user_sessions : sm->max_translations_per_thread;
+
+  sm->inside_vrf_id = c.inside_vrf;
+  sm->inside_fib_index = fib_table_find_or_create_and_lock (
+    FIB_PROTOCOL_IP4, c.inside_vrf, sm->fib_src_hi);
+
+  sm->outside_vrf_id = c.outside_vrf;
+  sm->outside_fib_index = fib_table_find_or_create_and_lock (
+    FIB_PROTOCOL_IP4, c.outside_vrf, sm->fib_src_hi);
+
+  sm->worker_in2out_cb = nat44_ei_get_in2out_worker_index;
+  sm->worker_out2in_cb = nat44_ei_get_out2in_worker_index;
+
+  sm->in2out_node_index = sm->ei_in2out_node_index;
+  sm->out2in_node_index = sm->ei_out2in_node_index;
+
+  sm->in2out_output_node_index = sm->ei_in2out_output_node_index;
+
+  if (sm->pat)
+    {
+      sm->icmp_match_in2out_cb = icmp_match_in2out_slow;
+      sm->icmp_match_out2in_cb = icmp_match_out2in_slow;
+    }
+  else
+    {
+      sm->icmp_match_in2out_cb = icmp_match_in2out_fast;
+      sm->icmp_match_out2in_cb = icmp_match_out2in_fast;
+    }
+
+  nat_reset_timeouts (&sm->timeouts);
+  nat44_ei_db_init (nm->translations, nm->translation_buckets,
+		    nm->user_buckets);
   nat44_ei_set_alloc_default ();
   nat_ha_enable ();
+
+  // TODO: function for reset counters
+  vlib_zero_simple_counter (&sm->total_users, 0);
+  vlib_zero_simple_counter (&sm->total_sessions, 0);
+  vlib_zero_simple_counter (&sm->user_limit_reached, 0);
+
+  sm->enabled = 1;
+
   return 0;
 }
 
-void
+int
 nat44_ei_plugin_disable ()
 {
+  nat44_ei_main_t *nm = &nat44_ei_main;
+  snat_main_t *sm = &snat_main;
+  snat_interface_t *i, *vec;
+  int error = 0;
+
+  // first unregister all nodes from interfaces
+  vec = vec_dup (sm->interfaces);
+  vec_foreach (i, vec)
+    {
+      if (nat_interface_is_inside (i))
+	error = snat_interface_add_del (i->sw_if_index, 1, 1);
+      if (nat_interface_is_outside (i))
+	error = snat_interface_add_del (i->sw_if_index, 0, 1);
+
+      if (error)
+	{
+	  nat_log_err ("error occurred while removing interface %u",
+		       i->sw_if_index);
+	}
+    }
+  vec_free (vec);
+  sm->interfaces = 0;
+
+  vec = vec_dup (sm->output_feature_interfaces);
+  vec_foreach (i, vec)
+    {
+      if (nat_interface_is_inside (i))
+	error = snat_interface_add_del_output_feature (i->sw_if_index, 1, 1);
+      if (nat_interface_is_outside (i))
+	error = snat_interface_add_del_output_feature (i->sw_if_index, 0, 1);
+
+      if (error)
+	{
+	  nat_log_err ("error occurred while removing interface %u",
+		       i->sw_if_index);
+	}
+    }
+  vec_free (vec);
+  sm->output_feature_interfaces = 0;
+
   nat_ha_disable ();
+  nat44_ei_db_free ();
+
+  nat44_addresses_free (&sm->addresses);
+  nat44_addresses_free (&sm->twice_nat_addresses);
+
+  vec_free (sm->to_resolve);
+  vec_free (sm->auto_add_sw_if_indices);
+  vec_free (sm->auto_add_sw_if_indices_twice_nat);
+
+  sm->to_resolve = 0;
+  sm->auto_add_sw_if_indices = 0;
+  sm->auto_add_sw_if_indices_twice_nat = 0;
+
+  sm->forwarding_enabled = 0;
+
+  sm->enabled = 0;
+  clib_memset (&nm->rconfig, 0, sizeof (nm->rconfig));
+  clib_memset (&sm->rconfig, 0, sizeof (sm->rconfig));
+
+  return error;
 }
 
 void
@@ -525,6 +663,651 @@ nat44_ei_set_alloc_mape (u16 psid, u16 psid_offset, u16 psid_length)
   sm->psid_length = psid_length;
 }
 
