NAT44: active-passive HA (VPP-1571)
[vpp.git] / src / plugins / nat / out2in.c
index f250136..3d045a9 100755 (executable)
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+/**
+ * @file
+ * @brief NAT44 endpoint-dependent outside to inside network translation
+ */
 
 #include <vlib/vlib.h>
 #include <vnet/vnet.h>
 #include <vnet/pg/pg.h>
-#include <vnet/handoff.h>
 
 #include <vnet/ip/ip.h>
 #include <vnet/udp/udp.h>
 #include <vnet/fib/ip4_fib.h>
 #include <nat/nat.h>
 #include <nat/nat_ipfix_logging.h>
-#include <nat/nat_det.h>
+#include <nat/nat_reass.h>
+#include <nat/nat_inlines.h>
+#include <nat/nat_syslog.h>
+#include <nat/nat_ha.h>
 
 #include <vppinfra/hash.h>
 #include <vppinfra/error.h>
 #include <vppinfra/elog.h>
 
-typedef struct {
+typedef struct
+{
   u32 sw_if_index;
   u32 next_index;
   u32 session_index;
 } snat_out2in_trace_t;
 
-typedef struct {
-  u32 next_worker_index;
-  u8 do_handoff;
-} snat_out2in_worker_handoff_trace_t;
-
 /* packet trace format function */
-static u8 * format_snat_out2in_trace (u8 * s, va_list * args)
+static u8 *
+format_snat_out2in_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 *);
-  snat_out2in_trace_t * t = va_arg (*args, snat_out2in_trace_t *);
+  snat_out2in_trace_t *t = va_arg (*args, snat_out2in_trace_t *);
 
-  s = format (s, "NAT44_OUT2IN: sw_if_index %d, next index %d, session index %d",
-              t->sw_if_index, t->next_index, t->session_index);
+  s =
+    format (s,
+           "NAT44_OUT2IN: sw_if_index %d, next index %d, session index %d",
+           t->sw_if_index, t->next_index, t->session_index);
   return s;
 }
 
-static u8 * format_snat_out2in_fast_trace (u8 * s, va_list * args)
+static u8 *
+format_snat_out2in_fast_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 *);
-  snat_out2in_trace_t * t = va_arg (*args, snat_out2in_trace_t *);
+  snat_out2in_trace_t *t = va_arg (*args, snat_out2in_trace_t *);
 
   s = format (s, "NAT44_OUT2IN_FAST: sw_if_index %d, next index %d",
-              t->sw_if_index, t->next_index);
+             t->sw_if_index, t->next_index);
   return s;
 }
 
-static u8 * format_snat_out2in_worker_handoff_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 *);
-  snat_out2in_worker_handoff_trace_t * t =
-    va_arg (*args, snat_out2in_worker_handoff_trace_t *);
-  char * m;
-
-  m = t->do_handoff ? "next worker" : "same worker";
-  s = format (s, "NAT44_OUT2IN_WORKER_HANDOFF: %s %d", m, t->next_worker_index);
-
-  return s;
-}
-
-vlib_node_registration_t snat_out2in_node;
-vlib_node_registration_t snat_out2in_fast_node;
-vlib_node_registration_t snat_out2in_worker_handoff_node;
-vlib_node_registration_t snat_det_out2in_node;
-
 #define foreach_snat_out2in_error                       \
-_(UNSUPPORTED_PROTOCOL, "Unsupported protocol")         \
-_(OUT2IN_PACKETS, "Good out2in packets processed")      \
+_(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")
-
-typedef enum {
+_(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")\
+_(TCP_PACKETS, "TCP packets")                           \
+_(UDP_PACKETS, "UDP packets")                           \
+_(ICMP_PACKETS, "ICMP packets")                         \
+_(OTHER_PACKETS, "other protocol packets")              \
+_(FRAGMENTS, "fragments")                               \
+_(CACHED_FRAGMENTS, "cached fragments")                 \
+_(PROCESSED_FRAGMENTS, "processed fragments")
+
+typedef enum
+{
 #define _(sym,str) SNAT_OUT2IN_ERROR_##sym,
   foreach_snat_out2in_error
 #undef _
-  SNAT_OUT2IN_N_ERROR,
+    SNAT_OUT2IN_N_ERROR,
 } snat_out2in_error_t;
 
-static char * snat_out2in_error_strings[] = {
+static char *snat_out2in_error_strings[] = {
 #define _(sym,string) string,
   foreach_snat_out2in_error
 #undef _
 };
 
-typedef enum {
+typedef enum
+{
   SNAT_OUT2IN_NEXT_DROP,
   SNAT_OUT2IN_NEXT_LOOKUP,
   SNAT_OUT2IN_NEXT_ICMP_ERROR,
+  SNAT_OUT2IN_NEXT_REASS,
   SNAT_OUT2IN_N_NEXT,
 } snat_out2in_next_t;
 
