nat: ED: global session LRU list
[vpp.git] / src / plugins / nat / out2in_ed.c
index dce6c56..5b70b0c 100644 (file)
 #include <vppinfra/error.h>
 #include <nat/nat.h>
 #include <nat/nat_ipfix_logging.h>
-#include <nat/nat_reass.h>
 #include <nat/nat_inlines.h>
-
-#define foreach_nat_out2in_ed_error                     \
-_(UNSUPPORTED_PROTOCOL, "Unsupported protocol")         \
-_(OUT2IN_PACKETS, "Good out2in packets processed")      \
-_(OUT_OF_PORTS, "Out of ports")                         \
-_(BAD_ICMP_TYPE, "unsupported ICMP type")               \
-_(NO_TRANSLATION, "No translation")                     \
-_(MAX_SESSIONS_EXCEEDED, "Maximum sessions exceeded")   \
-_(DROP_FRAGMENT, "Drop fragment")                       \
-_(MAX_REASS, "Maximum reassemblies exceeded")           \
-_(MAX_FRAG, "Maximum fragments per reassembly exceeded")
-
-typedef enum
-{
-#define _(sym,str) NAT_OUT2IN_ED_ERROR_##sym,
-  foreach_nat_out2in_ed_error
-#undef _
-    NAT_OUT2IN_ED_N_ERROR,
-} nat_out2in_ed_error_t;
+#include <nat/nat44/inlines.h>
+#include <nat/nat_syslog.h>
+#include <nat/nat_ha.h>
 
 static char *nat_out2in_ed_error_strings[] = {
 #define _(sym,string) string,
@@ -55,17 +38,6 @@ static char *nat_out2in_ed_error_strings[] = {
 #undef _
 };
 
-typedef enum
-{
-  NAT44_ED_OUT2IN_NEXT_DROP,
-  NAT44_ED_OUT2IN_NEXT_LOOKUP,
-  NAT44_ED_OUT2IN_NEXT_ICMP_ERROR,
-  NAT44_ED_OUT2IN_NEXT_IN2OUT,
-  NAT44_ED_OUT2IN_NEXT_SLOW_PATH,
-  NAT44_ED_OUT2IN_NEXT_REASS,
-  NAT44_ED_OUT2IN_N_NEXT,
-} nat44_ed_out2in_next_t;
-
 typedef struct
 {
   u32 sw_if_index;
@@ -74,10 +46,6 @@ typedef struct
   u32 is_slow_path;
 } nat44_ed_out2in_trace_t;
 
-vlib_node_registration_t nat44_ed_out2in_node;
-vlib_node_registration_t nat44_ed_out2in_slowpath_node;
-vlib_node_registration_t nat44_ed_out2in_reass_node;
-
 static u8 *
 format_nat44_ed_out2in_trace (u8 * s, va_list * args)
 {
@@ -106,18 +74,19 @@ icmp_out2in_ed_slow_path (snat_main_t * sm, vlib_buffer_t * b0,
   next0 = icmp_out2in (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, node,
                       next0, thread_index, p_s0, 0);
   snat_session_t *s0 = *p_s0;
-  if (PREDICT_TRUE (next0 != NAT44_ED_OUT2IN_NEXT_DROP && s0))
+  if (PREDICT_TRUE (next0 != NAT_NEXT_DROP && s0))
     {
       /* Accounting */
       nat44_session_update_counters (s0, now,
                                     vlib_buffer_length_in_chain
-                                    (sm->vlib_main, b0));
+                                    (sm->vlib_main, b0), thread_index);
       /* Per-user LRU list maintenance */
       nat44_session_update_lru (sm, s0, thread_index);
     }
   return next0;
 }
 
+#ifndef CLIB_MARCH_VARIANT
 int
 nat44_o2i_ed_is_idle_session_cb (clib_bihash_kv_16_8_t * kv, void *arg)
 {
@@ -160,18 +129,40 @@ nat44_o2i_ed_is_idle_session_cb (clib_bihash_kv_16_8_t * kv, void *arg)
       ed_kv.key[0] = ed_key.as_u64[0];
       ed_kv.key[1] = ed_key.as_u64[1];
       if (clib_bihash_add_del_16_8 (&tsm->in2out_ed, &ed_kv, 0))
-       nat_log_warn ("in2out_ed key del failed");
+       nat_elog_warn ("in2out_ed key del failed");
+
+      ed_bihash_kv_t bihash_key;
+      clib_memset (&bihash_key, 0, sizeof (bihash_key));
+      bihash_key.k.dst_address = s->ext_host_addr.as_u32;
+      bihash_key.k.dst_port = s->ext_host_port;
+      bihash_key.k.src_address = s->out2in.addr.as_u32;
+      bihash_key.k.src_port = s->out2in.port;
+      bihash_key.k.protocol = s->out2in.protocol;
+      clib_bihash_add_del_16_8 (&sm->ed_ext_ports, &bihash_key.kv,
+                               0 /* is_add */ );
 
       if (snat_is_unk_proto_session (s))
        goto delete;
 
-      snat_ipfix_logging_nat44_ses_delete (s->in2out.addr.as_u32,
+      snat_ipfix_logging_nat44_ses_delete (ctx->thread_index,
+                                          s->in2out.addr.as_u32,
                                           s->out2in.addr.as_u32,
                                           s->in2out.protocol,
                                           s->in2out.port,
                                           s->out2in.port,
                                           s->in2out.fib_index);
 
+      nat_syslog_nat44_sdel (s->user_index, 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->in2out.protocol, is_twice_nat_session (s));
+
+      nat_ha_sdel (&s->out2in.addr, s->out2in.port, &s->ext_host_addr,
+                  s->ext_host_port, s->out2in.protocol, s->out2in.fib_index,
+                  ctx->thread_index);
+
       if (is_twice_nat_session (s))
        {
          for (i = 0; i < vec_len (sm->twice_nat_addresses); i++)
@@ -201,6 +192,7 @@ nat44_o2i_ed_is_idle_session_cb (clib_bihash_kv_16_8_t * kv, void *arg)
 
   return 0;
 }
+#endif
 
 static snat_session_t *
 create_session_for_static_mapping_ed (snat_main_t * sm,
@@ -221,25 +213,27 @@ create_session_for_static_mapping_ed (snat_main_t * sm,
   snat_session_key_t eh_key;
   nat44_is_idle_session_ctx_t ctx;
 
-  if (PREDICT_FALSE (maximum_sessions_exceeded (sm, thread_index)))
+  if (PREDICT_FALSE (nat44_maximum_sessions_exceeded (sm, thread_index)))
     {
       b->error = node->errors[NAT_OUT2IN_ED_ERROR_MAX_SESSIONS_EXCEEDED];
-      nat_log_notice ("maximum sessions exceeded");
+      nat_elog_notice ("maximum sessions exceeded");
       return 0;
     }
 
   u = nat_user_get_or_create (sm, &l_key.addr, l_key.fib_index, thread_index);
   if (!u)
     {
-      nat_log_warn ("create NAT user failed");
+      b->error = node->errors[NAT_OUT2IN_ED_ERROR_MAX_SESSIONS_EXCEEDED];
+      nat_elog_warn ("create NAT user failed");
       return 0;
     }
 
   s = nat_ed_session_alloc (sm, u, thread_index, now);
   if (!s)
     {
+      b->error = node->errors[NAT_OUT2IN_ED_ERROR_MAX_USER_SESS_EXCEEDED];
       nat44_delete_user_with_no_session (sm, u, thread_index);
-      nat_log_warn ("create NAT session failed");
+      nat_elog_warn ("create NAT session failed");
       return 0;
     }
 
@@ -268,7 +262,7 @@ create_session_for_static_mapping_ed (snat_main_t * sm,
   if (clib_bihash_add_or_overwrite_stale_16_8 (&tsm->out2in_ed, &kv,
                                               nat44_o2i_ed_is_idle_session_cb,
                                               &ctx))
-    nat_log_notice ("out2in-ed key add failed");
+    nat_elog_notice ("out2in-ed key add failed");
 
   if (twice_nat == TWICE_NAT || (twice_nat == TWICE_NAT_SELF &&
                                 ip->src_address.as_u32 == l_key.addr.as_u32))
@@ -282,7 +276,7 @@ create_session_for_static_mapping_ed (snat_main_t * sm,
          b->error = node->errors[NAT_OUT2IN_ED_ERROR_OUT_OF_PORTS];
          nat44_delete_session (sm, s, thread_index);
          if (clib_bihash_add_del_16_8 (&tsm->out2in_ed, &kv, 0))
-           nat_log_notice ("out2in-ed key del failed");
+           nat_elog_notice ("out2in-ed key del failed");
          return 0;
        }
       s->ext_host_nat_addr.as_u32 = eh_key.addr.as_u32;
@@ -300,60 +294,31 @@ create_session_for_static_mapping_ed (snat_main_t * sm,
   if (clib_bihash_add_or_overwrite_stale_16_8 (&tsm->in2out_ed, &kv,
                                               nat44_i2o_ed_is_idle_session_cb,
                                               &ctx))
-    nat_log_notice ("in2out-ed key add failed");
+    nat_elog_notice ("in2out-ed key add failed");
+
+  snat_ipfix_logging_nat44_ses_create (thread_index,
+                                      s->in2out.addr.as_u32,
+                                      s->out2in.addr.as_u32,
+                                      s->in2out.protocol,
+                                      s->in2out.port,
+                                      s->out2in.port, s->in2out.fib_index);
+
+  nat_syslog_nat44_sadd (s->user_index, 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->in2out.protocol, is_twice_nat_session (s));
+
+  nat_ha_sadd (&s->in2out.addr, s->in2out.port, &s->out2in.addr,
+              s->out2in.port, &s->ext_host_addr, s->ext_host_port,
+              &s->ext_host_nat_addr, s->ext_host_nat_port,
+              s->in2out.protocol, s->in2out.fib_index, s->flags,
+              thread_index, 0);
 