+static void
+nat44_ei_add_static_mapping_when_resolved (ip4_address_t l_addr, u16 l_port,
+					   u16 e_port, nat_protocol_t proto,
+					   u32 sw_if_index, u32 vrf_id,
+					   int addr_only, int identity_nat,
+					   u8 *tag)
+{
+  snat_main_t *sm = &snat_main;
+  snat_static_map_resolve_t *rp;
+
+  vec_add2 (sm->to_resolve, rp, 1);
+  clib_memset (rp, 0, sizeof (*rp));
+
+  rp->l_addr.as_u32 = l_addr.as_u32;
+  rp->l_port = l_port;
+  rp->e_port = e_port;
+  rp->sw_if_index = sw_if_index;
+  rp->vrf_id = vrf_id;
+  rp->proto = proto;
+  rp->addr_only = addr_only;
+  rp->identity_nat = identity_nat;
+  rp->tag = vec_dup (tag);
+}
+
+int
+nat44_ei_del_session (snat_main_t *sm, ip4_address_t *addr, u16 port,
+		      nat_protocol_t proto, u32 vrf_id, int is_in)
+{
+  snat_main_per_thread_data_t *tsm;
+  clib_bihash_kv_8_8_t kv, value;
+  ip4_header_t ip;
+  u32 fib_index = fib_table_find (FIB_PROTOCOL_IP4, vrf_id);
+  snat_session_t *s;
+  clib_bihash_8_8_t *t;
+
+  if (sm->endpoint_dependent)
+    return VNET_API_ERROR_UNSUPPORTED;
+
+  ip.dst_address.as_u32 = ip.src_address.as_u32 = addr->as_u32;
+  if (sm->num_workers > 1)
+    tsm = vec_elt_at_index (sm->per_thread_data,
+			    sm->worker_in2out_cb (&ip, fib_index, 0));
+  else
+    tsm = vec_elt_at_index (sm->per_thread_data, sm->num_workers);
+
+  init_nat_k (&kv, *addr, port, fib_index, proto);
+  t = is_in ? &tsm->in2out : &tsm->out2in;
+  if (!clib_bihash_search_8_8 (t, &kv, &value))
+    {
+      if (pool_is_free_index (tsm->sessions, value.value))
+	return VNET_API_ERROR_UNSPECIFIED;
+
+      s = pool_elt_at_index (tsm->sessions, value.value);
+      nat_free_session_data (sm, s, tsm - sm->per_thread_data, 0);
+      nat44_delete_session (sm, s, tsm - sm->per_thread_data);
+      return 0;
+    }
+
+  return VNET_API_ERROR_NO_SUCH_ENTRY;
+}
+
+int
+nat44_ei_add_del_static_mapping (ip4_address_t l_addr, ip4_address_t e_addr,
+				 u16 l_port, u16 e_port, nat_protocol_t proto,
+				 u32 sw_if_index, u32 vrf_id, u8 addr_only,
+				 u8 identity_nat, u8 *tag, u8 is_add)
+{
+  snat_main_t *sm = &snat_main;
+  snat_static_mapping_t *m = 0;
+  clib_bihash_kv_8_8_t kv, value;
+  snat_address_t *a = 0;
+  u32 fib_index = ~0;
+  snat_interface_t *interface;
+  snat_main_per_thread_data_t *tsm;
+  snat_user_key_t u_key;
+  snat_user_t *u;
+  dlist_elt_t *head, *elt;
+  u32 elt_index, head_index;
+  u32 ses_index;
+  u64 user_index;
+  snat_session_t *s;
+  snat_static_map_resolve_t *rp, *rp_match = 0;
+  nat44_lb_addr_port_t *local;
+  u32 find = ~0;
+  int i;
+
+  if (sw_if_index != ~0)
+    {
+      ip4_address_t *first_int_addr;
+
+      for (i = 0; i < vec_len (sm->to_resolve); i++)
+	{
+	  rp = sm->to_resolve + i;
+	  if (rp->sw_if_index != sw_if_index ||
+	      rp->l_addr.as_u32 != l_addr.as_u32 || rp->vrf_id != vrf_id ||
+	      rp->addr_only != addr_only)
+	    continue;
+
+	  if (!addr_only)
+	    {
+	      if ((rp->l_port != l_port && rp->e_port != e_port) ||
+		  rp->proto != proto)
+		continue;
+	    }
+
+	  rp_match = rp;
+	  break;
+	}
+
+      /* Might be already set... */
+      first_int_addr = ip4_interface_first_address (
+	sm->ip4_main, sw_if_index, 0 /* just want the address */);
+
+      if (is_add)
+	{
+	  if (rp_match)
+	    return VNET_API_ERROR_VALUE_EXIST;
+
+	  nat44_ei_add_static_mapping_when_resolved (
+	    l_addr, l_port, e_port, proto, sw_if_index, vrf_id, addr_only,
+	    identity_nat, tag);
+
+	  /* DHCP resolution required? */
+	  if (!first_int_addr)
+	    return 0;
+
+	  e_addr.as_u32 = first_int_addr->as_u32;
+	  /* Identity mapping? */
+	  if (l_addr.as_u32 == 0)
+	    l_addr.as_u32 = e_addr.as_u32;
+	}
+      else
+	{
+	  if (!rp_match)
+	    return VNET_API_ERROR_NO_SUCH_ENTRY;
+
+	  vec_del1 (sm->to_resolve, i);
+
+	  if (!first_int_addr)
+	    return 0;
+
+	  e_addr.as_u32 = first_int_addr->as_u32;
+	  /* Identity mapping? */
+	  if (l_addr.as_u32 == 0)
+	    l_addr.as_u32 = e_addr.as_u32;
+	}
+    }
+
+  init_nat_k (&kv, e_addr, addr_only ? 0 : e_port, 0, addr_only ? 0 : proto);
+  if (!clib_bihash_search_8_8 (&sm->static_mapping_by_external, &kv, &value))
+    m = pool_elt_at_index (sm->static_mappings, value.value);
+
+  if (is_add)
+    {
+      if (m)
+	{
+	  // identity mapping for second vrf
+	  if (is_identity_static_mapping (m))
+	    {
+	      pool_foreach (local, m->locals)
+		{
+		  if (local->vrf_id == vrf_id)
+		    return VNET_API_ERROR_VALUE_EXIST;
+		}
+	      pool_get (m->locals, local);
+	      local->vrf_id = vrf_id;
+	      local->fib_index = fib_table_find_or_create_and_lock (
+		FIB_PROTOCOL_IP4, vrf_id, sm->fib_src_low);
+	      init_nat_kv (&kv, m->local_addr, m->local_port, local->fib_index,
+			   m->proto, m - sm->static_mappings);
+	      clib_bihash_add_del_8_8 (&sm->static_mapping_by_local, &kv, 1);
+	      return 0;
+	    }
+	  return VNET_API_ERROR_VALUE_EXIST;