+#ifndef CLIB_MARCH_VARIANT
+int
+nat44_o2i_is_idle_session_cb (clib_bihash_kv_8_8_t * kv, void *arg)
+{
+  snat_main_t *sm = &snat_main;
+  nat44_is_idle_session_ctx_t *ctx = arg;
+  snat_session_t *s;
+  u64 sess_timeout_time;
+  snat_main_per_thread_data_t *tsm = vec_elt_at_index (sm->per_thread_data,
+                                                      ctx->thread_index);
+  clib_bihash_kv_8_8_t s_kv;
+
+  s = pool_elt_at_index (tsm->sessions, kv->value);
+  sess_timeout_time = s->last_heard + (f64) nat44_session_get_timeout (sm, s);
+  if (ctx->now >= sess_timeout_time)
+    {
+      s_kv.key = s->in2out.as_u64;
+      if (clib_bihash_add_del_8_8 (&tsm->in2out, &s_kv, 0))
+       nat_log_warn ("out2in key del failed");
+
+      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_apmdel (s->user_index, s->in2out.fib_index,
+                              &s->in2out.addr, s->in2out.port,
+                              &s->out2in.addr, s->out2in.port,
+                              s->in2out.protocol);
+
+      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 (!snat_is_session_static (s))
+       snat_free_outside_address_and_port (sm->addresses, ctx->thread_index,
+                                           &s->out2in);
+
+      nat44_delete_session (sm, s, ctx->thread_index);
+      return 1;
+    }
+
+  return 0;
+}
+#endif
+
 /**
  * @brief Create session for static mapping.
  *
@@ -125,121 +175,96 @@ typedef enum {
  * @returns SNAT session if successfully created otherwise 0.
  */
 static inline snat_session_t *
-create_session_for_static_mapping (snat_main_t *sm,
-                                   vlib_buffer_t *b0,
-                                   snat_session_key_t in2out,
-                                   snat_session_key_t out2in,
-                                   vlib_node_runtime_t * node,
-                                   u32 thread_index)
+create_session_for_static_mapping (snat_main_t * sm,
+                                  vlib_buffer_t * b0,
+                                  snat_session_key_t in2out,
+                                  snat_session_key_t out2in,
+                                  vlib_node_runtime_t * node,
+                                  u32 thread_index, f64 now)
 {
   snat_user_t *u;
-  snat_user_key_t user_key;
   snat_session_t *s;
-  clib_bihash_kv_8_8_t kv0, value0;
-  dlist_elt_t * per_user_translation_list_elt;
-  dlist_elt_t * per_user_list_head_elt;
+  clib_bihash_kv_8_8_t kv0;
   ip4_header_t *ip0;
+  udp_header_t *udp0;
+  nat44_is_idle_session_ctx_t ctx0;
 
-  if (PREDICT_FALSE (maximum_sessions_exceeded(sm, thread_index)))
+  if (PREDICT_FALSE (maximum_sessions_exceeded (sm, thread_index)))
     {
       b0->error = node->errors[SNAT_OUT2IN_ERROR_MAX_SESSIONS_EXCEEDED];
+      nat_log_notice ("maximum sessions exceeded");
       return 0;
     }
 
   ip0 = vlib_buffer_get_current (b0);
+  udp0 = ip4_next_header (ip0);
 
-  user_key.addr = in2out.addr;
-  user_key.fib_index = in2out.fib_index;
-  kv0.key = user_key.as_u64;
-
-  /* Ever heard of the "user" = inside ip4 address before? */
-  if (clib_bihash_search_8_8 (&sm->per_thread_data[thread_index].user_hash,
-                              &kv0, &value0))
+  u =
+    nat_user_get_or_create (sm, &in2out.addr, in2out.fib_index, thread_index);
+  if (!u)
     {
-      /* no, make a new one */
-      pool_get (sm->per_thread_data[thread_index].users, u);
-      memset (u, 0, sizeof (*u));
-      u->addr = in2out.addr;
-      u->fib_index = in2out.fib_index;
-
-      pool_get (sm->per_thread_data[thread_index].list_pool,
-                per_user_list_head_elt);
-
-      u->sessions_per_user_list_head_index = per_user_list_head_elt -
-        sm->per_thread_data[thread_index].list_pool;
-
-      clib_dlist_init (sm->per_thread_data[thread_index].list_pool,
-                       u->sessions_per_user_list_head_index);
-
-      kv0.value = u - sm->per_thread_data[thread_index].users;
-
-      /* add user */
-      clib_bihash_add_del_8_8 (&sm->per_thread_data[thread_index].user_hash,
-                               &kv0, 1 /* is_add */);
+      nat_log_warn ("create NAT user failed");
+      return 0;
     }
-  else
+
+  s = nat_session_alloc_or_recycle (sm, u, thread_index, now);
+  if (!s)
     {
-      u = pool_elt_at_index (sm->per_thread_data[thread_index].users,
-                             value0.value);
+      nat44_delete_user_with_no_session (sm, u, thread_index);
+      nat_log_warn ("create NAT session failed");
+      return 0;
     }
 