   return s;
 }
 
-static_always_inline int
-icmp_get_ed_key (ip4_header_t * ip0, nat_ed_ses_key_t * p_key0)
-{
-  icmp46_header_t *icmp0;
-  nat_ed_ses_key_t key0;
-  icmp_echo_header_t *echo0, *inner_echo0 = 0;
-  ip4_header_t *inner_ip0;
-  void *l4_header = 0;
-  icmp46_header_t *inner_icmp0;
-
-  icmp0 = (icmp46_header_t *) ip4_next_header (ip0);
-  echo0 = (icmp_echo_header_t *) (icmp0 + 1);
-
-  if (!icmp_is_error_message (icmp0))
-    {
-      key0.proto = IP_PROTOCOL_ICMP;
-      key0.l_addr = ip0->dst_address;
-      key0.r_addr = ip0->src_address;
-      key0.l_port = echo0->identifier;
-      key0.r_port = 0;
-    }
-  else
-    {
-      inner_ip0 = (ip4_header_t *) (echo0 + 1);
-      l4_header = ip4_next_header (inner_ip0);
-      key0.proto = inner_ip0->protocol;
-      key0.l_addr = inner_ip0->src_address;
-      key0.r_addr = inner_ip0->dst_address;
-      switch (ip_proto_to_snat_proto (inner_ip0->protocol))
-       {
-       case SNAT_PROTOCOL_ICMP:
-         inner_icmp0 = (icmp46_header_t *) l4_header;
-         inner_echo0 = (icmp_echo_header_t *) (inner_icmp0 + 1);
-         key0.l_port = inner_echo0->identifier;
-         key0.r_port = 0;
-         break;
-       case SNAT_PROTOCOL_UDP:
-       case SNAT_PROTOCOL_TCP:
-         key0.l_port = ((tcp_udp_header_t *) l4_header)->src_port;
-         key0.r_port = ((tcp_udp_header_t *) l4_header)->dst_port;
-         break;
-       default:
-         return -1;
-       }
-    }
-  *p_key0 = key0;
-  return 0;
-}
-
 static int
 next_src_nat (snat_main_t * sm, ip4_header_t * ip, u8 proto, u16 src_port,
              u16 dst_port, u32 thread_index, u32 rx_fib_index)
@@ -370,8 +335,8 @@ next_src_nat (snat_main_t * sm, ip4_header_t * ip, u8 proto, u16 src_port,
 }
 
 static void
-create_bypass_for_fwd (snat_main_t * sm, ip4_header_t * ip, u32 rx_fib_index,
-                      u32 thread_index)
+create_bypass_for_fwd (snat_main_t * sm, vlib_buffer_t * b, ip4_header_t * ip,
+                      u32 rx_fib_index, u32 thread_index)
 {
   nat_ed_ses_key_t key;
   clib_bihash_kv_16_8_t kv, value;
@@ -383,7 +348,7 @@ create_bypass_for_fwd (snat_main_t * sm, ip4_header_t * ip, u32 rx_fib_index,
 
   if (ip->protocol == IP_PROTOCOL_ICMP)
     {
-      if (icmp_get_ed_key (ip, &key))
+      if (get_icmp_o2i_ed_key (b, ip, &key))
        return;
     }
   else if (ip->protocol == IP_PROTOCOL_UDP || ip->protocol == IP_PROTOCOL_TCP)
@@ -412,14 +377,16 @@ create_bypass_for_fwd (snat_main_t * sm, ip4_header_t * ip, u32 rx_fib_index,
     }
   else
     {
-      if (PREDICT_FALSE (maximum_sessions_exceeded (sm, thread_index)))
+      u32 proto;
+
+      if (PREDICT_FALSE (nat44_maximum_sessions_exceeded (sm, thread_index)))
        return;
 
       u = nat_user_get_or_create (sm, &ip->dst_address, sm->inside_fib_index,
                                  thread_index);
       if (!u)
        {
-         nat_log_warn ("create NAT user failed");
+         nat_elog_warn ("create NAT user failed");
          return;
        }
 
@@ -427,38 +394,60 @@ create_bypass_for_fwd (snat_main_t * sm, ip4_header_t * ip, u32 rx_fib_index,
       if (!s)
        {
          nat44_delete_user_with_no_session (sm, u, thread_index);
-         nat_log_warn ("create NAT session failed");
+         nat_elog_warn ("create NAT session failed");
          return;
        }
 
+      proto = ip_proto_to_snat_proto (key.proto);
+
       s->ext_host_addr = key.r_addr;
       s->ext_host_port = key.r_port;
       s->flags |= SNAT_SESSION_FLAG_FWD_BYPASS;
       s->out2in.addr = key.l_addr;
       s->out2in.port = key.l_port;
-      s->out2in.protocol = ip_proto_to_snat_proto (key.proto);
+      s->out2in.protocol = proto;
+      if (proto == ~0)
+       {
+         s->flags |= SNAT_SESSION_FLAG_UNKNOWN_PROTO;
+         s->out2in.port = ip->protocol;
+       }
       s->out2in.fib_index = 0;
       s->in2out = s->out2in;
       user_session_increment (sm, u, 0);
 
       kv.value = s - tsm->sessions;
       if (clib_bihash_add_del_16_8 (&tsm->in2out_ed, &kv, 1))
-       nat_log_notice ("in2out_ed key add failed");
+       nat_elog_notice ("in2out_ed key add failed");
     }
 
   if (ip->protocol == IP_PROTOCOL_TCP)
     {
       tcp_header_t *tcp = ip4_next_header (ip);
-      if (nat44_set_tcp_session_state_o2i (sm, s, tcp, thread_index))
+      if (nat44_set_tcp_session_state_o2i
+         (sm, now, s, tcp->flags, tcp->ack_number, tcp->seq_number,
+          thread_index))
        return;
     }
 
   /* Accounting */
-  nat44_session_update_counters (s, now, 0);
+  nat44_session_update_counters (s, now, 0, thread_index);
   /* Per-user LRU list maintenance */
   nat44_session_update_lru (sm, s, thread_index);
 }
 
+static inline void
+create_bypass_for_fwd_worker (snat_main_t * sm, vlib_buffer_t * b,
+                             ip4_header_t * ip, u32 rx_fib_index)
+{
+  ip4_header_t ip_wkr = {
+    .src_address = ip->dst_address,
+  };
+  u32 thread_index = sm->worker_in2out_cb (&ip_wkr, rx_fib_index, 0);
+
+  create_bypass_for_fwd (sm, b, ip, rx_fib_index, thread_index);
+}
+
+#ifndef CLIB_MARCH_VARIANT
 u32
 icmp_match_out2in_ed (snat_main_t * sm, vlib_node_runtime_t * node,
                      u32 thread_index, vlib_buffer_t * b, ip4_header_t * ip,
@@ -466,22 +455,20 @@ icmp_match_out2in_ed (snat_main_t * sm, vlib_node_runtime_t * node,
                      u8 * p_dont_translate, void *d, void *e)
 {
   u32 next = ~0, sw_if_index, rx_fib_index;
-  icmp46_header_t *icmp;
   nat_ed_ses_key_t key;
   clib_bihash_kv_16_8_t kv, value;
   snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
   snat_session_t *s = 0;
-  u8 dont_translate = 0, is_addr_only;
+  u8 dont_translate = 0, is_addr_only, identity_nat;
   snat_session_key_t e_key, l_key;
 
-  icmp = (icmp46_header_t *) ip4_next_header (ip);
   sw_if_index = vnet_buffer (b)->sw_if_index[VLIB_RX];
   rx_fib_index = ip4_fib_table_get_index_for_sw_if_index (sw_if_index);
 
-  if (icmp_get_ed_key (ip, &key))
+  if (get_icmp_o2i_ed_key (b, ip, &key))
     {
       b->error = node->errors[NAT_OUT2IN_ED_ERROR_UNSUPPORTED_PROTOCOL];
-      next = NAT44_ED_OUT2IN_NEXT_DROP;
+      next = NAT_NEXT_DROP;
       goto out;
     }
   key.fib_index = rx_fib_index;
@@ -496,7 +483,7 @@ icmp_match_out2in_ed (snat_main_t * sm, vlib_node_runtime_t * node,
       e_key.protocol = ip_proto_to_snat_proto (key.proto);
       e_key.fib_index = rx_fib_index;
       if (snat_static_mapping_match
-         (sm, e_key, &l_key, 1, &is_addr_only, 0, 0, 0))
+         (sm, e_key, &l_key, 1, &is_addr_only, 0, 0, 0, &identity_nat))
        {
          if (!sm->forwarding_enabled)
            {
@@ -508,7 +495,7 @@ icmp_match_out2in_ed (snat_main_t * sm, vlib_node_runtime_t * node,
                  goto out;
                }
              b->error = node->errors[NAT_OUT2IN_ED_ERROR_NO_TRANSLATION];
-             next = NAT44_ED_OUT2IN_NEXT_DROP;
+             next = NAT_NEXT_DROP;
              goto out;
            }
          else
@@ -517,19 +504,31 @@ icmp_match_out2in_ed (snat_main_t * sm, vlib_node_runtime_t * node,
              if (next_src_nat (sm, ip, key.proto, key.l_port, key.r_port,
                                thread_index, rx_fib_index))
                {
-                 next = NAT44_ED_OUT2IN_NEXT_IN2OUT;
+                 next = NAT_NEXT_IN2OUT_ED_FAST_PATH;
                  goto out;
                }
-             create_bypass_for_fwd (sm, ip, rx_fib_index, thread_index);
+             if (sm->num_workers > 1)
+               create_bypass_for_fwd_worker (sm, b, ip, rx_fib_index);
+             else
+               create_bypass_for_fwd (sm, b, ip, rx_fib_index, thread_index);
              goto out;
            }
        }
 
-      if (PREDICT_FALSE (icmp->type != ICMP4_echo_reply &&
-                        (icmp->type != ICMP4_echo_request || !is_addr_only)))
+      if (PREDICT_FALSE
+         (vnet_buffer (b)->ip.reass.icmp_type_or_tcp_flags !=
+          ICMP4_echo_reply
+          && (vnet_buffer (b)->ip.reass.icmp_type_or_tcp_flags !=
+              ICMP4_echo_request || !is_addr_only)))
        {
          b->error = node->errors[NAT_OUT2IN_ED_ERROR_BAD_ICMP_TYPE];
-         next = NAT44_ED_OUT2IN_NEXT_DROP;
+         next = NAT_NEXT_DROP;
+         goto out;
+       }
+
+      if (PREDICT_FALSE (identity_nat))
+       {
+         dont_translate = 1;
          goto out;
        }
 
@@ -541,18 +540,22 @@ icmp_match_out2in_ed (snat_main_t * sm, vlib_node_runtime_t * node,
 
       if (!s)
        {
-         next = NAT44_ED_OUT2IN_NEXT_DROP;
+         next = NAT_NEXT_DROP;
          goto out;
        }
     }
   else
     {
-      if (PREDICT_FALSE (icmp->type != ICMP4_echo_reply &&
-                        icmp->type != ICMP4_echo_request &&
-                        !icmp_is_error_message (icmp)))
+      if (PREDICT_FALSE
+         (vnet_buffer (b)->ip.reass.icmp_type_or_tcp_flags !=
+          ICMP4_echo_reply
+          && vnet_buffer (b)->ip.reass.icmp_type_or_tcp_flags !=
+          ICMP4_echo_request
+          && !icmp_type_is_error_message (vnet_buffer (b)->ip.
+                                          reass.icmp_type_or_tcp_flags)))
        {
          b->error = node->errors[NAT_OUT2IN_ED_ERROR_BAD_ICMP_TYPE];
-         next = NAT44_ED_OUT2IN_NEXT_DROP;
+         next = NAT_NEXT_DROP;
          goto out;
        }
 