+	}
+
+      /* Convert VRF id to FIB index */
+      if (vrf_id != ~0)
+	{
+	  fib_index = fib_table_find_or_create_and_lock (
+	    FIB_PROTOCOL_IP4, vrf_id, sm->fib_src_low);
+	}
+      /* If not specified use inside VRF id from NAT44 plugin config */
+      else
+	{
+	  fib_index = sm->inside_fib_index;
+	  vrf_id = sm->inside_vrf_id;
+	  fib_table_lock (fib_index, FIB_PROTOCOL_IP4, sm->fib_src_low);
+	}
+
+      if (!identity_nat)
+	{
+	  init_nat_k (&kv, l_addr, addr_only ? 0 : l_port, fib_index,
+		      addr_only ? 0 : proto);
+	  if (!clib_bihash_search_8_8 (&sm->static_mapping_by_local, &kv,
+				       &value))
+	    return VNET_API_ERROR_VALUE_EXIST;
+	}
+
+      /* Find external address in allocated addresses and reserve port for
+	 address and port pair mapping when dynamic translations enabled */
+      if (!(addr_only || sm->static_mapping_only))
+	{
+	  for (i = 0; i < vec_len (sm->addresses); i++)
+	    {
+	      if (sm->addresses[i].addr.as_u32 == e_addr.as_u32)
+		{
+		  a = sm->addresses + i;
+		  /* External port must be unused */
+		  switch (proto)
+		    {
+#define _(N, j, n, s)                                                         \
+  case NAT_PROTOCOL_##N:                                                      \
+    if (a->busy_##n##_port_refcounts[e_port])                                 \
+      return VNET_API_ERROR_INVALID_VALUE;                                    \
+    ++a->busy_##n##_port_refcounts[e_port];                                   \
+    if (e_port > 1024)                                                        \
+      {                                                                       \
+	a->busy_##n##_ports++;                                                \
+	a->busy_##n##_ports_per_thread[get_thread_idx_by_port (e_port)]++;    \
+      }                                                                       \
+    break;
+		      foreach_nat_protocol
+#undef _
+			default : nat_elog_info ("unknown protocol");
+		      return VNET_API_ERROR_INVALID_VALUE_2;
+		    }
+		  break;
+		}
+	    }
+	  /* External address must be allocated */
+	  if (!a && (l_addr.as_u32 != e_addr.as_u32))
+	    {
+	      if (sw_if_index != ~0)
+		{
+		  for (i = 0; i < vec_len (sm->to_resolve); i++)
+		    {
+		      rp = sm->to_resolve + i;
+		      if (rp->addr_only)
+			continue;
+		      if (rp->sw_if_index != sw_if_index &&
+			  rp->l_addr.as_u32 != l_addr.as_u32 &&
+			  rp->vrf_id != vrf_id && rp->l_port != l_port &&
+			  rp->e_port != e_port && rp->proto != proto)
+			continue;
+
+		      vec_del1 (sm->to_resolve, i);
+		      break;
+		    }
+		}
+	      return VNET_API_ERROR_NO_SUCH_ENTRY;
+	    }
+	}
+
+      pool_get (sm->static_mappings, m);
+      clib_memset (m, 0, sizeof (*m));
+      m->tag = vec_dup (tag);
+      m->local_addr = l_addr;
+      m->external_addr = e_addr;
+
+      if (addr_only)
+	m->flags |= NAT_STATIC_MAPPING_FLAG_ADDR_ONLY;
+      else
+	{
+	  m->local_port = l_port;
+	  m->external_port = e_port;
+	  m->proto = proto;
+	}
+
+      if (identity_nat)
+	{
+	  m->flags |= NAT_STATIC_MAPPING_FLAG_IDENTITY_NAT;
+	  pool_get (m->locals, local);
+	  local->vrf_id = vrf_id;
+	  local->fib_index = fib_index;
+	}
+      else
+	{
+	  m->vrf_id = vrf_id;
+	  m->fib_index = fib_index;
+	}
+
+      if (sm->num_workers > 1)
+	{
+	  ip4_header_t ip = {
+	    .src_address = m->local_addr,
+	  };
+	  vec_add1 (m->workers, sm->worker_in2out_cb (&ip, m->fib_index, 0));
+	  tsm = vec_elt_at_index (sm->per_thread_data, m->workers[0]);
+	}
+      else
+	tsm = vec_elt_at_index (sm->per_thread_data, sm->num_workers);
+
+      init_nat_kv (&kv, m->local_addr, m->local_port, fib_index, m->proto,
+		   m - sm->static_mappings);
+      clib_bihash_add_del_8_8 (&sm->static_mapping_by_local, &kv, 1);
+
+      init_nat_kv (&kv, m->external_addr, m->external_port, 0, m->proto,
+		   m - sm->static_mappings);
+      clib_bihash_add_del_8_8 (&sm->static_mapping_by_external, &kv, 1);
+
+      /* Delete dynamic sessions matching local address (+ local port) */
+      // TODO: based on type of NAT EI/ED
+      if (!(sm->static_mapping_only))
+	{
+	  u_key.addr = m->local_addr;
+	  u_key.fib_index = m->fib_index;
+	  kv.key = u_key.as_u64;
+	  if (!clib_bihash_search_8_8 (&tsm->user_hash, &kv, &value))
+	    {
+	      user_index = value.value;
+	      u = pool_elt_at_index (tsm->users, user_index);
+	      if (u->nsessions)
+		{
+		  head_index = u->sessions_per_user_list_head_index;
+		  head = pool_elt_at_index (tsm->list_pool, head_index);
+		  elt_index = head->next;
+		  elt = pool_elt_at_index (tsm->list_pool, elt_index);
+		  ses_index = elt->value;
+		  while (ses_index != ~0)
+		    {
+		      s = pool_elt_at_index (tsm->sessions, ses_index);
+		      elt = pool_elt_at_index (tsm->list_pool, elt->next);
+		      ses_index = elt->value;
+
