nat: nat44-ed configuration refactor & cleanup
[vpp.git] / src / plugins / nat / nat44-ed / nat44_ed.c
index 0d62e78..4e13907 100644 (file)
@@ -36,6 +36,8 @@
 #include <nat/nat44-ed/nat44_ed_affinity.h>
 #include <nat/nat44-ed/nat44_ed_inlines.h>
 
+#include <vpp/stats/stat_segment.h>
+
 snat_main_t snat_main;
 
 static_always_inline void nat_validate_interface_counters (snat_main_t *sm,
@@ -74,7 +76,6 @@ static_always_inline void nat_validate_interface_counters (snat_main_t *sm,
     }                                                                         \
   while (0)
 
-/* *INDENT-OFF* */
 /* Hook up input features */
 VNET_FEATURE_INIT (nat_pre_in2out, static) = {
   .arc_name = "ip4-unicast",
@@ -148,12 +149,14 @@ VNET_FEATURE_INIT (ip4_snat_out2in_fast, static) = {
 VNET_FEATURE_INIT (ip4_snat_in2out_output, static) = {
   .arc_name = "ip4-output",
   .node_name = "nat44-in2out-output",
-  .runs_after = VNET_FEATURES ("acl-plugin-out-ip4-fa","ip4-sv-reassembly-output-feature"),
+  .runs_after = VNET_FEATURES ("ip4-sv-reassembly-output-feature"),
+  .runs_before = VNET_FEATURES ("acl-plugin-out-ip4-fa"),
 };
 VNET_FEATURE_INIT (ip4_snat_in2out_output_worker_handoff, static) = {
   .arc_name = "ip4-output",
   .node_name = "nat44-in2out-output-worker-handoff",
-  .runs_after = VNET_FEATURES ("acl-plugin-out-ip4-fa","ip4-sv-reassembly-output-feature"),
+  .runs_after = VNET_FEATURES ("ip4-sv-reassembly-output-feature"),
+  .runs_before = VNET_FEATURES ("acl-plugin-out-ip4-fa"),
 };
 VNET_FEATURE_INIT (nat_pre_in2out_output, static) = {
   .arc_name = "ip4-output",
@@ -172,19 +175,11 @@ VLIB_PLUGIN_REGISTER () = {
     .version = VPP_BUILD_VER,
     .description = "Network Address Translation (NAT)",
 };
-/* *INDENT-ON* */
 
 static void nat44_ed_db_init (u32 translations, u32 translation_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);
-
-static u32 nat44_ed_get_worker_in2out_cb (vlib_buffer_t *b, ip4_header_t *ip,
-                                         u32 rx_fib_index, u8 is_output);
-
 u32 nat_calc_bihash_buckets (u32 n_elts);
 
 u8 *
@@ -330,7 +325,6 @@ snat_add_address (snat_main_t * sm, ip4_address_t * addr, u32 vrf_id,
   vlib_thread_main_t *tm = vlib_get_thread_main ();
 
   /* Check if address already exists */
-  /* *INDENT-OFF* */
   vec_foreach (ap, twice_nat ? sm->twice_nat_addresses : sm->addresses)
     {
       if (ap->addr.as_u32 == addr->as_u32)
@@ -339,7 +333,6 @@ snat_add_address (snat_main_t * sm, ip4_address_t * addr, u32 vrf_id,
           return VNET_API_ERROR_VALUE_EXIST;
         }
     }
-  /* *INDENT-ON* */
 
   if (twice_nat)
     vec_add2 (sm->twice_nat_addresses, ap, 1);
@@ -354,7 +347,6 @@ snat_add_address (snat_main_t * sm, ip4_address_t * addr, u32 vrf_id,
   else
     ap->fib_index = ~0;
 
-  /* *INDENT-OFF* */
   #define _(N, i, n, s) \
     clib_memset(ap->busy_##n##_port_refcounts, 0, sizeof(ap->busy_##n##_port_refcounts));\
     ap->busy_##n##_ports = 0; \
@@ -362,13 +354,11 @@ snat_add_address (snat_main_t * sm, ip4_address_t * addr, u32 vrf_id,
     vec_validate_init_empty (ap->busy_##n##_ports_per_thread, tm->n_vlib_mains - 1, 0);
     foreach_nat_protocol
   #undef _
-  /* *INDENT-ON* */
 
   if (twice_nat)
     return 0;
 
   /* Add external address to FIB */
-  /* *INDENT-OFF* */
   pool_foreach (i, sm->interfaces)
    {
      if (nat_interface_is_inside (i))
@@ -385,7 +375,6 @@ snat_add_address (snat_main_t * sm, ip4_address_t * addr, u32 vrf_id,
      snat_add_del_addr_to_fib (addr, 32, i->sw_if_index, 1);
      break;
   }
-  /* *INDENT-ON* */
 
   return 0;
 }
@@ -394,47 +383,17 @@ static int
 is_snat_address_used_in_static_mapping (snat_main_t * sm, ip4_address_t addr)
 {
   snat_static_mapping_t *m;
-  /* *INDENT-OFF* */
   pool_foreach (m, sm->static_mappings)
    {
-      if (is_addr_only_static_mapping (m) ||
-          is_out2in_only_static_mapping (m) ||
-          is_identity_static_mapping (m))
-        continue;
-      if (m->external_addr.as_u32 == addr.as_u32)
-        return 1;
+     if (is_sm_addr_only (m->flags) || is_sm_out2in_only (m->flags) ||
+        is_sm_identity_nat (m->flags))
+       continue;
+     if (m->external_addr.as_u32 == addr.as_u32)
+       return 1;
   }
-  /* *INDENT-ON* */
-
   return 0;
 }
 
-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, u8 *tag, int twice_nat,
-                                      int out2in_only, int identity_nat,
-                                      ip4_address_t pool_addr, int exact)
-{
-  snat_static_map_resolve_t *rp;
-
-  vec_add2 (sm->to_resolve, rp, 1);
-  rp->l_addr.as_u32 = l_addr.as_u32;
-  rp->l_port = l_port;
-  rp->sw_if_index = sw_if_index;
-  rp->e_port = e_port;
-  rp->vrf_id = vrf_id;
-  rp->proto = proto;
-  rp->addr_only = addr_only;
-  rp->twice_nat = twice_nat;
-  rp->out2in_only = out2in_only;
-  rp->identity_nat = identity_nat;
-  rp->tag = vec_dup (tag);
-  rp->pool_addr = pool_addr;
-  rp->exact = exact;
-}
-
 u32
 get_thread_idx_by_port (u16 e_port)
 {
@@ -460,7 +419,6 @@ nat_ed_static_mapping_del_sessions (snat_main_t * sm,
 {
   snat_session_t *s;
   u32 *indexes_to_free = NULL;
-  /* *INDENT-OFF* */
   pool_foreach (s, tsm->sessions) {
     if (s->in2out.fib_index != fib_index ||
         s->in2out.addr.as_u32 != l_addr.as_u32)
@@ -485,7 +443,6 @@ nat_ed_static_mapping_del_sessions (snat_main_t * sm,
     if (!addr_only)
       break;
   }
-  /* *INDENT-ON* */
   u32 *ses_index;
   vec_foreach (ses_index, indexes_to_free)
   {
@@ -496,619 +453,814 @@ nat_ed_static_mapping_del_sessions (snat_main_t * sm,
 }
 
 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)
+nat44_ed_reserve_port (ip4_address_t addr, u16 port, nat_protocol_t proto)
 {
+  u32 ti = get_thread_idx_by_port (port);
   snat_main_t *sm = &snat_main;
-  snat_static_mapping_t *m;
-  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_static_map_resolve_t *rp, *rp_match = 0;
-  nat44_lb_addr_port_t *local;
-  u32 find = ~0;
   int i;
 
-  /* If the external address is a specific interface address */
-  if (sw_if_index != ~0)
+  for (i = 0; i < vec_len (sm->addresses); i++)
     {
-      ip4_address_t *first_int_addr;
+      a = sm->addresses + i;
 
-      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;
-           }
+      if (a->addr.as_u32 != addr.as_u32)
+       continue;
 
-         rp_match = rp;
-         break;
+      switch (proto)
+       {
+#define _(N, j, n, s)                                                         \
+  case NAT_PROTOCOL_##N:                                                      \
+    if (a->busy_##n##_port_refcounts[port])                                   \
+      goto done;                                                              \
+    ++a->busy_##n##_port_refcounts[port];                                     \
+    if (port > 1024)                                                          \
+      {                                                                       \
+       a->busy_##n##_ports++;                                                \
+       a->busy_##n##_ports_per_thread[ti]++;                                 \
+      }                                                                       \
+    break;
+         foreach_nat_protocol
+#undef _
+           default : nat_elog_info (sm, "unknown protocol");
+         goto done;
        }
 
-      /* Might be already set... */
-      first_int_addr = ip4_interface_first_address
-       (sm->ip4_main, sw_if_index, 0 /* just want the address */ );
+      return 0;
+    }
 
-      if (is_add)
-       {
-         if (rp_match)
-           return VNET_API_ERROR_VALUE_EXIST;
+done:
+  return 1;
+}
 
-         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);
+int
+nat44_ed_free_port (ip4_address_t addr, u16 port, nat_protocol_t proto)
+{
+  u32 ti = get_thread_idx_by_port (port);
+  snat_main_t *sm = &snat_main;
+  snat_address_t *a = 0;
+  int i;
 
-         /* DHCP resolution required? */
-         if (first_int_addr == 0)
-           {
-             return 0;
-           }
-         else
-           {
-             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;
+  for (i = 0; i < vec_len (sm->addresses); i++)
+    {
+      a = sm->addresses + i;
 
-         vec_del1 (sm->to_resolve, i);
+      if (a->addr.as_u32 != addr.as_u32)
+       continue;
 
-         if (first_int_addr)
-           {
-             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
-           return 0;
+      switch (proto)
+       {
+#define _(N, j, n, s)                                                         \
+  case NAT_PROTOCOL_##N:                                                      \
+    --a->busy_##n##_port_refcounts[port];                                     \
+    if (port > 1024)                                                          \
+      {                                                                       \
+       a->busy_##n##_ports--;                                                \
+       a->busy_##n##_ports_per_thread[ti]--;                                 \
+      }                                                                       \
+    break;
+         foreach_nat_protocol
+#undef _
+           default : nat_elog_info (sm, "unknown protocol");
+         goto done;
        }
+
+      return 0;
     }
 
-  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 = 0;
-  else
-    m = pool_elt_at_index (sm->static_mappings, value.value);
+done:
+  return 1;
+}
 
-  if (is_add)
-    {
-      if (m)
-       {
-         if (is_identity_static_mapping (m))
-           {
-              /* *INDENT-OFF* */
-              pool_foreach (local, m->locals)
-               {
-                if (local->vrf_id == vrf_id)
-                  return VNET_API_ERROR_VALUE_EXIST;
-              }
-              /* *INDENT-ON* */
-             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, 0, m - sm->static_mappings);
-             clib_bihash_add_del_8_8 (&sm->static_mapping_by_local, &kv, 1);
-             return 0;
-           }
-         else
-           return VNET_API_ERROR_VALUE_EXIST;
-       }
+void
+nat44_ed_add_resolve_record (ip4_address_t l_addr, u16 l_port, u16 e_port,
+                            nat_protocol_t proto, u32 vrf_id, u32 sw_if_index,
+                            u32 flags, ip4_address_t pool_addr, u8 *tag)
+{
+  snat_static_map_resolve_t *rp;
+  snat_main_t *sm = &snat_main;
 
-      if (twice_nat && addr_only)
-       return VNET_API_ERROR_UNSUPPORTED;
+  vec_add2 (sm->to_resolve, rp, 1);
+  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->flags = flags;
+  rp->pool_addr = pool_addr;
+  rp->tag = vec_dup (tag);
+}
 
-      /* 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 SNAT plugin startup 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);
-       }
+int
+nat44_ed_get_resolve_record (ip4_address_t l_addr, u16 l_port, u16 e_port,
+                            nat_protocol_t proto, u32 vrf_id, u32 sw_if_index,
+                            u32 flags, int *out)
+{
+  snat_static_map_resolve_t *rp;
+  snat_main_t *sm = &snat_main;
+  int i;
 
-      if (!(out2in_only || 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;
-       }
+  for (i = 0; i < vec_len (sm->to_resolve); i++)
+    {
+      rp = sm->to_resolve + i;
 
-      /* 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 || out2in_only))
+      if (rp->sw_if_index == sw_if_index && rp->vrf_id == vrf_id)
        {
-         for (i = 0; i < vec_len (sm->addresses); i++)
+         if (is_sm_identity_nat (rp->flags) && is_sm_identity_nat (flags))
            {
-             if (sm->addresses[i].addr.as_u32 == e_addr.as_u32)
+             if (!(is_sm_addr_only (rp->flags) && is_sm_addr_only (flags)))
                {
-                 a = sm->addresses + i;
-                 /* External port must be unused */
-                 switch (proto)
+                 if (rp->e_port != e_port || rp->proto != 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 (sm, "unknown protocol");
-                     return VNET_API_ERROR_INVALID_VALUE_2;
+                     continue;
                    }
-                 break;
                }
            }
-         /* External address must be allocated */
-         if (!a && (l_addr.as_u32 != e_addr.as_u32))
+         else if (rp->l_addr.as_u32 == l_addr.as_u32)
            {
-             if (sw_if_index != ~0)
+             if (!(is_sm_addr_only (rp->flags) && is_sm_addr_only (flags)))
                {
-                 for (i = 0; i < vec_len (sm->to_resolve); i++)
+                 if (rp->l_port != l_port || rp->e_port != e_port ||
+                     rp->proto != proto)
                    {
-                     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;
+                     continue;
                    }
                }
-             return VNET_API_ERROR_NO_SUCH_ENTRY;
            }
+         else
+           {
+             continue;
+           }
+         if (out)
+           {
+             *out = i;
+           }
+         return 0;
        }
+    }
+  return 1;
+}
 
-      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;
-      m->twice_nat = twice_nat;
+int
+nat44_ed_del_resolve_record (ip4_address_t l_addr, u16 l_port, u16 e_port,
+                            nat_protocol_t proto, u32 vrf_id, u32 sw_if_index,
+                            u32 flags)
+{
+  snat_main_t *sm = &snat_main;
+  int i;
+  if (!nat44_ed_get_resolve_record (l_addr, l_port, e_port, proto, vrf_id,
+                                   sw_if_index, flags, &i))
+    {
+      vec_del1 (sm->to_resolve, i);
+      return 0;
+    }
+  return 1;
+}
 
