nat: respect arc features (multi worker)
[vpp.git] / src / plugins / nat / out2in_ed.c
index 4236285..a81d58e 100644 (file)
 #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/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)
 {
@@ -106,16 +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)
 {
@@ -137,7 +108,7 @@ nat44_o2i_ed_is_idle_session_cb (clib_bihash_kv_16_8_t * kv, void *arg)
     {
       ed_key.l_addr = s->in2out.addr;
       ed_key.r_addr = s->ext_host_addr;
-      ed_key.fib_index = s->out2in.fib_index;
+      ed_key.fib_index = s->in2out.fib_index;
       if (snat_is_unk_proto_session (s))
        {
          ed_key.proto = s->in2out.port;
@@ -158,18 +129,30 @@ 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");
 
       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++)
@@ -199,6 +182,7 @@ 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,
@@ -222,22 +206,22 @@ create_session_for_static_mapping_ed (snat_main_t * sm,
   if (PREDICT_FALSE (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");
+      nat_elog_warn ("create NAT user failed");
       return 0;
     }
 
-  s = nat_ed_session_alloc (sm, u, thread_index);
+  s = nat_ed_session_alloc (sm, u, thread_index, now);
   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 0;
     }
 
@@ -266,7 +250,7 @@ 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))
@@ -280,7 +264,7 @@ 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;
@@ -298,60 +282,31 @@ 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)
@@ -381,7 +336,7 @@ 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 (ip, &key))
        return;
     }
   else if (ip->protocol == IP_PROTOCOL_UDP || ip->protocol == IP_PROTOCOL_TCP)
@@ -410,6 +365,8 @@ create_bypass_for_fwd (snat_main_t * sm, ip4_header_t * ip, u32 rx_fib_index,
     }
   else
     {
+      u32 proto;
+
       if (PREDICT_FALSE (maximum_sessions_exceeded (sm, thread_index)))
        return;
 
@@ -417,31 +374,38 @@ create_bypass_for_fwd (snat_main_t * sm, ip4_header_t * ip, u32 rx_fib_index,
                                  thread_index);
       if (!u)
        {
-         nat_log_warn ("create NAT user failed");
+         nat_elog_warn ("create NAT user failed");
          return;
        }
 
-      s = nat_ed_session_alloc (sm, u, thread_index);
+      s = nat_ed_session_alloc (sm, u, thread_index, now);
       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)
@@ -452,9 +416,24 @@ create_bypass_for_fwd (snat_main_t * sm, ip4_header_t * ip, u32 rx_fib_index,
     }
 
   /* 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, 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, 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,
@@ -467,17 +446,17 @@ icmp_match_out2in_ed (snat_main_t * sm, vlib_node_runtime_t * node,
   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 (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;
@@ -492,7 +471,7 @@ 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)
            {
@@ -504,7 +483,7 @@ 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
@@ -513,10 +492,13 @@ 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, ip, rx_fib_index);
+             else
+               create_bypass_for_fwd (sm, ip, rx_fib_index, thread_index);
              goto out;
            }
        }
@@ -525,7 +507,13 @@ icmp_match_out2in_ed (snat_main_t * sm, vlib_node_runtime_t * node,
                         (icmp->type != 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;
        }
 
@@ -537,7 +525,7 @@ 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;
        }
     }
@@ -548,7 +536,7 @@ icmp_match_out2in_ed (snat_main_t * sm, vlib_node_runtime_t * node,
                         !icmp_is_error_message (icmp)))
        {
          b->error = node->errors[NAT_OUT2IN_ED_ERROR_BAD_ICMP_TYPE];
-         next = NAT44_ED_OUT2IN_NEXT_DROP;
+         next = NAT_NEXT_DROP;
          goto out;
        }
 
@@ -564,6 +552,7 @@ out:
     *(snat_session_t **) d = s;
   return next;
 }
+#endif
 
 static snat_session_t *
 nat44_ed_out2in_unknown_proto (snat_main_t * sm,
@@ -598,7 +587,7 @@ nat44_ed_out2in_unknown_proto (snat_main_t * sm,
       if (PREDICT_FALSE (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;
        }
 
@@ -618,16 +607,16 @@ nat44_ed_out2in_unknown_proto (snat_main_t * sm,
                                  thread_index);
       if (!u)
        {
-         nat_log_warn ("create NAT user failed");
+         nat_elog_warn ("create NAT user failed");
          return 0;
        }
 