+		      if (snat_is_session_static (s))
+			continue;
+
+		      if (!addr_only && s->in2out.port != m->local_port)
+			continue;
+
+		      nat_free_session_data (sm, s, tsm - sm->per_thread_data,
+					     0);
+		      nat44_delete_session (sm, s, tsm - sm->per_thread_data);
+
+		      if (!addr_only)
+			break;
+		    }
+		}
+	    }
+	}
+    }
+  else
+    {
+      if (!m)
+	{
+	  if (sw_if_index != ~0)
+	    return 0;
+	  else
+	    return VNET_API_ERROR_NO_SUCH_ENTRY;
+	}
+
+      if (identity_nat)
+	{
+	  if (vrf_id == ~0)
+	    vrf_id = sm->inside_vrf_id;
+
+	  pool_foreach (local, m->locals)
+	    {
+	      if (local->vrf_id == vrf_id)
+		find = local - m->locals;
+	    }
+	  if (find == ~0)
+	    return VNET_API_ERROR_NO_SUCH_ENTRY;
+
+	  local = pool_elt_at_index (m->locals, find);
+	  fib_index = local->fib_index;
+	  pool_put (m->locals, local);
+	}
+      else
+	fib_index = m->fib_index;
+
+      /* Free external address port */
+      if (!(addr_only || sm->static_mapping_only))
+	{
+	  for (i = 0; i < vec_len (sm->addresses); i++)
+	    {
+	      if (sm->addresses[i].addr.as_u32 == e_addr.as_u32)
+		{
+		  a = sm->addresses + i;
+		  switch (proto)
+		    {
+#define _(N, j, n, s)                                                         \
+  case NAT_PROTOCOL_##N:                                                      \
+    --a->busy_##n##_port_refcounts[e_port];                                   \
+    if (e_port > 1024)                                                        \
+      {                                                                       \
+	a->busy_##n##_ports--;                                                \
+	a->busy_##n##_ports_per_thread[get_thread_idx_by_port (e_port)]--;    \
+      }                                                                       \
+    break;
+		      foreach_nat_protocol
+#undef _
+			default : return VNET_API_ERROR_INVALID_VALUE_2;
+		    }
+		  break;
+		}
+	    }
+	}
+
+      if (sm->num_workers > 1)
+	tsm = vec_elt_at_index (sm->per_thread_data, m->workers[0]);
+      else
+	tsm = vec_elt_at_index (sm->per_thread_data, sm->num_workers);
+
+      init_nat_k (&kv, m->local_addr, m->local_port, fib_index, m->proto);
+      clib_bihash_add_del_8_8 (&sm->static_mapping_by_local, &kv, 0);
+
+      /* Delete session(s) for static mapping if exist */
+      if (!(sm->static_mapping_only) ||
+	  (sm->static_mapping_only && sm->static_mapping_connection_tracking))
+	{
+	  u_key.addr = m->local_addr;
+	  u_key.fib_index = fib_index;
+	  kv.key = u_key.as_u64;
+	  nat44_ei_static_mapping_del_sessions (sm, tsm, u_key, addr_only,
+						e_addr, e_port);
+	}
+
+      fib_table_unlock (fib_index, FIB_PROTOCOL_IP4, sm->fib_src_low);
+      if (pool_elts (m->locals))
+	return 0;
+
+      init_nat_k (&kv, m->external_addr, m->external_port, 0, m->proto);
+      clib_bihash_add_del_8_8 (&sm->static_mapping_by_external, &kv, 0);
+
+      vec_free (m->tag);
+      vec_free (m->workers);
+      /* Delete static mapping from pool */
+      pool_put (sm->static_mappings, m);
+    }
+
+  if (!addr_only || (l_addr.as_u32 == e_addr.as_u32))
+    return 0;
+
+  /* Add/delete external address to FIB */
+  pool_foreach (interface, sm->interfaces)
+    {
+      if (nat_interface_is_inside (interface) || sm->out2in_dpo)
+	continue;
+
+      snat_add_del_addr_to_fib (&e_addr, 32, interface->sw_if_index, is_add);
+      break;
+    }
+  pool_foreach (interface, sm->output_feature_interfaces)
+    {
+      if (nat_interface_is_inside (interface) || sm->out2in_dpo)
+	continue;
+
+      snat_add_del_addr_to_fib (&e_addr, 32, interface->sw_if_index, is_add);
+      break;
+    }
+  return 0;
+}
+
+int
+nat44_ei_static_mapping_match (ip4_address_t match_addr, u16 match_port,
+			       u32 match_fib_index,
+			       nat_protocol_t match_protocol,
+			       ip4_address_t *mapping_addr, u16 *mapping_port,
+			       u32 *mapping_fib_index, u8 by_external,
+			       u8 *is_addr_only, u8 *is_identity_nat)
+{
+  snat_main_t *sm = &snat_main;
+  clib_bihash_kv_8_8_t kv, value;
+  snat_static_mapping_t *m;
+  u16 port;
+
+  if (by_external)
+    {
+      init_nat_k (&kv, match_addr, match_port, 0, match_protocol);
+      if (clib_bihash_search_8_8 (&sm->static_mapping_by_external, &kv,
+				  &value))
+	{
+	  /* Try address only mapping */
+	  init_nat_k (&kv, match_addr, 0, 0, 0);
+	  if (clib_bihash_search_8_8 (&sm->static_mapping_by_external, &kv,
+				      &value))
+	    return 1;
+	}
+      m = pool_elt_at_index (sm->static_mappings, value.value);
+
+      *mapping_fib_index = m->fib_index;
+      *mapping_addr = m->local_addr;
+      port = m->local_port;
+    }
+  else
+    {
+      init_nat_k (&kv, match_addr, match_port, match_fib_index,
+		  match_protocol);
+      if (clib_bihash_search_8_8 (&sm->static_mapping_by_local, &kv, &value))
+	{
+	  /* Try address only mapping */
