nat: add saddr info to nat44-ed o2i flow's rewrite
[vpp.git] / src / plugins / nat / nat44-ed / nat44_ed_in2out.c
index 885851c..9b4dac3 100644 (file)
 #include <vnet/udp/udp_local.h>
 #include <vppinfra/error.h>
 
-#include <nat/lib/nat_syslog.h>
 #include <nat/lib/nat_inlines.h>
 #include <nat/lib/ipfix_logging.h>
 
 #include <nat/nat44-ed/nat44_ed.h>
 #include <nat/nat44-ed/nat44_ed_inlines.h>
 
-/* number of attempts to get a port for ED overloading algorithm, if rolling
- * a dice this many times doesn't produce a free port, it's treated
- * as if there were no free ports available to conserve resources */
-#define ED_PORT_ALLOC_ATTEMPTS (10)
-
 static char *nat_in2out_ed_error_strings[] = {
 #define _(sym,string) string,
   foreach_nat_in2out_ed_error
@@ -55,6 +49,7 @@ typedef struct
   u8 is_slow_path;
   u8 translation_via_i2of;
   u8 lookup_skipped;
+  u8 tcp_state;
 } nat_in2out_ed_trace_t;
 
 static u8 *
@@ -69,12 +64,13 @@ format_nat_in2out_ed_trace (u8 * s, va_list * args)
     t->is_slow_path ? "NAT44_IN2OUT_ED_SLOW_PATH" :
     "NAT44_IN2OUT_ED_FAST_PATH";
 
-  s = format (s, "%s: sw_if_index %d, next index %d, session %d", tag,
-             t->sw_if_index, t->next_index, t->session_index);
+  s = format (s, "%s: sw_if_index %d, next index %d", tag, t->sw_if_index,
+             t->next_index);
   if (~0 != t->session_index)
     {
-      s = format (s, ", translation result '%U' via %s",
-                 format_nat_ed_translation_error, t->translation_error,
+      s = format (s, ", session %d, translation result '%U' via %s",
+                 t->session_index, format_nat_ed_translation_error,
+                 t->translation_error,
                  t->translation_via_i2of ? "i2of" : "o2if");
       s = format (s, "\n  i2of %U", format_nat_6t_flow, &t->i2of);
       s = format (s, "\n  o2if %U", format_nat_6t_flow, &t->o2if);
@@ -83,7 +79,7 @@ format_nat_in2out_ed_trace (u8 * s, va_list * args)
     {
       if (t->lookup_skipped)
        {
-         s = format (s, "\n lookup skipped - cached session index used");
+         s = format (s, "\n  lookup skipped - cached session index used");
        }
       else
        {
@@ -91,93 +87,33 @@ format_nat_in2out_ed_trace (u8 * s, va_list * args)
                      &t->search_key);
        }
     }
-
-  return s;
-}
-
-/**
- * @brief Check if packet should be translated
- *
- * Packets aimed at outside interface and external address with active session
- * should be translated.
- *
- * @param sm            NAT main
- * @param rt            NAT runtime data
- * @param sw_if_index0  index of the inside interface
- * @param ip0           IPv4 header
- * @param proto0        NAT protocol
- * @param rx_fib_index0 RX FIB index
- *
- * @returns 0 if packet should be translated otherwise 1
- */
-static inline int
-snat_not_translate_fast (snat_main_t *sm, vlib_node_runtime_t *node,
-                        u32 sw_if_index0, ip4_header_t *ip0, u32 proto0,
-                        u32 rx_fib_index0)
-{
-  fib_node_index_t fei = FIB_NODE_INDEX_INVALID;
-  nat_outside_fib_t *outside_fib;
-  fib_prefix_t pfx = {
-    .fp_proto = FIB_PROTOCOL_IP4,
-    .fp_len = 32,
-    .fp_addr = {
-               .ip4.as_u32 = ip0->dst_address.as_u32,
-               }
-    ,
-  };
-
-  /* Don't NAT packet aimed at the intfc address */
-  if (PREDICT_FALSE (
-       is_interface_addr (sm, node, sw_if_index0, ip0->dst_address.as_u32)))
-    return 1;
-
-  fei = fib_table_lookup (rx_fib_index0, &pfx);
-  if (FIB_NODE_INDEX_INVALID != fei)
+  if (IP_PROTOCOL_TCP == t->i2of.match.proto)
     {
-      u32 sw_if_index = fib_entry_get_resolving_interface (fei);
-      if (sw_if_index == ~0)
-       {
-         vec_foreach (outside_fib, sm->outside_fibs)
-           {
-             fei = fib_table_lookup (outside_fib->fib_index, &pfx);
-             if (FIB_NODE_INDEX_INVALID != fei)
-               {
-                 sw_if_index = fib_entry_get_resolving_interface (fei);
-                 if (sw_if_index != ~0)
-                   break;
-               }
-           }
-       }
-      if (sw_if_index == ~0)
-       return 1;
-
-      snat_interface_t *i;
-      pool_foreach (i, sm->interfaces)
-       {
-         /* NAT packet aimed at outside interface */
-         if ((nat_interface_is_outside (i)) &&
-             (sw_if_index == i->sw_if_index))
-           return 0;
-       }
+      s = format (s, "\n  TCP state: %U", format_nat44_ed_tcp_state,
+                 t->tcp_state);
     }
 
-  return 1;
+  return s;
 }
 
 static int
 nat_ed_alloc_addr_and_port_with_snat_address (
-  snat_main_t *sm, u32 nat_proto, u32 thread_index, snat_address_t *a,
+  snat_main_t *sm, uproto, u32 thread_index, snat_address_t *a,
   u16 port_per_thread, u32 snat_thread_index, snat_session_t *s,
   ip4_address_t *outside_addr, u16 *outside_port)
 {
-  const u16 port_thread_offset = (port_per_thread * snat_thread_index) + 1024;
+  const u16 port_thread_offset =
+    (port_per_thread * snat_thread_index) + ED_USER_PORT_OFFSET;
+
+  /* Backup original match in case of failure */
+  const nat_6t_t match = s->o2i.match;
 
   s->o2i.match.daddr = a->addr;
   /* first try port suggested by caller */
   u16 port = clib_net_to_host_u16 (*outside_port);
   u16 port_offset = port - port_thread_offset;
-  if (port <= port_thread_offset ||
-      port > port_thread_offset + port_per_thread)
+  if (port < port_thread_offset ||
+      port >= port_thread_offset + port_per_thread)
     {
       /* need to pick a different port, suggested port doesn't fit in
        * this thread's port range */
@@ -187,27 +123,13 @@ nat_ed_alloc_addr_and_port_with_snat_address (
   u16 attempts = ED_PORT_ALLOC_ATTEMPTS;
   do
     {
-      if (NAT_PROTOCOL_ICMP == nat_proto)
+      if (IP_PROTOCOL_ICMP == proto)
        {
          s->o2i.match.sport = clib_host_to_net_u16 (port);
        }
       s->o2i.match.dport = clib_host_to_net_u16 (port);
       if (0 == nat_ed_ses_o2i_flow_hash_add_del (sm, thread_index, s, 2))
        {
-#define _(N, i, n, s)                                                         \
-  case NAT_PROTOCOL_##N:                                                      \
-    ++a->busy_##n##_port_refcounts[port];                                     \
-    a->busy_##n##_ports_per_thread[thread_index]++;                           \
-    a->busy_##n##_ports++;                                                    \
-    break;
-         switch (nat_proto)
-           {
-             foreach_nat_protocol;
-           default:
-             nat_elog_info (sm, "unknown protocol");
-             return 1;
-           }
-#undef _
          *outside_addr = a->addr;
          *outside_port = clib_host_to_net_u16 (port);
          return 0;
@@ -217,58 +139,141 @@ nat_ed_alloc_addr_and_port_with_snat_address (
       --attempts;
     }
   while (attempts > 0);
+
+  /* Revert match */
+  s->o2i.match = match;
   return 1;
 }
 