-      if (twice_nat == TWICE_NAT && exact)
-       {
-         m->flags |= NAT_STATIC_MAPPING_FLAG_EXACT_ADDRESS;
-         m->pool_addr = pool_addr;
-       }
+static_always_inline int
+nat44_ed_validate_sm_input (u32 flags)
+{
+  // identity nat can be initiated only from inside interface
+  if (is_sm_identity_nat (flags) && is_sm_out2in_only (flags))
+    {
+      return VNET_API_ERROR_UNSUPPORTED;
+    }
 
-      if (out2in_only)
-       m->flags |= NAT_STATIC_MAPPING_FLAG_OUT2IN_ONLY;
-      if (addr_only)
-       m->flags |= NAT_STATIC_MAPPING_FLAG_ADDR_ONLY;
-      if (identity_nat)
+  if (is_sm_twice_nat (flags) || is_sm_self_twice_nat (flags))
+    {
+      if (is_sm_addr_only (flags) || is_sm_identity_nat (flags))
        {
-         m->flags |= NAT_STATIC_MAPPING_FLAG_IDENTITY_NAT;
-         pool_get (m->locals, local);
-         local->vrf_id = vrf_id;
-         local->fib_index = fib_index;
+         return VNET_API_ERROR_UNSUPPORTED;
        }
-      else
+    }
+  return 0;
+}
+
+int
+nat44_ed_add_static_mapping (ip4_address_t l_addr, ip4_address_t e_addr,
+                            u16 l_port, u16 e_port, nat_protocol_t proto,
+                            u32 vrf_id, u32 sw_if_index, u32 flags,
+                            ip4_address_t pool_addr, u8 *tag)
+{
+  snat_main_t *sm = &snat_main;
+  clib_bihash_kv_8_8_t kv, value;
+  snat_interface_t *interface;
+  nat44_lb_addr_port_t *local;
+  snat_static_mapping_t *m;
+  u32 fib_index = ~0;
+  int rv;
+
+  rv = nat44_ed_validate_sm_input (flags);
+  if (rv != 0)
+    {
+      return rv;
+    }
+
+  if (is_sm_addr_only (flags))
+    {
+      e_port = l_port = proto = 0;
+    }
+
+  if (is_sm_switch_address (flags))
+    {
+      // this mapping is interface bound
+      ip4_address_t *first_int_addr;
+
+      // check if this record isn't registered for resolve
+      if (!nat44_ed_get_resolve_record (l_addr, l_port, e_port, proto, vrf_id,
+                                       sw_if_index, flags, 0))
        {
-         m->vrf_id = vrf_id;
-         m->fib_index = fib_index;
+         return VNET_API_ERROR_VALUE_EXIST;
        }
-      if (!addr_only)
+      // register record for resolve
+      nat44_ed_add_resolve_record (l_addr, l_port, e_port, proto, vrf_id,
+                                  sw_if_index, flags, pool_addr, tag);
+
+      first_int_addr =
+       ip4_interface_first_address (sm->ip4_main, sw_if_index, 0);
+      if (!first_int_addr)
        {
-         m->local_port = l_port;
-         m->external_port = e_port;
-         m->proto = proto;
+         // dhcp resolution required
+         return 0;
        }
 
-      if (sm->num_workers > 1)
+      e_addr.as_u32 = first_int_addr->as_u32;
+    }
+
+  if (is_sm_identity_nat (flags))
+    {
+      l_port = e_port;
+      l_addr.as_u32 = e_addr.as_u32;
+    }
+
+  // fib index 0
+  init_nat_k (&kv, e_addr, e_port, 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_sm_identity_nat (m->flags))
        {
-         ip4_header_t ip = {
-           .src_address = m->local_addr,
-         };
-         vec_add1 (m->workers,
-                   sm->worker_in2out_cb (0, &ip, m->fib_index, 0));
-         tsm = vec_elt_at_index (sm->per_thread_data, m->workers[0]);
+         return VNET_API_ERROR_VALUE_EXIST;
        }
-      else
-       tsm = vec_elt_at_index (sm->per_thread_data, sm->num_workers);
 
-      if (!out2in_only)
+      // case:
+      // adding local identity nat record for different vrf table
+      pool_foreach (local, m->locals)
        {
-         init_nat_kv (&kv, m->local_addr, m->local_port, fib_index, m->proto,
-                      0, m - sm->static_mappings);
-         clib_bihash_add_del_8_8 (&sm->static_mapping_by_local, &kv, 1);
+         if (local->vrf_id == vrf_id)
+           {
+             return VNET_API_ERROR_VALUE_EXIST;
+           }
        }
 
-      init_nat_kv (&kv, m->external_addr, m->external_port, 0, m->proto, 0,
-                  m - sm->static_mappings);
-      clib_bihash_add_del_8_8 (&sm->static_mapping_by_external, &kv, 1);
+      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, 0, m - sm->static_mappings);
+      clib_bihash_add_del_8_8 (&sm->static_mapping_by_local, &kv, 1);
+
+      return 0;
+    }
+
+  if (vrf_id != ~0)
+    {
+      fib_index = fib_table_find_or_create_and_lock (FIB_PROTOCOL_IP4, vrf_id,
+                                                    sm->fib_src_low);
     }
   else
     {
-      if (!m)
-       {
-         if (sw_if_index != ~0)
-           return 0;
-         else
-           return VNET_API_ERROR_NO_SUCH_ENTRY;
-       }
+      // fallback to default vrf
+      vrf_id = sm->inside_vrf_id;
+      fib_index = sm->inside_fib_index;
+      fib_table_lock (fib_index, FIB_PROTOCOL_IP4, sm->fib_src_low);
+    }
 
-      if (identity_nat)
+  // test if local mapping record doesn't exist
+  // identity nat supports multiple records in local mapping
+  if (!(is_sm_out2in_only (flags) || is_sm_identity_nat (flags)))
+    {
+      init_nat_k (&kv, l_addr, l_port, fib_index, proto);
+      if (!clib_bihash_search_8_8 (&sm->static_mapping_by_local, &kv, &value))
        {
-         if (vrf_id == ~0)
-           vrf_id = sm->inside_vrf_id;
-
-          /* *INDENT-OFF* */
-          pool_foreach (local, m->locals)
-           {
-           if (local->vrf_id == vrf_id)
-              find = local - m->locals;
-         }
-          /* *INDENT-ON* */
-         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);
+         return VNET_API_ERROR_VALUE_EXIST;
        }
-      else
-       fib_index = m->fib_index;
+    }
 
-      /* Free external address port */
-      if (!(addr_only || sm->static_mapping_only || out2in_only))
+  if (!(is_sm_out2in_only (flags) || is_sm_addr_only (flags) ||
+       sm->static_mapping_only))
+    {
+      if (nat44_ed_reserve_port (e_addr, e_port, proto))
        {
-         for (i = 0; i < vec_len (sm->addresses); i++)
+         // remove resolve record
+         if (is_sm_switch_address (flags) && !is_sm_identity_nat (flags))
            {
-             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 : nat_elog_info (sm, "unknown protocol");
-                     return VNET_API_ERROR_INVALID_VALUE_2;
-                   }
-                 break;
-               }
+             nat44_ed_del_resolve_record (l_addr, l_port, e_port, proto,
+                                          vrf_id, sw_if_index, flags);
            }
+         return VNET_API_ERROR_NO_SUCH_ENTRY;
        }
+    }
 
-      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);
+  pool_get (sm->static_mappings, m);
+  clib_memset (m, 0, sizeof (*m));
 
-      init_nat_k (&kv, m->local_addr, m->local_port, fib_index, m->proto);
-      if (!out2in_only)
-       clib_bihash_add_del_8_8 (&sm->static_mapping_by_local, &kv, 0);
+  m->flags = flags;
+  m->local_addr = l_addr;
+  m->external_addr = e_addr;
 
-      /* Delete session(s) for static mapping if exist */
-      if (!(sm->static_mapping_only) ||
-         (sm->static_mapping_only && sm->static_mapping_connection_tracking))
-       {
-         nat_ed_static_mapping_del_sessions (
-           sm, tsm, m->local_addr, m->local_port, m->proto, fib_index,
-           addr_only, e_addr, e_port);
-       }
+  m->tag = vec_dup (tag);
+
+  if (is_sm_exact_address (flags) && is_sm_twice_nat (flags))
+    {
+      m->pool_addr = pool_addr;
+    }
+
+  if (!is_sm_addr_only (flags))
+    {
+      m->local_port = l_port;
+      m->external_port = e_port;
+      m->proto = proto;
+    }
+
+  if (is_sm_identity_nat (flags))
+    {
+      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;
+    }
 
-      fib_table_unlock (fib_index, FIB_PROTOCOL_IP4, sm->fib_src_low);
-      if (pool_elts (m->locals))
-       return 0;
+  if (!is_sm_out2in_only (flags))
+    {
+      init_nat_kv (&kv, m->local_addr, m->local_port, fib_index, m->proto, 0,
+                  m - sm->static_mappings);
+      clib_bihash_add_del_8_8 (&sm->static_mapping_by_local, &kv, 1);
+    }
 
-      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);
+  init_nat_kv (&kv, m->external_addr, m->external_port, 0, m->proto, 0,
+              m - sm->static_mappings);
+  clib_bihash_add_del_8_8 (&sm->static_mapping_by_external, &kv, 1);
 
-      vec_free (m->tag);
-      vec_free (m->workers);
-      /* Delete static mapping from pool */
-      pool_put (sm->static_mappings, m);
+  if (sm->num_workers > 1)
+    {
+      // store worker index for this record
+      ip4_header_t ip = {
+       .src_address = m->local_addr,
+      };
+      u32 worker_index;
+      worker_index =
+       nat44_ed_get_in2out_worker_index (0, &ip, m->fib_index, 0);
+      vec_add1 (m->workers, worker_index);
     }
 
-  if (!addr_only || (l_addr.as_u32 == e_addr.as_u32))
+  if (is_sm_identity_nat (flags) || !is_sm_addr_only (flags))
     return 0;
 
-  /* Add/delete external address to FIB */
-  /* *INDENT-OFF* */
   pool_foreach (interface, sm->interfaces)
-   {
-     if (nat_interface_is_inside (interface))
-       continue;
+    {
+      if (nat_interface_is_inside (interface))
+       continue;
+
+      snat_add_del_addr_to_fib (&e_addr, 32, interface->sw_if_index, 1);
+      break;
+    }
 
-     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))
-       continue;
+    {
+      if (nat_interface_is_inside (interface))
+       continue;
 
-     snat_add_del_addr_to_fib (&e_addr, 32, interface->sw_if_index, is_add);
-     break;
-  }
-  /* *INDENT-ON* */
+      snat_add_del_addr_to_fib (&e_addr, 32, interface->sw_if_index, 1);
+      break;
+    }
+
+  return 0;
+}
+
+int
+nat44_ed_del_static_mapping (ip4_address_t l_addr, ip4_address_t e_addr,
+                            u16 l_port, u16 e_port, nat_protocol_t proto,
+                            u32 vrf_id, u32 sw_if_index, u32 flags)
+{
+  snat_main_per_thread_data_t *tsm;
+  snat_main_t *sm = &snat_main;
+
+  clib_bihash_kv_8_8_t kv, value;
+  snat_interface_t *interface;
+  nat44_lb_addr_port_t *local;
+  snat_static_mapping_t *m;
+  u32 fib_index = ~0;
+  int rv;
+
+  rv = nat44_ed_validate_sm_input (flags);
+  if (rv != 0)
+    {
+      return rv;
+    }
+
+  if (is_sm_addr_only (flags))
+    {
+      e_port = l_port = proto = 0;
+    }
+
+  if (is_sm_switch_address (flags))
+    {
+      // this mapping is interface bound
+      ip4_address_t *first_int_addr;
+
+      // delete record registered for resolve
+      if (nat44_ed_del_resolve_record (l_addr, l_port, e_port, proto, vrf_id,
+                                      sw_if_index, flags))
+       {
+         return VNET_API_ERROR_NO_SUCH_ENTRY;
+       }
+
+      first_int_addr =
+       ip4_interface_first_address (sm->ip4_main, sw_if_index, 0);
+      if (!first_int_addr)
+       {
+         // dhcp resolution required
+         return 0;
+       }
+
+      e_addr.as_u32 = first_int_addr->as_u32;
+    }
+
+  if (is_sm_identity_nat (flags))
+    {
+      l_port = e_port;
+      l_addr.as_u32 = e_addr.as_u32;
+    }
+
+  // fib index 0
+  init_nat_k (&kv, e_addr, e_port, 0, proto);
+
+  if (clib_bihash_search_8_8 (&sm->static_mapping_by_external, &kv, &value))
+    {
+      if (is_sm_switch_address (flags))
+       {
+         return 0;
+       }
+      return VNET_API_ERROR_NO_SUCH_ENTRY;
+    }
+
+  m = pool_elt_at_index (sm->static_mappings, value.value);
+
+  if (is_sm_identity_nat (flags))
+    {
+      u8 failure = 1;
+
+      if (!is_sm_switch_address (flags))
+       {
+         vrf_id = sm->inside_vrf_id;
+       }
+
+      pool_foreach (local, m->locals)
+       {
+         if (local->vrf_id == vrf_id)
+           {
+             local = pool_elt_at_index (m->locals, local - m->locals);
+             fib_index = local->fib_index;
+             pool_put (m->locals, local);
+             failure = 0;
+           }
+       }
+
+      if (failure)
+       {
+         return VNET_API_ERROR_NO_SUCH_ENTRY;
+       }
+    }
+  else
+    {
+      fib_index = m->fib_index;
+    }
+
+  if (!(is_sm_out2in_only (flags) || is_sm_addr_only (flags) ||
+       sm->static_mapping_only))
+    {
+      if (nat44_ed_free_port (e_addr, e_port, proto))
+       {
+         return VNET_API_ERROR_INVALID_VALUE;
+       }
+    }
+
+  if (!is_sm_out2in_only (flags))
+    {
+      init_nat_k (&kv, l_addr, l_port, fib_index, proto);
+      clib_bihash_add_del_8_8 (&sm->static_mapping_by_local, &kv, 0);
+    }
+
+  if (!sm->static_mapping_only || sm->static_mapping_connection_tracking)
+    {
+      // delete sessions for static mapping
+      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);
+
+      nat_ed_static_mapping_del_sessions (
+       sm, tsm, m->local_addr, m->local_port, m->proto, fib_index,
+       is_sm_addr_only (flags), e_addr, e_port);
+    }
+
+  fib_table_unlock (fib_index, FIB_PROTOCOL_IP4, sm->fib_src_low);
+
+  if (pool_elts (m->locals))
+    return 0;
+
+  // fib_index 0
+  init_nat_k (&kv, e_addr, e_port, 0, proto);
+  clib_bihash_add_del_8_8 (&sm->static_mapping_by_external, &kv, 0);
+
+  vec_free (m->tag);
+  vec_free (m->workers);
+  pool_put (sm->static_mappings, m);
+
+  if (is_sm_identity_nat (flags) || !is_sm_addr_only (flags))
+    return 0;
+
+  pool_foreach (interface, sm->interfaces)
+    {
+      if (nat_interface_is_inside (interface))
+       continue;
+
+      snat_add_del_addr_to_fib (&e_addr, 32, interface->sw_if_index, 0);
+      break;
+    }
+
+  pool_foreach (interface, sm->output_feature_interfaces)
+    {
+      if (nat_interface_is_inside (interface))
+       continue;
+
+      snat_add_del_addr_to_fib (&e_addr, 32, interface->sw_if_index, 0);
+      break;
+    }
 