       /* Create a new session */
-      s = nat_ed_session_alloc (sm, u, thread_index);
+      s = nat_ed_session_alloc (sm, u, thread_index, now);
       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 0;
        }
 
@@ -645,13 +634,13 @@ 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 */
@@ -662,7 +651,10 @@ 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);
 
   return s;
 }
@@ -673,14 +665,16 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
                                vlib_frame_t * frame, int is_slow_path)
 {
   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 = is_slow_path ? sm->ed_out2in_slowpath_node_index :
+    sm->ed_out2in_node_index;
 
   from = vlib_frame_vector_args (frame);
   n_left_from = frame->n_vectors;
@@ -711,6 +705,7 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
          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;
+         u8 identity_nat0, identity_nat1;
 
          /* Prefetch next iteration. */
          {
@@ -737,7 +732,9 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
          b0 = vlib_get_buffer (vm, bi0);
          b1 = vlib_get_buffer (vm, bi1);
 
-         next0 = NAT44_ED_OUT2IN_NEXT_LOOKUP;
+         next0 = nat_buffer_opaque (b0)->arc_next;
+         next1 = nat_buffer_opaque (b1)->arc_next;
+
          vnet_buffer (b0)->snat.flags = 0;
          ip0 = vlib_buffer_get_current (b0);
 
@@ -752,7 +749,7 @@ 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 trace00;
            }
 
@@ -769,10 +766,11 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
                    nat44_ed_out2in_unknown_proto (sm, b0, ip0, rx_fib_index0,
                                                   thread_index, now, vm,
                                                   node);
+                 other_packets++;
                  if (!sm->forwarding_enabled)
                    {
                      if (!s0)
-                       next0 = NAT44_ED_OUT2IN_NEXT_DROP;
+                       next0 = NAT_NEXT_DROP;
                      goto trace00;
                    }
                }
@@ -782,6 +780,7 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
                  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 trace00;
                }
            }
@@ -789,19 +788,20 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
            {
              if (PREDICT_FALSE (proto0 == ~0))
                {
-                 next0 = NAT44_ED_OUT2IN_NEXT_SLOW_PATH;
+                 next0 = NAT_NEXT_OUT2IN_ED_SLOW_PATH;
                  goto trace00;
                }
 
              if (ip4_is_fragment (ip0))
                {
-                 next0 = NAT44_ED_OUT2IN_NEXT_REASS;
+                 next0 = NAT_NEXT_OUT2IN_ED_REASS;
+                 fragments++;
                  goto trace00;
                }
 
              if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
                {
-                 next0 = NAT44_ED_OUT2IN_NEXT_SLOW_PATH;
+                 next0 = NAT_NEXT_OUT2IN_ED_SLOW_PATH;
                  goto trace00;
                }
            }
@@ -822,7 +822,8 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
                  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))
+                                                &ip0->src_address,
+                                                &identity_nat0))
                    {
                      /*
                       * Send DHCP packets to the ipv4 stack, or we won't
@@ -833,7 +834,6 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
                                             clib_host_to_net_u16
                                             (UDP_DST_PORT_dhcp_to_client))))
                        {
-                         vnet_feature_next (&next0, b0);
                          goto trace00;
                        }
 
@@ -841,7 +841,7 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
                        {
                          b0->error =
                            node->errors[NAT_OUT2IN_ED_ERROR_NO_TRANSLATION];
-                         next0 = NAT44_ED_OUT2IN_NEXT_DROP;
+                         next0 = NAT_NEXT_DROP;
                        }
                      else
                        {
@@ -849,15 +849,29 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
                                            udp0->src_port, udp0->dst_port,
                                            thread_index, rx_fib_index0))
                            {
-                             next0 = NAT44_ED_OUT2IN_NEXT_IN2OUT;
+                             next0 = NAT_NEXT_IN2OUT_ED_FAST_PATH;
                              goto trace00;
                            }
-                         create_bypass_for_fwd (sm, ip0, rx_fib_index0,
-                                                thread_index);
+                         if (sm->num_workers > 1)
+                           create_bypass_for_fwd_worker (sm, ip0,
+                                                         rx_fib_index0);
+                         else
+                           create_bypass_for_fwd (sm, ip0, rx_fib_index0,
+                                                  thread_index);
                        }
                      goto trace00;
                    }
 