@@ -568,6 +571,7 @@ out:
     *(snat_session_t **) d = s;
   return next;
 }
+#endif
 
 static snat_session_t *
 nat44_ed_out2in_unknown_proto (snat_main_t * sm,
@@ -599,10 +603,10 @@ nat44_ed_out2in_unknown_proto (snat_main_t * sm,
     }
   else
     {
-      if (PREDICT_FALSE (maximum_sessions_exceeded (sm, thread_index)))
+      if (PREDICT_FALSE (nat44_maximum_sessions_exceeded (sm, thread_index)))
        {
          b->error = node->errors[NAT_OUT2IN_ED_ERROR_MAX_SESSIONS_EXCEEDED];
-         nat_log_notice ("maximum sessions exceeded");
+         nat_elog_notice ("maximum sessions exceeded");
          return 0;
        }
 
@@ -622,7 +626,8 @@ nat44_ed_out2in_unknown_proto (snat_main_t * sm,
                                  thread_index);
       if (!u)
        {
-         nat_log_warn ("create NAT user failed");
+         b->error = node->errors[NAT_OUT2IN_ED_ERROR_CANNOT_CREATE_USER];
+         nat_elog_warn ("create NAT user failed");
          return 0;
        }
 
@@ -630,8 +635,9 @@ nat44_ed_out2in_unknown_proto (snat_main_t * sm,
       s = nat_ed_session_alloc (sm, u, thread_index, now);
       if (!s)
        {
+         b->error = node->errors[NAT_OUT2IN_ED_ERROR_MAX_USER_SESS_EXCEEDED];
          nat44_delete_user_with_no_session (sm, u, thread_index);
-         nat_log_warn ("create NAT session failed");
+         nat_elog_warn ("create NAT session failed");
          return 0;
        }
 
@@ -649,13 +655,13 @@ nat44_ed_out2in_unknown_proto (snat_main_t * sm,
       /* Add to lookup tables */
       s_kv.value = s - tsm->sessions;
       if (clib_bihash_add_del_16_8 (&tsm->out2in_ed, &s_kv, 1))
-       nat_log_notice ("out2in key add failed");
+       nat_elog_notice ("out2in key add failed");
 
       make_ed_kv (&s_kv, &ip->dst_address, &ip->src_address, ip->protocol,
                  m->fib_index, 0, 0);
       s_kv.value = s - tsm->sessions;
       if (clib_bihash_add_del_16_8 (&tsm->in2out_ed, &s_kv, 1))
-       nat_log_notice ("in2out key add failed");
+       nat_elog_notice ("in2out key add failed");
     }
 
   /* Update IP checksum */
@@ -666,7 +672,8 @@ nat44_ed_out2in_unknown_proto (snat_main_t * sm,
   vnet_buffer (b)->sw_if_index[VLIB_TX] = s->in2out.fib_index;
 
   /* Accounting */
-  nat44_session_update_counters (s, now, vlib_buffer_length_in_chain (vm, b));
+  nat44_session_update_counters (s, now, vlib_buffer_length_in_chain (vm, b),
+                                thread_index);
   /* Per-user LRU list maintenance */
   nat44_session_update_lru (sm, s, thread_index);
 
@@ -674,19 +681,20 @@ nat44_ed_out2in_unknown_proto (snat_main_t * sm,
 }
 
 static inline uword
-nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
-                               vlib_node_runtime_t * node,
-                               vlib_frame_t * frame, int is_slow_path)
+nat44_ed_out2in_fast_path_node_fn_inline (vlib_main_t * vm,
+                                         vlib_node_runtime_t * node,
+                                         vlib_frame_t * frame)
 {
   u32 n_left_from, *from, *to_next, pkts_processed = 0, stats_node_index;
-  nat44_ed_out2in_next_t next_index;
+  nat_next_t next_index;
   snat_main_t *sm = &snat_main;
   f64 now = vlib_time_now (vm);
   u32 thread_index = vm->thread_index;
   snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
+  u32 tcp_packets = 0, udp_packets = 0, icmp_packets = 0, other_packets =
+    0, fragments = 0;
 
-  stats_node_index = is_slow_path ? nat44_ed_out2in_slowpath_node.index :
-    nat44_ed_out2in_node.index;
+  stats_node_index = sm->ed_out2in_node_index;
 
   from = vlib_frame_vector_args (frame);
   n_left_from = frame->n_vectors;
@@ -698,52 +706,31 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
 
       vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
 
-      while (n_left_from >= 4 && n_left_to_next >= 2)
+      while (n_left_from > 0 && n_left_to_next > 0)
        {
-         u32 bi0, bi1;
-         vlib_buffer_t *b0, *b1;
+         u32 bi0;
+         vlib_buffer_t *b0;
          u32 next0, sw_if_index0, rx_fib_index0, proto0, old_addr0,
            new_addr0;
-         u32 next1, sw_if_index1, rx_fib_index1, proto1, old_addr1,
-           new_addr1;
-         u16 old_port0, new_port0, old_port1, new_port1;
-         ip4_header_t *ip0, *ip1;
-         udp_header_t *udp0, *udp1;
-         tcp_header_t *tcp0, *tcp1;
-         icmp46_header_t *icmp0, *icmp1;
-         snat_session_t *s0 = 0, *s1 = 0;
-         clib_bihash_kv_16_8_t kv0, value0, kv1, value1;
-         ip_csum_t sum0, sum1;
-         snat_session_key_t e_key0, l_key0, e_key1, l_key1;
-         lb_nat_type_t lb_nat0, lb_nat1;
-         twice_nat_type_t twice_nat0, twice_nat1;
-
-         /* Prefetch next iteration. */
-         {
-           vlib_buffer_t *p2, *p3;
-
-           p2 = vlib_get_buffer (vm, from[2]);
-           p3 = vlib_get_buffer (vm, from[3]);
-
-           vlib_prefetch_buffer_header (p2, LOAD);
-           vlib_prefetch_buffer_header (p3, LOAD);
-
-           CLIB_PREFETCH (p2->data, CLIB_CACHE_LINE_BYTES, STORE);
-           CLIB_PREFETCH (p3->data, CLIB_CACHE_LINE_BYTES, STORE);
-         }
-
-         /* speculatively enqueue b0 and b1 to the current next frame */
-         to_next[0] = bi0 = from[0];
-         to_next[1] = bi1 = from[1];
-         from += 2;
-         to_next += 2;
-         n_left_from -= 2;
-         n_left_to_next -= 2;
+         u16 old_port0, new_port0;
+         ip4_header_t *ip0;
+         udp_header_t *udp0;
+         tcp_header_t *tcp0;
+         snat_session_t *s0 = 0;
+         clib_bihash_kv_16_8_t kv0, value0;
+         ip_csum_t sum0;
+
+         /* speculatively enqueue b0 to the current next frame */
+         bi0 = from[0];
+         to_next[0] = bi0;
+         from += 1;
+         to_next += 1;
+         n_left_from -= 1;
+         n_left_to_next -= 1;
 
          b0 = vlib_get_buffer (vm, bi0);
-         b1 = vlib_get_buffer (vm, bi1);
+         next0 = nat_buffer_opaque (b0)->arc_next;
 
-         next0 = NAT44_ED_OUT2IN_NEXT_LOOKUP;
          vnet_buffer (b0)->snat.flags = 0;
          ip0 = vlib_buffer_get_current (b0);
 
@@ -758,135 +745,67 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
              icmp4_error_set_vnet_buffer (b0, ICMP4_time_exceeded,
                                           ICMP4_time_exceeded_ttl_exceeded_in_transit,
                                           0);
-             next0 = NAT44_ED_OUT2IN_NEXT_ICMP_ERROR;
-             goto trace00;
+             next0 = NAT_NEXT_ICMP_ERROR;
+             goto trace0;
            }
 
          udp0 = ip4_next_header (ip0);
          tcp0 = (tcp_header_t *) udp0;
-         icmp0 = (icmp46_header_t *) udp0;
          proto0 = ip_proto_to_snat_proto (ip0->protocol);
 
-         if (is_slow_path)
+         if (PREDICT_FALSE (proto0 == ~0))
            {
-             if (PREDICT_FALSE (proto0 == ~0))
-               {
-                 s0 =
-                   nat44_ed_out2in_unknown_proto (sm, b0, ip0, rx_fib_index0,
-                                                  thread_index, now, vm,
-                                                  node);
-                 if (!sm->forwarding_enabled)
-                   {
-                     if (!s0)
-                       next0 = NAT44_ED_OUT2IN_NEXT_DROP;
-                     goto trace00;
-                   }
-               }
-
-             if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
-               {
-                 next0 = icmp_out2in_ed_slow_path
-                   (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, node,
-                    next0, now, thread_index, &s0);
-                 goto trace00;
-               }
+             next0 = NAT_NEXT_OUT2IN_ED_SLOW_PATH;
+             goto trace0;
            }
-         else
-           {
-             if (PREDICT_FALSE (proto0 == ~0))
-               {
-                 next0 = NAT44_ED_OUT2IN_NEXT_SLOW_PATH;
-                 goto trace00;
-               }
-
-             if (ip4_is_fragment (ip0))
-               {
-                 next0 = NAT44_ED_OUT2IN_NEXT_REASS;
-                 goto trace00;
-               }
 
-             if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
-               {
-                 next0 = NAT44_ED_OUT2IN_NEXT_SLOW_PATH;
-                 goto trace00;
-               }
+         if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
+           {
+             next0 = NAT_NEXT_OUT2IN_ED_SLOW_PATH;
+             goto trace0;
            }
 
          make_ed_kv (&kv0, &ip0->dst_address, &ip0->src_address,
-                     ip0->protocol, rx_fib_index0, udp0->dst_port,
-                     udp0->src_port);
+                     ip0->protocol, rx_fib_index0,
+                     vnet_buffer (b0)->ip.reass.l4_dst_port,
+                     vnet_buffer (b0)->ip.reass.l4_src_port);
 
          if (clib_bihash_search_16_8 (&tsm->out2in_ed, &kv0, &value0))
            {
-             if (is_slow_path)
-               {
-                 /* Try to match static mapping by external address and port,
-                    destination address and port in packet */
-                 e_key0.addr = ip0->dst_address;
-                 e_key0.port = udp0->dst_port;
-                 e_key0.protocol = proto0;
-                 e_key0.fib_index = rx_fib_index0;
-                 if (snat_static_mapping_match (sm, e_key0, &l_key0, 1, 0,
-                                                &twice_nat0, &lb_nat0,
-                                                &ip0->src_address))
-                   {
-                     /*
-                      * 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 == SNAT_PROTOCOL_UDP
-                                        && (udp0->dst_port ==
-                                            clib_host_to_net_u16
-                                            (UDP_DST_PORT_dhcp_to_client))))
-                       {
-                         vnet_feature_next (&next0, b0);
-                         goto trace00;
-                       }
-
-                     if (!sm->forwarding_enabled)
-                       {
-                         b0->error =
-                           node->errors[NAT_OUT2IN_ED_ERROR_NO_TRANSLATION];
-                         next0 = NAT44_ED_OUT2IN_NEXT_DROP;
-                       }
-                     else
-                       {
-                         if (next_src_nat (sm, ip0, ip0->protocol,
-                                           udp0->src_port, udp0->dst_port,
-                                           thread_index, rx_fib_index0))
-                           {
-                             next0 = NAT44_ED_OUT2IN_NEXT_IN2OUT;
-                             goto trace00;
-                           }
-                         create_bypass_for_fwd (sm, ip0, rx_fib_index0,
-                                                thread_index);
-                       }
-                     goto trace00;
-                   }
-
-                 /* Create session initiated by host from external network */
-                 s0 = create_session_for_static_mapping_ed (sm, b0, l_key0,
-                                                            e_key0, node,
-                                                            thread_index,
-                                                            twice_nat0,
-                                                            lb_nat0, now);
+             next0 = NAT_NEXT_OUT2IN_ED_SLOW_PATH;
+             goto trace0;
+           }
+         s0 = pool_elt_at_index (tsm->sessions, value0.value);
 