 static int
-nat_ed_alloc_addr_and_port (snat_main_t *sm, u32 rx_fib_index, u32 nat_proto,
+nat_ed_alloc_addr_and_port (snat_main_t *sm, u32 rx_fib_index,
+                           u32 tx_sw_if_index, u32 nat_proto,
                            u32 thread_index, ip4_address_t s_addr,
-                           u16 port_per_thread, u32 snat_thread_index,
+                           ip4_address_t d_addr, u32 snat_thread_index,
                            snat_session_t *s, ip4_address_t *outside_addr,
                            u16 *outside_port)
 {
-  int i;
-  snat_address_t *a, *ga = 0;
-
   if (vec_len (sm->addresses) > 0)
     {
-      int s_addr_offset = s_addr.as_u32 % vec_len (sm->addresses);
-
-      for (i = s_addr_offset; i < vec_len (sm->addresses); ++i)
+      u32 s_addr_offset = (s_addr.as_u32 + (s_addr.as_u32 >> 8) +
+                          (s_addr.as_u32 >> 16) + (s_addr.as_u32 >> 24)) %
+                         vec_len (sm->addresses);
+      snat_address_t *a, *ja = 0, *ra = 0, *ba = 0;
+      int i;
+
+      // output feature
+      if (tx_sw_if_index != ~0)
        {
-         a = sm->addresses + i;
-         if (a->fib_index == rx_fib_index)
+         for (i = s_addr_offset; i < vec_len (sm->addresses); ++i)
            {
-             return nat_ed_alloc_addr_and_port_with_snat_address (
-               sm, nat_proto, thread_index, a, port_per_thread,
-               snat_thread_index, s, outside_addr, outside_port);
+             a = sm->addresses + i;
+             if (a->fib_index == rx_fib_index)
+               {
+                 if (a->sw_if_index == tx_sw_if_index)
+                   {
+                     if ((a->addr_len != ~0) &&
+                         (a->net.as_u32 ==
+                          (d_addr.as_u32 & ip4_main.fib_masks[a->addr_len])))
+
+                       {
+                         return nat_ed_alloc_addr_and_port_with_snat_address (
+                           sm, nat_proto, thread_index, a,
+                           sm->port_per_thread, snat_thread_index, s,
+                           outside_addr, outside_port);
+                       }
+                     ra = a;
+                   }
+                 ja = a;
+               }
+             else if (a->fib_index == ~0)
+               {
+                 ba = a;
+               }
            }
-         else if (a->fib_index == ~0)
+         for (i = 0; i < s_addr_offset; ++i)
            {
-             ga = a;
+             a = sm->addresses + i;
+             if (a->fib_index == rx_fib_index)
+               {
+                 if (a->sw_if_index == tx_sw_if_index)
+                   {
+                     if ((a->addr_len != ~0) &&
+                         (a->net.as_u32 ==
+                          (d_addr.as_u32 & ip4_main.fib_masks[a->addr_len])))
+
+                       {
+                         return nat_ed_alloc_addr_and_port_with_snat_address (
+                           sm, nat_proto, thread_index, a,
+                           sm->port_per_thread, snat_thread_index, s,
+                           outside_addr, outside_port);
+                       }
+                     ra = a;
+                   }
+                 ja = a;
+               }
+             else if (a->fib_index == ~0)
+               {
+                 ba = a;
+               }
            }
-       }
-
-      for (i = 0; i < s_addr_offset; ++i)
-       {
-         a = sm->addresses + i;
-         if (a->fib_index == rx_fib_index)
+         if (ra)
            {
              return nat_ed_alloc_addr_and_port_with_snat_address (
-               sm, nat_proto, thread_index, a, port_per_thread,
+               sm, nat_proto, thread_index, ra, sm->port_per_thread,
                snat_thread_index, s, outside_addr, outside_port);
            }
-         else if (a->fib_index == ~0)
+       }
+      else
+       {
+         // first try nat pool addresses to sw interface addreses mappings
+         for (i = s_addr_offset; i < vec_len (sm->addresses); ++i)
            {
-             ga = a;
+             a = sm->addresses + i;
+             if (a->fib_index == rx_fib_index)
+               {
+                 if ((a->addr_len != ~0) &&
+                     (a->net.as_u32 ==
+                      (d_addr.as_u32 & ip4_main.fib_masks[a->addr_len])))
+                   {
+                     return nat_ed_alloc_addr_and_port_with_snat_address (
+                       sm, nat_proto, thread_index, a, sm->port_per_thread,
+                       snat_thread_index, s, outside_addr, outside_port);
+                   }
+                 ja = a;
+               }
+             else if (a->fib_index == ~0)
+               {
+                 ba = a;
+               }
+           }
+         for (i = 0; i < s_addr_offset; ++i)
+           {
+             a = sm->addresses + i;
+             if (a->fib_index == rx_fib_index)
+               {
+                 if ((a->addr_len != ~0) &&
+                     (a->net.as_u32 ==
+                      (d_addr.as_u32 & ip4_main.fib_masks[a->addr_len])))
+                   {
+                     return nat_ed_alloc_addr_and_port_with_snat_address (
+                       sm, nat_proto, thread_index, a, sm->port_per_thread,
+                       snat_thread_index, s, outside_addr, outside_port);
+                   }
+                 ja = a;
+               }
+             else if (a->fib_index == ~0)
+               {
+                 ba = a;
+               }
            }
        }
 
-      if (ga)
+      if (ja || ba)
        {
+         a = ja ? ja : ba;
          return nat_ed_alloc_addr_and_port_with_snat_address (
-           sm, nat_proto, thread_index, a, port_per_thread, snat_thread_index,
-           s, outside_addr, outside_port);
+           sm, nat_proto, thread_index, a, sm->port_per_thread,
+           snat_thread_index, s, outside_addr, outside_port);
        }
     }
   /* Totally out of translations to use... */
@@ -276,89 +281,172 @@ nat_ed_alloc_addr_and_port (snat_main_t *sm, u32 rx_fib_index, u32 nat_proto,
   return 1;
 }
 
+static_always_inline int
+nat44_ed_external_sm_lookup (snat_main_t *sm, ip4_address_t match_addr,
+                            u16 match_port, ip_protocol_t match_protocol,
+                            ip4_address_t *daddr, u16 *dport)
+{
+  snat_static_mapping_t *m =
+    nat44_ed_sm_o2i_lookup (sm, match_addr, match_port, 0, match_protocol);
+  if (!m)
+    {
+      /* Try address only mapping */
+      m = nat44_ed_sm_o2i_lookup (sm, match_addr, 0, 0, 0);
+      if (!m)
+       return 0;
+    }
+  *daddr = m->local_addr;
+  if (dport)
+    {
+      /* Address only mapping doesn't change port */
+      *dport = is_sm_addr_only (m->flags) ? match_port : m->local_port;
+    }
+  return 1;
+}
+
+static_always_inline vrf_table_t *
+get_vrf_table_by_fib (u32 fib_index)
+{
+  snat_main_t *sm = &snat_main;
+  vrf_table_t *t;
+
+  pool_foreach (t, sm->vrf_tables)
+    {
+      if (fib_index == t->table_fib_index)
+       {
+         return t;
+       }
+    }
+
+  return 0;
+}
+
 static_always_inline u32
-nat_outside_fib_index_lookup (snat_main_t * sm, ip4_address_t addr)
+get_tx_fib_index (u32 rx_fib_index, ip4_address_t addr)
 {
   fib_node_index_t fei = FIB_NODE_INDEX_INVALID;
-  nat_outside_fib_t *outside_fib;
   fib_prefix_t pfx = {
     .fp_proto = FIB_PROTOCOL_IP4,
     .fp_len = 32,
     .fp_addr = {.ip4.as_u32 = addr.as_u32,}
     ,
   };
-  // TODO: multiple vrfs none can resolve addr
-  vec_foreach (outside_fib, sm->outside_fibs)
+
+  snat_main_t *sm = &snat_main;
+  vrf_table_t *t = get_vrf_table_by_fib (rx_fib_index);
+  // default to rx fib
+  u32 tx_fib_index = rx_fib_index;
+
+  if (0 != t)
+    {
+      // managed routes to other fibs
+      vrf_route_t *r;
+      pool_foreach (r, t->routes)
+       {
+         fei = fib_table_lookup (r->fib_index, &pfx);
+         if ((FIB_NODE_INDEX_INVALID != fei) &&
+             (~0 != fib_entry_get_resolving_interface (fei)))
+           {
+             tx_fib_index = r->fib_index;
+             break;
+           }
+       }
+    }
+  else
     {
-      fei = fib_table_lookup (outside_fib->fib_index, &pfx);
-      if (FIB_NODE_INDEX_INVALID != fei)
-        {
-          if (fib_entry_get_resolving_interface (fei) != ~0)
-            {
-              return outside_fib->fib_index;
-            }
-        }
+      // default to configured fib
+      tx_fib_index = sm->outside_fib_index;
+
+      // default routes to other fibs
+      nat_fib_t *f;
+      vec_foreach (f, sm->outside_fibs)
+       {
+         fei = fib_table_lookup (f->fib_index, &pfx);
+         if ((FIB_NODE_INDEX_INVALID != fei) &&
+             (~0 != fib_entry_get_resolving_interface (fei)))
+           {
+             tx_fib_index = f->fib_index;
+             break;
+           }
+       }
     }
-  return ~0;
+
+  return tx_fib_index;
 }
 
 static_always_inline int
-nat44_ed_external_sm_lookup (snat_main_t *sm, ip4_address_t match_addr,
-                            u16 match_port, nat_protocol_t match_protocol,
-                            u32 match_fib_index, ip4_address_t *daddr,
-                            u16 *dport)
+is_destination_resolvable (u32 rx_fib_index, ip4_address_t addr)
 {
-  clib_bihash_kv_8_8_t kv, value;
-  init_nat_k (&kv, match_addr, match_port, match_fib_index, match_protocol);
-  if (clib_bihash_search_8_8 (&sm->static_mapping_by_external, &kv, &value))
+  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 = addr.as_u32,}
+    ,
+  };
+
+  snat_main_t *sm = &snat_main;
+  vrf_table_t *t = get_vrf_table_by_fib (rx_fib_index);
+  u32 ii;
+
+  if (0 != t)
     {
-      /* Try address only mapping */
-      init_nat_k (&kv, match_addr, 0, 0, 0);
-      if (clib_bihash_search_8_8 (&sm->static_mapping_by_external, &kv,
-                                 &value))
-       return 0;
+      // managed routes to other fibs
+      vrf_route_t *r;
+      pool_foreach (r, t->routes)
+       {
+         fei = fib_table_lookup (r->fib_index, &pfx);
+         if ((FIB_NODE_INDEX_INVALID != fei) &&
+             (~0 != (ii = fib_entry_get_resolving_interface (fei))))
+           {
+             return 1;
+           }
+       }
     }
-
-  snat_static_mapping_t *m =
-    pool_elt_at_index (sm->static_mappings, value.value);
-  *daddr = m->local_addr;
-  if (dport)
+  else
     {
-      /* Address only mapping doesn't change port */
-      *dport = is_addr_only_static_mapping (m) ? match_port : m->local_port;
+      // default routes to other fibs
+      nat_fib_t *f;
+      vec_foreach (f, sm->outside_fibs)
+       {
+         fei = fib_table_lookup (f->fib_index, &pfx);
+         if ((FIB_NODE_INDEX_INVALID != fei) &&
+             (~0 != (ii = fib_entry_get_resolving_interface (fei))))
+           {
+             snat_interface_t *i;
+             pool_foreach (i, sm->interfaces)
+               {
+                 if ((nat44_ed_is_interface_outside (i)) &&
+                     (ii == i->sw_if_index))
+                   {
+                     return 1;
+                   }
+               }
+           }
+       }
     }
-  return 1;
+
+  return 0;
 }
 