+                 if (PREDICT_FALSE (identity_nat0))
+                   goto trace00;
+
+                 if ((proto0 == SNAT_PROTOCOL_TCP) && !tcp_is_init (tcp0))
+                   {
+                     b0->error = node->errors[NAT_OUT2IN_ED_ERROR_NON_SYN];
+                     next0 = NAT_NEXT_DROP;
+                     goto trace00;
+                   }
+
                  /* Create session initiated by host from external network */
                  s0 = create_session_for_static_mapping_ed (sm, b0, l_key0,
                                                             e_key0, node,
@@ -867,13 +881,13 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
 
                  if (!s0)
                    {
-                     next0 = NAT44_ED_OUT2IN_NEXT_DROP;
+                     next0 = NAT_NEXT_DROP;
                      goto trace00;
                    }
                }
              else
                {
-                 next0 = NAT44_ED_OUT2IN_NEXT_SLOW_PATH;
+                 next0 = NAT_NEXT_OUT2IN_ED_SLOW_PATH;
                  goto trace00;
                }
            }
@@ -895,11 +909,11 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
                                   src_address);
          ip0->checksum = ip_csum_fold (sum0);
 
+         old_port0 = udp0->dst_port;
+         new_port0 = udp0->dst_port = s0->in2out.port;
+
          if (PREDICT_TRUE (proto0 == SNAT_PROTOCOL_TCP))
            {
-             old_port0 = tcp0->dst_port;
-             new_port0 = tcp0->dst_port = s0->in2out.port;
-
              sum0 = tcp0->checksum;
              sum0 = ip_csum_update (sum0, old_addr0, new_addr0, ip4_header_t,
                                     dst_address);
@@ -917,25 +931,48 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
                  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, s0, tcp0, thread_index))
                goto trace00;
            }
+         else if (udp0->checksum)
+           {
+             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 (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, udp0->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;
+               }
+             udp0->checksum = ip_csum_fold (sum0);
+             udp_packets++;
+           }
          else
            {
-             udp0->dst_port = s0->in2out.port;
-             if (is_twice_nat_session (s0))
+             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:
          if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
@@ -951,9 +988,8 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
                t->session_index = s0 - tsm->sessions;
            }
 
-         pkts_processed += next0 != NAT44_ED_OUT2IN_NEXT_DROP;
+         pkts_processed += next0 == nat_buffer_opaque (b0)->arc_next;
 
-         next1 = NAT44_ED_OUT2IN_NEXT_LOOKUP;
          vnet_buffer (b1)->snat.flags = 0;
          ip1 = vlib_buffer_get_current (b1);
 
@@ -968,7 +1004,7 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
              icmp4_error_set_vnet_buffer (b1, ICMP4_time_exceeded,
                                           ICMP4_time_exceeded_ttl_exceeded_in_transit,
                                           0);
-             next1 = NAT44_ED_OUT2IN_NEXT_ICMP_ERROR;
+             next1 = NAT_NEXT_ICMP_ERROR;
              goto trace01;
            }
 
@@ -985,10 +1021,11 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
                    nat44_ed_out2in_unknown_proto (sm, b1, ip1, rx_fib_index1,
                                                   thread_index, now, vm,
                                                   node);
+                 other_packets++;
                  if (!sm->forwarding_enabled)
                    {
                      if (!s1)
-                       next1 = NAT44_ED_OUT2IN_NEXT_DROP;
+                       next1 = NAT_NEXT_DROP;
                      goto trace01;
                    }
                }
@@ -998,6 +1035,7 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
                  next1 = icmp_out2in_ed_slow_path
                    (sm, b1, ip1, icmp1, sw_if_index1, rx_fib_index1, node,
                     next1, now, thread_index, &s1);
+                 icmp_packets++;
                  goto trace01;
                }
            }
@@ -1005,19 +1043,20 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
            {
              if (PREDICT_FALSE (proto1 == ~0))
                {
-                 next1 = NAT44_ED_OUT2IN_NEXT_SLOW_PATH;
+                 next1 = NAT_NEXT_OUT2IN_ED_SLOW_PATH;
                  goto trace01;
                }
 
              if (ip4_is_fragment (ip1))
                {
-                 next1 = NAT44_ED_OUT2IN_NEXT_REASS;
+                 next1 = NAT_NEXT_OUT2IN_ED_REASS;
+                 fragments++;
                  goto trace01;
                }
 