   return 0;
 }
 
 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,
-                                twice_nat_type_t twice_nat, u8 out2in_only,
-                                u8 * tag, u32 affinity)
+nat44_ed_add_lb_static_mapping (ip4_address_t e_addr, u16 e_port,
+                               nat_protocol_t proto,
+                               nat44_lb_addr_port_t *locals, u32 flags,
+                               u8 *tag, u32 affinity)
 {
   snat_main_t *sm = &snat_main;
   snat_static_mapping_t *m;
   clib_bihash_kv_8_8_t kv, value;
   snat_address_t *a = 0;
-  int i;
+
   nat44_lb_addr_port_t *local;
-  snat_main_per_thread_data_t *tsm;
-  snat_session_t *s;
   uword *bitmap = 0;
 
+  int i;
+
   init_nat_k (&kv, e_addr, e_port, 0, proto);
   if (clib_bihash_search_8_8 (&sm->static_mapping_by_external, &kv, &value))
     m = 0;
   else
     m = pool_elt_at_index (sm->static_mappings, value.value);
 
-  if (is_add)
-    {
-      if (m)
-       return VNET_API_ERROR_VALUE_EXIST;
+  if (m)
+    return VNET_API_ERROR_VALUE_EXIST;
 
-      if (vec_len (locals) < 2)
-       return VNET_API_ERROR_INVALID_VALUE;
+  if (vec_len (locals) < 2)
+    return VNET_API_ERROR_INVALID_VALUE;
 
-      /* Find external address in allocated addresses and reserve port for
-         address and port pair mapping when dynamic translations enabled */
-      if (!(sm->static_mapping_only || out2in_only))
+  /* Find external address in allocated addresses and reserve port for
+     address and port pair mapping when dynamic translations enabled */
+  if (!(sm->static_mapping_only || is_sm_out2in_only (flags)))
+    {
+      for (i = 0; i < vec_len (sm->addresses); i++)
        {
-         for (i = 0; i < vec_len (sm->addresses); i++)
+         if (sm->addresses[i].addr.as_u32 == e_addr.as_u32)
            {
-             if (sm->addresses[i].addr.as_u32 == e_addr.as_u32)
+             a = sm->addresses + i;
+             /* External port must be unused */
+             switch (proto)
                {
-                 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
+#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 (sm, "unknown protocol");
-                     return VNET_API_ERROR_INVALID_VALUE_2;
-                   }
-                 break;
+                   default : nat_elog_info (sm, "unknown protocol");
+                 return VNET_API_ERROR_INVALID_VALUE_2;
                }
+             break;
            }
-         /* External address must be allocated */
-         if (!a)
-           return VNET_API_ERROR_NO_SUCH_ENTRY;
        }
+      /* External address must be allocated */
+      if (!a)
+       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->external_addr = e_addr;
-      m->external_port = e_port;
-      m->proto = proto;
-      m->twice_nat = twice_nat;
-      m->flags |= NAT_STATIC_MAPPING_FLAG_LB;
-      if (out2in_only)
-       m->flags |= NAT_STATIC_MAPPING_FLAG_OUT2IN_ONLY;
-      m->affinity = affinity;
-
-      if (affinity)
-       m->affinity_per_service_list_head_index =
-         nat_affinity_get_per_service_list_head_index ();
-      else
-       m->affinity_per_service_list_head_index = ~0;
+  pool_get (sm->static_mappings, m);
+  clib_memset (m, 0, sizeof (*m));
+  m->tag = vec_dup (tag);
+  m->external_addr = e_addr;
+  m->external_port = e_port;
+  m->affinity = affinity;
+  m->proto = proto;
 
-      init_nat_kv (&kv, m->external_addr, m->external_port, 0, m->proto, 0,
-                  m - sm->static_mappings);
-      if (clib_bihash_add_del_8_8 (&sm->static_mapping_by_external, &kv, 1))
+  m->flags = flags;
+  m->flags |= NAT_SM_FLAG_LB;
+
+  if (affinity)
+    m->affinity_per_service_list_head_index =
+      nat_affinity_get_per_service_list_head_index ();
+  else
+    m->affinity_per_service_list_head_index = ~0;
+
+  init_nat_kv (&kv, m->external_addr, m->external_port, 0, m->proto, 0,
+              m - sm->static_mappings);
+  if (clib_bihash_add_del_8_8 (&sm->static_mapping_by_external, &kv, 1))
+    {
+      nat_elog_err (sm, "static_mapping_by_external key add failed");
+      return VNET_API_ERROR_UNSPECIFIED;
+    }
+
+  for (i = 0; i < vec_len (locals); i++)
+    {
+      locals[i].fib_index = fib_table_find_or_create_and_lock (
+       FIB_PROTOCOL_IP4, locals[i].vrf_id, sm->fib_src_low);
+      if (!is_sm_out2in_only (flags))
        {
-         nat_elog_err (sm, "static_mapping_by_external key add failed");
-         return VNET_API_ERROR_UNSPECIFIED;
+         init_nat_kv (&kv, locals[i].addr, locals[i].port,
+                      locals[i].fib_index, m->proto, 0,
+                      m - sm->static_mappings);
+         clib_bihash_add_del_8_8 (&sm->static_mapping_by_local, &kv, 1);
        }
-
-      for (i = 0; i < vec_len (locals); i++)
+      locals[i].prefix = (i == 0) ?
+                          locals[i].probability :
+                          (locals[i - 1].prefix + locals[i].probability);
+      pool_get (m->locals, local);
+      *local = locals[i];
+      if (sm->num_workers > 1)
        {
-         locals[i].fib_index =
-           fib_table_find_or_create_and_lock (FIB_PROTOCOL_IP4,
-                                              locals[i].vrf_id,
-                                              sm->fib_src_low);
-         if (!out2in_only)
-           {
-             init_nat_kv (&kv, locals[i].addr, locals[i].port,
-                          locals[i].fib_index, m->proto, 0,
-                          m - sm->static_mappings);
-             clib_bihash_add_del_8_8 (&sm->static_mapping_by_local, &kv, 1);
-           }
-         locals[i].prefix = (i == 0) ? locals[i].probability :
-           (locals[i - 1].prefix + locals[i].probability);
-         pool_get (m->locals, local);
-         *local = locals[i];
-         if (sm->num_workers > 1)
-           {
-             ip4_header_t ip = {
-               .src_address = locals[i].addr,
-             };
-             bitmap = clib_bitmap_set (
-               bitmap, sm->worker_in2out_cb (0, &ip, m->fib_index, 0), 1);
-           }
+         ip4_header_t ip = {
+           .src_address = locals[i].addr,
+         };
+         bitmap = clib_bitmap_set (
+           bitmap, nat44_ed_get_in2out_worker_index (0, &ip, m->fib_index, 0),
+           1);
        }
+    }
 
-      /* Assign workers */
-      if (sm->num_workers > 1)
+  /* Assign workers */
+  if (sm->num_workers > 1)
+    {
+      clib_bitmap_foreach (i, bitmap)
        {
-          /* *INDENT-OFF* */
-          clib_bitmap_foreach (i, bitmap)
-             {
-               vec_add1(m->workers, i);
-            }
-          /* *INDENT-ON* */
+         vec_add1 (m->workers, i);
        }
     }
+
+  return 0;
+}
+
+int
+nat44_ed_del_lb_static_mapping (ip4_address_t e_addr, u16 e_port,
+                               nat_protocol_t proto, u32 flags)
+{
+  snat_main_t *sm = &snat_main;
+  snat_static_mapping_t *m;
+  clib_bihash_kv_8_8_t kv, value;
+  snat_address_t *a = 0;
+
+  nat44_lb_addr_port_t *local;
+  snat_main_per_thread_data_t *tsm;
+  snat_session_t *s;
+  int i;
+
+  init_nat_k (&kv, e_addr, e_port, 0, proto);
+  if (clib_bihash_search_8_8 (&sm->static_mapping_by_external, &kv, &value))
+    m = 0;
   else
-    {
-      if (!m)
-       return VNET_API_ERROR_NO_SUCH_ENTRY;
+    m = pool_elt_at_index (sm->static_mappings, value.value);
+
+  if (!m)
+    return VNET_API_ERROR_NO_SUCH_ENTRY;
 
-      if (!is_lb_static_mapping (m))
-       return VNET_API_ERROR_INVALID_VALUE;
+  if (!is_sm_lb (m->flags))
+    return VNET_API_ERROR_INVALID_VALUE;
 
-      /* Free external address port */
-      if (!(sm->static_mapping_only || out2in_only))
+  /* Free external address port */
+  if (!(sm->static_mapping_only || is_sm_out2in_only (flags)))
+    {
+      for (i = 0; i < vec_len (sm->addresses); i++)
        {
-         for (i = 0; i < vec_len (sm->addresses); i++)
+         if (sm->addresses[i].addr.as_u32 == e_addr.as_u32)
            {
-             if (sm->addresses[i].addr.as_u32 == e_addr.as_u32)
+             a = sm->addresses + i;
+             switch (proto)
                {
-                 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
+#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 : nat_elog_info (sm, "unknown protocol");
-                     return VNET_API_ERROR_INVALID_VALUE_2;
-                   }
-                 break;
+                   default : nat_elog_info (sm, "unknown protocol");
+                 return VNET_API_ERROR_INVALID_VALUE_2;
                }
+             break;
            }
        }
+    }
 
-      init_nat_k (&kv, m->external_addr, m->external_port, 0, m->proto);
-      if (clib_bihash_add_del_8_8 (&sm->static_mapping_by_external, &kv, 0))
-       {
-         nat_elog_err (sm, "static_mapping_by_external key del failed");
-         return VNET_API_ERROR_UNSPECIFIED;
-       }
-
-      /* *INDENT-OFF* */
-      pool_foreach (local, m->locals)
-      {
-          fib_table_unlock (local->fib_index, FIB_PROTOCOL_IP4,
-                            sm->fib_src_low);
-          if (!out2in_only)
-            {
-             init_nat_k (&kv, local->addr, local->port, local->fib_index,
-                         m->proto);
-             if (clib_bihash_add_del_8_8 (&sm->static_mapping_by_local, &kv,
-                                          0))
-               {
-                 nat_elog_err (sm, "static_mapping_by_local key del failed");
-                 return VNET_API_ERROR_UNSPECIFIED;
-               }
-           }
+  init_nat_k (&kv, m->external_addr, m->external_port, 0, m->proto);
+  if (clib_bihash_add_del_8_8 (&sm->static_mapping_by_external, &kv, 0))
+    {
+      nat_elog_err (sm, "static_mapping_by_external key del failed");
+      return VNET_API_ERROR_UNSPECIFIED;
+    }
 
-         if (sm->num_workers > 1)
+  pool_foreach (local, m->locals)
+    {
+      fib_table_unlock (local->fib_index, FIB_PROTOCOL_IP4, sm->fib_src_low);
+      if (!is_sm_out2in_only (flags))
+       {
+         init_nat_k (&kv, local->addr, local->port, local->fib_index,
+                     m->proto);
+         if (clib_bihash_add_del_8_8 (&sm->static_mapping_by_local, &kv, 0))
            {
-             ip4_header_t ip = {
-               .src_address = local->addr,
-             };
-             tsm = vec_elt_at_index (
-               sm->per_thread_data,
-               sm->worker_in2out_cb (0, &ip, m->fib_index, 0));
+             nat_elog_err (sm, "static_mapping_by_local key del failed");
+             return VNET_API_ERROR_UNSPECIFIED;
            }
-         else
-           tsm = vec_elt_at_index (sm->per_thread_data, sm->num_workers);
+       }
 
-         /* Delete sessions */
-         pool_foreach (s, tsm->sessions)
-           {
-             if (!(is_lb_session (s)))
-               continue;
+      if (sm->num_workers > 1)
+       {
+         ip4_header_t ip = {
+           .src_address = local->addr,
+         };
+         tsm = vec_elt_at_index (
+           sm->per_thread_data,
+           nat44_ed_get_in2out_worker_index (0, &ip, m->fib_index, 0));
+       }
+      else
+       tsm = vec_elt_at_index (sm->per_thread_data, sm->num_workers);
 
-             if ((s->in2out.addr.as_u32 != local->addr.as_u32) ||
-                 s->in2out.port != local->port)
-               continue;
+      /* Delete sessions */
+      pool_foreach (s, tsm->sessions)
+       {
+         if (!(is_lb_session (s)))
+           continue;
 
-             nat_free_session_data (sm, s, tsm - sm->per_thread_data, 0);
-             nat_ed_session_delete (sm, s, tsm - sm->per_thread_data, 1);
-           }
-      }
-      /* *INDENT-ON* */
-      if (m->affinity)
-       nat_affinity_flush_service (m->affinity_per_service_list_head_index);
-      pool_free (m->locals);
-      vec_free (m->tag);
-      vec_free (m->workers);
+         if ((s->in2out.addr.as_u32 != local->addr.as_u32) ||
+             s->in2out.port != local->port)
+           continue;
 