 static u32
-slow_path_ed (snat_main_t *sm, vlib_buffer_t *b, ip4_address_t l_addr,
-             ip4_address_t r_addr, u16 l_port, u16 r_port, u8 proto,
-             u32 rx_fib_index, snat_session_t **sessionp,
-             vlib_node_runtime_t *node, u32 next, u32 thread_index, f64 now)
+slow_path_ed (vlib_main_t *vm, snat_main_t *sm, vlib_buffer_t *b,
+             ip4_address_t l_addr, ip4_address_t r_addr, u16 l_port,
+             u16 r_port, u8 proto, u32 rx_fib_index, u32 tx_sw_if_index,
+             snat_session_t **sessionp, vlib_node_runtime_t *node, u32 next,
+             u32 thread_index, f64 now)
 {
   snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
   ip4_address_t outside_addr;
   u16 outside_port;
-  u32 outside_fib_index;
-  u8 is_identity_nat;
+  u32 tx_fib_index;
+  u8 is_identity_nat = 0;
 
-  u32 nat_proto = ip_proto_to_nat_proto (proto);
   snat_session_t *s = NULL;
   lb_nat_type_t lb = 0;
   ip4_address_t daddr = r_addr;
   u16 dport = r_port;
 
-  if (PREDICT_TRUE (nat_proto == NAT_PROTOCOL_TCP))
-    {
-      if (PREDICT_FALSE
-         (!tcp_flags_is_init
-          (vnet_buffer (b)->ip.reass.icmp_type_or_tcp_flags)))
-       {
-         b->error = node->errors[NAT_IN2OUT_ED_ERROR_NON_SYN];
-         return NAT_NEXT_DROP;
-       }
-    }
-
   if (PREDICT_FALSE
       (nat44_ed_maximum_sessions_exceeded (sm, rx_fib_index, thread_index)))
     {
@@ -372,68 +460,61 @@ slow_path_ed (snat_main_t *sm, vlib_buffer_t *b, ip4_address_t l_addr,
        }
     }
 
-  outside_fib_index = sm->outside_fib_index;
-
-  switch (vec_len (sm->outside_fibs))
-    {
-    case 0:
-      outside_fib_index = sm->outside_fib_index;
-      break;
-    case 1:
-      outside_fib_index = sm->outside_fibs[0].fib_index;
-      break;
-    default:
-      outside_fib_index = nat_outside_fib_index_lookup (sm, r_addr);
-      break;
-    }
-
   ip4_address_t sm_addr;
   u16 sm_port;
   u32 sm_fib_index;
-  /* First try to match static mapping by local address and port */
-  int is_sm;
-  if (snat_static_mapping_match (sm, l_addr, l_port, rx_fib_index, nat_proto,
-                                &sm_addr, &sm_port, &sm_fib_index, 0, 0, 0,
-                                &lb, 0, &is_identity_nat, 0))
-    {
-      is_sm = 0;
-    }
-  else
+  int is_sm = 0;
+  // First try to match static mapping by local address and port
+  if (!snat_static_mapping_match (vm, l_addr, l_port, rx_fib_index, proto,
+                                 &sm_addr, &sm_port, &sm_fib_index, 0, 0, 0,
+                                 &lb, 0, &is_identity_nat, 0))
     {
+      if (PREDICT_FALSE (is_identity_nat))
+       {
+         *sessionp = NULL;
+         return next;
+       }
       is_sm = 1;
     }
 
-  if (PREDICT_FALSE (is_sm && is_identity_nat))
+  if (PREDICT_TRUE (proto == IP_PROTOCOL_TCP))
     {
-      *sessionp = NULL;
-      return next;
+      if (PREDICT_FALSE (!tcp_flags_is_init (
+           vnet_buffer (b)->ip.reass.icmp_type_or_tcp_flags)))
+       {
+         b->error = node->errors[NAT_IN2OUT_ED_ERROR_NON_SYN];
+         return NAT_NEXT_DROP;
+       }
     }
 
   s = nat_ed_session_alloc (sm, thread_index, now, proto);
   ASSERT (s);
 
+  tx_fib_index = get_tx_fib_index (rx_fib_index, r_addr);
+
   if (!is_sm)
     {
       s->in2out.addr = l_addr;
       s->in2out.port = l_port;
-      s->nat_proto = nat_proto;
+      s->proto = proto;
       s->in2out.fib_index = rx_fib_index;
-      s->out2in.fib_index = outside_fib_index;
+      s->out2in.fib_index = tx_fib_index;
 
       // suggest using local port to allocation function
       outside_port = l_port;
 
-      // hairpinning?
-      int is_hairpinning = nat44_ed_external_sm_lookup (
-       sm, r_addr, r_port, nat_proto, outside_fib_index, &daddr, &dport);
-      s->flags |= is_hairpinning * SNAT_SESSION_FLAG_HAIRPINNING;
+      if (PREDICT_FALSE (nat44_ed_external_sm_lookup (sm, r_addr, r_port,
+                                                     proto, &daddr, &dport)))
+       {
+         s->flags |= SNAT_SESSION_FLAG_HAIRPINNING;
+       }
 
       // destination addr/port updated with real values in
       // nat_ed_alloc_addr_and_port
       nat_6t_o2i_flow_init (sm, thread_index, s, daddr, dport, daddr, 0,
                            s->out2in.fib_index, proto);
       nat_6t_flow_daddr_rewrite_set (&s->o2i, l_addr.as_u32);
-      if (NAT_PROTOCOL_ICMP == nat_proto)
+      if (IP_PROTOCOL_ICMP == proto)
        {
          nat_6t_flow_icmp_id_rewrite_set (&s->o2i, l_port);
        }
@@ -442,11 +523,11 @@ slow_path_ed (snat_main_t *sm, vlib_buffer_t *b, ip4_address_t l_addr,
          nat_6t_flow_dport_rewrite_set (&s->o2i, l_port);
        }
       nat_6t_flow_txfib_rewrite_set (&s->o2i, rx_fib_index);
+      nat_6t_flow_saddr_rewrite_set (&s->o2i, r_addr.as_u32);
 
       if (nat_ed_alloc_addr_and_port (
-           sm, rx_fib_index, nat_proto, thread_index, l_addr,
-           sm->port_per_thread, tsm->snat_thread_index, s, &outside_addr,
-           &outside_port))
+           sm, rx_fib_index, tx_sw_if_index, proto, thread_index, l_addr,
+           r_addr, tsm->snat_thread_index, s, &outside_addr, &outside_port))
        {
          nat_elog_notice (sm, "addresses exhausted");
          b->error = node->errors[NAT_IN2OUT_ED_ERROR_OUT_OF_PORTS];
@@ -463,17 +544,17 @@ slow_path_ed (snat_main_t *sm, vlib_buffer_t *b, ip4_address_t l_addr,
       s->out2in.port = outside_port = sm_port;
       s->in2out.addr = l_addr;
       s->in2out.port = l_port;
-      s->nat_proto = nat_proto;
+      s->proto = proto;
       s->in2out.fib_index = rx_fib_index;
-      s->out2in.fib_index = outside_fib_index;
+      s->out2in.fib_index = tx_fib_index;
       s->flags |= SNAT_SESSION_FLAG_STATIC_MAPPING;
 
       // hairpinning?
-      int is_hairpinning = nat44_ed_external_sm_lookup (
-       sm, r_addr, r_port, nat_proto, outside_fib_index, &daddr, &dport);
+      int is_hairpinning = nat44_ed_external_sm_lookup (sm, r_addr, r_port,
+                                                       proto, &daddr, &dport);
       s->flags |= is_hairpinning * SNAT_SESSION_FLAG_HAIRPINNING;
 