              if (PREDICT_FALSE (proto1 == SNAT_PROTOCOL_ICMP))
                {
-                 next1 = NAT44_ED_OUT2IN_NEXT_SLOW_PATH;
+                 next1 = NAT_NEXT_OUT2IN_ED_SLOW_PATH;
                  goto trace01;
                }
            }
@@ -1038,7 +1077,8 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
                  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))
+                                                &ip1->src_address,
+                                                &identity_nat1))
                    {
                      /*
                       * Send DHCP packets to the ipv4 stack, or we won't
@@ -1049,7 +1089,6 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
                                             clib_host_to_net_u16
                                             (UDP_DST_PORT_dhcp_to_client))))
                        {
-                         vnet_feature_next (&next1, b1);
                          goto trace01;
                        }
 
@@ -1057,7 +1096,7 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
                        {
                          b1->error =
                            node->errors[NAT_OUT2IN_ED_ERROR_NO_TRANSLATION];
-                         next1 = NAT44_ED_OUT2IN_NEXT_DROP;
+                         next1 = NAT_NEXT_DROP;
                        }
                      else
                        {
@@ -1065,15 +1104,29 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
                                            udp1->src_port, udp1->dst_port,
                                            thread_index, rx_fib_index1))
                            {
-                             next1 = NAT44_ED_OUT2IN_NEXT_IN2OUT;
+                             next1 = NAT_NEXT_IN2OUT_ED_FAST_PATH;
                              goto trace01;
                            }
-                         create_bypass_for_fwd (sm, ip1, rx_fib_index1,
-                                                thread_index);
+                         if (sm->num_workers > 1)
+                           create_bypass_for_fwd_worker (sm, ip1,
+                                                         rx_fib_index1);
+                         else
+                           create_bypass_for_fwd (sm, ip1, rx_fib_index1,
+                                                  thread_index);
                        }
                      goto trace01;
                    }
 
+                 if (PREDICT_FALSE (identity_nat1))
+                   goto trace01;
+
+                 if ((proto1 == SNAT_PROTOCOL_TCP) && !tcp_is_init (tcp1))
+                   {
+                     b1->error = node->errors[NAT_OUT2IN_ED_ERROR_NON_SYN];
+                     next1 = NAT_NEXT_DROP;
+                     goto trace01;
+                   }
+
                  /* Create session initiated by host from external network */
                  s1 = create_session_for_static_mapping_ed (sm, b1, l_key1,
                                                             e_key1, node,
@@ -1083,13 +1136,13 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
 
                  if (!s1)
                    {
-                     next1 = NAT44_ED_OUT2IN_NEXT_DROP;
+                     next1 = NAT_NEXT_DROP;
                      goto trace01;
                    }
                }
              else
                {
-                 next1 = NAT44_ED_OUT2IN_NEXT_SLOW_PATH;
+                 next1 = NAT_NEXT_OUT2IN_ED_SLOW_PATH;
                  goto trace01;
                }
            }
@@ -1111,11 +1164,11 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
                                   src_address);
          ip1->checksum = ip_csum_fold (sum1);
 
+         old_port1 = udp1->dst_port;
+         new_port1 = udp1->dst_port = s1->in2out.port;
+
          if (PREDICT_TRUE (proto1 == SNAT_PROTOCOL_TCP))
            {
-             old_port1 = tcp1->dst_port;
-             new_port1 = tcp1->dst_port = s1->in2out.port;
-
              sum1 = tcp1->checksum;
              sum1 = ip_csum_update (sum1, old_addr1, new_addr1, ip4_header_t,
                                     dst_address);
@@ -1133,25 +1186,48 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
                  ip1->src_address.as_u32 = s1->ext_host_nat_addr.as_u32;
                }
              tcp1->checksum = ip_csum_fold (sum1);
+             tcp_packets++;
              if (nat44_set_tcp_session_state_o2i
                  (sm, s1, tcp1, thread_index))
                goto trace01;
            }
+         else if (udp1->checksum)
+           {
+             sum1 = udp1->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 (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, dst_address);
+                 sum1 = ip_csum_update (sum1, udp1->src_port,
+                                        s1->ext_host_nat_port, ip4_header_t,
+                                        length);
+                 udp1->src_port = s1->ext_host_nat_port;
+                 ip1->src_address.as_u32 = s1->ext_host_nat_addr.as_u32;
+               }
+             udp1->checksum = ip_csum_fold (sum1);
+             udp_packets++;
+           }
          else
            {
-             udp1->dst_port = s1->in2out.port;
-             if (is_twice_nat_session (s1))
+             if (PREDICT_FALSE (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;
+             udp_packets++;
            }
 