-      pool_put (sm->static_mappings, m);
+         nat_free_session_data (sm, s, tsm - sm->per_thread_data, 0);
+         nat_ed_session_delete (sm, s, tsm - sm->per_thread_data, 1);
+       }
     }
 
+  if (m->affinity)
+    {
+      nat_affinity_flush_service (m->affinity_per_service_list_head_index);
+    }
+
+  pool_free (m->locals);
+  vec_free (m->tag);
+  vec_free (m->workers);
+  pool_put (sm->static_mappings, m);
+
   return 0;
 }
 
 int
-nat44_lb_static_mapping_add_del_local (ip4_address_t e_addr, u16 e_port,
-                                      ip4_address_t l_addr, u16 l_port,
-                                      nat_protocol_t proto, u32 vrf_id,
-                                      u8 probability, u8 is_add)
+nat44_ed_add_del_lb_static_mapping_local (ip4_address_t e_addr, u16 e_port,
+                                         ip4_address_t l_addr, u16 l_port,
+                                         nat_protocol_t proto, u32 vrf_id,
+                                         u8 probability, u8 is_add)
 {
   snat_main_t *sm = &snat_main;
   snat_static_mapping_t *m = 0;
@@ -1127,10 +1279,9 @@ nat44_lb_static_mapping_add_del_local (ip4_address_t e_addr, u16 e_port,
   if (!m)
     return VNET_API_ERROR_NO_SUCH_ENTRY;
 
-  if (!is_lb_static_mapping (m))
+  if (!is_sm_lb (m->flags))
     return VNET_API_ERROR_INVALID_VALUE;
 
-  /* *INDENT-OFF* */
   pool_foreach (local, m->locals)
    {
     if ((local->addr.as_u32 == l_addr.as_u32) && (local->port == l_port) &&
@@ -1140,7 +1291,6 @@ nat44_lb_static_mapping_add_del_local (ip4_address_t e_addr, u16 e_port,
         break;
       }
   }
-  /* *INDENT-ON* */
 
   if (is_add)
     {
@@ -1157,7 +1307,7 @@ nat44_lb_static_mapping_add_del_local (ip4_address_t e_addr, u16 e_port,
        fib_table_find_or_create_and_lock (FIB_PROTOCOL_IP4, vrf_id,
                                           sm->fib_src_low);
 
-      if (!is_out2in_only_static_mapping (m))
+      if (!is_sm_out2in_only (m->flags))
        {
          init_nat_kv (&kv, l_addr, l_port, local->fib_index, proto, 0,
                       m - sm->static_mappings);
@@ -1176,7 +1326,7 @@ nat44_lb_static_mapping_add_del_local (ip4_address_t e_addr, u16 e_port,
       fib_table_unlock (match_local->fib_index, FIB_PROTOCOL_IP4,
                        sm->fib_src_low);
 
-      if (!is_out2in_only_static_mapping (m))
+      if (!is_sm_out2in_only (m->flags))
        {
          init_nat_k (&kv, l_addr, l_port, match_local->fib_index, proto);
          if (clib_bihash_add_del_8_8 (&sm->static_mapping_by_local, &kv, 0))
@@ -1188,15 +1338,14 @@ nat44_lb_static_mapping_add_del_local (ip4_address_t e_addr, u16 e_port,
          ip4_header_t ip = {
            .src_address = local->addr,
          };
-         tsm =
-           vec_elt_at_index (sm->per_thread_data,
-                             sm->worker_in2out_cb (0, &ip, m->fib_index, 0));
+         tsm = vec_elt_at_index (
+           sm->per_thread_data,
+           nat44_ed_get_in2out_worker_index (0, &ip, m->fib_index, 0));
        }
       else
        tsm = vec_elt_at_index (sm->per_thread_data, sm->num_workers);
 
       /* Delete sessions */
-      /* *INDENT-OFF* */
       pool_foreach (s, tsm->sessions) {
         if (!(is_lb_session (s)))
           continue;
@@ -1208,14 +1357,12 @@ nat44_lb_static_mapping_add_del_local (ip4_address_t e_addr, u16 e_port,
         nat_free_session_data (sm, s, tsm - sm->per_thread_data, 0);
         nat_ed_session_delete (sm, s, tsm - sm->per_thread_data, 1);
       }
-      /* *INDENT-ON* */
 
       pool_put (m->locals, match_local);
     }
 
   vec_free (m->workers);
 
-  /* *INDENT-OFF* */
   pool_foreach (local, m->locals)
    {
     vec_add1 (locals, local - m->locals);
@@ -1224,10 +1371,10 @@ nat44_lb_static_mapping_add_del_local (ip4_address_t e_addr, u16 e_port,
         ip4_header_t ip;
        ip.src_address.as_u32 = local->addr.as_u32,
        bitmap = clib_bitmap_set (
-         bitmap, sm->worker_in2out_cb (0, &ip, local->fib_index, 0), 1);
+         bitmap,
+         nat44_ed_get_in2out_worker_index (0, &ip, local->fib_index, 0), 1);
       }
   }
-  /* *INDENT-ON* */
 
   ASSERT (vec_len (locals) > 1);
 
@@ -1243,9 +1390,7 @@ nat44_lb_static_mapping_add_del_local (ip4_address_t e_addr, u16 e_port,
   /* Assign workers */
   if (sm->num_workers > 1)
     {
-      /* *INDENT-OFF* */
       clib_bitmap_foreach (i, bitmap)  { vec_add1(m->workers, i); }
-      /* *INDENT-ON* */
     }
 
   return 0;
@@ -1282,23 +1427,15 @@ snat_del_address (snat_main_t * sm, ip4_address_t addr, u8 delete_sm,
 
   if (delete_sm)
     {
-      ip4_address_t pool_addr = { 0 };
-      /* *INDENT-OFF* */
       pool_foreach (m, sm->static_mappings)
        {
           if (m->external_addr.as_u32 == addr.as_u32)
-            (void) snat_add_static_mapping (m->local_addr, m->external_addr,
-                                            m->local_port, m->external_port,
-                                            m->vrf_id,
-                                            is_addr_only_static_mapping(m), ~0,
-                                            m->proto, 0 /* is_add */,
-                                            m->twice_nat,
-                                            is_out2in_only_static_mapping(m),
-                                            m->tag,
-                                            is_identity_static_mapping(m),
-                                            pool_addr, 0);
+           {
+             nat44_ed_del_static_mapping (m->local_addr, m->external_addr,
+                                          m->local_port, m->external_port,
+                                          m->proto, m->vrf_id, ~0, m->flags);
+           }
       }
-      /* *INDENT-ON* */
     }
   else
     {
@@ -1376,7 +1513,6 @@ expire_per_vrf_sessions (u32 fib_index)
   snat_main_per_thread_data_t *tsm;
   snat_main_t *sm = &snat_main;
 
-  /* *INDENT-OFF* */
   vec_foreach (tsm, sm->per_thread_data)
     {
       vec_foreach (per_vrf_sessions, tsm->per_vrf_sessions_vec)
@@ -1388,7 +1524,6 @@ expire_per_vrf_sessions (u32 fib_index)
             }
         }
     }
-  /* *INDENT-ON* */
 }
 
 void
@@ -1428,17 +1563,46 @@ update_per_vrf_sessions_vec (u32 fib_index, int is_del)
     }
 }
 
+static_always_inline nat_outside_fib_t *
+nat44_ed_get_outside_fib (nat_outside_fib_t *outside_fibs, u32 fib_index)
+{
+  nat_outside_fib_t *f;
+  vec_foreach (f, outside_fibs)
+    {
+      if (f->fib_index == fib_index)
+       {
+         return f;
+       }
+    }
+  return 0;
+}
+
+static_always_inline snat_interface_t *
+nat44_ed_get_interface (snat_interface_t *interfaces, u32 sw_if_index)
+{
+  snat_interface_t *i;
+  pool_foreach (i, interfaces)
+    {
+      if (i->sw_if_index == sw_if_index)
+       {
+         return i;
+       }
+    }
+  return 0;
+}
+
 int
-snat_interface_add_del (u32 sw_if_index, u8 is_inside, int is_del)
+nat44_ed_add_interface (u32 sw_if_index, u8 is_inside)
 {
+  const char *del_feature_name, *feature_name;
   snat_main_t *sm = &snat_main;
+
+  nat_outside_fib_t *outside_fib;
+  snat_static_mapping_t *m;
   snat_interface_t *i;
-  const char *feature_name, *del_feature_name;
   snat_address_t *ap;
-  snat_static_mapping_t *m;
-  nat_outside_fib_t *outside_fib;
-  u32 fib_index = fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP4,
-                                                      sw_if_index);
+  u32 fib_index;
+  int rv;
 
   if (!sm->enabled)
     {
@@ -1446,205 +1610,350 @@ snat_interface_add_del (u32 sw_if_index, u8 is_inside, int is_del)
       return VNET_API_ERROR_UNSUPPORTED;
     }
 
-  /* *INDENT-OFF* */
-  pool_foreach (i, sm->output_feature_interfaces)
-   {
-    if (i->sw_if_index == sw_if_index)
-      {
-        nat_log_err ("error interface already configured");
-        return VNET_API_ERROR_VALUE_EXIST;
-      }
-  }
-  /* *INDENT-ON* */
+  if (nat44_ed_get_interface (sm->output_feature_interfaces, sw_if_index))
+    {
+      nat_log_err ("error interface already configured");
+      return VNET_API_ERROR_VALUE_EXIST;
+    }
 
-  if (sm->static_mapping_only && !(sm->static_mapping_connection_tracking))
-    feature_name = is_inside ? "nat44-in2out-fast" : "nat44-out2in-fast";
-  else
+  i = nat44_ed_get_interface (sm->interfaces, sw_if_index);
+  if (i)
     {
+      if ((nat_interface_is_inside (i) && is_inside) ||
+         (nat_interface_is_outside (i) && !is_inside))
+       {
+         return 0;
+       }
       if (sm->num_workers > 1)
-       feature_name =
-         is_inside ? "nat44-in2out-worker-handoff" :
-         "nat44-out2in-worker-handoff";
+       {
+         del_feature_name = !is_inside ? "nat44-in2out-worker-handoff" :
+                                         "nat44-out2in-worker-handoff";
+         feature_name = "nat44-handoff-classify";
+       }
       else
-       feature_name = is_inside ? "nat-pre-in2out" : "nat-pre-out2in";
+       {
+         del_feature_name = !is_inside ? "nat-pre-in2out" : "nat-pre-out2in";
+
+         feature_name = "nat44-ed-classify";
+       }
+
+      rv = ip4_sv_reass_enable_disable_with_refcnt (sw_if_index, 1);
+      if (rv)
+       return rv;
+      vnet_feature_enable_disable ("ip4-unicast", del_feature_name,
+                                  sw_if_index, 0, 0, 0);
+      vnet_feature_enable_disable ("ip4-unicast", feature_name, sw_if_index, 1,
+                                  0, 0);
     }
+  else
+    {
+      if (sm->num_workers > 1)
+       {
+         feature_name = is_inside ? "nat44-in2out-worker-handoff" :
+                                    "nat44-out2in-worker-handoff";
+       }
+      else
+       {
+         feature_name = is_inside ? "nat-pre-in2out" : "nat-pre-out2in";
+       }
 
-  ASSERT (sm->frame_queue_nelts > 0);
+      nat_validate_interface_counters (sm, sw_if_index);
+      rv = ip4_sv_reass_enable_disable_with_refcnt (sw_if_index, 1);
+      if (rv)
+       return rv;
+      vnet_feature_enable_disable ("ip4-unicast", feature_name, sw_if_index, 1,
+                                  0, 0);
 
-  if (sm->fq_in2out_index == ~0 && sm->num_workers > 1)
-    sm->fq_in2out_index = vlib_frame_queue_main_init (sm->in2out_node_index,
-                                                     sm->frame_queue_nelts);
+      pool_get (sm->interfaces, i);
+      i->sw_if_index = sw_if_index;
+      i->flags = 0;
+    }
 
-  if (sm->fq_out2in_index == ~0 && sm->num_workers > 1)
-    sm->fq_out2in_index = vlib_frame_queue_main_init (sm->out2in_node_index,
-                                                     sm->frame_queue_nelts);
+  fib_index =
+    fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP4, sw_if_index);
 
-  update_per_vrf_sessions_vec (fib_index, is_del);
+  update_per_vrf_sessions_vec (fib_index, 0 /*is_del*/);
 
   if (!is_inside)
     {
-      /* *INDENT-OFF* */
-      vec_foreach (outside_fib, sm->outside_fibs)
-        {
-          if (outside_fib->fib_index == fib_index)
-            {
-              if (is_del)
-                {
-                 outside_fib->refcount--;
-                  if (!outside_fib->refcount)
-                    vec_del1 (sm->outside_fibs, outside_fib - sm->outside_fibs);
-                }
-              else
-                outside_fib->refcount++;
-              goto feature_set;
-            }
-        }
-      /* *INDENT-ON* */
-      if (!is_del)
+      i->flags |= NAT_INTERFACE_FLAG_IS_OUTSIDE;
+
+      outside_fib = nat44_ed_get_outside_fib (sm->outside_fibs, fib_index);
+      if (outside_fib)
+       {
+         outside_fib->refcount++;
+       }
+      else
        {
          vec_add2 (sm->outside_fibs, outside_fib, 1);
-         outside_fib->refcount = 1;
          outside_fib->fib_index = fib_index;
+         outside_fib->refcount = 1;
        }
+
+      vec_foreach (ap, sm->addresses)
+       {
+         snat_add_del_addr_to_fib (&ap->addr, 32, sw_if_index, 1);
+       }
+      pool_foreach (m, sm->static_mappings)
+       {
+         if (!(is_sm_addr_only (m->flags)) ||
+             (m->local_addr.as_u32 == m->external_addr.as_u32))
+           {
+             continue;
+           }
+         snat_add_del_addr_to_fib (&m->external_addr, 32, sw_if_index, 1);
+       }
+    }
+  else
+    {
+      i->flags |= NAT_INTERFACE_FLAG_IS_INSIDE;
     }
 