-  pool_get (sm->per_thread_data[thread_index].sessions, s);
-  memset (s, 0, sizeof (*s));
-
-  s->outside_address_index = ~0;
   s->flags |= SNAT_SESSION_FLAG_STATIC_MAPPING;
-  s->ext_host_addr.as_u32 = ip0->dst_address.as_u32;
-  u->nstaticsessions++;
-
-  /* Create list elts */
-  pool_get (sm->per_thread_data[thread_index].list_pool,
-            per_user_translation_list_elt);
-  clib_dlist_init (sm->per_thread_data[thread_index].list_pool,
-                   per_user_translation_list_elt -
-                   sm->per_thread_data[thread_index].list_pool);
-
-  per_user_translation_list_elt->value =
-    s - sm->per_thread_data[thread_index].sessions;
-  s->per_user_index =
-    per_user_translation_list_elt - sm->per_thread_data[thread_index].list_pool;
-  s->per_user_list_head_index = u->sessions_per_user_list_head_index;
-
-  clib_dlist_addtail (sm->per_thread_data[thread_index].list_pool,
-                      s->per_user_list_head_index,
-                      per_user_translation_list_elt -
-                      sm->per_thread_data[thread_index].list_pool);
-
+  s->ext_host_addr.as_u32 = ip0->src_address.as_u32;
+  s->ext_host_port = udp0->src_port;
+  user_session_increment (sm, u, 1 /* static */ );
   s->in2out = in2out;
   s->out2in = out2in;
   s->in2out.protocol = out2in.protocol;
 
   /* Add to translation hashes */
+  ctx0.now = now;
+  ctx0.thread_index = thread_index;
   kv0.key = s->in2out.as_u64;
   kv0.value = s - sm->per_thread_data[thread_index].sessions;
-  if (clib_bihash_add_del_8_8 (&sm->per_thread_data[thread_index].in2out, &kv0,
-                               1 /* is_add */))
-      clib_warning ("in2out key add failed");
+  if (clib_bihash_add_or_overwrite_stale_8_8
+      (&sm->per_thread_data[thread_index].in2out, &kv0,
+       nat44_i2o_is_idle_session_cb, &ctx0))
+    nat_log_notice ("in2out key add failed");
 
   kv0.key = s->out2in.as_u64;
-  kv0.value = s - sm->per_thread_data[thread_index].sessions;
 
-  if (clib_bihash_add_del_8_8 (&sm->per_thread_data[thread_index].out2in, &kv0,
-                               1 /* is_add */))
-      clib_warning ("out2in key add failed");
+  if (clib_bihash_add_or_overwrite_stale_8_8
+      (&sm->per_thread_data[thread_index].out2in, &kv0,
+       nat44_o2i_is_idle_session_cb, &ctx0))
+    nat_log_notice ("out2in key add failed");
 
   /* log NAT event */
-  snat_ipfix_logging_nat44_ses_create(s->in2out.addr.as_u32,
-                                      s->out2in.addr.as_u32,
-                                      s->in2out.protocol,
-                                      s->in2out.port,
-                                      s->out2in.port,
-                                      s->in2out.fib_index);
-   return s;
+  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_apmadd (s->user_index, s->in2out.fib_index,
+                          &s->in2out.addr, s->in2out.port, &s->out2in.addr,
+                          s->out2in.port, s->in2out.protocol);
+
+  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;
 }
 
+#ifndef CLIB_MARCH_VARIANT
 static_always_inline
-snat_out2in_error_t icmp_get_key(ip4_header_t *ip0,
-                                 snat_session_key_t *p_key0)
+  snat_out2in_error_t icmp_get_key (ip4_header_t * ip0,
+                                   snat_session_key_t * p_key0)
 {
   icmp46_header_t *icmp0;
   snat_session_key_t key0;
@@ -249,7 +274,7 @@ snat_out2in_error_t icmp_get_key(ip4_header_t *ip0,
   icmp46_header_t *inner_icmp0;
 
   icmp0 = (icmp46_header_t *) ip4_next_header (ip0);
-  echo0 = (icmp_echo_header_t *)(icmp0+1);
+  echo0 = (icmp_echo_header_t *) (icmp0 + 1);
 