-      if (NAT_PROTOCOL_ICMP == nat_proto)
+      if (IP_PROTOCOL_ICMP == proto)
        {
          nat_6t_o2i_flow_init (sm, thread_index, s, daddr, sm_port, sm_addr,
                                sm_port, s->out2in.fib_index, proto);
@@ -487,6 +568,7 @@ slow_path_ed (snat_main_t *sm, vlib_buffer_t *b, ip4_address_t l_addr,
        }
       nat_6t_flow_daddr_rewrite_set (&s->o2i, l_addr.as_u32);
       nat_6t_flow_txfib_rewrite_set (&s->o2i, rx_fib_index);
+      nat_6t_flow_saddr_rewrite_set (&s->o2i, r_addr.as_u32);
       if (nat_ed_ses_o2i_flow_hash_add_del (sm, thread_index, s, 2))
        {
          nat_elog_notice (sm, "out2in key add failed");
@@ -496,7 +578,6 @@ slow_path_ed (snat_main_t *sm, vlib_buffer_t *b, ip4_address_t l_addr,
 
   if (lb)
     s->flags |= SNAT_SESSION_FLAG_LOAD_BALANCING;
-  s->flags |= SNAT_SESSION_FLAG_ENDPOINT_DEPENDENT;
   s->ext_host_addr = r_addr;
   s->ext_host_port = r_port;
 
@@ -504,7 +585,8 @@ slow_path_ed (snat_main_t *sm, vlib_buffer_t *b, ip4_address_t l_addr,
                        rx_fib_index, proto);
   nat_6t_flow_saddr_rewrite_set (&s->i2o, outside_addr.as_u32);
   nat_6t_flow_daddr_rewrite_set (&s->i2o, daddr.as_u32);
-  if (NAT_PROTOCOL_ICMP == nat_proto)
+
+  if (IP_PROTOCOL_ICMP == proto)
     {
       nat_6t_flow_icmp_id_rewrite_set (&s->i2o, outside_port);
     }
@@ -513,7 +595,7 @@ slow_path_ed (snat_main_t *sm, vlib_buffer_t *b, ip4_address_t l_addr,
       nat_6t_flow_sport_rewrite_set (&s->i2o, outside_port);
       nat_6t_flow_dport_rewrite_set (&s->i2o, dport);
     }
-  nat_6t_flow_txfib_rewrite_set (&s->i2o, outside_fib_index);
+  nat_6t_flow_txfib_rewrite_set (&s->i2o, tx_fib_index);
 
   if (nat_ed_ses_i2o_flow_hash_add_del (sm, thread_index, s, 1))
     {
@@ -522,17 +604,14 @@ slow_path_ed (snat_main_t *sm, vlib_buffer_t *b, ip4_address_t l_addr,
     }
 
   /* log NAT event */
-  nat_ipfix_logging_nat44_ses_create (thread_index,
-                                     s->in2out.addr.as_u32,
-                                     s->out2in.addr.as_u32,
-                                     s->nat_proto,
-                                     s->in2out.port,
-                                     s->out2in.port, s->in2out.fib_index);
+  nat_ipfix_logging_nat44_ses_create (
+    thread_index, s->in2out.addr.as_u32, s->out2in.addr.as_u32, s->proto,
+    s->in2out.port, s->out2in.port, s->in2out.fib_index);
 
   nat_syslog_nat44_sadd (0, s->in2out.fib_index, &s->in2out.addr,
                         s->in2out.port, &s->ext_host_nat_addr,
                         s->ext_host_nat_port, &s->out2in.addr, s->out2in.port,
-                        &s->ext_host_addr, s->ext_host_port, s->nat_proto, 0);
+                        &s->ext_host_addr, s->ext_host_port, s->proto, 0);
 
   per_vrf_sessions_register_session (s, thread_index);
 
@@ -541,12 +620,6 @@ slow_path_ed (snat_main_t *sm, vlib_buffer_t *b, ip4_address_t l_addr,
 error:
   if (s)
     {
-      if (!is_sm)
-       {
-         snat_free_outside_address_and_port (sm->addresses, thread_index,
-                                             &outside_addr, outside_port,
-                                             nat_proto);
-       }
       nat_ed_session_delete (sm, s, thread_index, 1);
     }
   *sessionp = s = NULL;
@@ -554,37 +627,55 @@ error:
 }
 
 static_always_inline int
-nat44_ed_not_translate (snat_main_t *sm, vlib_node_runtime_t *node,
+nat44_ed_not_translate (vlib_main_t *vm, vlib_node_runtime_t *node,
                        u32 sw_if_index, vlib_buffer_t *b, ip4_header_t *ip,
-                       u32 proto, u32 rx_fib_index, u32 thread_index)
+                       u32 proto, u32 rx_fib_index)
 {
+  snat_main_t *sm = &snat_main;
+
   clib_bihash_kv_16_8_t kv, value;
+  ip4_address_t placeholder_addr;
+  u32 placeholder_fib_index;
+  u16 placeholder_port;
+
+  init_ed_k (&kv, ip->dst_address.as_u32,
+            vnet_buffer (b)->ip.reass.l4_dst_port, ip->src_address.as_u32,
+            vnet_buffer (b)->ip.reass.l4_src_port, sm->outside_fib_index,
+            ip->protocol);
+
+  // do nat if active session or is static mapping
+  if (!clib_bihash_search_16_8 (&sm->flow_hash, &kv, &value) ||
+      !snat_static_mapping_match (
+       vm, ip->dst_address, vnet_buffer (b)->ip.reass.l4_dst_port,
+       sm->outside_fib_index, proto, &placeholder_addr, &placeholder_port,
+       &placeholder_fib_index, 1, 0, 0, 0, 0, 0, 0))
+    {
+      return 0;
+    }
 
-  init_ed_k (&kv, ip->dst_address, vnet_buffer (b)->ip.reass.l4_dst_port,
-            ip->src_address, vnet_buffer (b)->ip.reass.l4_src_port,
-            sm->outside_fib_index, ip->protocol);
+  // do not nat if forwarding enabled
+  if (sm->forwarding_enabled)
+    {
+      return 1;
+    }
 
-  /* NAT packet aimed at external address if has active sessions */
-  if (clib_bihash_search_16_8 (&sm->flow_hash, &kv, &value))
+  // do not nat packet aimed at the interface address
+  if (PREDICT_FALSE (
+       is_interface_addr (sm, node, sw_if_index, ip->dst_address.as_u32)))
     {
-      /* or is static mappings */
-      ip4_address_t placeholder_addr;
-      u16 placeholder_port;
-      u32 placeholder_fib_index;
-      if (!snat_static_mapping_match (
-           sm, ip->dst_address, vnet_buffer (b)->ip.reass.l4_dst_port,
-           sm->outside_fib_index, proto, &placeholder_addr, &placeholder_port,
-           &placeholder_fib_index, 1, 0, 0, 0, 0, 0, 0))
-       return 0;
+      return 1;
     }
-  else
-    return 0;
 
-  if (sm->forwarding_enabled)
-    return 1;
+  // do nat packets with resolvable destination
+  // destination can be resolved either by:
+  // a) vrf routing table entry
+  // b) (non output feature) outside interface fib
+  if (is_destination_resolvable (rx_fib_index, ip->dst_address))
+    {
+      return 0;
+    }
 
-  return snat_not_translate_fast (sm, node, sw_if_index, ip, proto,
-                                 rx_fib_index);
+  return 1;
 }
 
 static_always_inline int
@@ -608,18 +699,18 @@ nat_not_translate_output_feature_fwd (snat_main_t * sm, ip4_header_t * ip,
                                              &lookup_sport, &lookup_daddr,
                                              &lookup_dport, &lookup_protocol))
        return 0;
-      init_ed_k (&kv, lookup_saddr, lookup_sport, lookup_daddr, lookup_dport,
-                0, lookup_protocol);
+      init_ed_k (&kv, lookup_saddr.as_u32, lookup_sport, lookup_daddr.as_u32,
+                lookup_dport, 0, lookup_protocol);
     }
   else if (ip->protocol == IP_PROTOCOL_UDP || ip->protocol == IP_PROTOCOL_TCP)
     {
-      init_ed_k (&kv, ip->src_address, vnet_buffer (b)->ip.reass.l4_src_port,
-                ip->dst_address, vnet_buffer (b)->ip.reass.l4_dst_port, 0,
-                ip->protocol);
+      init_ed_k (&kv, ip->src_address.as_u32,
+                vnet_buffer (b)->ip.reass.l4_src_port, ip->dst_address.as_u32,
+                vnet_buffer (b)->ip.reass.l4_dst_port, 0, ip->protocol);
     }
   else
     {
-      init_ed_k (&kv, ip->src_address, 0, ip->dst_address, 0, 0,
+      init_ed_k (&kv, ip->src_address.as_u32, 0, ip->dst_address.as_u32, 0, 0,
                 ip->protocol);
     }
 
@@ -630,11 +721,13 @@ nat_not_translate_output_feature_fwd (snat_main_t * sm, ip4_header_t * ip,
        pool_elt_at_index (tsm->sessions,
                           ed_value_get_session_index (&value));
 