+	  init_nat_k (&kv, match_addr, 0, match_fib_index, 0);
+	  if (clib_bihash_search_8_8 (&sm->static_mapping_by_local, &kv,
+				      &value))
+	    return 1;
+	}
+      m = pool_elt_at_index (sm->static_mappings, value.value);
+
+      *mapping_fib_index = sm->outside_fib_index;
+      *mapping_addr = m->external_addr;
+      port = m->external_port;
+    }
+
+  /* Address only mapping doesn't change port */
+  if (is_addr_only_static_mapping (m))
+    *mapping_port = match_port;
+  else
+    *mapping_port = port;
+
+  if (PREDICT_FALSE (is_addr_only != 0))
+    *is_addr_only = is_addr_only_static_mapping (m);
+
+  if (PREDICT_FALSE (is_identity_nat != 0))
+    *is_identity_nat = is_identity_static_mapping (m);
+
+  return 0;
+}
+
+static void
+nat44_ei_worker_db_free (snat_main_per_thread_data_t *tsm)
+{
+  pool_free (tsm->list_pool);
+  pool_free (tsm->lru_pool);
+  pool_free (tsm->sessions);
+  pool_free (tsm->users);
+
+  clib_bihash_free_8_8 (&tsm->in2out);
+  clib_bihash_free_8_8 (&tsm->out2in);
+  clib_bihash_free_8_8 (&tsm->user_hash);
+}
+
+static void
+nat44_ei_worker_db_init (snat_main_per_thread_data_t *tsm, u32 translations,
+			 u32 translation_buckets, u32 user_buckets)
+{
+  dlist_elt_t *head;
+
+  pool_alloc (tsm->list_pool, translations);
+  pool_alloc (tsm->lru_pool, translations);
+  pool_alloc (tsm->sessions, translations);
+
+  clib_bihash_init_8_8 (&tsm->in2out, "in2out", translation_buckets, 0);
+  clib_bihash_init_8_8 (&tsm->out2in, "out2in", translation_buckets, 0);
+  clib_bihash_init_8_8 (&tsm->user_hash, "users", user_buckets, 0);
+
+  clib_bihash_set_kvp_format_fn_8_8 (&tsm->in2out, format_session_kvp);
+  clib_bihash_set_kvp_format_fn_8_8 (&tsm->out2in, format_session_kvp);
+  clib_bihash_set_kvp_format_fn_8_8 (&tsm->user_hash, format_user_kvp);
+
+  pool_get (tsm->lru_pool, head);
+  tsm->tcp_trans_lru_head_index = head - tsm->lru_pool;
+  clib_dlist_init (tsm->lru_pool, tsm->tcp_trans_lru_head_index);
+
+  pool_get (tsm->lru_pool, head);
+  tsm->tcp_estab_lru_head_index = head - tsm->lru_pool;
+  clib_dlist_init (tsm->lru_pool, tsm->tcp_estab_lru_head_index);
+
+  pool_get (tsm->lru_pool, head);
+  tsm->udp_lru_head_index = head - tsm->lru_pool;
+  clib_dlist_init (tsm->lru_pool, tsm->udp_lru_head_index);
+
+  pool_get (tsm->lru_pool, head);
+  tsm->icmp_lru_head_index = head - tsm->lru_pool;
+  clib_dlist_init (tsm->lru_pool, tsm->icmp_lru_head_index);
+
+  pool_get (tsm->lru_pool, head);
+  tsm->unk_proto_lru_head_index = head - tsm->lru_pool;
+  clib_dlist_init (tsm->lru_pool, tsm->unk_proto_lru_head_index);
+}
+
+static void
+nat44_ei_db_free ()
+{
+  snat_main_t *sm = &snat_main;
+  snat_main_per_thread_data_t *tsm;
+
+  pool_free (sm->static_mappings);
+  clib_bihash_free_8_8 (&sm->static_mapping_by_local);
+  clib_bihash_free_8_8 (&sm->static_mapping_by_external);
+
+  if (sm->pat)
+    {
+      vec_foreach (tsm, sm->per_thread_data)
+	{
+	  nat44_ei_worker_db_free (tsm);
+	}
+    }
+}
+
+static void
+nat44_ei_db_init (u32 translations, u32 translation_buckets, u32 user_buckets)
+{
+  snat_main_t *sm = &snat_main;
+  snat_main_per_thread_data_t *tsm;
+
+  u32 static_mapping_buckets = 1024;
+  u32 static_mapping_memory_size = 64 << 20;
+
+  clib_bihash_init_8_8 (&sm->static_mapping_by_local,
+			"static_mapping_by_local", static_mapping_buckets,
+			static_mapping_memory_size);
+  clib_bihash_init_8_8 (&sm->static_mapping_by_external,
+			"static_mapping_by_external", static_mapping_buckets,
+			static_mapping_memory_size);
+  clib_bihash_set_kvp_format_fn_8_8 (&sm->static_mapping_by_local,
+				     format_static_mapping_kvp);
+  clib_bihash_set_kvp_format_fn_8_8 (&sm->static_mapping_by_external,
+				     format_static_mapping_kvp);
+
+  if (sm->pat)
+    {
+      vec_foreach (tsm, sm->per_thread_data)
+	{
+	  nat44_ei_worker_db_init (tsm, translations, translation_buckets,
+				   user_buckets);
+	}
+    }
+}
+
+void
+nat44_ei_sessions_clear ()
+{
+  nat44_ei_main_t *nm = &nat44_ei_main;
+
+  snat_main_per_thread_data_t *tsm;
+  snat_main_t *sm = &snat_main;
+
+  if (sm->pat)
+    {
+      vec_foreach (tsm, sm->per_thread_data)
+	{
+	  nat44_ei_worker_db_free (tsm);
+	  nat44_ei_worker_db_init (tsm, nm->translations,
+				   nm->translation_buckets, nm->user_buckets);
+	}
+    }
+
+  // TODO: function for reset counters
+  vlib_zero_simple_counter (&sm->total_users, 0);
+  vlib_zero_simple_counter (&sm->total_sessions, 0);
+  vlib_zero_simple_counter (&sm->user_limit_reached, 0);
+}
+
 /*
  * fd.io coding-style-patch-verification: ON
  *
diff --git a/src/plugins/nat/nat44-ei/nat44_ei.h b/src/plugins/nat/nat44-ei/nat44_ei.h
index ac430bee5c3..510e73de59a 100644
--- a/src/plugins/nat/nat44-ei/nat44_ei.h
+++ b/src/plugins/nat/nat44-ei/nat44_ei.h
@@ -19,9 +19,38 @@
 #ifndef __included_nat44_ei_h__
 #define __included_nat44_ei_h__
 