-feature_set:
-  /* *INDENT-OFF* */
-  pool_foreach (i, sm->interfaces)
-   {
-    if (i->sw_if_index == sw_if_index)
-      {
-        if (is_del)
-          {
-            if (nat_interface_is_inside(i) && nat_interface_is_outside(i))
-              {
-                if (is_inside)
-                  i->flags &= ~NAT_INTERFACE_FLAG_IS_INSIDE;
-                else
-                  i->flags &= ~NAT_INTERFACE_FLAG_IS_OUTSIDE;
-
-                if (sm->num_workers > 1)
-                  {
-                    del_feature_name = "nat44-handoff-classify";
-                    feature_name = !is_inside ?  "nat44-in2out-worker-handoff" :
-                                                 "nat44-out2in-worker-handoff";
-                  }
-               else
-                 {
-                   del_feature_name = "nat44-ed-classify";
-                   feature_name =
-                     !is_inside ? "nat-pre-in2out" : "nat-pre-out2in";
-                 }
+  return 0;
+}
 
-               int rv = ip4_sv_reass_enable_disable_with_refcnt (sw_if_index, 0);
-               if (rv)
-                 return rv;
-                vnet_feature_enable_disable ("ip4-unicast", del_feature_name,
-                                             sw_if_index, 0, 0, 0);
-                vnet_feature_enable_disable ("ip4-unicast", feature_name,
-                                             sw_if_index, 1, 0, 0);
-             }
-           else
-             {
-               int rv = ip4_sv_reass_enable_disable_with_refcnt (sw_if_index, 0);
-               if (rv)
-                 return rv;
-                vnet_feature_enable_disable ("ip4-unicast", feature_name,
-                                             sw_if_index, 0, 0, 0);
-                pool_put (sm->interfaces, i);
-             }
-         }
-       else
-         {
-           if ((nat_interface_is_inside (i) && is_inside) ||
-               (nat_interface_is_outside (i) && !is_inside))
-             return 0;
+int
+nat44_ed_del_interface (u32 sw_if_index, u8 is_inside)
+{
+  const char *del_feature_name, *feature_name;
+  snat_main_t *sm = &snat_main;
 
-           if (sm->num_workers > 1)
-             {
-               del_feature_name = !is_inside ? "nat44-in2out-worker-handoff" :
-                                               "nat44-out2in-worker-handoff";
-               feature_name = "nat44-handoff-classify";
-             }
-           else
-             {
-               del_feature_name =
-                 !is_inside ? "nat-pre-in2out" : "nat-pre-out2in";
+  nat_outside_fib_t *outside_fib;
+  snat_static_mapping_t *m;
+  snat_interface_t *i;
+  snat_address_t *ap;
+  u32 fib_index;
+  int rv;
 
-               feature_name = "nat44-ed-classify";
-             }
+  if (!sm->enabled)
+    {
+      nat_log_err ("nat44 is disabled");
+      return VNET_API_ERROR_UNSUPPORTED;
+    }
 
-           int rv = ip4_sv_reass_enable_disable_with_refcnt (sw_if_index, 1);
-           if (rv)
-             return rv;
-            vnet_feature_enable_disable ("ip4-unicast", del_feature_name,
-                                         sw_if_index, 0, 0, 0);
-            vnet_feature_enable_disable ("ip4-unicast", feature_name,
-                                         sw_if_index, 1, 0, 0);
-           goto set_flags;
-         }
+  i = nat44_ed_get_interface (sm->interfaces, sw_if_index);
+  if (i == 0)
+    {
+      nat_log_err ("error interface couldn't be found");
+      return VNET_API_ERROR_NO_SUCH_ENTRY;
+    }
 
-       goto fib;
-      }
-  }
-  /* *INDENT-ON* */
+  if (nat_interface_is_inside (i) && nat_interface_is_outside (i))
+    {
+      if (sm->num_workers > 1)
+       {
+         del_feature_name = "nat44-handoff-classify";
+         feature_name = !is_inside ? "nat44-in2out-worker-handoff" :
+                                     "nat44-out2in-worker-handoff";
+       }
+      else
+       {
+         del_feature_name = "nat44-ed-classify";
+         feature_name = !is_inside ? "nat-pre-in2out" : "nat-pre-out2in";
+       }
+
+      rv = ip4_sv_reass_enable_disable_with_refcnt (sw_if_index, 0);
+      if (rv)
+       {
+         return rv;
+       }
+      vnet_feature_enable_disable ("ip4-unicast", del_feature_name,
+                                  sw_if_index, 0, 0, 0);
+      vnet_feature_enable_disable ("ip4-unicast", feature_name, sw_if_index, 1,
+                                  0, 0);
+
+      if (is_inside)
+       {
+         i->flags &= ~NAT_INTERFACE_FLAG_IS_INSIDE;
+       }
+      else
+       {
+         i->flags &= ~NAT_INTERFACE_FLAG_IS_OUTSIDE;
+       }
+    }
+  else
+    {
+      if (sm->num_workers > 1)
+       {
+         feature_name = is_inside ? "nat44-in2out-worker-handoff" :
+                                    "nat44-out2in-worker-handoff";
+       }
+      else
+       {
+         feature_name = is_inside ? "nat-pre-in2out" : "nat-pre-out2in";
+       }
+
+      rv = ip4_sv_reass_enable_disable_with_refcnt (sw_if_index, 0);
+      if (rv)
+       {
+         return rv;
+       }
+      vnet_feature_enable_disable ("ip4-unicast", feature_name, sw_if_index, 0,
+                                  0, 0);
+
+      // remove interface
+      pool_put (sm->interfaces, i);
+    }
+
+  fib_index =
+    fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP4, sw_if_index);
+
+  update_per_vrf_sessions_vec (fib_index, 1 /*is_del*/);
+
+  if (!is_inside)
+    {
+      outside_fib = nat44_ed_get_outside_fib (sm->outside_fibs, fib_index);
+      if (outside_fib)
+       {
+         outside_fib->refcount--;
+         if (!outside_fib->refcount)
+           {
+             vec_del1 (sm->outside_fibs, outside_fib - sm->outside_fibs);
+           }
+       }
+
+      vec_foreach (ap, sm->addresses)
+       {
+         snat_add_del_addr_to_fib (&ap->addr, 32, sw_if_index, 0);
+       }
+
+      pool_foreach (m, sm->static_mappings)
+       {
+         if (!(is_sm_addr_only (m->flags)) ||
+             (m->local_addr.as_u32 == m->external_addr.as_u32))
+           {
+             continue;
+           }
+         snat_add_del_addr_to_fib (&m->external_addr, 32, sw_if_index, 0);
+       }
+    }
+
+  return 0;
+}
+
+int
+nat44_ed_add_output_interface (u32 sw_if_index)
+{
+  snat_main_t *sm = &snat_main;
+
+  nat_outside_fib_t *outside_fib;
+  snat_static_mapping_t *m;
+  snat_interface_t *i;
+  snat_address_t *ap;
+  u32 fib_index;
+  int rv;
+
+  if (!sm->enabled)
+    {
+      nat_log_err ("nat44 is disabled");
+      return VNET_API_ERROR_UNSUPPORTED;
+    }
+
+  if (nat44_ed_get_interface (sm->interfaces, sw_if_index))
+    {
+      nat_log_err ("error interface already configured");
+      return VNET_API_ERROR_VALUE_EXIST;
+    }
+
+  if (nat44_ed_get_interface (sm->output_feature_interfaces, sw_if_index))
+    {
+      nat_log_err ("error interface already configured");
+      return VNET_API_ERROR_VALUE_EXIST;
+    }
+
+  if (sm->num_workers > 1)
+    {
+      rv = ip4_sv_reass_enable_disable_with_refcnt (sw_if_index, 1);
+      if (rv)
+       {
+         return rv;
+       }
+
+      rv = ip4_sv_reass_output_enable_disable_with_refcnt (sw_if_index, 1);
+      if (rv)
+       {
+         return rv;
+       }
+
+      vnet_feature_enable_disable (
+       "ip4-unicast", "nat44-out2in-worker-handoff", sw_if_index, 1, 0, 0);
+      vnet_feature_enable_disable ("ip4-output",
+                                  "nat44-in2out-output-worker-handoff",
+                                  sw_if_index, 1, 0, 0);
+    }
+  else
+    {
+      rv = ip4_sv_reass_enable_disable_with_refcnt (sw_if_index, 1);
+      if (rv)
+       {
+         return rv;
+       }
+
+      rv = ip4_sv_reass_output_enable_disable_with_refcnt (sw_if_index, 1);
+      if (rv)
+       {
+         return rv;
+       }
 
-  if (is_del)
-    {
-      nat_log_err ("error interface couldn't be found");
-      return VNET_API_ERROR_NO_SUCH_ENTRY;
+      vnet_feature_enable_disable ("ip4-unicast", "nat-pre-out2in",
+                                  sw_if_index, 1, 0, 0);
+      vnet_feature_enable_disable ("ip4-output", "nat-pre-in2out-output",
+                                  sw_if_index, 1, 0, 0);
     }
 
-  pool_get (sm->interfaces, i);
-  i->sw_if_index = sw_if_index;
-  i->flags = 0;
   nat_validate_interface_counters (sm, sw_if_index);
 
-  vnet_feature_enable_disable ("ip4-unicast", feature_name, sw_if_index, 1, 0,
-                              0);
+  pool_get (sm->output_feature_interfaces, i);
+  i->sw_if_index = sw_if_index;
+  i->flags = 0;
+  i->flags |= NAT_INTERFACE_FLAG_IS_INSIDE;
+  i->flags |= NAT_INTERFACE_FLAG_IS_OUTSIDE;
 
-  int rv = ip4_sv_reass_enable_disable_with_refcnt (sw_if_index, 1);
-  if (rv)
-    return rv;
+  fib_index =
+    fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP4, sw_if_index);
+  update_per_vrf_sessions_vec (fib_index, 0 /*is_del*/);
 
-set_flags:
-  if (is_inside)
+  outside_fib = nat44_ed_get_outside_fib (sm->outside_fibs, fib_index);
+  if (outside_fib)
     {
-      i->flags |= NAT_INTERFACE_FLAG_IS_INSIDE;
-      return 0;
+      outside_fib->refcount++;
     }
   else
-    i->flags |= NAT_INTERFACE_FLAG_IS_OUTSIDE;
+    {
+      vec_add2 (sm->outside_fibs, outside_fib, 1);
+      outside_fib->fib_index = fib_index;
+      outside_fib->refcount = 1;
+    }
 
-  /* Add/delete external addresses to FIB */
-fib:
-  /* *INDENT-OFF* */
   vec_foreach (ap, sm->addresses)
-    snat_add_del_addr_to_fib(&ap->addr, 32, sw_if_index, !is_del);
+    {
+      snat_add_del_addr_to_fib (&ap->addr, 32, sw_if_index, 1);
+    }
 
   pool_foreach (m, sm->static_mappings)
-   {
-    if (!(is_addr_only_static_mapping(m)) || (m->local_addr.as_u32 == m->external_addr.as_u32))
-      continue;
-
-    snat_add_del_addr_to_fib(&m->external_addr, 32, sw_if_index, !is_del);
-  }
-  /* *INDENT-ON* */
+    {
+      if (!((is_sm_addr_only (m->flags))) ||
+         (m->local_addr.as_u32 == m->external_addr.as_u32))
+       {
+         continue;
+       }
+      snat_add_del_addr_to_fib (&m->external_addr, 32, sw_if_index, 1);
+    }
 
   return 0;
 }
 
 int
-snat_interface_add_del_output_feature (u32 sw_if_index,
-                                      u8 is_inside, int is_del)
+nat44_ed_del_output_interface (u32 sw_if_index)
 {
   snat_main_t *sm = &snat_main;
+
+  nat_outside_fib_t *outside_fib;
+  snat_static_mapping_t *m;
   snat_interface_t *i;
   snat_address_t *ap;
-  snat_static_mapping_t *m;
-  nat_outside_fib_t *outside_fib;
-  u32 fib_index = fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP4,
-                                                      sw_if_index);
+  u32 fib_index;
+  int rv;
 
   if (!sm->enabled)
     {
@@ -1652,156 +1961,84 @@ snat_interface_add_del_output_feature (u32 sw_if_index,
       return VNET_API_ERROR_UNSUPPORTED;
     }
 
-  if (sm->static_mapping_only && !(sm->static_mapping_connection_tracking))
+  i = nat44_ed_get_interface (sm->output_feature_interfaces, sw_if_index);
+  if (!i)
     {
-      nat_log_err ("error unsupported");
-      return VNET_API_ERROR_UNSUPPORTED;
+      nat_log_err ("error interface couldn't be found");
+      return VNET_API_ERROR_NO_SUCH_ENTRY;
     }
 
-  /* *INDENT-OFF* */
-  pool_foreach (i, sm->interfaces)
-   {
-    if (i->sw_if_index == sw_if_index)
-      {
-        nat_log_err ("error interface already configured");
-        return VNET_API_ERROR_VALUE_EXIST;
-      }
-  }
-  /* *INDENT-ON* */
-
-  update_per_vrf_sessions_vec (fib_index, is_del);
-
-  if (!is_inside)
+  if (sm->num_workers > 1)
     {
-      /* *INDENT-OFF* */
-      vec_foreach (outside_fib, sm->outside_fibs)
-        {
-          if (outside_fib->fib_index == fib_index)
-            {
-              if (is_del)
-                {
-                 outside_fib->refcount--;
-                  if (!outside_fib->refcount)
-                    vec_del1 (sm->outside_fibs, outside_fib - sm->outside_fibs);
-                }
-              else
-                outside_fib->refcount++;
-              goto feature_set;
-            }
-        }
-      /* *INDENT-ON* */
-      if (!is_del)
+      rv = ip4_sv_reass_enable_disable_with_refcnt (sw_if_index, 0);
+      if (rv)
        {
-         vec_add2 (sm->outside_fibs, outside_fib, 1);
-         outside_fib->refcount = 1;
-         outside_fib->fib_index = fib_index;
+         return rv;
        }
-    }
 