-      if (is_fwd_bypass_session (s))
+      if (na44_ed_is_fwd_bypass_session (s))
        {
          if (ip->protocol == IP_PROTOCOL_TCP)
            {
-             nat44_set_tcp_session_state_i2o (sm, now, s, b, thread_index);
+             nat44_set_tcp_session_state_i2o (
+               sm, now, s, vnet_buffer (b)->ip.reass.icmp_type_or_tcp_flags,
+               thread_index);
            }
          /* Accounting */
          nat44_session_update_counters (s, now,
@@ -652,10 +745,11 @@ nat_not_translate_output_feature_fwd (snat_main_t * sm, ip4_header_t * ip,
 }
 
 static_always_inline int
-nat44_ed_not_translate_output_feature (snat_main_t * sm, ip4_header_t * ip,
-                                      u16 src_port, u16 dst_port,
-                                      u32 thread_index, u32 rx_sw_if_index,
-                                      u32 tx_sw_if_index, f64 now)
+nat44_ed_not_translate_output_feature (snat_main_t *sm, vlib_buffer_t *b,
+                                      ip4_header_t *ip, u16 src_port,
+                                      u16 dst_port, u32 thread_index,
+                                      u32 rx_sw_if_index, u32 tx_sw_if_index,
+                                      int is_multi_worker)
 {
   clib_bihash_kv_16_8_t kv, value;
   snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
@@ -665,26 +759,40 @@ nat44_ed_not_translate_output_feature (snat_main_t * sm, ip4_header_t * ip,
   u32 tx_fib_index = ip4_fib_table_get_index_for_sw_if_index (tx_sw_if_index);
 
   /* src NAT check */
-  init_ed_k (&kv, ip->src_address, src_port, ip->dst_address, dst_port,
-            tx_fib_index, ip->protocol);
+  init_ed_k (&kv, ip->src_address.as_u32, src_port, ip->dst_address.as_u32,
+            dst_port, tx_fib_index, ip->protocol);
   if (!clib_bihash_search_16_8 (&sm->flow_hash, &kv, &value))
     {
       ASSERT (thread_index == ed_value_get_thread_index (&value));
       s =
        pool_elt_at_index (tsm->sessions,
                           ed_value_get_session_index (&value));
-      if (nat44_is_ses_closed (s)
-         && (!s->tcp_closed_timestamp || now >= s->tcp_closed_timestamp))
-       {
-         nat_free_session_data (sm, s, thread_index, 0);
-         nat_ed_session_delete (sm, s, thread_index, 1);
-       }
       return 1;
     }
 
   /* dst NAT check */
-  init_ed_k (&kv, ip->dst_address, dst_port, ip->src_address, src_port,
-            rx_fib_index, ip->protocol);
+  if (is_multi_worker &&
+      PREDICT_TRUE (!pool_is_free_index (
+       tsm->sessions, vnet_buffer2 (b)->nat.cached_dst_nat_session_index)))
+    {
+      nat_6t_t lookup;
+      lookup.fib_index = rx_fib_index;
+      lookup.proto = ip->protocol;
+      lookup.daddr.as_u32 = ip->src_address.as_u32;
+      lookup.dport = src_port;
+      lookup.saddr.as_u32 = ip->dst_address.as_u32;
+      lookup.sport = dst_port;
+      s = pool_elt_at_index (
+       tsm->sessions, vnet_buffer2 (b)->nat.cached_dst_nat_session_index);
+      if (PREDICT_TRUE (nat_6t_t_eq (&s->i2o.match, &lookup)))
+       {
+         goto skip_dst_nat_lookup;
+       }
+      s = NULL;
+    }
+
+  init_ed_k (&kv, ip->dst_address.as_u32, dst_port, ip->src_address.as_u32,
+            src_port, rx_fib_index, ip->protocol);
   if (!clib_bihash_search_16_8 (&sm->flow_hash, &kv, &value))
     {
       ASSERT (thread_index == ed_value_get_thread_index (&value));
@@ -692,15 +800,17 @@ nat44_ed_not_translate_output_feature (snat_main_t * sm, ip4_header_t * ip,
        pool_elt_at_index (tsm->sessions,
                           ed_value_get_session_index (&value));
 
-      if (is_fwd_bypass_session (s))
+    skip_dst_nat_lookup:
+      if (na44_ed_is_fwd_bypass_session (s))
        return 0;
 
       /* hairpinning */
       pool_foreach (i, sm->output_feature_interfaces)
-       {
-        if ((nat_interface_is_inside (i)) && (rx_sw_if_index == i->sw_if_index))
-           return 0;
-      }
+       {
+         if ((nat44_ed_is_interface_inside (i)) &&
+             (rx_sw_if_index == i->sw_if_index))
+           return 0;
+       }
       return 1;
     }
 
@@ -710,9 +820,10 @@ nat44_ed_not_translate_output_feature (snat_main_t * sm, ip4_header_t * ip,
 static inline u32
 icmp_in2out_ed_slow_path (snat_main_t *sm, vlib_buffer_t *b, ip4_header_t *ip,
                          icmp46_header_t *icmp, u32 sw_if_index,
-                         u32 rx_fib_index, vlib_node_runtime_t *node,
-                         u32 next, f64 now, u32 thread_index,
-                         nat_protocol_t nat_proto, snat_session_t **s_p)
+                         u32 tx_sw_if_index, u32 rx_fib_index,
+                         vlib_node_runtime_t *node, u32 next, f64 now,
+                         u32 thread_index, snat_session_t **s_p,
+                         int is_multi_worker)
 {
   vlib_main_t *vm = vlib_get_main ();
   u16 checksum;
@@ -731,20 +842,19 @@ icmp_in2out_ed_slow_path (snat_main_t *sm, vlib_buffer_t *b, ip4_header_t *ip,
       return NAT_NEXT_DROP;
     }
 
-  if (vnet_buffer (b)->sw_if_index[VLIB_TX] != ~0)
+  if (tx_sw_if_index != ~0)
     {
       if (PREDICT_FALSE (nat44_ed_not_translate_output_feature (
-           sm, ip, lookup_sport, lookup_dport, thread_index, sw_if_index,
-           vnet_buffer (b)->sw_if_index[VLIB_TX], now)))
+           sm, b, ip, lookup_sport, lookup_dport, thread_index, sw_if_index,
+           tx_sw_if_index, is_multi_worker)))
        {
          return next;
        }
     }
   else
     {
-      if (PREDICT_FALSE (nat44_ed_not_translate (sm, node, sw_if_index, b, ip,
-                                                NAT_PROTOCOL_ICMP,
-                                                rx_fib_index, thread_index)))
+      if (PREDICT_FALSE (nat44_ed_not_translate (
+           vm, node, sw_if_index, b, ip, IP_PROTOCOL_ICMP, rx_fib_index)))
        {
          return next;
        }
@@ -757,9 +867,10 @@ icmp_in2out_ed_slow_path (snat_main_t *sm, vlib_buffer_t *b, ip4_header_t *ip,
       return NAT_NEXT_DROP;
     }
 
-  next = slow_path_ed (sm, b, ip->src_address, ip->dst_address, lookup_sport,
-                      lookup_dport, ip->protocol, rx_fib_index, &s, node,
-                      next, thread_index, vlib_time_now (vm));
+  next =
+    slow_path_ed (vm, sm, b, ip->src_address, ip->dst_address, lookup_sport,
+                 lookup_dport, ip->protocol, rx_fib_index, tx_sw_if_index, &s,
+                 node, next, thread_index, vlib_time_now (vm));
 
   if (NAT_NEXT_DROP == next)
     goto out;
@@ -797,12 +908,11 @@ nat44_ed_in2out_slowpath_unknown_proto (snat_main_t *sm, vlib_buffer_t *b,
                                        vlib_main_t *vm,
                                        vlib_node_runtime_t *node)
 {
-  clib_bihash_kv_8_8_t kv, value;
   clib_bihash_kv_16_8_t s_kv, s_value;
   snat_static_mapping_t *m = NULL;
   snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
   snat_session_t *s = NULL;
-  u32 outside_fib_index = sm->outside_fib_index;
+  u32 tx_fib_index;
   int i;
   ip4_address_t new_src_addr = { 0 };
   ip4_address_t new_dst_addr = ip->dst_address;
@@ -817,25 +927,13 @@ nat44_ed_in2out_slowpath_unknown_proto (snat_main_t *sm, vlib_buffer_t *b,
       return 0;
     }
 
-  switch (vec_len (sm->outside_fibs))
-    {
-    case 0:
-      outside_fib_index = sm->outside_fib_index;
-      break;
-    case 1:
-      outside_fib_index = sm->outside_fibs[0].fib_index;
-      break;
-    default:
-      outside_fib_index = nat_outside_fib_index_lookup (sm, ip->dst_address);
-      break;
-    }
-
-  init_nat_k (&kv, ip->src_address, 0, rx_fib_index, 0);
+  tx_fib_index = get_tx_fib_index (rx_fib_index, ip->dst_address);
 