-int nat44_ei_plugin_enable ();
+typedef struct
+{
+  /* maximum number of users */
+  u32 users;
+  /* maximum number of sessions */
+  u32 sessions;
+  /* maximum number of ssessions per user */
+  u32 user_sessions;
 
-void nat44_ei_plugin_disable ();
+  /* plugin features */
+  u8 static_mapping_only;
+  u8 connection_tracking;
+  u8 out2in_dpo;
+
+  u32 inside_vrf;
+  u32 outside_vrf;
+
+} nat44_ei_config_t;
+
+typedef struct
+{
+  u32 translations;
+  u32 translation_buckets;
+  u32 user_buckets;
+
+  nat44_ei_config_t rconfig;
+
+} nat44_ei_main_t;
+
+int nat44_ei_plugin_enable (nat44_ei_config_t c);
+
+int nat44_ei_plugin_disable ();
 
 /**
  * @brief Delete specific NAT44 EI user and his sessions
@@ -71,6 +100,71 @@ void nat44_ei_set_alloc_mape (u16 psid, u16 psid_offset, u16 psid_length);
  */
 void nat44_ei_set_alloc_range (u16 start_port, u16 end_port);
 
+/**
+ * @brief Add/delete NAT44-EI static mapping
+ *
+ * @param l_addr       local IPv4 address
+ * @param e_addr       external IPv4 address
+ * @param l_port       local port number
+ * @param e_port       external port number
+ * @param proto        L4 protocol
+ * @param sw_if_index  use interface address as external IPv4 address
+ * @param vrf_id       local VRF ID
+ * @param addr_only    1 = 1:1NAT, 0 = 1:1NAPT
+ * @param identity_nat identity NAT
+ * @param tag opaque   string tag
+ * @param is_add       1 = add, 0 = delete
+ *
+ * @return 0 on success, non-zero value otherwise
+
+ */
+int nat44_ei_add_del_static_mapping (ip4_address_t l_addr,
+				     ip4_address_t e_addr, u16 l_port,
+				     u16 e_port, nat_protocol_t proto,
+				     u32 sw_if_index, u32 vrf_id, u8 addr_only,
+				     u8 identity_nat, u8 *tag, u8 is_add);
+
+/**
+ * @brief Delete NAT44-EI session
+ *
+ * @param addr   IPv4 address
+ * @param port   L4 port number
+ * @param proto  L4 protocol
+ * @param vrf_id VRF ID
+ * @param is_in  1 = inside network address and port pair, 0 = outside
+ *
+ * @return 0 on success, non-zero value otherwise
+ */
+int nat44_ei_del_session (snat_main_t *sm, ip4_address_t *addr, u16 port,
+			  nat_protocol_t proto, u32 vrf_id, int is_in);
+
+/**
+ * @brief Match NAT44-EI static mapping.
+ *
+ * @param key             address and port to match
+ * @param addr            external/local address of the matched mapping
+ * @param port            port of the matched mapping
+ * @param fib_index       fib index of the matched mapping
+ * @param by_external     if 0 match by local address otherwise match by
+ * external address
+ * @param is_addr_only    1 if matched mapping is address only
+ * @param is_identity_nat 1 if indentity mapping
+ *
+ * @returns 0 if match found otherwise 1.
+ */
+int nat44_ei_static_mapping_match (ip4_address_t match_addr, u16 match_port,
+				   u32 match_fib_index,
+				   nat_protocol_t match_protocol,
+				   ip4_address_t *mapping_addr,
+				   u16 *mapping_port, u32 *mapping_fib_index,
+				   u8 by_external, u8 *is_addr_only,
+				   u8 *is_identity_nat);
+
+/**
+ * @brief Clear all active NAT44-EI sessions.
+ */
+void nat44_ei_sessions_clear ();
+
 #endif /* __included_nat44_ei_h__ */
 /*
  * fd.io coding-style-patch-verification: ON
diff --git a/src/plugins/nat/nat44-ei/nat44_ei_in2out.c b/src/plugins/nat/nat44-ei/nat44_ei_in2out.c
index 1c341318957..892518fff97 100644
--- a/src/plugins/nat/nat44-ei/nat44_ei_in2out.c
+++ b/src/plugins/nat/nat44-ei/nat44_ei_in2out.c
@@ -29,6 +29,7 @@
 #include <nat/nat_inlines.h>
 #include <nat/lib/nat_syslog.h>
 #include <nat/nat44-ei/nat44_ei_inlines.h>
+#include <nat/nat44-ei/nat44_ei.h>
 
 #include <vppinfra/hash.h>
 #include <vppinfra/error.h>
@@ -130,10 +131,10 @@ snat_not_translate (snat_main_t * sm, vlib_node_runtime_t * node,
       ip4_address_t placeholder_addr;
       u16 placeholder_port;
       u32 placeholder_fib_index;
-      if (!snat_static_mapping_match
-	  (sm, ip0->dst_address, udp0->dst_port, sm->outside_fib_index,
-	   proto0, &placeholder_addr, &placeholder_port,
-	   &placeholder_fib_index, 1, 0, 0, 0, 0, 0, 0))
+      if (!nat44_ei_static_mapping_match (ip0->dst_address, udp0->dst_port,
+					  sm->outside_fib_index, proto0,
+					  &placeholder_addr, &placeholder_port,
+					  &placeholder_fib_index, 1, 0, 0))
 	return 0;
     }
   else
@@ -270,9 +271,9 @@ slow_path (snat_main_t * sm, vlib_buffer_t * b0,
     }
 
   /* First try to match static mapping by local address and port */
-  if (snat_static_mapping_match
-      (sm, i2o_addr, i2o_port, rx_fib_index0, nat_proto, &sm_addr,
-       &sm_port, &sm_fib_index, 0, 0, 0, 0, 0, &identity_nat, 0))
+  if (nat44_ei_static_mapping_match (i2o_addr, i2o_port, rx_fib_index0,
+				     nat_proto, &sm_addr, &sm_port,
+				     &sm_fib_index, 0, 0, &identity_nat))
     {
       /* Try to create dynamic translation */
       if (sm->alloc_addr_and_port (
@@ -592,9 +593,9 @@ icmp_match_in2out_fast (snat_main_t * sm, vlib_node_runtime_t * node,
   u16 sm_port;
   u32 sm_fib_index;
 