-                 if (!s0)
-                   {
-                     next0 = NAT44_ED_OUT2IN_NEXT_DROP;
-                     goto trace00;
-                   }
+         if (s0->tcp_close_timestamp)
+           {
+             if (now >= s0->tcp_close_timestamp)
+               {
+                 // session is closed, go slow path
+                 next0 = NAT_NEXT_OUT2IN_ED_SLOW_PATH;
                }
              else
                {
-                 next0 = NAT44_ED_OUT2IN_NEXT_SLOW_PATH;
-                 goto trace00;
+                 // session in transitory timeout, drop
+                 b0->error = node->errors[NAT_OUT2IN_ED_ERROR_TCP_CLOSED];
+                 next0 = NAT_NEXT_DROP;
                }
+             goto trace0;
            }
-         else
+
+         // drop if session expired
+         u64 sess_timeout_time;
+         sess_timeout_time = s0->last_heard +
+           (f64) nat44_session_get_timeout (sm, s0);
+         if (now >= sess_timeout_time)
            {
-             s0 = pool_elt_at_index (tsm->sessions, value0.value);
+             // session is closed, go slow path
+             nat_free_session_data (sm, s0, thread_index, 0);
+             nat44_delete_session (sm, s0, thread_index);
+             next0 = NAT_NEXT_OUT2IN_ED_SLOW_PATH;
+             goto trace0;
            }
+         //
 
          old_addr0 = ip0->dst_address.as_u32;
          new_addr0 = ip0->dst_address.as_u32 = s0->in2out.addr.as_u32;
@@ -901,289 +820,159 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
                                   src_address);
          ip0->checksum = ip_csum_fold (sum0);
 
+         old_port0 = vnet_buffer (b0)->ip.reass.l4_dst_port;
+
          if (PREDICT_TRUE (proto0 == SNAT_PROTOCOL_TCP))
            {
-             old_port0 = tcp0->dst_port;
-             new_port0 = tcp0->dst_port = s0->in2out.port;
-
-             sum0 = tcp0->checksum;
+             if (!vnet_buffer (b0)->ip.reass.is_non_first_fragment)
+               {
+                 new_port0 = udp0->dst_port = s0->in2out.port;
+                 sum0 = tcp0->checksum;
+                 sum0 =
+                   ip_csum_update (sum0, old_addr0, new_addr0, ip4_header_t,
+                                   dst_address);
+                 sum0 =
+                   ip_csum_update (sum0, old_port0, new_port0, ip4_header_t,
+                                   length);
+                 if (is_twice_nat_session (s0))
+                   {
+                     sum0 = ip_csum_update (sum0, ip0->src_address.as_u32,
+                                            s0->ext_host_nat_addr.as_u32,
+                                            ip4_header_t, dst_address);
+                     sum0 =
+                       ip_csum_update (sum0,
+                                       vnet_buffer (b0)->ip.
+                                       reass.l4_src_port,
+                                       s0->ext_host_nat_port, ip4_header_t,
+                                       length);
+                     tcp0->src_port = s0->ext_host_nat_port;
+                     ip0->src_address.as_u32 = s0->ext_host_nat_addr.as_u32;
+                   }
+                 tcp0->checksum = ip_csum_fold (sum0);
+               }
+             tcp_packets++;
+             if (nat44_set_tcp_session_state_o2i
+                 (sm, now, s0,
+                  vnet_buffer (b0)->ip.reass.icmp_type_or_tcp_flags,
+                  vnet_buffer (b0)->ip.reass.tcp_ack_number,
+                  vnet_buffer (b0)->ip.reass.tcp_seq_number, thread_index))
+               goto trace0;
+           }
+         else if (!vnet_buffer (b0)->ip.reass.is_non_first_fragment
+                  && udp0->checksum)
+           {
+             new_port0 = udp0->dst_port = s0->in2out.port;
+             sum0 = udp0->checksum;
              sum0 = ip_csum_update (sum0, old_addr0, new_addr0, ip4_header_t,
                                     dst_address);
              sum0 = ip_csum_update (sum0, old_port0, new_port0, ip4_header_t,
                                     length);
-             if (is_twice_nat_session (s0))
+             if (PREDICT_FALSE (is_twice_nat_session (s0)))
                {
                  sum0 = ip_csum_update (sum0, ip0->src_address.as_u32,
                                         s0->ext_host_nat_addr.as_u32,
                                         ip4_header_t, dst_address);
-                 sum0 = ip_csum_update (sum0, tcp0->src_port,
-                                        s0->ext_host_nat_port, ip4_header_t,
-                                        length);
-                 tcp0->src_port = s0->ext_host_nat_port;
+                 sum0 =
+                   ip_csum_update (sum0,
+                                   vnet_buffer (b0)->ip.reass.l4_src_port,
+                                   s0->ext_host_nat_port, ip4_header_t,
+                                   length);
+                 udp0->src_port = s0->ext_host_nat_port;
                  ip0->src_address.as_u32 = s0->ext_host_nat_addr.as_u32;
                }
-             tcp0->checksum = ip_csum_fold (sum0);
-             if (nat44_set_tcp_session_state_o2i
-                 (sm, s0, tcp0, thread_index))
-               goto trace00;
+             udp0->checksum = ip_csum_fold (sum0);
+             udp_packets++;
            }
          else
            {
-             udp0->dst_port = s0->in2out.port;
-             if (is_twice_nat_session (s0))
+             if (!vnet_buffer (b0)->ip.reass.is_non_first_fragment)
                {
-                 udp0->src_port = s0->ext_host_nat_port;
-                 ip0->src_address.as_u32 = s0->ext_host_nat_addr.as_u32;
+                 new_port0 = udp0->dst_port = s0->in2out.port;
+                 if (PREDICT_FALSE (is_twice_nat_session (s0)))
+                   {
+                     udp0->src_port = s0->ext_host_nat_port;
+                     ip0->src_address.as_u32 = s0->ext_host_nat_addr.as_u32;
+                   }
                }
-             udp0->checksum = 0;
+             udp_packets++;
            }
 
          /* Accounting */
          nat44_session_update_counters (s0, now,
-                                        vlib_buffer_length_in_chain (vm,
-                                                                     b0));
+                                        vlib_buffer_length_in_chain (vm, b0),
+                                        thread_index);
          /* Per-user LRU list maintenance */
          nat44_session_update_lru (sm, s0, thread_index);
 
-       trace00:
+       trace0:
          if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
                             && (b0->flags & VLIB_BUFFER_IS_TRACED)))
            {
              nat44_ed_out2in_trace_t *t =
                vlib_add_trace (vm, node, b0, sizeof (*t));
-             t->is_slow_path = is_slow_path;
              t->sw_if_index = sw_if_index0;
              t->next_index = next0;
-             t->session_index = ~0;
+             t->is_slow_path = 0;
+
              if (s0)
                t->session_index = s0 - tsm->sessions;
-           }
-
-         pkts_processed += next0 != NAT44_ED_OUT2IN_NEXT_DROP;
-
-         next1 = NAT44_ED_OUT2IN_NEXT_LOOKUP;
-         vnet_buffer (b1)->snat.flags = 0;
-         ip1 = vlib_buffer_get_current (b1);
-
-         sw_if_index1 = vnet_buffer (b1)->sw_if_index[VLIB_RX];
-         rx_fib_index1 =
-           fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP4,
-                                                sw_if_index1);
-
-         if (PREDICT_FALSE (ip1->ttl == 1))
-           {
-             vnet_buffer (b1)->sw_if_index[VLIB_TX] = (u32) ~ 0;
-             icmp4_error_set_vnet_buffer (b1, ICMP4_time_exceeded,
-                                          ICMP4_time_exceeded_ttl_exceeded_in_transit,
-                                          0);
-             next1 = NAT44_ED_OUT2IN_NEXT_ICMP_ERROR;
-             goto trace01;
-           }
-
-         udp1 = ip4_next_header (ip1);
-         tcp1 = (tcp_header_t *) udp1;
-         icmp1 = (icmp46_header_t *) udp1;
-         proto1 = ip_proto_to_snat_proto (ip1->protocol);
-
-         if (is_slow_path)
-           {
-             if (PREDICT_FALSE (proto1 == ~0))
-               {
-                 s1 =
-                   nat44_ed_out2in_unknown_proto (sm, b1, ip1, rx_fib_index1,
-                                                  thread_index, now, vm,
-                                                  node);
-                 if (!sm->forwarding_enabled)
-                   {
-                     if (!s1)
-                       next1 = NAT44_ED_OUT2IN_NEXT_DROP;
-                     goto trace01;
-                   }
-               }
-
-             if (PREDICT_FALSE (proto1 == SNAT_PROTOCOL_ICMP))
-               {
-                 next1 = icmp_out2in_ed_slow_path
-                   (sm, b1, ip1, icmp1, sw_if_index1, rx_fib_index1, node,
-                    next1, now, thread_index, &s1);
-                 goto trace01;
-               }
-           }
-         else
-           {
-             if (PREDICT_FALSE (proto1 == ~0))
-               {
-                 next1 = NAT44_ED_OUT2IN_NEXT_SLOW_PATH;
-                 goto trace01;
-               }
-
-             if (ip4_is_fragment (ip1))
-               {
-                 next1 = NAT44_ED_OUT2IN_NEXT_REASS;
-                 goto trace01;
-               }
-
-             if (PREDICT_FALSE (proto1 == SNAT_PROTOCOL_ICMP))
-               {
-                 next1 = NAT44_ED_OUT2IN_NEXT_SLOW_PATH;
-                 goto trace01;
-               }
-           }
-
-         make_ed_kv (&kv1, &ip1->dst_address, &ip1->src_address,
-                     ip1->protocol, rx_fib_index1, udp1->dst_port,
-                     udp1->src_port);
-
-         if (clib_bihash_search_16_8 (&tsm->out2in_ed, &kv1, &value1))
-           {
-             if (is_slow_path)
-               {
-                 /* Try to match static mapping by external address and port,
-                    destination address and port in packet */
-                 e_key1.addr = ip1->dst_address;
-                 e_key1.port = udp1->dst_port;
-                 e_key1.protocol = proto1;
-                 e_key1.fib_index = rx_fib_index1;
-                 if (snat_static_mapping_match (sm, e_key1, &l_key1, 1, 0,
-                                                &twice_nat1, &lb_nat1,
-                                                &ip1->src_address))
-                   {
-                     /*
-                      * Send DHCP packets to the ipv4 stack, or we won't
-                      * be able to use dhcp client on the outside interface
-                      */
-                     if (PREDICT_FALSE (proto1 == SNAT_PROTOCOL_UDP
-                                        && (udp1->dst_port ==
-                                            clib_host_to_net_u16
-                                            (UDP_DST_PORT_dhcp_to_client))))
-                       {
-                         vnet_feature_next (&next1, b1);
-                         goto trace01;
-                       }
-
-                     if (!sm->forwarding_enabled)
-                       {
-                         b1->error =
-                           node->errors[NAT_OUT2IN_ED_ERROR_NO_TRANSLATION];
-                         next1 = NAT44_ED_OUT2IN_NEXT_DROP;
-                       }
-                     else
-                       {
-                         if (next_src_nat (sm, ip1, ip1->protocol,
-                                           udp1->src_port, udp1->dst_port,
-                                           thread_index, rx_fib_index1))
-                           {
-                             next1 = NAT44_ED_OUT2IN_NEXT_IN2OUT;
-                             goto trace01;
-                           }
-                         create_bypass_for_fwd (sm, ip1, rx_fib_index1,
-                                                thread_index);
-                       }
-                     goto trace01;
-                   }
-
-                 /* Create session initiated by host from external network */
-                 s1 = create_session_for_static_mapping_ed (sm, b1, l_key1,
-                                                            e_key1, node,
-                                                            thread_index,
-                                                            twice_nat1,
-                                                            lb_nat1, now);
-
-                 if (!s1)
-                   {
-                     next1 = NAT44_ED_OUT2IN_NEXT_DROP;
-                     goto trace01;
-                   }
-               }
              else
-               {
-                 next1 = NAT44_ED_OUT2IN_NEXT_SLOW_PATH;
-                 goto trace01;
-               }
-           }
-         else
-           {
-             s1 = pool_elt_at_index (tsm->sessions, value1.value);
+               t->session_index = ~0;
            }
 