          /* Accounting */
          nat44_session_update_counters (s1, now,
-                                        vlib_buffer_length_in_chain (vm,
-                                                                     b1));
+                                        vlib_buffer_length_in_chain (vm, b1),
+                                        thread_index);
+         /* Per-user LRU list maintenance */
+         nat44_session_update_lru (sm, s1, thread_index);
 
        trace01:
          if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
@@ -1167,7 +1243,7 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
                t->session_index = s1 - tsm->sessions;
            }
 
-         pkts_processed += next1 != NAT44_ED_OUT2IN_NEXT_DROP;
+         pkts_processed += next1 == nat_buffer_opaque (b1)->arc_next;
 
          /* verify speculative enqueues, maybe switch current next frame */
          vlib_validate_buffer_enqueue_x2 (vm, node, next_index,
@@ -1192,6 +1268,7 @@ 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];
@@ -1202,7 +1279,8 @@ 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);
 
@@ -1217,7 +1295,7 @@ 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;
            }
 
@@ -1234,10 +1312,11 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
                    nat44_ed_out2in_unknown_proto (sm, b0, ip0, rx_fib_index0,
                                                   thread_index, now, vm,
                                                   node);
+                 other_packets++;
                  if (!sm->forwarding_enabled)
                    {
                      if (!s0)
-                       next0 = NAT44_ED_OUT2IN_NEXT_DROP;
+                       next0 = NAT_NEXT_DROP;
                      goto trace0;
                    }
                }
@@ -1247,6 +1326,7 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
                  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;
                }
            }
@@ -1254,19 +1334,20 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
            {
              if (PREDICT_FALSE (proto0 == ~0))
                {
-                 next0 = NAT44_ED_OUT2IN_NEXT_SLOW_PATH;
+                 next0 = NAT_NEXT_OUT2IN_ED_SLOW_PATH;
                  goto trace0;
                }
 
              if (ip4_is_fragment (ip0))
                {
-                 next0 = NAT44_ED_OUT2IN_NEXT_REASS;
+                 next0 = NAT_NEXT_OUT2IN_ED_REASS;
+                 fragments++;
                  goto trace0;
                }
 
              if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
                {
-                 next0 = NAT44_ED_OUT2IN_NEXT_SLOW_PATH;
+                 next0 = NAT_NEXT_OUT2IN_ED_SLOW_PATH;
                  goto trace0;
                }
            }
@@ -1287,7 +1368,8 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
                  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))
+                                                &ip0->src_address,
+                                                &identity_nat0))
                    {
                      /*
                       * Send DHCP packets to the ipv4 stack, or we won't
@@ -1298,7 +1380,6 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
                                             clib_host_to_net_u16
                                             (UDP_DST_PORT_dhcp_to_client))))
                        {
-                         vnet_feature_next (&next0, b0);
                          goto trace0;
                        }
 
@@ -1306,7 +1387,7 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
                        {
                          b0->error =
                            node->errors[NAT_OUT2IN_ED_ERROR_NO_TRANSLATION];
-                         next0 = NAT44_ED_OUT2IN_NEXT_DROP;
+                         next0 = NAT_NEXT_DROP;
                        }
                      else
                        {
@@ -1314,15 +1395,29 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
                                            udp0->src_port, udp0->dst_port,
                                            thread_index, rx_fib_index0))
                            {
-                             next0 = NAT44_ED_OUT2IN_NEXT_IN2OUT;
+                             next0 = NAT_NEXT_IN2OUT_ED_FAST_PATH;
                              goto trace0;
                            }
-                         create_bypass_for_fwd (sm, ip0, rx_fib_index0,
-                                                thread_index);
+                         if (sm->num_workers > 1)
+                           create_bypass_for_fwd_worker (sm, ip0,
+                                                         rx_fib_index0);
+                         else
+                           create_bypass_for_fwd (sm, ip0, rx_fib_index0,
+                                                  thread_index);
                        }
                      goto trace0;
                    }
 