-feature_set:
-  if (is_inside)
-    {
-         int rv =
-           ip4_sv_reass_enable_disable_with_refcnt (sw_if_index, !is_del);
-         if (rv)
-           return rv;
-         rv =
-           ip4_sv_reass_output_enable_disable_with_refcnt (sw_if_index,
-                                                           !is_del);
-         if (rv)
-           return rv;
-      goto fq;
-    }
-
-  if (sm->num_workers > 1)
-    {
-      int rv = ip4_sv_reass_enable_disable_with_refcnt (sw_if_index, !is_del);
-      if (rv)
-       return rv;
-      rv =
-       ip4_sv_reass_output_enable_disable_with_refcnt (sw_if_index, !is_del);
+      rv = ip4_sv_reass_output_enable_disable_with_refcnt (sw_if_index, 0);
       if (rv)
-       return rv;
-      vnet_feature_enable_disable ("ip4-unicast",
-                                  "nat44-out2in-worker-handoff",
-                                  sw_if_index, !is_del, 0, 0);
+       {
+         return rv;
+       }
+
+      vnet_feature_enable_disable (
+       "ip4-unicast", "nat44-out2in-worker-handoff", sw_if_index, 0, 0, 0);
       vnet_feature_enable_disable ("ip4-output",
                                   "nat44-in2out-output-worker-handoff",
-                                  sw_if_index, !is_del, 0, 0);
+                                  sw_if_index, 0, 0, 0);
     }
   else
     {
-         int rv =
-           ip4_sv_reass_enable_disable_with_refcnt (sw_if_index, !is_del);
-         if (rv)
-           return rv;
-         rv =
-           ip4_sv_reass_output_enable_disable_with_refcnt (sw_if_index,
-                                                           !is_del);
-         if (rv)
-           return rv;
-         vnet_feature_enable_disable ("ip4-unicast", "nat-pre-out2in",
-                                      sw_if_index, !is_del, 0, 0);
-         vnet_feature_enable_disable ("ip4-output", "nat-pre-in2out-output",
-                                      sw_if_index, !is_del, 0, 0);
-    }
-
-fq:
-  if (sm->fq_in2out_output_index == ~0 && sm->num_workers > 1)
-    sm->fq_in2out_output_index =
-      vlib_frame_queue_main_init (sm->in2out_output_node_index, 0);
-
-  if (sm->fq_out2in_index == ~0 && sm->num_workers > 1)
-    sm->fq_out2in_index =
-      vlib_frame_queue_main_init (sm->out2in_node_index, 0);
-
-  /* *INDENT-OFF* */
-  pool_foreach (i, sm->output_feature_interfaces)
-   {
-    if (i->sw_if_index == sw_if_index)
-      {
-        if (is_del)
-          pool_put (sm->output_feature_interfaces, i);
-        else
-          return VNET_API_ERROR_VALUE_EXIST;
+      rv = ip4_sv_reass_enable_disable_with_refcnt (sw_if_index, 0);
+      if (rv)
+       {
+         return rv;
+       }
 
-        goto fib;
-      }
-  }
-  /* *INDENT-ON* */
+      rv = ip4_sv_reass_output_enable_disable_with_refcnt (sw_if_index, 0);
+      if (rv)
+       {
+         return rv;
+       }
 
-  if (is_del)
-    {
-      nat_log_err ("error interface couldn't be found");
-      return VNET_API_ERROR_NO_SUCH_ENTRY;
+      vnet_feature_enable_disable ("ip4-unicast", "nat-pre-out2in",
+                                  sw_if_index, 0, 0, 0);
+      vnet_feature_enable_disable ("ip4-output", "nat-pre-in2out-output",
+                                  sw_if_index, 0, 0, 0);
     }
 
-  pool_get (sm->output_feature_interfaces, i);
-  i->sw_if_index = sw_if_index;
-  i->flags = 0;
-  nat_validate_interface_counters (sm, sw_if_index);
-  if (is_inside)
-    i->flags |= NAT_INTERFACE_FLAG_IS_INSIDE;
-  else
-    i->flags |= NAT_INTERFACE_FLAG_IS_OUTSIDE;
+  // remove interface
+  pool_put (sm->output_feature_interfaces, i);
 
-  /* Add/delete external addresses to FIB */
-fib:
-  if (is_inside)
-    return 0;
+  fib_index =
+    fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP4, sw_if_index);
+  update_per_vrf_sessions_vec (fib_index, 1 /*is_del*/);
+
+  outside_fib = nat44_ed_get_outside_fib (sm->outside_fibs, fib_index);
+  if (outside_fib)
+    {
+      outside_fib->refcount--;
+      if (!outside_fib->refcount)
+       {
+         vec_del1 (sm->outside_fibs, outside_fib - sm->outside_fibs);
+       }
+    }
 
-  /* *INDENT-OFF* */
   vec_foreach (ap, sm->addresses)
-    snat_add_del_addr_to_fib(&ap->addr, 32, sw_if_index, !is_del);
+    {
+      snat_add_del_addr_to_fib (&ap->addr, 32, sw_if_index, 0);
+    }
 
   pool_foreach (m, sm->static_mappings)
-   {
-    if (!((is_addr_only_static_mapping(m)))  || (m->local_addr.as_u32 == m->external_addr.as_u32))
-      continue;
-
-    snat_add_del_addr_to_fib(&m->external_addr, 32, sw_if_index, !is_del);
-  }
-  /* *INDENT-ON* */
+    {
+      if (!((is_sm_addr_only (m->flags))) ||
+         (m->local_addr.as_u32 == m->external_addr.as_u32))
+       {
+         continue;
+       }
+      snat_add_del_addr_to_fib (&m->external_addr, 32, sw_if_index, 0);
+    }
 
   return 0;
 }
@@ -1819,7 +2056,6 @@ snat_set_workers (uword * bitmap)
     return VNET_API_ERROR_INVALID_WORKER;
 
   vec_free (sm->workers);
-  /* *INDENT-OFF* */
   clib_bitmap_foreach (i, bitmap)
     {
       vec_add1(sm->workers, i);
@@ -1827,7 +2063,6 @@ snat_set_workers (uword * bitmap)
       sm->per_thread_data[sm->first_worker_index + i].thread_index = i;
       j++;
     }
-  /* *INDENT-ON* */
 
   sm->port_per_thread = (0xffff - 1024) / _vec_len (sm->workers);
 
@@ -1860,7 +2095,6 @@ snat_update_outside_fib (ip4_main_t * im, uword opaque,
       return;
     }
 
-  /* *INDENT-OFF* */
   pool_foreach (i, sm->interfaces)
      {
       if (i->sw_if_index == sw_if_index)
@@ -1880,7 +2114,6 @@ snat_update_outside_fib (ip4_main_t * im, uword opaque,
           match = 1;
         }
     }
-  /* *INDENT-ON* */
 
   if (!match)
     return;
@@ -1991,14 +2224,14 @@ static clib_error_t *
 nat_ip_table_add_del (vnet_main_t * vnm, u32 table_id, u32 is_add)
 {
   u32 fib_index;
-
-      // TODO: consider removing all NAT interfaces
-      if (!is_add)
+  if (!is_add)
+    {
+      fib_index = ip4_fib_index_from_table_id (table_id);
+      if (fib_index != ~0)
        {
-         fib_index = ip4_fib_index_from_table_id (table_id);
-         if (fib_index != ~0)
-           expire_per_vrf_sessions (fib_index);
+         expire_per_vrf_sessions (fib_index);
        }
+    }
   return 0;
 }
 
@@ -2077,11 +2310,14 @@ nat_init (vlib_main_t * vm)
   sm->log_level = NAT_LOG_ERROR;
 
   nat44_set_node_indexes (sm, vm);
+
   sm->log_class = vlib_log_register_class ("nat", 0);
   nat_ipfix_logging_init (vm);
 
   nat_init_simple_counter (sm->total_sessions, "total-sessions",
                           "/nat44-ed/total-sessions");
+  sm->max_cfg_sessions_gauge = stat_segment_new_entry (
+    (u8 *) "/nat44-ed/max-cfg-sessions", STAT_DIR_TYPE_SCALAR_INDEX);
 
 #define _(x)                                                                  \
   nat_init_simple_counter (sm->counters.fastpath.in2out.x, #x,                \
@@ -2114,14 +2350,15 @@ nat_init (vlib_main_t * vm)
   /* Use all available workers by default */
   if (sm->num_workers > 1)
     {
-
       for (i = 0; i < sm->num_workers; i++)
        bitmap = clib_bitmap_set (bitmap, i, 1);
       snat_set_workers (bitmap);
       clib_bitmap_free (bitmap);
     }
   else
-    sm->per_thread_data[0].snat_thread_index = 0;
+    {
+      sm->per_thread_data[0].snat_thread_index = 0;
+    }
 
   /* callbacks to call when interface address changes. */
   cbi.function = snat_ip4_add_del_interface_address_cb;
@@ -2155,19 +2392,12 @@ nat44_plugin_enable (nat44_config_t c)
 
   fail_if_enabled ();
 
-  // UPDATE based on these appropriate API/CLI
-  // 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.static_mapping_only && !c.connection_tracking)
     {
       nat_log_err ("unsupported combination of configuration");
       return 1;
     }
 
-  // nat44 feature configuration
   sm->static_mapping_only = c.static_mapping_only;
   sm->static_mapping_connection_tracking = c.connection_tracking;
 
@@ -2180,9 +2410,10 @@ nat44_plugin_enable (nat44_config_t c)
     c.sessions = 63 * 1024;
 
   sm->max_translations_per_thread = c.sessions;
+  stat_segment_set_state_counter (sm->max_cfg_sessions_gauge,
+                                 sm->max_translations_per_thread);
   sm->translation_buckets = nat_calc_bihash_buckets (c.sessions);
 
-  // ED only feature
   vec_add1 (sm->max_translations_per_fib, sm->max_translations_per_thread);
 
   sm->inside_vrf_id = c.inside_vrf;
@@ -2194,9 +2425,6 @@ nat44_plugin_enable (nat44_config_t c)
   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_ed_get_worker_in2out_cb;
-  sm->worker_out2in_cb = nat44_ed_get_worker_out2in_cb;
-
   nat44_ed_db_init (sm->max_translations_per_thread, sm->translation_buckets);
 
   nat_affinity_enable ();
@@ -2206,7 +2434,28 @@ nat44_plugin_enable (nat44_config_t c)
   vlib_zero_simple_counter (&sm->total_sessions, 0);
 
   if (!sm->frame_queue_nelts)
-    sm->frame_queue_nelts = NAT_FQ_NELTS_DEFAULT;
+    {
+      sm->frame_queue_nelts = NAT_FQ_NELTS_DEFAULT;
+    }
+
+  if (sm->num_workers > 1)
+    {
+      if (sm->fq_in2out_index == ~0)
+       {
+         sm->fq_in2out_index = vlib_frame_queue_main_init (
+           sm->in2out_node_index, sm->frame_queue_nelts);
+       }
+      if (sm->fq_out2in_index == ~0)
+       {
+         sm->fq_out2in_index = vlib_frame_queue_main_init (
+           sm->out2in_node_index, sm->frame_queue_nelts);
+       }
+      if (sm->fq_in2out_output_index == ~0)
+       {
+         sm->fq_in2out_output_index = vlib_frame_queue_main_init (
+           sm->in2out_output_node_index, sm->frame_queue_nelts);
+       }
+    }
 
   sm->enabled = 1;
   sm->rconfig = c;
@@ -2233,44 +2482,44 @@ int
 nat44_plugin_disable ()
 {
   snat_main_t *sm = &snat_main;
-  snat_interface_t *i, *vec;
+  snat_interface_t *i, *pool;
   int error = 0;
 
   fail_if_disabled ();
 
-  // first unregister all nodes from interfaces
-  vec = vec_dup (sm->interfaces);
-  vec_foreach (i, vec)
+  pool = pool_dup (sm->interfaces);
+  pool_foreach (i, pool)
     {
-      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 (nat_interface_is_inside (i))
+       {
+         error = nat44_ed_del_interface (i->sw_if_index, 1);
+       }
+      if (nat_interface_is_outside (i))
+       {
+         error = nat44_ed_del_interface (i->sw_if_index, 0);
+       }
       if (error)
         {
           nat_log_err ("error occurred while removing interface %u",
                        i->sw_if_index);
         }
     }
-  vec_free (vec);
+  pool_free (sm->interfaces);
+  pool_free (pool);
   sm->interfaces = 0;
 
-  vec = vec_dup (sm->output_feature_interfaces);
-  vec_foreach (i, vec)
+  pool = pool_dup (sm->output_feature_interfaces);
+  pool_foreach (i, pool)
     {
-      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);
-
+      error = nat44_ed_del_output_interface (i->sw_if_index);
       if (error)
         {
           nat_log_err ("error occurred while removing interface %u",
                        i->sw_if_index);
         }
     }
-  vec_free (vec);
+  pool_free (sm->output_feature_interfaces);
+  pool_free (pool);
   sm->output_feature_interfaces = 0;
 
   vec_free (sm->max_translations_per_fib);
@@ -2405,19 +2654,14 @@ nat_set_outside_address_and_port (snat_address_t *addresses, u32 thread_index,
 }
 
 int
-snat_static_mapping_match (snat_main_t * sm,
-                          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,
-                          twice_nat_type_t * twice_nat,
-                          lb_nat_type_t * lb, ip4_address_t * ext_host_addr,
-                          u8 * is_identity_nat, snat_static_mapping_t ** out)
+snat_static_mapping_match (vlib_main_t *vm, snat_main_t *sm,
+                          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, twice_nat_type_t *twice_nat,
+                          lb_nat_type_t *lb, ip4_address_t *ext_host_addr,
+                          u8 *is_identity_nat, snat_static_mapping_t **out)
 {
   clib_bihash_kv_8_8_t kv, value;
   clib_bihash_8_8_t *mapping_hash;
@@ -2456,15 +2700,13 @@ snat_static_mapping_match (snat_main_t * sm,
 
   if (by_external)
     {
-      if (is_lb_static_mapping (m))
+      if (is_sm_lb (m->flags))
        {
          if (PREDICT_FALSE (lb != 0))
            *lb = m->affinity ? AFFINITY_LB_NAT : LB_NAT;
-         if (m->affinity && !nat_affinity_find_and_lock (ext_host_addr[0],
-                                                         match_addr,
-                                                         match_protocol,
-                                                         match_port,
-                                                         &backend_index))
+         if (m->affinity && !nat_affinity_find_and_lock (
+                              vm, ext_host_addr[0], match_addr,
+                              match_protocol, match_port, &backend_index))
            {
              local = pool_elt_at_index (m->locals, backend_index);
              *mapping_addr = local->addr;
@@ -2484,8 +2726,8 @@ snat_static_mapping_match (snat_main_t * sm,
                  .src_address = local->addr,
                };
 