-         old_addr1 = ip1->dst_address.as_u32;
-         new_addr1 = ip1->dst_address.as_u32 = s1->in2out.addr.as_u32;
-         vnet_buffer (b1)->sw_if_index[VLIB_TX] = s1->in2out.fib_index;
+         pkts_processed += next0 == nat_buffer_opaque (b0)->arc_next;
+         /* verify speculative enqueue, maybe switch current next frame */
+         vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
+                                          to_next, n_left_to_next,
+                                          bi0, next0);
+       }
 
-         sum1 = ip1->checksum;
-         sum1 = ip_csum_update (sum1, old_addr1, new_addr1, ip4_header_t,
-                                dst_address);
-         if (PREDICT_FALSE (is_twice_nat_session (s1)))
-           sum1 = ip_csum_update (sum1, ip1->src_address.as_u32,
-                                  s1->ext_host_nat_addr.as_u32, ip4_header_t,
-                                  src_address);
-         ip1->checksum = ip_csum_fold (sum1);
+      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
+    }
 
-         if (PREDICT_TRUE (proto1 == SNAT_PROTOCOL_TCP))
-           {
-             old_port1 = tcp1->dst_port;
-             new_port1 = tcp1->dst_port = s1->in2out.port;
+  vlib_node_increment_counter (vm, stats_node_index,
+                              NAT_OUT2IN_ED_ERROR_OUT2IN_PACKETS,
+                              pkts_processed);
+  vlib_node_increment_counter (vm, stats_node_index,
+                              NAT_OUT2IN_ED_ERROR_TCP_PACKETS, tcp_packets);
+  vlib_node_increment_counter (vm, stats_node_index,
+                              NAT_OUT2IN_ED_ERROR_UDP_PACKETS, udp_packets);
+  vlib_node_increment_counter (vm, stats_node_index,
+                              NAT_OUT2IN_ED_ERROR_ICMP_PACKETS,
+                              icmp_packets);
+  vlib_node_increment_counter (vm, stats_node_index,
+                              NAT_OUT2IN_ED_ERROR_OTHER_PACKETS,
+                              other_packets);
+  vlib_node_increment_counter (vm, stats_node_index,
+                              NAT_OUT2IN_ED_ERROR_FRAGMENTS, fragments);
+  return frame->n_vectors;
+}
 
-             sum1 = tcp1->checksum;
-             sum1 = ip_csum_update (sum1, old_addr1, new_addr1, ip4_header_t,
-                                    dst_address);
-             sum1 = ip_csum_update (sum1, old_port1, new_port1, ip4_header_t,
-                                    length);
-             if (is_twice_nat_session (s1))
-               {
-                 sum1 = ip_csum_update (sum1, ip1->src_address.as_u32,
-                                        s1->ext_host_nat_addr.as_u32,
-                                        ip4_header_t, dst_address);
-                 sum1 = ip_csum_update (sum1, tcp1->src_port,
-                                        s1->ext_host_nat_port, ip4_header_t,
-                                        length);
-                 tcp1->src_port = s1->ext_host_nat_port;
-                 ip1->src_address.as_u32 = s1->ext_host_nat_addr.as_u32;
-               }
-             tcp1->checksum = ip_csum_fold (sum1);
-             if (nat44_set_tcp_session_state_o2i
-                 (sm, s1, tcp1, thread_index))
-               goto trace01;
-           }
-         else
-           {
-             udp1->dst_port = s1->in2out.port;
-             if (is_twice_nat_session (s1))
-               {
-                 udp1->src_port = s1->ext_host_nat_port;
-                 ip1->src_address.as_u32 = s1->ext_host_nat_addr.as_u32;
-               }
-             udp1->checksum = 0;
-           }
+static inline uword
+nat44_ed_out2in_slow_path_node_fn_inline (vlib_main_t * vm,
+                                         vlib_node_runtime_t * node,
+                                         vlib_frame_t * frame)
+{
+  u32 n_left_from, *from, *to_next, pkts_processed = 0, stats_node_index;
+  nat_next_t next_index;
+  snat_main_t *sm = &snat_main;
+  f64 now = vlib_time_now (vm);
+  u32 thread_index = vm->thread_index;
+  snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
+  u32 tcp_packets = 0, udp_packets = 0, icmp_packets = 0, other_packets =
+    0, fragments = 0;
 
-         /* Accounting */
-         nat44_session_update_counters (s1, now,
-                                        vlib_buffer_length_in_chain (vm,
-                                                                     b1));
-         /* Per-user LRU list maintenance */
-         nat44_session_update_lru (sm, s1, thread_index);
+  stats_node_index = sm->ed_out2in_slowpath_node_index;
 
-       trace01:
-         if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
-                            && (b1->flags & VLIB_BUFFER_IS_TRACED)))
-           {
-             nat44_ed_out2in_trace_t *t =
-               vlib_add_trace (vm, node, b1, sizeof (*t));
-             t->is_slow_path = is_slow_path;
-             t->sw_if_index = sw_if_index1;
-             t->next_index = next1;
-             t->session_index = ~0;
-             if (s1)
-               t->session_index = s1 - tsm->sessions;
-           }
+  from = vlib_frame_vector_args (frame);
+  n_left_from = frame->n_vectors;
+  next_index = node->cached_next_index;
 
-         pkts_processed += next1 != NAT44_ED_OUT2IN_NEXT_DROP;
+  while (n_left_from > 0)
+    {
+      u32 n_left_to_next;
 
-         /* verify speculative enqueues, maybe switch current next frame */
-         vlib_validate_buffer_enqueue_x2 (vm, node, next_index,
-                                          to_next, n_left_to_next,
-                                          bi0, bi1, next0, next1);
-       }
+      vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
 
       while (n_left_from > 0 && n_left_to_next > 0)
        {
@@ -1202,6 +991,7 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
          snat_session_key_t e_key0, l_key0;
          lb_nat_type_t lb_nat0;
          twice_nat_type_t twice_nat0;
+         u8 identity_nat0;
 
          /* speculatively enqueue b0 to the current next frame */
          bi0 = from[0];
@@ -1212,7 +1002,8 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
          n_left_to_next -= 1;
 
          b0 = vlib_get_buffer (vm, bi0);
-         next0 = NAT44_ED_OUT2IN_NEXT_LOOKUP;
+         next0 = nat_buffer_opaque (b0)->arc_next;
+
          vnet_buffer (b0)->snat.flags = 0;
          ip0 = vlib_buffer_get_current (b0);
 
@@ -1227,7 +1018,7 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
              icmp4_error_set_vnet_buffer (b0, ICMP4_time_exceeded,
                                           ICMP4_time_exceeded_ttl_exceeded_in_transit,
                                           0);
-             next0 = NAT44_ED_OUT2IN_NEXT_ICMP_ERROR;
+             next0 = NAT_NEXT_ICMP_ERROR;
              goto trace0;
            }
 
@@ -1236,126 +1027,126 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
          icmp0 = (icmp46_header_t *) udp0;
          proto0 = ip_proto_to_snat_proto (ip0->protocol);
 
-         if (is_slow_path)
+         if (PREDICT_FALSE (proto0 == ~0))
            {
-             if (PREDICT_FALSE (proto0 == ~0))
+             s0 =
+               nat44_ed_out2in_unknown_proto (sm, b0, ip0, rx_fib_index0,
+                                              thread_index, now, vm, node);
+             if (!sm->forwarding_enabled)
                {
-                 s0 =
-                   nat44_ed_out2in_unknown_proto (sm, b0, ip0, rx_fib_index0,
-                                                  thread_index, now, vm,
-                                                  node);
-                 if (!sm->forwarding_enabled)
-                   {
-                     if (!s0)
-                       next0 = NAT44_ED_OUT2IN_NEXT_DROP;
-                     goto trace0;
-                   }
+                 if (!s0)
+                   next0 = NAT_NEXT_DROP;
                }
+             other_packets++;
+             goto trace0;
+           }
 