-  /* Try to find static mapping first */
-  if (!clib_bihash_search_8_8 (&sm->static_mapping_by_local, &kv, &value))
+  // Try to find static mapping first
+  m = nat44_ed_sm_i2o_lookup (sm, ip->src_address, 0, rx_fib_index,
+                             ip->protocol);
+  if (m)
     {
-      m = pool_elt_at_index (sm->static_mappings, value.value);
       new_src_addr = m->external_addr;
     }
   else
@@ -844,8 +942,9 @@ nat44_ed_in2out_slowpath_unknown_proto (snat_main_t *sm, vlib_buffer_t *b,
        {
          if (s->ext_host_addr.as_u32 == ip->dst_address.as_u32)
            {
-             init_ed_k (&s_kv, s->out2in.addr, 0, ip->dst_address, 0,
-                        outside_fib_index, ip->protocol);
+             init_ed_k (&s_kv, s->out2in.addr.as_u32, 0,
+                        ip->dst_address.as_u32, 0, tx_fib_index,
+                        ip->protocol);
              if (clib_bihash_search_16_8 (&sm->flow_hash, &s_kv, &s_value))
                {
                  new_src_addr = s->out2in.addr;
@@ -858,8 +957,9 @@ nat44_ed_in2out_slowpath_unknown_proto (snat_main_t *sm, vlib_buffer_t *b,
        {
          for (i = 0; i < vec_len (sm->addresses); i++)
            {
-             init_ed_k (&s_kv, sm->addresses[i].addr, 0, ip->dst_address, 0,
-                        outside_fib_index, ip->protocol);
+             init_ed_k (&s_kv, sm->addresses[i].addr.as_u32, 0,
+                        ip->dst_address.as_u32, 0, tx_fib_index,
+                        ip->protocol);
              if (clib_bihash_search_16_8 (&sm->flow_hash, &s_kv, &s_value))
                {
                  new_src_addr = sm->addresses[i].addr;
@@ -885,28 +985,25 @@ nat44_ed_in2out_slowpath_unknown_proto (snat_main_t *sm, vlib_buffer_t *b,
   nat_6t_i2o_flow_init (sm, thread_index, s, ip->src_address, 0,
                        ip->dst_address, 0, rx_fib_index, ip->protocol);
   nat_6t_flow_saddr_rewrite_set (&s->i2o, new_src_addr.as_u32);
-  nat_6t_flow_txfib_rewrite_set (&s->i2o, outside_fib_index);
+  nat_6t_flow_txfib_rewrite_set (&s->i2o, tx_fib_index);
 
   // hairpinning?
-  int is_hairpinning =
-    nat44_ed_external_sm_lookup (sm, ip->dst_address, 0, NAT_PROTOCOL_OTHER,
-                                outside_fib_index, &new_dst_addr, NULL);
+  int is_hairpinning = nat44_ed_external_sm_lookup (
+    sm, ip->dst_address, 0, ip->protocol, &new_dst_addr, NULL);
   s->flags |= is_hairpinning * SNAT_SESSION_FLAG_HAIRPINNING;
 
   nat_6t_flow_daddr_rewrite_set (&s->i2o, new_dst_addr.as_u32);
-  nat_6t_flow_txfib_rewrite_set (&s->i2o, outside_fib_index);
+  nat_6t_flow_txfib_rewrite_set (&s->i2o, tx_fib_index);
 
   nat_6t_o2i_flow_init (sm, thread_index, s, new_dst_addr, 0, new_src_addr, 0,
-                       outside_fib_index, ip->protocol);
+                       tx_fib_index, ip->protocol);
   nat_6t_flow_saddr_rewrite_set (&s->o2i, ip->dst_address.as_u32);
   nat_6t_flow_daddr_rewrite_set (&s->o2i, ip->src_address.as_u32);
   nat_6t_flow_txfib_rewrite_set (&s->o2i, rx_fib_index);
 
   s->ext_host_addr.as_u32 = ip->dst_address.as_u32;
-  s->flags |= SNAT_SESSION_FLAG_UNKNOWN_PROTO;
-  s->flags |= SNAT_SESSION_FLAG_ENDPOINT_DEPENDENT;
   s->out2in.addr.as_u32 = new_src_addr.as_u32;
-  s->out2in.fib_index = outside_fib_index;
+  s->out2in.fib_index = tx_fib_index;
   s->in2out.addr.as_u32 = ip->src_address.as_u32;
   s->in2out.fib_index = rx_fib_index;
   s->in2out.port = s->out2in.port = ip->protocol;
@@ -963,11 +1060,13 @@ nat44_ed_in2out_fast_path_node_fn_inline (vlib_main_t *vm,
   while (n_left_from > 0)
     {
       vlib_buffer_t *b0;
-      u32 sw_if_index0, rx_fib_index0, iph_offset0 = 0;
-      nat_protocol_t proto0;
+      u32 rx_sw_if_index0, rx_fib_index0, iph_offset0 = 0;
+      u32 tx_sw_if_index0;
+      u32 cntr_sw_if_index0;
+      ip_protocol_t proto0;
       ip4_header_t *ip0;
       snat_session_t *s0 = 0;
-      clib_bihash_kv_16_8_t kv0, value0;
+      clib_bihash_kv_16_8_t kv0 = { 0 }, value0;
       nat_translation_error_e translation_error = NAT_ED_TRNSL_ERR_SUCCESS;
       nat_6t_flow_t *f = 0;
       nat_6t_t lookup;
@@ -985,7 +1084,7 @@ nat44_ed_in2out_fast_path_node_fn_inline (vlib_main_t *vm,
 
          vlib_prefetch_buffer_header (p2, LOAD);
 
-         CLIB_PREFETCH (p2->data, CLIB_CACHE_LINE_BYTES, LOAD);
+         clib_prefetch_load (p2->data);
        }
 
       if (is_output_feature)
@@ -998,12 +1097,15 @@ nat44_ed_in2out_fast_path_node_fn_inline (vlib_main_t *vm,
       ip0 =
        (ip4_header_t *) ((u8 *) vlib_buffer_get_current (b0) + iph_offset0);
 
-      sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
-      rx_fib_index0 =
-       fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP4, sw_if_index0);
+      rx_sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
+      tx_sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_TX];
+      cntr_sw_if_index0 =
+       is_output_feature ? tx_sw_if_index0 : rx_sw_if_index0;
+      rx_fib_index0 = fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP4,
+                                                          rx_sw_if_index0);
       lookup.fib_index = rx_fib_index0;
 
-      if (PREDICT_FALSE (ip0->ttl == 1))
+      if (PREDICT_FALSE (!is_output_feature && ip0->ttl == 1))
        {
          vnet_buffer (b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
          icmp4_error_set_vnet_buffer (b0, ICMP4_time_exceeded,
@@ -1013,7 +1115,7 @@ nat44_ed_in2out_fast_path_node_fn_inline (vlib_main_t *vm,
          goto trace0;
        }
 
-      proto0 = ip_proto_to_nat_proto (ip0->protocol);
+      proto0 = ip0->protocol;
 
       if (is_output_feature)
        {
@@ -1023,7 +1125,7 @@ nat44_ed_in2out_fast_path_node_fn_inline (vlib_main_t *vm,
            goto trace0;
        }
 
-      if (PREDICT_FALSE (proto0 == NAT_PROTOCOL_ICMP))
+      if (PREDICT_FALSE (proto0 == IP_PROTOCOL_ICMP))
        {
          if (vnet_buffer (b0)->ip.reass.icmp_type_or_tcp_flags !=
                ICMP4_echo_request &&
@@ -1077,8 +1179,8 @@ nat44_ed_in2out_fast_path_node_fn_inline (vlib_main_t *vm,
          s0 = NULL;
        }
 
-      init_ed_k (&kv0, lookup.saddr, lookup.sport, lookup.daddr, lookup.dport,
-                lookup.fib_index, lookup.proto);
+      init_ed_k (&kv0, lookup.saddr.as_u32, lookup.sport, lookup.daddr.as_u32,
+                lookup.dport, lookup.fib_index, lookup.proto);
 
       // lookup flow
       if (clib_bihash_search_16_8 (&sm->flow_hash, &kv0, &value0))
@@ -1095,28 +1197,15 @@ nat44_ed_in2out_fast_path_node_fn_inline (vlib_main_t *vm,
 
     skip_lookup:
 
+      ASSERT (thread_index == s0->thread_index);
+
       if (PREDICT_FALSE (per_vrf_sessions_is_expired (s0, thread_index)))
        {
          // session is closed, go slow path
-         nat_free_session_data (sm, s0, thread_index, 0);
+         nat44_ed_free_session_data (sm, s0, thread_index, 0);
          nat_ed_session_delete (sm, s0, thread_index, 1);
-         next[0] = NAT_NEXT_OUT2IN_ED_SLOW_PATH;
-         goto trace0;
-       }
-
-      if (s0->tcp_closed_timestamp)
-       {
-         if (now >= s0->tcp_closed_timestamp)
-           {
-             // session is closed, go slow path, freed in slow path
-             next[0] = def_slow;
-           }
-         else
-           {
-             // session in transitory timeout, drop
-             b0->error = node->errors[NAT_IN2OUT_ED_ERROR_TCP_CLOSED];
-             next[0] = NAT_NEXT_DROP;
-           }
+         s0 = 0;
+         next[0] = def_slow;
          goto trace0;
        }
 