+                 if (PREDICT_FALSE (identity_nat0))
+                   goto trace0;
+
+                 if ((proto0 == SNAT_PROTOCOL_TCP) && !tcp_is_init (tcp0))
+                   {
+                     b0->error = node->errors[NAT_OUT2IN_ED_ERROR_NON_SYN];
+                     next0 = NAT_NEXT_DROP;
+                     goto trace0;
+                   }
+
                  /* Create session initiated by host from external network */
                  s0 = create_session_for_static_mapping_ed (sm, b0, l_key0,
                                                             e_key0, node,
@@ -1332,13 +1427,13 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
 
                  if (!s0)
                    {
-                     next0 = NAT44_ED_OUT2IN_NEXT_DROP;
+                     next0 = NAT_NEXT_DROP;
                      goto trace0;
                    }
                }
              else
                {
-                 next0 = NAT44_ED_OUT2IN_NEXT_SLOW_PATH;
+                 next0 = NAT_NEXT_OUT2IN_ED_SLOW_PATH;
                  goto trace0;
                }
            }
@@ -1360,11 +1455,11 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
                                   src_address);
          ip0->checksum = ip_csum_fold (sum0);
 
+         old_port0 = udp0->dst_port;
+         new_port0 = udp0->dst_port = s0->in2out.port;
+
          if (PREDICT_TRUE (proto0 == SNAT_PROTOCOL_TCP))
            {
-             old_port0 = tcp0->dst_port;
-             new_port0 = tcp0->dst_port = s0->in2out.port;
-
              sum0 = tcp0->checksum;
              sum0 = ip_csum_update (sum0, old_addr0, new_addr0, ip4_header_t,
                                     dst_address);
@@ -1382,25 +1477,48 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
                  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, s0, tcp0, thread_index))
                goto trace0;
            }
+         else if (udp0->checksum)
+           {
+             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 (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, udp0->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;
+               }
+             udp0->checksum = ip_csum_fold (sum0);
+             udp_packets++;
+           }
          else
            {
-             udp0->dst_port = s0->in2out.port;
-             if (is_twice_nat_session (s0))
+             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);
 
        trace0:
          if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
@@ -1416,7 +1534,7 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
                t->session_index = s0 - tsm->sessions;
            }
 
-         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,
@@ -1429,82 +1547,28 @@ 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)
-{
-  return nat44_ed_out2in_node_fn_inline (vm, node, frame, 0);
-}
-
-/* *INDENT-OFF* */
-VLIB_REGISTER_NODE (nat44_ed_out2in_node) = {
-  .function = nat44_ed_out2in_fast_path_fn,
-  .name = "nat44-ed-out2in",
-  .vector_size = sizeof (u32),
-  .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)
-{
-  return nat44_ed_out2in_node_fn_inline (vm, node, frame, 1);
-}
-
-/* *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),
-  .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 inline uword
+nat44_ed_out2in_reass_node_fn_inline (vlib_main_t * vm,
+                                     vlib_node_runtime_t * node,
+                                     vlib_frame_t * frame)
 {
   u32 n_left_from, *from, *to_next;
-  nat44_ed_out2in_next_t next_index;
+  nat_next_t next_index;
   u32 pkts_processed = 0;
   snat_main_t *sm = &snat_main;
   f64 now = vlib_time_now (vm);
@@ -1542,6 +1606,7 @@ nat44_ed_out2in_reass_node_fn (vlib_main_t * vm,
          snat_session_key_t e_key0, l_key0;
          lb_nat_type_t lb0;
          twice_nat_type_t twice_nat0;
+         u8 identity_nat0;
 
          /* speculatively enqueue b0 to the current next frame */
          bi0 = from[0];
@@ -1552,7 +1617,7 @@ nat44_ed_out2in_reass_node_fn (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;
 
          sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
          rx_fib_index0 =
@@ -1561,7 +1626,7 @@ nat44_ed_out2in_reass_node_fn (vlib_main_t * vm,
 
          if (PREDICT_FALSE (nat_reass_is_drop_frag (0)))
            {
-             next0 = NAT44_ED_OUT2IN_NEXT_DROP;
+             next0 = NAT_NEXT_DROP;
              b0->error = node->errors[NAT_OUT2IN_ED_ERROR_DROP_FRAGMENT];
              goto trace0;
            }
@@ -1580,9 +1645,9 @@ nat44_ed_out2in_reass_node_fn (vlib_main_t * vm,
 
          if (PREDICT_FALSE (!reass0))
            {
-             next0 = NAT44_ED_OUT2IN_NEXT_DROP;
+             next0 = NAT_NEXT_DROP;
              b0->error = node->errors[NAT_OUT2IN_ED_ERROR_MAX_REASS];
-             nat_log_notice ("maximum reassemblies exceeded");
+             nat_elog_notice ("maximum reassemblies exceeded");
              goto trace0;
            }
 