-               if (sm->worker_in2out_cb (0, &ip, m->fib_index, 0) ==
-                   thread_index)
+               if (nat44_ed_get_in2out_worker_index (0, &ip, m->fib_index,
+                                                     0) == thread_index)
                  {
                    vec_add1 (tmp, i);
                  }
@@ -2531,28 +2773,39 @@ snat_static_mapping_match (snat_main_t * sm,
          *mapping_fib_index = m->fib_index;
          *mapping_addr = m->local_addr;
          /* Address only mapping doesn't change port */
-         *mapping_port = is_addr_only_static_mapping (m) ? match_port
-           : m->local_port;
+         *mapping_port =
+           is_sm_addr_only (m->flags) ? match_port : m->local_port;
        }
     }
   else
     {
       *mapping_addr = m->external_addr;
       /* Address only mapping doesn't change port */
-      *mapping_port = is_addr_only_static_mapping (m) ? match_port
-       : m->external_port;
+      *mapping_port =
+       is_sm_addr_only (m->flags) ? match_port : m->external_port;
       *mapping_fib_index = sm->outside_fib_index;
     }
 
 end:
   if (PREDICT_FALSE (is_addr_only != 0))
-    *is_addr_only = is_addr_only_static_mapping (m);
+    *is_addr_only = is_sm_addr_only (m->flags);
 
   if (PREDICT_FALSE (twice_nat != 0))
-    *twice_nat = m->twice_nat;
+    {
+      *twice_nat = TWICE_NAT_DISABLED;
+
+      if (is_sm_twice_nat (m->flags))
+       {
+         *twice_nat = TWICE_NAT;
+       }
+      else if (is_sm_self_twice_nat (m->flags))
+       {
+         *twice_nat = TWICE_NAT_SELF;
+       }
+    }
 
   if (PREDICT_FALSE (is_identity_nat != 0))
-    *is_identity_nat = is_identity_static_mapping (m);
+    *is_identity_nat = is_sm_identity_nat (m->flags);
 
   if (out != 0)
     *out = m;
@@ -2560,9 +2813,9 @@ end:
   return 0;
 }
 
-static u32
-nat44_ed_get_worker_in2out_cb (vlib_buffer_t *b, ip4_header_t *ip,
-                              u32 rx_fib_index, u8 is_output)
+u32
+nat44_ed_get_in2out_worker_index (vlib_buffer_t *b, ip4_header_t *ip,
+                                 u32 rx_fib_index, u8 is_output)
 {
   snat_main_t *sm = &snat_main;
   u32 next_worker_index = sm->first_worker_index;
@@ -2571,61 +2824,69 @@ nat44_ed_get_worker_in2out_cb (vlib_buffer_t *b, ip4_header_t *ip,
   clib_bihash_kv_16_8_t kv16, value16;
 
   u32 fib_index = rx_fib_index;
-  if (PREDICT_FALSE (is_output))
-    {
-      fib_index = sm->outside_fib_index;
-      nat_outside_fib_t *outside_fib;
-      fib_node_index_t fei = FIB_NODE_INDEX_INVALID;
-      fib_prefix_t pfx = {
-       .fp_proto = FIB_PROTOCOL_IP4,
-       .fp_len = 32,
-       .fp_addr = {
-                   .ip4.as_u32 = ip->dst_address.as_u32,
-                   }
-       ,
-      };
-
-      switch (vec_len (sm->outside_fibs))
+  if (b)
+    {
+      if (PREDICT_FALSE (is_output))
        {
-       case 0:
          fib_index = sm->outside_fib_index;
-         break;
-       case 1:
-         fib_index = sm->outside_fibs[0].fib_index;
-         break;
-       default:
-            /* *INDENT-OFF* */
-            vec_foreach (outside_fib, sm->outside_fibs)
-              {
-                fei = fib_table_lookup (outside_fib->fib_index, &pfx);
-                if (FIB_NODE_INDEX_INVALID != fei)
-                  {
-                    if (fib_entry_get_resolving_interface (fei) != ~0)
-                      {
-                        fib_index = outside_fib->fib_index;
-                        break;
-                      }
-                  }
-              }
-            /* *INDENT-ON* */
-         break;
+         nat_outside_fib_t *outside_fib;
+         fib_node_index_t fei = FIB_NODE_INDEX_INVALID;
+         fib_prefix_t pfx = {
+                 .fp_proto = FIB_PROTOCOL_IP4,
+                 .fp_len = 32,
+                 .fp_addr = {
+                         .ip4.as_u32 = ip->dst_address.as_u32,
+                 } ,
+         };
+
+         switch (vec_len (sm->outside_fibs))
+           {
+           case 0:
+             fib_index = sm->outside_fib_index;
+             break;
+           case 1:
+             fib_index = sm->outside_fibs[0].fib_index;
+             break;
+           default:
+             vec_foreach (outside_fib, sm->outside_fibs)
+               {
+                 fei = fib_table_lookup (outside_fib->fib_index, &pfx);
+                 if (FIB_NODE_INDEX_INVALID != fei)
+                   {
+                     if (fib_entry_get_resolving_interface (fei) != ~0)
+                       {
+                         fib_index = outside_fib->fib_index;
+                         break;
+                       }
+                   }
+               }
+             break;
+           }
        }
-    }
 
-  if (b)
-    {
       init_ed_k (&kv16, ip->src_address, vnet_buffer (b)->ip.reass.l4_src_port,
                 ip->dst_address, vnet_buffer (b)->ip.reass.l4_dst_port,
                 fib_index, ip->protocol);
 
-      if (PREDICT_TRUE (
-           !clib_bihash_search_16_8 (&sm->flow_hash, &kv16, &value16)))
+      if (!clib_bihash_search_16_8 (&sm->flow_hash, &kv16, &value16))
        {
          next_worker_index = ed_value_get_thread_index (&value16);
          vnet_buffer2 (b)->nat.cached_session_index =
            ed_value_get_session_index (&value16);
          goto out;
        }
+
+      // dst NAT
+      init_ed_k (&kv16, ip->dst_address, vnet_buffer (b)->ip.reass.l4_dst_port,
+                ip->src_address, vnet_buffer (b)->ip.reass.l4_src_port,
+                rx_fib_index, ip->protocol);
+      if (!clib_bihash_search_16_8 (&sm->flow_hash, &kv16, &value16))
+       {
+         next_worker_index = ed_value_get_thread_index (&value16);
+         vnet_buffer2 (b)->nat.cached_dst_nat_session_index =
+           ed_value_get_session_index (&value16);
+         goto out;
+       }
     }
 
   hash = ip->src_address.as_u32 + (ip->src_address.as_u32 >> 8) +
@@ -2655,48 +2916,22 @@ out:
   return next_worker_index;
 }
 
-static u32
-nat44_ed_get_worker_out2in_cb (vlib_buffer_t * b, ip4_header_t * ip,
-                              u32 rx_fib_index, u8 is_output)
+u32
+nat44_ed_get_out2in_worker_index (vlib_buffer_t *b, ip4_header_t *ip,
+                                 u32 rx_fib_index, u8 is_output)
 {
   snat_main_t *sm = &snat_main;
   clib_bihash_kv_8_8_t kv, value;
   clib_bihash_kv_16_8_t kv16, value16;
-  snat_main_per_thread_data_t *tsm;
 
   u32 proto, next_worker_index = 0;
-  udp_header_t *udp;
   u16 port;
   snat_static_mapping_t *m;
   u32 hash;
 
   proto = ip_proto_to_nat_proto (ip->protocol);
 
-  if (PREDICT_TRUE (proto == NAT_PROTOCOL_UDP || proto == NAT_PROTOCOL_TCP))
-    {
-      udp = ip4_next_header (ip);
-
-      init_ed_k (&kv16, ip->dst_address, vnet_buffer (b)->ip.reass.l4_dst_port,
-                ip->src_address, vnet_buffer (b)->ip.reass.l4_src_port,
-                rx_fib_index, ip->protocol);
-
-      if (PREDICT_TRUE (
-           !clib_bihash_search_16_8 (&sm->flow_hash, &kv16, &value16)))
-       {
-         tsm =
-           vec_elt_at_index (sm->per_thread_data,
-                             ed_value_get_thread_index (&value16));
-         vnet_buffer2 (b)->nat.cached_session_index =
-           ed_value_get_session_index (&value16);
-         next_worker_index = sm->first_worker_index + tsm->thread_index;
-         nat_elog_debug_handoff (
-           sm, "HANDOFF OUT2IN (session)", next_worker_index, rx_fib_index,
-           clib_net_to_host_u32 (ip->src_address.as_u32),
-           clib_net_to_host_u32 (ip->dst_address.as_u32));
-         return next_worker_index;
-       }
-    }
-  else if (proto == NAT_PROTOCOL_ICMP)
+  if (PREDICT_FALSE (proto == NAT_PROTOCOL_ICMP))
     {
       ip4_address_t lookup_saddr, lookup_daddr;
       u16 lookup_sport, lookup_dport;
@@ -2710,10 +2945,7 @@ nat44_ed_get_worker_out2in_cb (vlib_buffer_t * b, ip4_header_t * ip,
          if (PREDICT_TRUE (
                !clib_bihash_search_16_8 (&sm->flow_hash, &kv16, &value16)))
            {
-             tsm =
-               vec_elt_at_index (sm->per_thread_data,
-                                 ed_value_get_thread_index (&value16));
-             next_worker_index = sm->first_worker_index + tsm->thread_index;
+             next_worker_index = ed_value_get_thread_index (&value16);
              nat_elog_debug_handoff (
                sm, "HANDOFF OUT2IN (session)", next_worker_index,
                rx_fib_index, clib_net_to_host_u32 (ip->src_address.as_u32),
@@ -2723,6 +2955,23 @@ nat44_ed_get_worker_out2in_cb (vlib_buffer_t * b, ip4_header_t * ip,
        }
     }
 
+  init_ed_k (&kv16, ip->src_address, vnet_buffer (b)->ip.reass.l4_src_port,
+            ip->dst_address, vnet_buffer (b)->ip.reass.l4_dst_port,
+            rx_fib_index, ip->protocol);
+
+  if (PREDICT_TRUE (
+       !clib_bihash_search_16_8 (&sm->flow_hash, &kv16, &value16)))
+    {
+      vnet_buffer2 (b)->nat.cached_session_index =
+       ed_value_get_session_index (&value16);
+      next_worker_index = ed_value_get_thread_index (&value16);
+      nat_elog_debug_handoff (sm, "HANDOFF OUT2IN (session)",
+                             next_worker_index, rx_fib_index,
+                             clib_net_to_host_u32 (ip->src_address.as_u32),
+                             clib_net_to_host_u32 (ip->dst_address.as_u32));
+      return next_worker_index;
+    }
+
   /* first try static mappings without port */
   if (PREDICT_FALSE (pool_elts (sm->static_mappings)))
     {
@@ -2744,11 +2993,11 @@ nat44_ed_get_worker_out2in_cb (vlib_buffer_t * b, ip4_header_t * ip,
       goto done;
     }
 
-  udp = ip4_next_header (ip);
   port = vnet_buffer (b)->ip.reass.l4_dst_port;
 
   if (PREDICT_FALSE (ip->protocol == IP_PROTOCOL_ICMP))
     {
+      udp_header_t *udp = ip4_next_header (ip);
       icmp46_header_t *icmp = (icmp46_header_t *) udp;
       icmp_echo_header_t *echo = (icmp_echo_header_t *) (icmp + 1);
       if (!icmp_type_is_error_message
@@ -2786,7 +3035,7 @@ nat44_ed_get_worker_out2in_cb (vlib_buffer_t * b, ip4_header_t * ip,
          (&sm->static_mapping_by_external, &kv, &value))
        {
          m = pool_elt_at_index (sm->static_mappings, value.value);
-         if (!is_lb_static_mapping (m))
+         if (!is_sm_lb (m->flags))
            {
              next_worker_index = m->workers[0];
              goto done;
@@ -2859,6 +3108,9 @@ nat44_update_session_limit (u32 session_limit, u32 vrf_id)
     return 1;
   sm->max_translations_per_thread = nat44_get_max_session_limit ();
 
+  stat_segment_set_state_counter (sm->max_cfg_sessions_gauge,
+                                 sm->max_translations_per_thread);
+
   sm->translation_buckets =
     nat_calc_bihash_buckets (sm->max_translations_per_thread);
 
@@ -3000,8 +3252,8 @@ nat_ip4_add_del_addr_only_sm_cb (ip4_main_t * im,
   snat_static_map_resolve_t *rp;
   snat_static_mapping_t *m;
   clib_bihash_kv_8_8_t kv, value;
-  int i, rv;
   ip4_address_t l_addr;
+  int i, rv;
 
   if (!sm->enabled)
     return;
@@ -3042,18 +3294,23 @@ match:
     l_addr.as_u32 = address[0].as_u32;
   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, !is_delete, rp->twice_nat,
-                               rp->out2in_only, rp->tag, rp->identity_nat,
-                               rp->pool_addr, rp->exact);
+
+  if (is_delete)
+    {
+      rv = nat44_ed_del_static_mapping (l_addr, address[0], rp->l_port,
+                                       rp->e_port, rp->proto, rp->vrf_id, ~0,
+                                       rp->flags);
+    }
+  else
+    {
+      rv = nat44_ed_add_static_mapping (l_addr, address[0], rp->l_port,
+                                       rp->e_port, rp->proto, rp->vrf_id, ~0,
+                                       rp->flags, rp->pool_addr, rp->tag);
+    }
   if (rv)
-    nat_elog_notice_X1 (sm, "snat_add_static_mapping returned %d", "i4", rv);
+    {
+      nat_elog_notice_X1 (sm, "add_static_mapping returned %d", "i4", rv);
+    }
 }
 
 static void
@@ -3109,20 +3366,23 @@ match:
          /* On this interface? */
          if (rp->sw_if_index == sw_if_index)
            {
+
+             // TODO: remove if not needed (handled by function)
              /* Indetity mapping? */
              if (rp->l_addr.as_u32 == 0)
                l_addr.as_u32 = address[0].as_u32;
              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, 1,
-               rp->twice_nat, rp->out2in_only, rp->tag, rp->identity_nat,
-               rp->pool_addr, rp->exact);
+             rv = nat44_ed_add_static_mapping (
+               l_addr, address[0], rp->l_port, rp->e_port, rp->proto,
+               rp->vrf_id, ~0, rp->flags, rp->pool_addr, rp->tag);
              if (rv)
-               nat_elog_notice_X1 (sm, "snat_add_static_mapping returned %d",
-                                   "i4", rv);
+               {
+                 nat_elog_notice_X1 (sm, "add_static_mapping returned %d",
+                                     "i4", rv);
+               }
            }
        }
       return;
@@ -3215,8 +3475,9 @@ nat44_del_ed_session (snat_main_t * sm, ip4_address_t * addr, u16 port,
 