-  if (snat_static_mapping_match
-      (sm, *addr, *port, *fib_index, *proto, &sm_addr, &sm_port,
-       &sm_fib_index, 0, &is_addr_only, 0, 0, 0, 0, 0))
+  if (nat44_ei_static_mapping_match (*addr, *port, *fib_index, *proto,
+				     &sm_addr, &sm_port, &sm_fib_index, 0,
+				     &is_addr_only, 0))
     {
       if (PREDICT_FALSE (snat_not_translate_fast (sm, node, sw_if_index0, ip0,
 						  IP_PROTOCOL_ICMP,
@@ -1831,9 +1832,9 @@ VLIB_NODE_FN (snat_in2out_fast_node) (vlib_main_t * vm,
 	      goto trace0;
 	    }
 
-	  if (snat_static_mapping_match
-	      (sm, ip0->src_address, udp0->src_port, rx_fib_index0, proto0,
-	       &sm0_addr, &sm0_port, &sm0_fib_index, 0, 0, 0, 0, 0, 0, 0))
+	  if (nat44_ei_static_mapping_match (
+		ip0->src_address, udp0->src_port, rx_fib_index0, proto0,
+		&sm0_addr, &sm0_port, &sm0_fib_index, 0, 0, 0))
 	    {
 	      b0->error = node->errors[SNAT_IN2OUT_ERROR_NO_TRANSLATION];
 	      next0 = SNAT_IN2OUT_NEXT_DROP;
diff --git a/src/plugins/nat/nat44-ei/nat44_ei_out2in.c b/src/plugins/nat/nat44-ei/nat44_ei_out2in.c
index 8220f0dc9d8..b677e9bde89 100644
--- a/src/plugins/nat/nat44-ei/nat44_ei_out2in.c
+++ b/src/plugins/nat/nat44-ei/nat44_ei_out2in.c
@@ -29,6 +29,7 @@
 #include <nat/nat_inlines.h>
 #include <nat/lib/nat_syslog.h>
 #include <nat/nat44-ei/nat44_ei_inlines.h>
+#include <nat/nat44-ei/nat44_ei.h>
 
 #include <vppinfra/hash.h>
 #include <vppinfra/error.h>
@@ -354,10 +355,9 @@ icmp_match_out2in_slow (snat_main_t * sm, vlib_node_runtime_t * node,
     {
       /* Try to match static mapping by external address and port,
          destination address and port in packet */
-      if (snat_static_mapping_match
-	  (sm, *addr, *port, *fib_index, *proto,
-	   &mapping_addr, &mapping_port, &mapping_fib_index, 1, &is_addr_only,
-	   0, 0, 0, &identity_nat, 0))
+      if (nat44_ei_static_mapping_match (
+	    *addr, *port, *fib_index, *proto, &mapping_addr, &mapping_port,
+	    &mapping_fib_index, 1, &is_addr_only, &identity_nat))
 	{
 	  if (!sm->forwarding_enabled)
 	    {
@@ -481,9 +481,9 @@ icmp_match_out2in_fast (snat_main_t * sm, vlib_node_runtime_t * node,
       next0 = SNAT_OUT2IN_NEXT_DROP;
       goto out;
     }
-  if (snat_static_mapping_match
-      (sm, addr, port, rx_fib_index0, *proto, mapping_addr, mapping_port,
-       mapping_fib_index, 1, &is_addr_only, 0, 0, 0, 0, 0))
+  if (nat44_ei_static_mapping_match (addr, port, rx_fib_index0, *proto,
+				     mapping_addr, mapping_port,
+				     mapping_fib_index, 1, &is_addr_only, 0))
     {
       /* Don't NAT packet aimed at the intfc address */
       if (is_interface_addr (sm, node, sw_if_index0, ip0->dst_address.as_u32))
@@ -828,11 +828,10 @@ VLIB_NODE_FN (snat_out2in_node) (vlib_main_t * vm,
 	{
 	  /* Try to match static mapping by external address and port,
 	     destination address and port in packet */
-	  if (snat_static_mapping_match
-	      (sm, ip0->dst_address,
-	       vnet_buffer (b0)->ip.reass.l4_dst_port, rx_fib_index0,
-	       proto0, &sm_addr0, &sm_port0, &sm_fib_index0, 1, 0, 0, 0,
-	       0, &identity_nat0, 0))
+	  if (nat44_ei_static_mapping_match (
+		ip0->dst_address, vnet_buffer (b0)->ip.reass.l4_dst_port,
+		rx_fib_index0, proto0, &sm_addr0, &sm_port0, &sm_fib_index0, 1,
+		0, &identity_nat0))
 	    {
 	      /*
 	       * Send DHCP packets to the ipv4 stack, or we won't
@@ -1003,17 +1002,15 @@ VLIB_NODE_FN (snat_out2in_node) (vlib_main_t * vm,
       init_nat_k (&kv1, ip1->dst_address,
 		  vnet_buffer (b1)->ip.reass.l4_dst_port, rx_fib_index1,
 		  proto1);
-
       if (clib_bihash_search_8_8
 	  (&sm->per_thread_data[thread_index].out2in, &kv1, &value1))
 	{
 	  /* Try to match static mapping by external address and port,
 	     destination address and port in packet */
-	  if (snat_static_mapping_match
-	      (sm, ip1->dst_address,
-	       vnet_buffer (b1)->ip.reass.l4_dst_port, proto1,
-	       rx_fib_index1, &sm_addr1, &sm_port1, &sm_fib_index1, 1, 0,
-	       0, 0, 0, &identity_nat1, 0))
+	  if (nat44_ei_static_mapping_match (
+		ip1->dst_address, vnet_buffer (b1)->ip.reass.l4_dst_port,
+		rx_fib_index1, proto1, &sm_addr1, &sm_port1, &sm_fib_index1, 1,
+		0, &identity_nat1))
 	    {
 	      /*
 	       * Send DHCP packets to the ipv4 stack, or we won't
@@ -1227,11 +1224,10 @@ VLIB_NODE_FN (snat_out2in_node) (vlib_main_t * vm,
 	{
 	  /* Try to match static mapping by external address and port,
 	     destination address and port in packet */
-	  if (snat_static_mapping_match
-	      (sm, ip0->dst_address,
-	       vnet_buffer (b0)->ip.reass.l4_dst_port, rx_fib_index0,
-	       proto0, &sm_addr0, &sm_port0, &sm_fib_index0, 1, 0, 0, 0,
-	       0, &identity_nat0, 0))
+	  if (nat44_ei_static_mapping_match (
+		ip0->dst_address, vnet_buffer (b0)->ip.reass.l4_dst_port,
+		rx_fib_index0, proto0, &sm_addr0, &sm_port0, &sm_fib_index0, 1,
+		0, &identity_nat0))
 	    {
 	      /*
 	       * Send DHCP packets to the ipv4 stack, or we won't
@@ -1454,9 +1450,9 @@ VLIB_NODE_FN (snat_out2in_fast_node) (vlib_main_t * vm,
 	  goto trace00;
 	}
 