@@ -1594,7 +1659,7 @@ nat44_ed_out2in_reass_node_fn (vlib_main_t * vm,
                    (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 (PREDICT_TRUE (next0 != NAT_NEXT_DROP))
                    {
                      if (s0)
                        reass0->sess_index = s0 - per_thread_data->sessions;
@@ -1622,7 +1687,8 @@ nat44_ed_out2in_reass_node_fn (vlib_main_t * vm,
                  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))
+                                                &twice_nat0, &lb0, 0,
+                                                &identity_nat0))
                    {
                      /*
                       * Send DHCP packets to the ipv4 stack, or we won't
@@ -1634,7 +1700,6 @@ nat44_ed_out2in_reass_node_fn (vlib_main_t * vm,
                                             clib_host_to_net_u16
                                             (UDP_DST_PORT_dhcp_to_client))))
                        {
-                         vnet_feature_next (&next0, b0);
                          goto trace0;
                        }
 
@@ -1642,7 +1707,7 @@ nat44_ed_out2in_reass_node_fn (vlib_main_t * vm,
                        {
                          b0->error =
                            node->errors[NAT_OUT2IN_ED_ERROR_NO_TRANSLATION];
-                         next0 = NAT44_ED_OUT2IN_NEXT_DROP;
+                         next0 = NAT_NEXT_DROP;
                        }
                      else
                        {
@@ -1650,11 +1715,15 @@ nat44_ed_out2in_reass_node_fn (vlib_main_t * vm,
                                            udp0->src_port, udp0->dst_port,
                                            thread_index, rx_fib_index0))
                            {
-                             next0 = NAT44_ED_OUT2IN_NEXT_IN2OUT;
+                             next0 = NAT_NEXT_IN2OUT_ED_FAST_PATH;
                              goto trace0;
                            }
-                         create_bypass_for_fwd (sm, ip0, rx_fib_index0,
-                                                thread_index);
+                         if (sm->num_workers > 1)
+                           create_bypass_for_fwd_worker (sm, ip0,
+                                                         rx_fib_index0);
+                         else
+                           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);
@@ -1662,6 +1731,19 @@ nat44_ed_out2in_reass_node_fn (vlib_main_t * vm,
                      goto trace0;
                    }
 
+                 if (PREDICT_FALSE (identity_nat0))
+                   {
+                     reass0->flags |= NAT_REASS_FLAG_ED_DONT_TRANSLATE;
+                     goto trace0;
+                   }
+
+                 if ((proto0 == SNAT_PROTOCOL_TCP) && !tcp_is_init (tcp0))
+                   {
+                     b0->error = node->errors[NAT_OUT2IN_ED_ERROR_NON_SYN];
+                     next0 = NAT_NEXT_DROP;
+                     goto trace0;
+                   }
+
                  /* Create session initiated by host from external network */
                  s0 = create_session_for_static_mapping_ed (sm, b0, l_key0,
                                                             e_key0, node,
@@ -1672,7 +1754,7 @@ nat44_ed_out2in_reass_node_fn (vlib_main_t * vm,
                    {
                      b0->error =
                        node->errors[NAT_OUT2IN_ED_ERROR_NO_TRANSLATION];
-                     next0 = NAT44_ED_OUT2IN_NEXT_DROP;
+                     next0 = NAT_NEXT_DROP;
                      goto trace0;
                    }
                  reass0->sess_index = s0 - per_thread_data->sessions;
@@ -1693,12 +1775,12 @@ nat44_ed_out2in_reass_node_fn (vlib_main_t * vm,
              if (PREDICT_FALSE (reass0->sess_index == (u32) ~ 0))
                {
                  if (nat_ip4_reass_add_fragment
-                     (reass0, bi0, &fragments_to_drop))
+                     (thread_index, reass0, bi0, &fragments_to_drop))
                    {
                      b0->error = node->errors[NAT_OUT2IN_ED_ERROR_MAX_FRAG];
-                     nat_log_notice
+                     nat_elog_notice
                        ("maximum fragments per reassembly exceeded");
-                     next0 = NAT44_ED_OUT2IN_NEXT_DROP;
+                     next0 = NAT_NEXT_DROP;
                      goto trace0;
                    }
                  cached0 = 1;
@@ -1725,12 +1807,11 @@ nat44_ed_out2in_reass_node_fn (vlib_main_t * vm,
 