-             if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
-               {
-                 next0 = icmp_out2in_ed_slow_path
-                   (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, node,
-                    next0, now, thread_index, &s0);
-                 goto trace0;
-               }
+         if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
+           {
+             next0 = icmp_out2in_ed_slow_path
+               (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, node,
+                next0, now, thread_index, &s0);
+             icmp_packets++;
+             goto trace0;
            }
-         else
+
+         make_ed_kv (&kv0, &ip0->dst_address, &ip0->src_address,
+                     ip0->protocol, rx_fib_index0,
+                     vnet_buffer (b0)->ip.reass.l4_dst_port,
+                     vnet_buffer (b0)->ip.reass.l4_src_port);
+
+         s0 = NULL;
+         if (!clib_bihash_search_16_8 (&tsm->out2in_ed, &kv0, &value0))
            {
-             if (PREDICT_FALSE (proto0 == ~0))
-               {
-                 next0 = NAT44_ED_OUT2IN_NEXT_SLOW_PATH;
-                 goto trace0;
-               }
-
-             if (ip4_is_fragment (ip0))
-               {
-                 next0 = NAT44_ED_OUT2IN_NEXT_REASS;
-                 goto trace0;
-               }
+             s0 = pool_elt_at_index (tsm->sessions, value0.value);
 
-             if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
+             if (s0->tcp_close_timestamp && now >= s0->tcp_close_timestamp)
                {
-                 next0 = NAT44_ED_OUT2IN_NEXT_SLOW_PATH;
-                 goto trace0;
+                 nat_free_session_data (sm, s0, thread_index, 0);
+                 nat44_delete_session (sm, s0, thread_index);
+                 s0 = NULL;
                }
            }
 
-         make_ed_kv (&kv0, &ip0->dst_address, &ip0->src_address,
-                     ip0->protocol, rx_fib_index0, udp0->dst_port,
-                     udp0->src_port);
-
-         if (clib_bihash_search_16_8 (&tsm->out2in_ed, &kv0, &value0))
+         if (!s0)
            {
-             if (is_slow_path)
+             /* Try to match static mapping by external address and port,
+                destination address and port in packet */
+             e_key0.addr = ip0->dst_address;
+             e_key0.port = vnet_buffer (b0)->ip.reass.l4_dst_port;
+             e_key0.protocol = proto0;
+             e_key0.fib_index = rx_fib_index0;
+
+             if (snat_static_mapping_match (sm, e_key0, &l_key0, 1, 0,
+                                            &twice_nat0, &lb_nat0,
+                                            &ip0->src_address,
+                                            &identity_nat0))
                {
-                 /* Try to match static mapping by external address and port,
-                    destination address and port in packet */
-                 e_key0.addr = ip0->dst_address;
-                 e_key0.port = udp0->dst_port;
-                 e_key0.protocol = proto0;
-                 e_key0.fib_index = rx_fib_index0;
-                 if (snat_static_mapping_match (sm, e_key0, &l_key0, 1, 0,
-                                                &twice_nat0, &lb_nat0,
-                                                &ip0->src_address))
+                 /*
+                  * 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 == SNAT_PROTOCOL_UDP
+                                    && (vnet_buffer (b0)->ip.
+                                        reass.l4_dst_port ==
+                                        clib_host_to_net_u16
+                                        (UDP_DST_PORT_dhcp_to_client))))
                    {
-                     /*
-                      * 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 == SNAT_PROTOCOL_UDP
-                                        && (udp0->dst_port ==
-                                            clib_host_to_net_u16
-                                            (UDP_DST_PORT_dhcp_to_client))))
-                       {
-                         vnet_feature_next (&next0, b0);
-                         goto trace0;
-                       }
+                     goto trace0;
+                   }
 
-                     if (!sm->forwarding_enabled)
+                 if (!sm->forwarding_enabled)
+                   {
+                     b0->error =
+                       node->errors[NAT_OUT2IN_ED_ERROR_NO_TRANSLATION];
+                     next0 = NAT_NEXT_DROP;
+                   }
+                 else
+                   {
+                     if (next_src_nat (sm, ip0, ip0->protocol,
+                                       vnet_buffer (b0)->ip.
+                                       reass.l4_src_port,
+                                       vnet_buffer (b0)->ip.
+                                       reass.l4_dst_port, thread_index,
+                                       rx_fib_index0))
                        {
-                         b0->error =
-                           node->errors[NAT_OUT2IN_ED_ERROR_NO_TRANSLATION];
-                         next0 = NAT44_ED_OUT2IN_NEXT_DROP;
+                         next0 = NAT_NEXT_IN2OUT_ED_FAST_PATH;
+                         goto trace0;
                        }
+                     if (sm->num_workers > 1)
+                       create_bypass_for_fwd_worker (sm, b0, ip0,
+                                                     rx_fib_index0);
                      else
-                       {
-                         if (next_src_nat (sm, ip0, ip0->protocol,
-                                           udp0->src_port, udp0->dst_port,
-                                           thread_index, rx_fib_index0))
-                           {
-                             next0 = NAT44_ED_OUT2IN_NEXT_IN2OUT;
-                             goto trace0;
-                           }
-                         create_bypass_for_fwd (sm, ip0, rx_fib_index0,
-                                                thread_index);
-                       }
-                     goto trace0;
+                       create_bypass_for_fwd (sm, b0, ip0, rx_fib_index0,
+                                              thread_index);
                    }
+                 goto trace0;
+               }
 
-                 /* Create session initiated by host from external network */
-                 s0 = create_session_for_static_mapping_ed (sm, b0, l_key0,
-                                                            e_key0, node,
-                                                            thread_index,
-                                                            twice_nat0,
-                                                            lb_nat0, now);
+             if (PREDICT_FALSE (identity_nat0))
+               goto trace0;
 
-                 if (!s0)
-                   {
-                     next0 = NAT44_ED_OUT2IN_NEXT_DROP;
-                     goto trace0;
-                   }
+             if ((proto0 == SNAT_PROTOCOL_TCP)
+                 && !tcp_flags_is_init (vnet_buffer (b0)->ip.
+                                        reass.icmp_type_or_tcp_flags))
+               {
+                 b0->error = node->errors[NAT_OUT2IN_ED_ERROR_NON_SYN];
+                 next0 = NAT_NEXT_DROP;
+                 goto trace0;
                }
-             else
+
+             /* Create session initiated by host from external network */
+             s0 = create_session_for_static_mapping_ed (sm, b0, l_key0,
+                                                        e_key0, node,
+                                                        thread_index,
+                                                        twice_nat0,
+                                                        lb_nat0, now);
+             if (!s0)
                {
-                 next0 = NAT44_ED_OUT2IN_NEXT_SLOW_PATH;
+                 next0 = NAT_NEXT_DROP;
                  goto trace0;
                }
            }
-         else
-           {
-             s0 = pool_elt_at_index (tsm->sessions, value0.value);
-           }
 
          old_addr0 = ip0->dst_address.as_u32;
          new_addr0 = ip0->dst_address.as_u32 = s0->in2out.addr.as_u32;
@@ -1370,47 +1161,87 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
                                   src_address);
          ip0->checksum = ip_csum_fold (sum0);
 
+         old_port0 = vnet_buffer (b0)->ip.reass.l4_dst_port;
+
          if (PREDICT_TRUE (proto0 == SNAT_PROTOCOL_TCP))
            {
-             old_port0 = tcp0->dst_port;
-             new_port0 = tcp0->dst_port = s0->in2out.port;
-
-             sum0 = tcp0->checksum;
+             if (!vnet_buffer (b0)->ip.reass.is_non_first_fragment)
+               {
+                 new_port0 = udp0->dst_port = s0->in2out.port;
+                 sum0 = tcp0->checksum;
+                 sum0 =
+                   ip_csum_update (sum0, old_addr0, new_addr0, ip4_header_t,
+                                   dst_address);
+                 sum0 =
+                   ip_csum_update (sum0, old_port0, new_port0, ip4_header_t,
+                                   length);
+                 if (is_twice_nat_session (s0))
+                   {
+                     sum0 = ip_csum_update (sum0, ip0->src_address.as_u32,
+                                            s0->ext_host_nat_addr.as_u32,
+                                            ip4_header_t, dst_address);
+                     sum0 =
+                       ip_csum_update (sum0,
+                                       vnet_buffer (b0)->ip.
+                                       reass.l4_src_port,
+                                       s0->ext_host_nat_port, ip4_header_t,
+                                       length);
+                     tcp0->src_port = s0->ext_host_nat_port;
+                     ip0->src_address.as_u32 = s0->ext_host_nat_addr.as_u32;
+                   }
+                 tcp0->checksum = ip_csum_fold (sum0);
+               }
+             tcp_packets++;
+             if (nat44_set_tcp_session_state_o2i
+                 (sm, now, s0,
+                  vnet_buffer (b0)->ip.reass.icmp_type_or_tcp_flags,
+                  vnet_buffer (b0)->ip.reass.tcp_ack_number,
+                  vnet_buffer (b0)->ip.reass.tcp_seq_number, thread_index))
+               goto trace0;
+           }
+         else if (!vnet_buffer (b0)->ip.reass.is_non_first_fragment
+                  && udp0->checksum)
+           {
+             new_port0 = udp0->dst_port = s0->in2out.port;
+             sum0 = udp0->checksum;
              sum0 = ip_csum_update (sum0, old_addr0, new_addr0, ip4_header_t,
                                     dst_address);
              sum0 = ip_csum_update (sum0, old_port0, new_port0, ip4_header_t,
                                     length);
-             if (is_twice_nat_session (s0))
+             if (PREDICT_FALSE (is_twice_nat_session (s0)))
                {
                  sum0 = ip_csum_update (sum0, ip0->src_address.as_u32,
                                         s0->ext_host_nat_addr.as_u32,
                                         ip4_header_t, dst_address);
-                 sum0 = ip_csum_update (sum0, tcp0->src_port,
-                                        s0->ext_host_nat_port, ip4_header_t,
-                                        length);
-                 tcp0->src_port = s0->ext_host_nat_port;
+                 sum0 =
+                   ip_csum_update (sum0,
+                                   vnet_buffer (b0)->ip.reass.l4_src_port,
+                                   s0->ext_host_nat_port, ip4_header_t,
+                                   length);
+                 udp0->src_port = s0->ext_host_nat_port;
                  ip0->src_address.as_u32 = s0->ext_host_nat_addr.as_u32;
                }
-             tcp0->checksum = ip_csum_fold (sum0);
-             if (nat44_set_tcp_session_state_o2i
-                 (sm, s0, tcp0, thread_index))
-               goto trace0;
+             udp0->checksum = ip_csum_fold (sum0);
+             udp_packets++;
            }
          else
            {
-             udp0->dst_port = s0->in2out.port;
-             if (is_twice_nat_session (s0))
+             if (!vnet_buffer (b0)->ip.reass.is_non_first_fragment)
                {
-                 udp0->src_port = s0->ext_host_nat_port;
-                 ip0->src_address.as_u32 = s0->ext_host_nat_addr.as_u32;
+                 new_port0 = udp0->dst_port = s0->in2out.port;
+                 if (PREDICT_FALSE (is_twice_nat_session (s0)))
+                   {
+                     udp0->src_port = s0->ext_host_nat_port;
+                     ip0->src_address.as_u32 = s0->ext_host_nat_addr.as_u32;
+                   }
                }
-             udp0->checksum = 0;
+             udp_packets++;
            }
 