@@ -1126,8 +1215,9 @@ nat44_ed_in2out_fast_path_node_fn_inline (vlib_main_t *vm,
        s0->last_heard + (f64) nat44_session_get_timeout (sm, s0);
       if (now >= sess_timeout_time)
        {
-         nat_free_session_data (sm, s0, thread_index, 0);
+         nat44_ed_free_session_data (sm, s0, thread_index, 0);
          nat_ed_session_delete (sm, s0, thread_index, 1);
+         s0 = 0;
          // session is closed, go slow path
          next[0] = def_slow;
          goto trace0;
@@ -1147,40 +1237,46 @@ nat44_ed_in2out_fast_path_node_fn_inline (vlib_main_t *vm,
       else
        {
          translation_error = NAT_ED_TRNSL_ERR_FLOW_MISMATCH;
-         nat_free_session_data (sm, s0, thread_index, 0);
+         nat44_ed_free_session_data (sm, s0, thread_index, 0);
          nat_ed_session_delete (sm, s0, thread_index, 1);
+         s0 = 0;
          next[0] = NAT_NEXT_DROP;
+         b0->error = node->errors[NAT_IN2OUT_ED_ERROR_TRNSL_FAILED];
          goto trace0;
        }
 
       if (NAT_ED_TRNSL_ERR_SUCCESS !=
-         (translation_error = nat_6t_flow_buf_translate (
-            sm, b0, ip0, f, proto0, is_output_feature)))
+         (translation_error = nat_6t_flow_buf_translate_i2o (
+            vm, sm, b0, ip0, f, proto0, is_output_feature)))
        {
-         nat_free_session_data (sm, s0, thread_index, 0);
+         nat44_ed_free_session_data (sm, s0, thread_index, 0);
          nat_ed_session_delete (sm, s0, thread_index, 1);
+         s0 = 0;
          next[0] = NAT_NEXT_DROP;
+         b0->error = node->errors[NAT_IN2OUT_ED_ERROR_TRNSL_FAILED];
          goto trace0;
        }
 
       switch (proto0)
        {
-       case NAT_PROTOCOL_TCP:
+       case IP_PROTOCOL_TCP:
          vlib_increment_simple_counter (&sm->counters.fastpath.in2out.tcp,
-                                        thread_index, sw_if_index0, 1);
-         nat44_set_tcp_session_state_i2o (sm, now, s0, b0, thread_index);
+                                        thread_index, cntr_sw_if_index0, 1);
+         nat44_set_tcp_session_state_i2o (
+           sm, now, s0, vnet_buffer (b0)->ip.reass.icmp_type_or_tcp_flags,
+           thread_index);
          break;
-       case NAT_PROTOCOL_UDP:
+       case IP_PROTOCOL_UDP:
          vlib_increment_simple_counter (&sm->counters.fastpath.in2out.udp,
-                                        thread_index, sw_if_index0, 1);
+                                        thread_index, cntr_sw_if_index0, 1);
          break;
-       case NAT_PROTOCOL_ICMP:
+       case IP_PROTOCOL_ICMP:
          vlib_increment_simple_counter (&sm->counters.fastpath.in2out.icmp,
-                                        thread_index, sw_if_index0, 1);
+                                        thread_index, cntr_sw_if_index0, 1);
          break;
-       case NAT_PROTOCOL_OTHER:
+       default:
          vlib_increment_simple_counter (&sm->counters.fastpath.in2out.other,
-                                        thread_index, sw_if_index0, 1);
+                                        thread_index, cntr_sw_if_index0, 1);
          break;
        }
 
@@ -1198,7 +1294,7 @@ nat44_ed_in2out_fast_path_node_fn_inline (vlib_main_t *vm,
        {
          nat_in2out_ed_trace_t *t =
            vlib_add_trace (vm, node, b0, sizeof (*t));
-         t->sw_if_index = sw_if_index0;
+         t->sw_if_index = rx_sw_if_index0;
          t->next_index = next[0];
          t->is_slow_path = 0;
          t->translation_error = translation_error;
@@ -1211,6 +1307,7 @@ nat44_ed_in2out_fast_path_node_fn_inline (vlib_main_t *vm,
              clib_memcpy (&t->i2of, &s0->i2o, sizeof (t->i2of));
              clib_memcpy (&t->o2if, &s0->o2i, sizeof (t->o2if));
              t->translation_via_i2of = (&s0->i2o == f);
+             t->tcp_state = s0->tcp_state;
            }
          else
            {
@@ -1221,7 +1318,7 @@ nat44_ed_in2out_fast_path_node_fn_inline (vlib_main_t *vm,
       if (next[0] == NAT_NEXT_DROP)
        {
          vlib_increment_simple_counter (&sm->counters.fastpath.in2out.drops,
-                                        thread_index, sw_if_index0, 1);
+                                        thread_index, cntr_sw_if_index0, 1);
        }
 
       n_left_from--;
@@ -1234,10 +1331,11 @@ nat44_ed_in2out_fast_path_node_fn_inline (vlib_main_t *vm,
 }
 
 static inline uword
-nat44_ed_in2out_slow_path_node_fn_inline (vlib_main_t * vm,
-                                         vlib_node_runtime_t * node,
-                                         vlib_frame_t * frame,
-                                         int is_output_feature)
+nat44_ed_in2out_slow_path_node_fn_inline (vlib_main_t *vm,
+                                         vlib_node_runtime_t *node,
+                                         vlib_frame_t *frame,
+                                         int is_output_feature,
+                                         int is_multi_worker)
 {
   u32 n_left_from, *from;
   snat_main_t *sm = &snat_main;
@@ -1255,13 +1353,15 @@ nat44_ed_in2out_slow_path_node_fn_inline (vlib_main_t * vm,
   while (n_left_from > 0)
     {
       vlib_buffer_t *b0;
-      u32 sw_if_index0, rx_fib_index0, iph_offset0 = 0;
-      nat_protocol_t proto0;
+      u32 rx_sw_if_index0, rx_fib_index0, iph_offset0 = 0;
+      u32 tx_sw_if_index0;
+      u32 cntr_sw_if_index0;
+      ip_protocol_t proto0;
       ip4_header_t *ip0;
       udp_header_t *udp0;
       icmp46_header_t *icmp0;
       snat_session_t *s0 = 0;
-      clib_bihash_kv_16_8_t kv0, value0;
+      clib_bihash_kv_16_8_t kv0 = { 0 }, value0;
       int translation_error = NAT_ED_TRNSL_ERR_SUCCESS;
 
       b0 = *b;
@@ -1274,11 +1374,14 @@ nat44_ed_in2out_slow_path_node_fn_inline (vlib_main_t * vm,
       ip0 = (ip4_header_t *) ((u8 *) vlib_buffer_get_current (b0) +
                              iph_offset0);
 
-      sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
-      rx_fib_index0 =
-       fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP4, sw_if_index0);
+      rx_sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
+      tx_sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_TX];
+      cntr_sw_if_index0 =
+       is_output_feature ? tx_sw_if_index0 : rx_sw_if_index0;
+      rx_fib_index0 = fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP4,
+                                                          rx_sw_if_index0);
 
-      if (PREDICT_FALSE (ip0->ttl == 1))
+      if (PREDICT_FALSE (!is_output_feature && ip0->ttl == 1))
        {
          vnet_buffer (b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
          icmp4_error_set_vnet_buffer (b0, ICMP4_time_exceeded,
@@ -1290,101 +1393,108 @@ nat44_ed_in2out_slow_path_node_fn_inline (vlib_main_t * vm,
 
       udp0 = ip4_next_header (ip0);
       icmp0 = (icmp46_header_t *) udp0;
-      proto0 = ip_proto_to_nat_proto (ip0->protocol);
+      proto0 = ip0->protocol;
 
-      if (PREDICT_FALSE (proto0 == NAT_PROTOCOL_OTHER))
+      if (PREDICT_FALSE (nat44_ed_is_unk_proto (proto0)))
        {
          s0 = nat44_ed_in2out_slowpath_unknown_proto (
            sm, b0, ip0, rx_fib_index0, thread_index, now, vm, node);
          if (!s0)
            next[0] = NAT_NEXT_DROP;
 
-         if (NAT_ED_TRNSL_ERR_SUCCESS !=
-             (translation_error = nat_6t_flow_buf_translate (
-                sm, b0, ip0, &s0->i2o, proto0, is_output_feature)))
+         if (NAT_NEXT_DROP != next[0] && s0 &&
+             NAT_ED_TRNSL_ERR_SUCCESS !=
+               (translation_error = nat_6t_flow_buf_translate_i2o (
+                  vm, sm, b0, ip0, &s0->i2o, proto0, is_output_feature)))
            {
+             nat44_ed_free_session_data (sm, s0, thread_index, 0);
+             nat_ed_session_delete (sm, s0, thread_index, 1);
+             s0 = 0;
+             next[0] = NAT_NEXT_DROP;
+             b0->error = node->errors[NAT_IN2OUT_ED_ERROR_TRNSL_FAILED];
              goto trace0;
            }
 
          vlib_increment_simple_counter (&sm->counters.slowpath.in2out.other,
-                                        thread_index, sw_if_index0, 1);
+                                        thread_index, cntr_sw_if_index0, 1);
          goto trace0;
        }
 
-      if (PREDICT_FALSE (proto0 == NAT_PROTOCOL_ICMP))
+      if (PREDICT_FALSE (proto0 == IP_PROTOCOL_ICMP))
        {
-         next[0] = icmp_in2out_ed_slow_path (sm, b0, ip0, icmp0, sw_if_index0,
-                                             rx_fib_index0, node, next[0],
-                                             now, thread_index, proto0, &s0);
+         next[0] = icmp_in2out_ed_slow_path (
+           sm, b0, ip0, icmp0, rx_sw_if_index0, tx_sw_if_index0,
+           rx_fib_index0, node, next[0], now, thread_index, &s0,
+           is_multi_worker);
          if (NAT_NEXT_DROP != next[0] && s0 &&
              NAT_ED_TRNSL_ERR_SUCCESS !=
-               (translation_error = nat_6t_flow_buf_translate (
-                  sm, b0, ip0, &s0->i2o, proto0, is_output_feature)))
+               (translation_error = nat_6t_flow_buf_translate_i2o (
+                  vm, sm, b0, ip0, &s0->i2o, proto0, is_output_feature)))
            {
+             nat44_ed_free_session_data (sm, s0, thread_index, 0);
+             nat_ed_session_delete (sm, s0, thread_index, 1);
+             s0 = 0;
+             next[0] = NAT_NEXT_DROP;
+             b0->error = node->errors[NAT_IN2OUT_ED_ERROR_TRNSL_FAILED];
              goto trace0;
            }
 