          if (PREDICT_FALSE (ip4_is_first_fragment (ip0)))
            {
+             old_port0 = udp0->dst_port;
+             new_port0 = udp0->dst_port = s0->in2out.port;
+
              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,
@@ -1752,23 +1833,44 @@ nat44_ed_out2in_reass_node_fn (vlib_main_t * vm,
                    }
                  tcp0->checksum = ip_csum_fold (sum0);
                }
+             else if (udp0->checksum)
+               {
+                 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 (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, udp0->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;
+                   }
+                 udp0->checksum = ip_csum_fold (sum0);
+               }
              else
                {
-                 old_port0 = udp0->dst_port;
-                 udp0->dst_port = s0->in2out.port;
-                 if (is_twice_nat_session (s0))
+                 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;
                }
            }
 
          /* 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);
 
        trace0:
          if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
@@ -1788,7 +1890,7 @@ nat44_ed_out2in_reass_node_fn (vlib_main_t * vm,
            }
          else
            {
-             pkts_processed += next0 != NAT44_ED_OUT2IN_NEXT_DROP;
+             pkts_processed += next0 != NAT_NEXT_DROP;
 
              /* verify speculative enqueue, maybe switch current next frame */
              vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
@@ -1802,17 +1904,16 @@ nat44_ed_out2in_reass_node_fn (vlib_main_t * vm,
              u32 len = vec_len (fragments_to_loopback);
              if (len <= VLIB_FRAME_SIZE)
                {
-                 clib_memcpy (from, fragments_to_loopback,
-                              sizeof (u32) * len);
+                 clib_memcpy_fast (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);
+                 clib_memcpy_fast (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;
                }
@@ -1822,42 +1923,105 @@ nat44_ed_out2in_reass_node_fn (vlib_main_t * vm,
       vlib_put_next_frame (vm, node, next_index, n_left_to_next);
     }
 
-  vlib_node_increment_counter (vm, nat44_ed_out2in_reass_node.index,
+  vlib_node_increment_counter (vm, sm->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);
+                       NAT_NEXT_DROP);
 
   vec_free (fragments_to_drop);
   vec_free (fragments_to_loopback);
   return frame->n_vectors;
 }
 
+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);
+}
+
+/* *INDENT-OFF* */
+VLIB_REGISTER_NODE (nat44_ed_out2in_node) = {
+  .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),
+};
+/* *INDENT-ON* */
+
+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);
+}
+
+/* *INDENT-OFF* */
+VLIB_REGISTER_NODE (nat44_ed_out2in_slowpath_node) = {
+  .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),
+};
+/* *INDENT-ON* */
+
+VLIB_NODE_FN (nat44_ed_out2in_reass_node) (vlib_main_t * vm,
+                                          vlib_node_runtime_t * node,
+                                          vlib_frame_t * frame)
+{
+  return nat44_ed_out2in_reass_node_fn_inline (vm, node, frame);
+}
+
 /* *INDENT-OFF* */
 VLIB_REGISTER_NODE (nat44_ed_out2in_reass_node) = {
-  .function = nat44_ed_out2in_reass_node_fn,
   .name = "nat44-ed-out2in-reass",
   .vector_size = sizeof (u32),
+  .sibling_of = "nat-default",
   .format_trace = format_nat44_reass_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",
-  },
 };
 /* *INDENT-ON* */
 
-VLIB_NODE_FUNCTION_MULTIARCH (nat44_ed_out2in_reass_node,
-                             nat44_ed_out2in_reass_node_fn);
+static u8 *
+format_nat_pre_trace (u8 * s, va_list * args)
+{
+  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);
+}
+
+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 (nat_pre_out2in_node) = {
+  .name = "nat-pre-out2in",
+  .vector_size = sizeof (u32),
+  .sibling_of = "nat-default",
+  .format_trace = format_nat_pre_trace,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  .n_errors = 0,
+ };
+/* *INDENT-ON* */
 
 /*
  * fd.io coding-style-patch-verification: ON