          /* Accounting */
          nat44_session_update_counters (s0, now,
-                                        vlib_buffer_length_in_chain (vm,
-                                                                     b0));
+                                        vlib_buffer_length_in_chain (vm, b0),
+                                        thread_index);
          /* Per-user LRU list maintenance */
          nat44_session_update_lru (sm, s0, thread_index);
 
@@ -1420,15 +1251,17 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
            {
              nat44_ed_out2in_trace_t *t =
                vlib_add_trace (vm, node, b0, sizeof (*t));
-             t->is_slow_path = is_slow_path;
              t->sw_if_index = sw_if_index0;
              t->next_index = next0;
-             t->session_index = ~0;
+             t->is_slow_path = 1;
+
              if (s0)
                t->session_index = s0 - tsm->sessions;
+             else
+               t->session_index = ~0;
            }
 
-         pkts_processed += next0 != NAT44_ED_OUT2IN_NEXT_DROP;
+         pkts_processed += next0 == nat_buffer_opaque (b0)->arc_next;
          /* verify speculative enqueue, maybe switch current next frame */
          vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
                                           to_next, n_left_to_next,
@@ -1441,438 +1274,89 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
   vlib_node_increment_counter (vm, stats_node_index,
                               NAT_OUT2IN_ED_ERROR_OUT2IN_PACKETS,
                               pkts_processed);
+  vlib_node_increment_counter (vm, stats_node_index,
+                              NAT_OUT2IN_ED_ERROR_TCP_PACKETS, tcp_packets);
+  vlib_node_increment_counter (vm, stats_node_index,
+                              NAT_OUT2IN_ED_ERROR_UDP_PACKETS, udp_packets);
+  vlib_node_increment_counter (vm, stats_node_index,
+                              NAT_OUT2IN_ED_ERROR_ICMP_PACKETS,
+                              icmp_packets);
+  vlib_node_increment_counter (vm, stats_node_index,
+                              NAT_OUT2IN_ED_ERROR_OTHER_PACKETS,
+                              other_packets);
+  vlib_node_increment_counter (vm, stats_node_index,
+                              NAT_OUT2IN_ED_ERROR_FRAGMENTS, fragments);
   return frame->n_vectors;
 }
 
-static uword
-nat44_ed_out2in_fast_path_fn (vlib_main_t * vm,
-                             vlib_node_runtime_t * node,
-                             vlib_frame_t * frame)
+VLIB_NODE_FN (nat44_ed_out2in_node) (vlib_main_t * vm,
+                                    vlib_node_runtime_t * node,
+                                    vlib_frame_t * frame)
 {
-  return nat44_ed_out2in_node_fn_inline (vm, node, frame, 0);
+  return nat44_ed_out2in_fast_path_node_fn_inline (vm, node, frame);
 }
 
 /* *INDENT-OFF* */
 VLIB_REGISTER_NODE (nat44_ed_out2in_node) = {
-  .function = nat44_ed_out2in_fast_path_fn,
   .name = "nat44-ed-out2in",
   .vector_size = sizeof (u32),
+  .sibling_of = "nat-default",
   .format_trace = format_nat44_ed_out2in_trace,
   .type = VLIB_NODE_TYPE_INTERNAL,
   .n_errors = ARRAY_LEN(nat_out2in_ed_error_strings),
   .error_strings = nat_out2in_ed_error_strings,
   .runtime_data_bytes = sizeof (snat_runtime_t),
-  .n_next_nodes = NAT44_ED_OUT2IN_N_NEXT,
-  .next_nodes = {
-    [NAT44_ED_OUT2IN_NEXT_DROP] = "error-drop",
-    [NAT44_ED_OUT2IN_NEXT_LOOKUP] = "ip4-lookup",
-    [NAT44_ED_OUT2IN_NEXT_SLOW_PATH] = "nat44-ed-out2in-slowpath",
-    [NAT44_ED_OUT2IN_NEXT_ICMP_ERROR] = "ip4-icmp-error",
-    [NAT44_ED_OUT2IN_NEXT_IN2OUT] = "nat44-ed-in2out",
-    [NAT44_ED_OUT2IN_NEXT_REASS] = "nat44-ed-out2in-reass",
-  },
 };
 /* *INDENT-ON* */
 
-VLIB_NODE_FUNCTION_MULTIARCH (nat44_ed_out2in_node,
-                             nat44_ed_out2in_fast_path_fn);
-
-static uword
-nat44_ed_out2in_slow_path_fn (vlib_main_t * vm,
-                             vlib_node_runtime_t * node,
-                             vlib_frame_t * frame)
+VLIB_NODE_FN (nat44_ed_out2in_slowpath_node) (vlib_main_t * vm,
+                                             vlib_node_runtime_t * node,
+                                             vlib_frame_t * frame)
 {
-  return nat44_ed_out2in_node_fn_inline (vm, node, frame, 1);
+  return nat44_ed_out2in_slow_path_node_fn_inline (vm, node, frame);
 }
 
 /* *INDENT-OFF* */
 VLIB_REGISTER_NODE (nat44_ed_out2in_slowpath_node) = {
-  .function = nat44_ed_out2in_slow_path_fn,
   .name = "nat44-ed-out2in-slowpath",
   .vector_size = sizeof (u32),
+  .sibling_of = "nat-default",
   .format_trace = format_nat44_ed_out2in_trace,
   .type = VLIB_NODE_TYPE_INTERNAL,
   .n_errors = ARRAY_LEN(nat_out2in_ed_error_strings),
   .error_strings = nat_out2in_ed_error_strings,
   .runtime_data_bytes = sizeof (snat_runtime_t),
-  .n_next_nodes = NAT44_ED_OUT2IN_N_NEXT,
-  .next_nodes = {
-    [NAT44_ED_OUT2IN_NEXT_DROP] = "error-drop",
-    [NAT44_ED_OUT2IN_NEXT_LOOKUP] = "ip4-lookup",
-    [NAT44_ED_OUT2IN_NEXT_SLOW_PATH] = "nat44-ed-out2in-slowpath",
-    [NAT44_ED_OUT2IN_NEXT_ICMP_ERROR] = "ip4-icmp-error",
-    [NAT44_ED_OUT2IN_NEXT_IN2OUT] = "nat44-ed-in2out",
-    [NAT44_ED_OUT2IN_NEXT_REASS] = "nat44-ed-out2in-reass",
-  },
 };
 /* *INDENT-ON* */
 