-      if (snat_static_mapping_match
-	  (sm, ip0->dst_address, udp0->dst_port, rx_fib_index0, proto0,
-	   &sm_addr0, &sm_port0, &sm_fib_index0, 1, 0, 0, 0, 0, 0, 0))
+      if (nat44_ei_static_mapping_match (ip0->dst_address, udp0->dst_port,
+					 rx_fib_index0, proto0, &sm_addr0,
+					 &sm_port0, &sm_fib_index0, 1, 0, 0))
 	{
 	  b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
 	  goto trace00;
diff --git a/src/plugins/nat/nat44_api.c b/src/plugins/nat/nat44_api.c
index cfe2211acd3..c025db74f2e 100644
--- a/src/plugins/nat/nat44_api.c
+++ b/src/plugins/nat/nat44_api.c
@@ -828,13 +828,10 @@ static void
   tag = format (0, "%s", mp->tag);
   vec_terminate_c_string (tag);
 
-  rv = snat_add_static_mapping (local_addr, external_addr, local_port,
-				external_port, vrf_id,
-				mp->flags & NAT_API_IS_ADDR_ONLY,
-				external_sw_if_index, proto,
-				mp->is_add, twice_nat,
-				mp->flags & NAT_API_IS_OUT2IN_ONLY, tag, 0,
-				pool_addr, 0);
+  rv = snat_add_static_mapping (
+    local_addr, external_addr, local_port, external_port, vrf_id,
+    mp->flags & NAT_API_IS_ADDR_ONLY, external_sw_if_index, proto, mp->is_add,
+    twice_nat, mp->flags & NAT_API_IS_OUT2IN_ONLY, tag, 0, pool_addr, 0);
   vec_free (tag);
 
   REPLY_MACRO (VL_API_NAT44_ADD_DEL_STATIC_MAPPING_REPLY);
@@ -1622,7 +1619,7 @@ vl_api_nat44_del_session_t_handler (vl_api_nat44_del_session_t * mp)
       nat44_del_ed_session (sm, &addr, port, &eh_addr, eh_port, mp->protocol,
 			    vrf_id, is_in);
   else
-    rv = nat44_del_session (sm, &addr, port, proto, vrf_id, is_in);
+    rv = nat44_ei_del_session (sm, &addr, port, proto, vrf_id, is_in);
 
   REPLY_MACRO (VL_API_NAT44_DEL_SESSION_REPLY);
 }
diff --git a/src/plugins/nat/nat44_cli.c b/src/plugins/nat/nat44_cli.c
index 7415b5fe76f..adcf324850d 100644
--- a/src/plugins/nat/nat44_cli.c
+++ b/src/plugins/nat/nat44_cli.c
@@ -44,8 +44,6 @@ nat44_enable_command_fn (vlib_main_t * vm,
   nat44_config_t c = { 0 };
   u8 mode_set = 0;
 
-  // TODO: check this also inside the function so it can be
-  //       safely called from anyplace, also sanity checking required
   if (sm->enabled)
     return clib_error_return (0, "nat44 already enabled");
 
@@ -1148,11 +1146,10 @@ add_static_mapping_command_fn (vlib_main_t * vm,
       goto done;
     }
 
-  rv = snat_add_static_mapping (l_addr, e_addr, clib_host_to_net_u16 (l_port),
-				clib_host_to_net_u16 (e_port),
-				vrf_id, addr_only, sw_if_index, proto, is_add,
-				twice_nat, out2in_only, 0, 0, exact_addr,
-				exact);
+  rv = snat_add_static_mapping (
+    l_addr, e_addr, clib_host_to_net_u16 (l_port),
+    clib_host_to_net_u16 (e_port), vrf_id, addr_only, sw_if_index, proto,
+    is_add, twice_nat, out2in_only, 0, 0, exact_addr, exact);
 
   switch (rv)
     {
@@ -1230,11 +1227,9 @@ add_identity_mapping_command_fn (vlib_main_t * vm,
 	}
     }
 
-  rv =
-    snat_add_static_mapping (addr, addr, clib_host_to_net_u16 (port),
-			     clib_host_to_net_u16 (port), vrf_id, addr_only,
-			     sw_if_index, proto, is_add, 0, 0, 0, 1,
-			     pool_addr, 0);
+  rv = snat_add_static_mapping (
+    addr, addr, clib_host_to_net_u16 (port), clib_host_to_net_u16 (port),
+    vrf_id, addr_only, sw_if_index, proto, is_add, 0, 0, 0, 1, pool_addr, 0);
 
   switch (rv)
     {
@@ -1779,9 +1774,8 @@ nat44_del_session_command_fn (vlib_main_t * vm,
 			    clib_host_to_net_u16 (eh_port),
 			    nat_proto_to_ip_proto (proto), vrf_id, is_in);
   else
-    rv =
-      nat44_del_session (sm, &addr, clib_host_to_net_u16 (port), proto,
-			 vrf_id, is_in);
+    rv = nat44_ei_del_session (sm, &addr, clib_host_to_net_u16 (port), proto,
+			       vrf_id, is_in);
 
   switch (rv)
     {