   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 (0, &ip, fib_index, 0));
+    tsm = vec_elt_at_index (
+      sm->per_thread_data,
+      nat44_ed_get_in2out_worker_index (0, &ip, fib_index, 0));
   else
     tsm = vec_elt_at_index (sm->per_thread_data, sm->num_workers);
 
@@ -3241,7 +3502,6 @@ VLIB_NODE_FN (nat_default_node) (vlib_main_t * vm,
   return 0;
 }
 
-/* *INDENT-OFF* */
 VLIB_REGISTER_NODE (nat_default_node) = {
   .name = "nat-default",
   .vector_size = sizeof (u32),
@@ -3262,7 +3522,6 @@ VLIB_REGISTER_NODE (nat_default_node) = {
     [NAT_NEXT_OUT2IN_CLASSIFY] = "nat44-out2in-worker-handoff",
   },
 };
-/* *INDENT-ON* */
 
 void
 nat_6t_l3_l4_csum_calc (nat_6t_flow_t *f)
@@ -3331,15 +3590,14 @@ nat_6t_l3_l4_csum_calc (nat_6t_flow_t *f)
     }
 }
 
-static_always_inline int nat_6t_flow_icmp_translate (snat_main_t *sm,
-                                                    vlib_buffer_t *b,
-                                                    ip4_header_t *ip,
-                                                    nat_6t_flow_t *f);
+static_always_inline int
+nat_6t_flow_icmp_translate (vlib_main_t *vm, snat_main_t *sm, vlib_buffer_t *b,
+                           ip4_header_t *ip, nat_6t_flow_t *f);
 
 static_always_inline void
 nat_6t_flow_ip4_translate (snat_main_t *sm, vlib_buffer_t *b, ip4_header_t *ip,
                           nat_6t_flow_t *f, nat_protocol_t proto,
-                          int is_icmp_inner_ip4)
+                          int is_icmp_inner_ip4, int skip_saddr_rewrite)
 {
   udp_header_t *udp = ip4_next_header (ip);
   tcp_header_t *tcp = (tcp_header_t *) udp;
@@ -3382,7 +3640,10 @@ nat_6t_flow_ip4_translate (snat_main_t *sm, vlib_buffer_t *b, ip4_header_t *ip,
     {
       if (!is_icmp_inner_ip4)
        { // regular case
-         ip->src_address = f->rewrite.saddr;
+         if (!skip_saddr_rewrite)
+           {
+             ip->src_address = f->rewrite.saddr;
+           }
          ip->dst_address = f->rewrite.daddr;
        }
       else
@@ -3392,14 +3653,32 @@ nat_6t_flow_ip4_translate (snat_main_t *sm, vlib_buffer_t *b, ip4_header_t *ip,
        }
     }
 
-  ip_csum_t ip_sum = ip->checksum;
-  ip_sum = ip_csum_sub_even (ip_sum, f->l3_csum_delta);
-  ip->checksum = ip_csum_fold (ip_sum);
-  ASSERT (ip->checksum == ip4_header_checksum (ip));
+  if (skip_saddr_rewrite)
+    {
+      ip->checksum = ip4_header_checksum (ip);
+    }
+  else
+    {
+      ip_csum_t ip_sum = ip->checksum;
+      ip_sum = ip_csum_sub_even (ip_sum, f->l3_csum_delta);
+      ip->checksum = ip_csum_fold (ip_sum);
+    }
+  if (0xffff == ip->checksum)
+    ip->checksum = 0;
+  ASSERT (ip4_header_checksum_is_valid (ip));
+}
+
+static_always_inline int
+it_fits (vlib_main_t *vm, vlib_buffer_t *b, void *object, size_t size)
+{
+  int result = ((u8 *) object + size <=
+               (u8 *) vlib_buffer_get_current (b) + b->current_length) &&
+              vlib_object_within_buffer_data (vm, b, object, size);
+  return result;
 }
 
 static_always_inline int
-nat_6t_flow_icmp_translate (snat_main_t *sm, vlib_buffer_t *b,
+nat_6t_flow_icmp_translate (vlib_main_t *vm, snat_main_t *sm, vlib_buffer_t *b,
                            ip4_header_t *ip, nat_6t_flow_t *f)
 {
   if (IP_PROTOCOL_ICMP != ip->protocol)
@@ -3410,8 +3689,19 @@ nat_6t_flow_icmp_translate (snat_main_t *sm, vlib_buffer_t *b,
 
   if ((!vnet_buffer (b)->ip.reass.is_non_first_fragment))
     {
-      if (icmp->checksum == 0)
-       icmp->checksum = 0xffff;
+      if (!it_fits (vm, b, icmp, sizeof (*icmp)))
+       {
+         return NAT_ED_TRNSL_ERR_PACKET_TRUNCATED;
+       }
+
+      ssize_t icmp_offset = (u8 *) icmp - (u8 *) vlib_buffer_get_current (b);
+      ip_csum_t sum =
+       ip_incremental_checksum (0, icmp, b->current_length - icmp_offset);
+      sum = (u16) ~ip_csum_fold (sum);
+      if (sum != 0)
+       {
+         return NAT_ED_TRNSL_ERR_INVALID_CSUM;
+       }
 
       if (!icmp_type_is_error_message (icmp->type))
        {
@@ -3433,27 +3723,72 @@ nat_6t_flow_icmp_translate (snat_main_t *sm, vlib_buffer_t *b,
 
          if (!ip4_header_checksum_is_valid (inner_ip))
            {
-             return NAT_ED_TRNSL_ERR_TRANSLATION_FAILED;
+             return NAT_ED_TRNSL_ERR_INNER_IP_CORRUPT;
            }
 
          nat_protocol_t inner_proto =
            ip_proto_to_nat_proto (inner_ip->protocol);
 
-         ip_csum_t icmp_sum = icmp->checksum;
+         ip_csum_t old_icmp_sum = icmp->checksum;
+         ip_csum_t old_inner_ip_sum = inner_ip->checksum;
+         ip_csum_t old_udp_sum;
+         ip_csum_t old_tcp_sum;
+         ip_csum_t new_icmp_sum;
+         udp_header_t *udp;
+         tcp_header_t *tcp;
 
          switch (inner_proto)
            {
            case NAT_PROTOCOL_UDP:
+             udp = (udp_header_t *) (inner_ip + 1);
+             if (!it_fits (vm, b, udp, sizeof (*udp)))
+               {
+                 return NAT_ED_TRNSL_ERR_PACKET_TRUNCATED;
+               }
+             old_udp_sum = udp->checksum;
+             nat_6t_flow_ip4_translate (sm, b, inner_ip, f, inner_proto,
+                                        1 /* is_icmp_inner_ip4 */,
+                                        0 /* skip_saddr_rewrite */);
+             new_icmp_sum = ip_csum_sub_even (old_icmp_sum, f->l3_csum_delta);
+             new_icmp_sum = ip_csum_sub_even (new_icmp_sum, f->l4_csum_delta);
+             new_icmp_sum =
+               ip_csum_update (new_icmp_sum, old_inner_ip_sum,
+                               inner_ip->checksum, ip4_header_t, checksum);
+             new_icmp_sum =
+               ip_csum_update (new_icmp_sum, old_udp_sum, udp->checksum,
+                               udp_header_t, checksum);
+             new_icmp_sum = ip_csum_fold (new_icmp_sum);
+             icmp->checksum = new_icmp_sum;
+             break;
            case NAT_PROTOCOL_TCP:
+             tcp = (tcp_header_t *) (inner_ip + 1);
+             if (!it_fits (vm, b, tcp, sizeof (*tcp)))
+               {
+                 return NAT_ED_TRNSL_ERR_PACKET_TRUNCATED;
+               }
+             old_tcp_sum = tcp->checksum;
              nat_6t_flow_ip4_translate (sm, b, inner_ip, f, inner_proto,
-                                        1 /* is_icmp_inner_ip4 */);
-             icmp_sum = ip_csum_sub_even (icmp_sum, f->l3_csum_delta);
-             icmp->checksum = ip_csum_fold (icmp_sum);
+                                        1 /* is_icmp_inner_ip4 */,
+                                        0 /* skip_saddr_rewrite */);
+             new_icmp_sum = ip_csum_sub_even (old_icmp_sum, f->l3_csum_delta);
+             new_icmp_sum = ip_csum_sub_even (new_icmp_sum, f->l4_csum_delta);
+             new_icmp_sum =
+               ip_csum_update (new_icmp_sum, old_inner_ip_sum,
+                               inner_ip->checksum, ip4_header_t, checksum);
+             new_icmp_sum =
+               ip_csum_update (new_icmp_sum, old_tcp_sum, tcp->checksum,
+                               tcp_header_t, checksum);
+             new_icmp_sum = ip_csum_fold (new_icmp_sum);
+             icmp->checksum = new_icmp_sum;
              break;
            case NAT_PROTOCOL_ICMP:
              if (f->ops & NAT_FLOW_OP_ICMP_ID_REWRITE)
                {
                  icmp46_header_t *inner_icmp = ip4_next_header (inner_ip);
+                 if (!it_fits (vm, b, inner_icmp, sizeof (*inner_icmp)))
+                   {
+                     return NAT_ED_TRNSL_ERR_PACKET_TRUNCATED;
+                   }
                  icmp_echo_header_t *inner_echo =
                    (icmp_echo_header_t *) (inner_icmp + 1);
                  if (f->rewrite.icmp_id != inner_echo->identifier)
@@ -3478,29 +3813,66 @@ nat_6t_flow_icmp_translate (snat_main_t *sm, vlib_buffer_t *b,
            }
        }
     }
+
   return NAT_ED_TRNSL_ERR_SUCCESS;
 }
 
-nat_translation_error_e
-nat_6t_flow_buf_translate (snat_main_t *sm, vlib_buffer_t *b, ip4_header_t *ip,
-                          nat_6t_flow_t *f, nat_protocol_t proto,
-                          int is_output_feature)
+static_always_inline nat_translation_error_e
+nat_6t_flow_buf_translate (vlib_main_t *vm, snat_main_t *sm, vlib_buffer_t *b,
+                          ip4_header_t *ip, nat_6t_flow_t *f,
+                          nat_protocol_t proto, int is_output_feature,
+                          int is_i2o)
 {
   if (!is_output_feature && f->ops & NAT_FLOW_OP_TXFIB_REWRITE)
     {
       vnet_buffer (b)->sw_if_index[VLIB_TX] = f->rewrite.fib_index;
     }
 
-  nat_6t_flow_ip4_translate (sm, b, ip, f, proto, 0 /* is_icmp_inner_ip4 */);
-
   if (NAT_PROTOCOL_ICMP == proto)
     {
-      return nat_6t_flow_icmp_translate (sm, b, ip, f);
+      if (ip->src_address.as_u32 != f->rewrite.saddr.as_u32)
+       {
+         // packet is returned from a router, not from destination
+         // skip source address rewrite if in o2i path
+         nat_6t_flow_ip4_translate (sm, b, ip, f, proto,
+                                    0 /* is_icmp_inner_ip4 */,
+                                    !is_i2o /* skip_saddr_rewrite */);
+       }
+      else
+       {
+         nat_6t_flow_ip4_translate (sm, b, ip, f, proto,
+                                    0 /* is_icmp_inner_ip4 */,
+                                    0 /* skip_saddr_rewrite */);
+       }
+      return nat_6t_flow_icmp_translate (vm, sm, b, ip, f);
     }
 
+  nat_6t_flow_ip4_translate (sm, b, ip, f, proto, 0 /* is_icmp_inner_ip4 */,
+                            0 /* skip_saddr_rewrite */);
+
   return NAT_ED_TRNSL_ERR_SUCCESS;
 }
 
+nat_translation_error_e
+nat_6t_flow_buf_translate_i2o (vlib_main_t *vm, snat_main_t *sm,
+                              vlib_buffer_t *b, ip4_header_t *ip,
+                              nat_6t_flow_t *f, nat_protocol_t proto,
+                              int is_output_feature)
+{
+  return nat_6t_flow_buf_translate (vm, sm, b, ip, f, proto, is_output_feature,
+                                   1 /* is_i2o */);
+}
+
+nat_translation_error_e
+nat_6t_flow_buf_translate_o2i (vlib_main_t *vm, snat_main_t *sm,
+                              vlib_buffer_t *b, ip4_header_t *ip,
+                              nat_6t_flow_t *f, nat_protocol_t proto,
+                              int is_output_feature)
+{
+  return nat_6t_flow_buf_translate (vm, sm, b, ip, f, proto, is_output_feature,
+                                   0 /* is_i2o */);
+}
+
 u8 *
 format_nat_6t (u8 *s, va_list *args)
 {
@@ -3530,6 +3902,15 @@ format_nat_ed_translation_error (u8 *s, va_list *args)
     case NAT_ED_TRNSL_ERR_FLOW_MISMATCH:
       s = format (s, "flow-mismatch");
       break;
+    case NAT_ED_TRNSL_ERR_PACKET_TRUNCATED:
+      s = format (s, "packet-truncated");
+      break;
+    case NAT_ED_TRNSL_ERR_INNER_IP_CORRUPT:
+      s = format (s, "inner-ip-corrupted");
+      break;
+    case NAT_ED_TRNSL_ERR_INVALID_CSUM:
+      s = format (s, "invalid-checksum");
+      break;
     }
   return s;
 }