-         vlib_increment_simple_counter (&sm->counters.slowpath.in2out.icmp,
-                                        thread_index, sw_if_index0, 1);
+         if (NAT_NEXT_DROP != next[0])
+           {
+             vlib_increment_simple_counter (
+               &sm->counters.slowpath.in2out.icmp, thread_index,
+               cntr_sw_if_index0, 1);
+           }
          goto trace0;
        }
 
-      init_ed_k (&kv0, ip0->src_address,
-                vnet_buffer (b0)->ip.reass.l4_src_port, ip0->dst_address,
-                vnet_buffer (b0)->ip.reass.l4_dst_port, rx_fib_index0,
-                ip0->protocol);
+      init_ed_k (
+       &kv0, ip0->src_address.as_u32, vnet_buffer (b0)->ip.reass.l4_src_port,
+       ip0->dst_address.as_u32, vnet_buffer (b0)->ip.reass.l4_dst_port,
+       rx_fib_index0, ip0->protocol);
       if (!clib_bihash_search_16_8 (&sm->flow_hash, &kv0, &value0))
        {
          ASSERT (thread_index == ed_value_get_thread_index (&value0));
          s0 =
            pool_elt_at_index (tsm->sessions,
                               ed_value_get_session_index (&value0));
-
-         if (s0->tcp_closed_timestamp && now >= s0->tcp_closed_timestamp)
-           {
-             nat_free_session_data (sm, s0, thread_index, 0);
-             nat_ed_session_delete (sm, s0, thread_index, 1);
-             s0 = NULL;
-           }
        }
 
       if (!s0)
        {
          if (is_output_feature)
            {
-             if (PREDICT_FALSE
-                 (nat44_ed_not_translate_output_feature
-                  (sm, ip0, vnet_buffer (b0)->ip.reass.l4_src_port,
+             if (PREDICT_FALSE (nat44_ed_not_translate_output_feature (
+                   sm, b0, ip0, vnet_buffer (b0)->ip.reass.l4_src_port,
                    vnet_buffer (b0)->ip.reass.l4_dst_port, thread_index,
-                   sw_if_index0, vnet_buffer (b0)->sw_if_index[VLIB_TX],
-                   now)))
+                   rx_sw_if_index0, tx_sw_if_index0, is_multi_worker)))
                goto trace0;
 
              /*
               * Send DHCP packets to the ipv4 stack, or we won't
               * be able to use dhcp client on the outside interface
               */
-             if (PREDICT_FALSE
-                 (proto0 == NAT_PROTOCOL_UDP
-                  && (vnet_buffer (b0)->ip.reass.l4_dst_port ==
-                      clib_host_to_net_u16 (UDP_DST_PORT_dhcp_to_server))
-                  && ip0->dst_address.as_u32 == 0xffffffff))
+             if (PREDICT_FALSE (
+                   proto0 == IP_PROTOCOL_UDP &&
+                   (vnet_buffer (b0)->ip.reass.l4_dst_port ==
+                    clib_host_to_net_u16 (UDP_DST_PORT_dhcp_to_server)) &&
+                   ip0->dst_address.as_u32 == 0xffffffff))
                goto trace0;
            }
          else
            {
-             if (PREDICT_FALSE (nat44_ed_not_translate (
-                   sm, node, sw_if_index0, b0, ip0, proto0, rx_fib_index0,
-                   thread_index)))
+             if (PREDICT_FALSE (
+                   nat44_ed_not_translate (vm, node, rx_sw_if_index0, b0, ip0,
+                                           proto0, rx_fib_index0)))
                goto trace0;
            }
 
          next[0] =
-           slow_path_ed (sm, b0, ip0->src_address, ip0->dst_address,
+           slow_path_ed (vm, sm, b0, ip0->src_address, ip0->dst_address,
                          vnet_buffer (b0)->ip.reass.l4_src_port,
                          vnet_buffer (b0)->ip.reass.l4_dst_port,
-                         ip0->protocol, rx_fib_index0, &s0, node, next[0],
-                         thread_index, now);
+                         ip0->protocol, rx_fib_index0, tx_sw_if_index0, &s0,
+                         node, next[0], thread_index, now);
 
          if (PREDICT_FALSE (next[0] == NAT_NEXT_DROP))
            goto trace0;
@@ -1397,25 +1507,29 @@ nat44_ed_in2out_slow_path_node_fn_inline (vlib_main_t * vm,
       b0->flags |= VNET_BUFFER_F_IS_NATED;
 
       if (NAT_ED_TRNSL_ERR_SUCCESS !=
-         (translation_error = nat_6t_flow_buf_translate (
-            sm, b0, ip0, &s0->i2o, proto0, is_output_feature)))
+         (translation_error = nat_6t_flow_buf_translate_i2o (
+            vm, sm, b0, ip0, &s0->i2o, proto0, is_output_feature)))
        {
-         nat_free_session_data (sm, s0, thread_index, 0);
+         nat44_ed_free_session_data (sm, s0, thread_index, 0);
          nat_ed_session_delete (sm, s0, thread_index, 1);
-         s0 = NULL;
+         s0 = 0;
+         next[0] = NAT_NEXT_DROP;
+         b0->error = node->errors[NAT_IN2OUT_ED_ERROR_TRNSL_FAILED];
          goto trace0;
        }
 
-      if (PREDICT_TRUE (proto0 == NAT_PROTOCOL_TCP))
+      if (PREDICT_TRUE (proto0 == IP_PROTOCOL_TCP))
        {
          vlib_increment_simple_counter (&sm->counters.slowpath.in2out.tcp,
-                                        thread_index, sw_if_index0, 1);
-         nat44_set_tcp_session_state_i2o (sm, now, s0, b0, thread_index);
+                                        thread_index, cntr_sw_if_index0, 1);
+         nat44_set_tcp_session_state_i2o (
+           sm, now, s0, vnet_buffer (b0)->ip.reass.icmp_type_or_tcp_flags,
+           thread_index);
        }
       else
        {
          vlib_increment_simple_counter (&sm->counters.slowpath.in2out.udp,
-                                        thread_index, sw_if_index0, 1);
+                                        thread_index, cntr_sw_if_index0, 1);
        }
 
       /* Accounting */
@@ -1431,7 +1545,7 @@ nat44_ed_in2out_slow_path_node_fn_inline (vlib_main_t * vm,
        {
          nat_in2out_ed_trace_t *t =
            vlib_add_trace (vm, node, b0, sizeof (*t));
-         t->sw_if_index = sw_if_index0;
+         t->sw_if_index = rx_sw_if_index0;
          t->next_index = next[0];
          t->is_slow_path = 1;
          t->translation_error = translation_error;
@@ -1443,6 +1557,7 @@ nat44_ed_in2out_slow_path_node_fn_inline (vlib_main_t * vm,
              clib_memcpy (&t->i2of, &s0->i2o, sizeof (t->i2of));
              clib_memcpy (&t->o2if, &s0->o2i, sizeof (t->o2if));
              t->translation_via_i2of = 1;
+             t->tcp_state = s0->tcp_state;
            }
 
          else
@@ -1454,7 +1569,7 @@ nat44_ed_in2out_slow_path_node_fn_inline (vlib_main_t * vm,
       if (next[0] == NAT_NEXT_DROP)
        {
          vlib_increment_simple_counter (&sm->counters.slowpath.in2out.drops,
-                                        thread_index, sw_if_index0, 1);
+                                        thread_index, cntr_sw_if_index0, 1);
        }
 
       n_left_from--;
@@ -1522,7 +1637,14 @@ VLIB_NODE_FN (nat44_ed_in2out_slowpath_node) (vlib_main_t * vm,
                                              vlib_node_runtime_t *
                                              node, vlib_frame_t * frame)
 {
-  return nat44_ed_in2out_slow_path_node_fn_inline (vm, node, frame, 0);
+  if (snat_main.num_workers > 1)
+    {
+      return nat44_ed_in2out_slow_path_node_fn_inline (vm, node, frame, 0, 1);
+    }
+  else
+    {
+      return nat44_ed_in2out_slow_path_node_fn_inline (vm, node, frame, 0, 0);
+    }
 }
 
 VLIB_REGISTER_NODE (nat44_ed_in2out_slowpath_node) = {
@@ -1541,7 +1663,14 @@ VLIB_NODE_FN (nat44_ed_in2out_output_slowpath_node) (vlib_main_t * vm,
                                                     * node,
                                                     vlib_frame_t * frame)
 {
-  return nat44_ed_in2out_slow_path_node_fn_inline (vm, node, frame, 1);
+  if (snat_main.num_workers > 1)
+    {
+      return nat44_ed_in2out_slow_path_node_fn_inline (vm, node, frame, 1, 1);
+    }
+  else
+    {
+      return nat44_ed_in2out_slow_path_node_fn_inline (vm, node, frame, 1, 0);
+    }
 }
 
 VLIB_REGISTER_NODE (nat44_ed_in2out_output_slowpath_node) = {