-VLIB_NODE_FUNCTION_MULTIARCH (nat44_ed_out2in_slowpath_node,
-                             nat44_ed_out2in_slow_path_fn);
-
-static uword
-nat44_ed_out2in_reass_node_fn (vlib_main_t * vm,
-                              vlib_node_runtime_t * node,
-                              vlib_frame_t * frame)
+static u8 *
+format_nat_pre_trace (u8 * s, va_list * args)
 {
-  u32 n_left_from, *from, *to_next;
-  nat44_ed_out2in_next_t next_index;
-  u32 pkts_processed = 0;
-  snat_main_t *sm = &snat_main;
-  f64 now = vlib_time_now (vm);
-  u32 thread_index = vm->thread_index;
-  snat_main_per_thread_data_t *per_thread_data =
-    &sm->per_thread_data[thread_index];
-  u32 *fragments_to_drop = 0;
-  u32 *fragments_to_loopback = 0;
-
-  from = vlib_frame_vector_args (frame);
-  n_left_from = frame->n_vectors;
-  next_index = node->cached_next_index;
-
-  while (n_left_from > 0)
-    {
-      u32 n_left_to_next;
-
-      vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
-
-      while (n_left_from > 0 && n_left_to_next > 0)
-       {
-         u32 bi0, sw_if_index0, proto0, rx_fib_index0, new_addr0, old_addr0;
-         vlib_buffer_t *b0;
-         u32 next0;
-         u8 cached0 = 0;
-         ip4_header_t *ip0;
-         nat_reass_ip4_t *reass0;
-         udp_header_t *udp0;
-         tcp_header_t *tcp0;
-         icmp46_header_t *icmp0;
-         clib_bihash_kv_16_8_t kv0, value0;
-         snat_session_t *s0 = 0;
-         u16 old_port0, new_port0;
-         ip_csum_t sum0;
-         snat_session_key_t e_key0, l_key0;
-         lb_nat_type_t lb0;
-         twice_nat_type_t twice_nat0;
-
-         /* speculatively enqueue b0 to the current next frame */
-         bi0 = from[0];
-         to_next[0] = bi0;
-         from += 1;
-         to_next += 1;
-         n_left_from -= 1;
-         n_left_to_next -= 1;
-
-         b0 = vlib_get_buffer (vm, bi0);
-         next0 = NAT44_ED_OUT2IN_NEXT_LOOKUP;
-
-         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);
-
-         if (PREDICT_FALSE (nat_reass_is_drop_frag (0)))
-           {
-             next0 = NAT44_ED_OUT2IN_NEXT_DROP;
-             b0->error = node->errors[NAT_OUT2IN_ED_ERROR_DROP_FRAGMENT];
-             goto trace0;
-           }
-
-         ip0 = (ip4_header_t *) vlib_buffer_get_current (b0);
-         udp0 = ip4_next_header (ip0);
-         tcp0 = (tcp_header_t *) udp0;
-         icmp0 = (icmp46_header_t *) udp0;
-         proto0 = ip_proto_to_snat_proto (ip0->protocol);
-
-         reass0 = nat_ip4_reass_find_or_create (ip0->src_address,
-                                                ip0->dst_address,
-                                                ip0->fragment_id,
-                                                ip0->protocol,
-                                                1, &fragments_to_drop);
-
-         if (PREDICT_FALSE (!reass0))
-           {
-             next0 = NAT44_ED_OUT2IN_NEXT_DROP;
-             b0->error = node->errors[NAT_OUT2IN_ED_ERROR_MAX_REASS];
-             nat_log_notice ("maximum reassemblies exceeded");
-             goto trace0;
-           }
-
-         if (PREDICT_FALSE (ip4_is_first_fragment (ip0)))
-           {
-             if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
-               {
-                 next0 = icmp_out2in_ed_slow_path
-                   (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, node,
-                    next0, now, thread_index, &s0);
-
-                 if (PREDICT_TRUE (next0 != NAT44_ED_OUT2IN_NEXT_DROP))
-                   {
-                     if (s0)
-                       reass0->sess_index = s0 - per_thread_data->sessions;
-                     else
-                       reass0->flags |= NAT_REASS_FLAG_ED_DONT_TRANSLATE;
-                     reass0->thread_index = thread_index;
-                     nat_ip4_reass_get_frags (reass0,
-                                              &fragments_to_loopback);
-                   }
-
-                 goto trace0;
-               }
-
-             make_ed_kv (&kv0, &ip0->dst_address, &ip0->src_address,
-                         ip0->protocol, rx_fib_index0, udp0->dst_port,
-                         udp0->src_port);
-
-             if (clib_bihash_search_16_8
-                 (&per_thread_data->out2in_ed, &kv0, &value0))
-               {
-                 /* Try to match static mapping by external address and port,
-                    destination address and port in packet */
-                 e_key0.addr = ip0->dst_address;
-                 e_key0.port = udp0->dst_port;
-                 e_key0.protocol = proto0;
-                 e_key0.fib_index = rx_fib_index0;
-                 if (snat_static_mapping_match (sm, e_key0, &l_key0, 1, 0,
-                                                &twice_nat0, &lb0, 0))
-                   {
-                     /*
-                      * 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 == SNAT_PROTOCOL_UDP
-                                        && (udp0->dst_port
-                                            ==
-                                            clib_host_to_net_u16
-                                            (UDP_DST_PORT_dhcp_to_client))))
-                       {
-                         vnet_feature_next (&next0, b0);
-                         goto trace0;
-                       }
-
-                     if (!sm->forwarding_enabled)
-                       {
-                         b0->error =
-                           node->errors[NAT_OUT2IN_ED_ERROR_NO_TRANSLATION];
-                         next0 = NAT44_ED_OUT2IN_NEXT_DROP;
-                       }
-                     else
-                       {
-                         if (next_src_nat (sm, ip0, ip0->protocol,
-                                           udp0->src_port, udp0->dst_port,
-                                           thread_index, rx_fib_index0))
-                           {
-                             next0 = NAT44_ED_OUT2IN_NEXT_IN2OUT;
-                             goto trace0;
-                           }
-                         create_bypass_for_fwd (sm, ip0, rx_fib_index0,
-                                                thread_index);
-                         reass0->flags |= NAT_REASS_FLAG_ED_DONT_TRANSLATE;
-                         nat_ip4_reass_get_frags (reass0,
-                                                  &fragments_to_loopback);
-                       }
-                     goto trace0;
-                   }
-
-                 /* Create session initiated by host from external network */
-                 s0 = create_session_for_static_mapping_ed (sm, b0, l_key0,
-                                                            e_key0, node,
-                                                            thread_index,
-                                                            twice_nat0, lb0,
-                                                            now);
-                 if (!s0)
-                   {
-                     b0->error =
-                       node->errors[NAT_OUT2IN_ED_ERROR_NO_TRANSLATION];
-                     next0 = NAT44_ED_OUT2IN_NEXT_DROP;
-                     goto trace0;
-                   }
-                 reass0->sess_index = s0 - per_thread_data->sessions;
-                 reass0->thread_index = thread_index;
-               }
-             else
-               {
-                 s0 = pool_elt_at_index (per_thread_data->sessions,
-                                         value0.value);
-                 reass0->sess_index = value0.value;
-               }
-             nat_ip4_reass_get_frags (reass0, &fragments_to_loopback);
-           }
-         else
-           {
-             if (reass0->flags & NAT_REASS_FLAG_ED_DONT_TRANSLATE)
-               goto trace0;
-             if (PREDICT_FALSE (reass0->sess_index == (u32) ~ 0))
-               {
-                 if (nat_ip4_reass_add_fragment
-                     (reass0, bi0, &fragments_to_drop))
-                   {
-                     b0->error = node->errors[NAT_OUT2IN_ED_ERROR_MAX_FRAG];
-                     nat_log_notice
-                       ("maximum fragments per reassembly exceeded");
-                     next0 = NAT44_ED_OUT2IN_NEXT_DROP;
-                     goto trace0;
-                   }
-                 cached0 = 1;
-                 goto trace0;
-               }
-             s0 = pool_elt_at_index (per_thread_data->sessions,
-                                     reass0->sess_index);
-           }
-
-         old_addr0 = ip0->dst_address.as_u32;
-         ip0->dst_address = s0->in2out.addr;
-         new_addr0 = ip0->dst_address.as_u32;
-         vnet_buffer (b0)->sw_if_index[VLIB_TX] = s0->in2out.fib_index;
-
-         sum0 = ip0->checksum;
-         sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
-                                ip4_header_t,
-                                dst_address /* changed member */ );
-         if (PREDICT_FALSE (is_twice_nat_session (s0)))
-           sum0 = ip_csum_update (sum0, ip0->src_address.as_u32,
-                                  s0->ext_host_nat_addr.as_u32, ip4_header_t,
-                                  src_address);
-         ip0->checksum = ip_csum_fold (sum0);
-
-         if (PREDICT_FALSE (ip4_is_first_fragment (ip0)))
-           {
-             if (PREDICT_TRUE (proto0 == SNAT_PROTOCOL_TCP))
-               {
-                 old_port0 = tcp0->dst_port;
-                 tcp0->dst_port = s0->in2out.port;
-                 new_port0 = tcp0->dst_port;
-
-                 sum0 = tcp0->checksum;
-                 sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
-                                        ip4_header_t,
-                                        dst_address /* changed member */ );
-
-                 sum0 = ip_csum_update (sum0, old_port0, new_port0,
-                                        ip4_header_t /* cheat */ ,
-                                        length /* changed member */ );
-                 if (is_twice_nat_session (s0))
-                   {
-                     sum0 = ip_csum_update (sum0, ip0->src_address.as_u32,
-                                            s0->ext_host_nat_addr.as_u32,
-                                            ip4_header_t, dst_address);
-                     sum0 = ip_csum_update (sum0, tcp0->src_port,
-                                            s0->ext_host_nat_port,
-                                            ip4_header_t, length);
-                     tcp0->src_port = s0->ext_host_nat_port;
-                     ip0->src_address.as_u32 = s0->ext_host_nat_addr.as_u32;
-                   }
-                 tcp0->checksum = ip_csum_fold (sum0);
-               }
-             else
-               {
-                 old_port0 = udp0->dst_port;
-                 udp0->dst_port = s0->in2out.port;
-                 if (is_twice_nat_session (s0))
-                   {
-                     udp0->src_port = s0->ext_host_nat_port;
-                     ip0->src_address.as_u32 = s0->ext_host_nat_addr.as_u32;
-                   }
-                 udp0->checksum = 0;
-               }
-           }
-
-         /* Accounting */
-         nat44_session_update_counters (s0, now,
-                                        vlib_buffer_length_in_chain (vm,
-                                                                     b0));
-         /* Per-user LRU list maintenance */
-         nat44_session_update_lru (sm, s0, thread_index);
-
-       trace0:
-         if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
-                            && (b0->flags & VLIB_BUFFER_IS_TRACED)))
-           {
-             nat44_reass_trace_t *t =
-               vlib_add_trace (vm, node, b0, sizeof (*t));
-             t->cached = cached0;
-             t->sw_if_index = sw_if_index0;
-             t->next_index = next0;
-           }
-
-         if (cached0)
-           {
-             n_left_to_next++;
-             to_next--;
-           }
-         else
-           {
-             pkts_processed += next0 != NAT44_ED_OUT2IN_NEXT_DROP;
-
-             /* verify speculative enqueue, maybe switch current next frame */
-             vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
-                                              to_next, n_left_to_next,
-                                              bi0, next0);
-           }
-
-         if (n_left_from == 0 && vec_len (fragments_to_loopback))
-           {
-             from = vlib_frame_vector_args (frame);
-             u32 len = vec_len (fragments_to_loopback);
-             if (len <= VLIB_FRAME_SIZE)
-               {
-                 clib_memcpy (from, fragments_to_loopback,
-                              sizeof (u32) * len);
-                 n_left_from = len;
-                 vec_reset_length (fragments_to_loopback);
-               }
-             else
-               {
-                 clib_memcpy (from,
-                              fragments_to_loopback + (len -
-                                                       VLIB_FRAME_SIZE),
-                              sizeof (u32) * VLIB_FRAME_SIZE);
-                 n_left_from = VLIB_FRAME_SIZE;
-                 _vec_len (fragments_to_loopback) = len - VLIB_FRAME_SIZE;
-               }
-           }
-       }
-
-      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
-    }
-
-  vlib_node_increment_counter (vm, nat44_ed_out2in_reass_node.index,
-                              NAT_OUT2IN_ED_ERROR_OUT2IN_PACKETS,
-                              pkts_processed);
-
-  nat_send_all_to_node (vm, fragments_to_drop, node,
-                       &node->errors[NAT_OUT2IN_ED_ERROR_DROP_FRAGMENT],
-                       NAT44_ED_OUT2IN_NEXT_DROP);
+  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
+  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
+  nat_pre_trace_t *t = va_arg (*args, nat_pre_trace_t *);
+  return format (s, "out2in next_index %d", t->next_index);
+}
 
-  vec_free (fragments_to_drop);
-  vec_free (fragments_to_loopback);
-  return frame->n_vectors;
+VLIB_NODE_FN (nat_pre_out2in_node) (vlib_main_t * vm,
+                                   vlib_node_runtime_t * node,
+                                   vlib_frame_t * frame)
+{
+  return nat_pre_node_fn_inline (vm, node, frame,
+                                NAT_NEXT_OUT2IN_ED_FAST_PATH);
 }
 
 /* *INDENT-OFF* */
-VLIB_REGISTER_NODE (nat44_ed_out2in_reass_node) = {
-  .function = nat44_ed_out2in_reass_node_fn,
-  .name = "nat44-ed-out2in-reass",
+VLIB_REGISTER_NODE (nat_pre_out2in_node) = {
+  .name = "nat-pre-out2in",
   .vector_size = sizeof (u32),
-  .format_trace = format_nat44_reass_trace,
+  .sibling_of = "nat-default",
+  .format_trace = format_nat_pre_trace,
   .type = VLIB_NODE_TYPE_INTERNAL,
-  .n_errors = ARRAY_LEN(nat_out2in_ed_error_strings),
-  .error_strings = nat_out2in_ed_error_strings,
-  .n_next_nodes = NAT44_ED_OUT2IN_N_NEXT,
-  .next_nodes = {
-    [NAT44_ED_OUT2IN_NEXT_DROP] = "error-drop",
-    [NAT44_ED_OUT2IN_NEXT_LOOKUP] = "ip4-lookup",
-    [NAT44_ED_OUT2IN_NEXT_SLOW_PATH] = "nat44-ed-out2in-slowpath",
-    [NAT44_ED_OUT2IN_NEXT_ICMP_ERROR] = "ip4-icmp-error",
-    [NAT44_ED_OUT2IN_NEXT_IN2OUT] = "nat44-ed-in2out",
-    [NAT44_ED_OUT2IN_NEXT_REASS] = "nat44-ed-out2in-reass",
-  },
-};
+  .n_errors = 0,
+ };
 /* *INDENT-ON* */
 
-VLIB_NODE_FUNCTION_MULTIARCH (nat44_ed_out2in_reass_node,
-                             nat44_ed_out2in_reass_node_fn);
-
 /*
  * fd.io coding-style-patch-verification: ON
  *