   if (!icmp_is_error_message (icmp0))
     {
@@ -259,27 +284,27 @@ snat_out2in_error_t icmp_get_key(ip4_header_t *ip0,
     }
   else
     {
-      inner_ip0 = (ip4_header_t *)(echo0+1);
+      inner_ip0 = (ip4_header_t *) (echo0 + 1);
       l4_header = ip4_next_header (inner_ip0);
       key0.protocol = ip_proto_to_snat_proto (inner_ip0->protocol);
       key0.addr = inner_ip0->src_address;
       switch (key0.protocol)
-        {
-        case SNAT_PROTOCOL_ICMP:
-          inner_icmp0 = (icmp46_header_t*)l4_header;
-          inner_echo0 = (icmp_echo_header_t *)(inner_icmp0+1);
-          key0.port = inner_echo0->identifier;
-          break;
-        case SNAT_PROTOCOL_UDP:
-        case SNAT_PROTOCOL_TCP:
-          key0.port = ((tcp_udp_header_t*)l4_header)->src_port;
-          break;
-        default:
-          return SNAT_OUT2IN_ERROR_UNSUPPORTED_PROTOCOL;
-        }
+       {
+       case SNAT_PROTOCOL_ICMP:
+         inner_icmp0 = (icmp46_header_t *) l4_header;
+         inner_echo0 = (icmp_echo_header_t *) (inner_icmp0 + 1);
+         key0.port = inner_echo0->identifier;
+         break;
+       case SNAT_PROTOCOL_UDP:
+       case SNAT_PROTOCOL_TCP:
+         key0.port = ((tcp_udp_header_t *) l4_header)->src_port;
+         break;
+       default:
+         return SNAT_OUT2IN_ERROR_UNSUPPORTED_PROTOCOL;
+       }
     }
   *p_key0 = key0;
-  return -1; /* success */
+  return -1;                   /* success */
 }
 
 /**
@@ -296,11 +321,12 @@ snat_out2in_error_t icmp_get_key(ip4_header_t *ip0,
  * @param d                      optional parameter
  * @param e                      optional parameter
  */
-u32 icmp_match_out2in_slow(snat_main_t *sm, vlib_node_runtime_t *node,
-                           u32 thread_index, vlib_buffer_t *b0,
-                           ip4_header_t *ip0, u8 *p_proto,
-                           snat_session_key_t *p_value,
-                           u8 *p_dont_translate, void *d, void *e)
+u32
+icmp_match_out2in_slow (snat_main_t * sm, vlib_node_runtime_t * node,
+                       u32 thread_index, vlib_buffer_t * b0,
+                       ip4_header_t * ip0, u8 * p_proto,
+                       snat_session_key_t * p_value,
+                       u8 * p_dont_translate, void *d, void *e)
 {
   icmp46_header_t *icmp0;
   u32 sw_if_index0;
@@ -313,9 +339,10 @@ u32 icmp_match_out2in_slow(snat_main_t *sm, vlib_node_runtime_t *node,
   u8 is_addr_only;
   u32 next0 = ~0;
   int err;
+  u8 identity_nat;
 
   icmp0 = (icmp46_header_t *) ip4_next_header (ip0);
-  sw_if_index0 = vnet_buffer(b0)->sw_if_index[VLIB_RX];
+  sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
   rx_fib_index0 = ip4_fib_table_get_index_for_sw_if_index (sw_if_index0);
 
   key0.protocol = 0;
@@ -332,55 +359,71 @@ u32 icmp_match_out2in_slow(snat_main_t *sm, vlib_node_runtime_t *node,
   kv0.key = key0.as_u64;
 
   if (clib_bihash_search_8_8 (&sm->per_thread_data[thread_index].out2in, &kv0,
-                              &value0))
+                             &value0))
     {
       /* Try to match static mapping by external address and port,
          destination address and port in packet */
-      if (snat_static_mapping_match(sm, key0, &sm0, 1, &is_addr_only))
-        {
-          /* Don't NAT packet aimed at the intfc address */
-          if (PREDICT_FALSE(is_interface_addr(sm, node, sw_if_index0,
-                                              ip0->dst_address.as_u32)))
-            {
-              dont_translate = 1;
-              goto out;
-            }
-          b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
-          next0 = SNAT_OUT2IN_NEXT_DROP;
-          goto out;
-        }
-
-      if (PREDICT_FALSE(icmp0->type != ICMP4_echo_reply &&
-                        (icmp0->type != ICMP4_echo_request || !is_addr_only)))
-        {
-          b0->error = node->errors[SNAT_OUT2IN_ERROR_BAD_ICMP_TYPE];
-          next0 = SNAT_OUT2IN_NEXT_DROP;
-          goto out;
-        }
+      if (snat_static_mapping_match
+         (sm, key0, &sm0, 1, &is_addr_only, 0, 0, 0, &identity_nat))
+       {
+         if (!sm->forwarding_enabled)
+           {
+             /* Don't NAT packet aimed at the intfc address */
+             if (PREDICT_FALSE (is_interface_addr (sm, node, sw_if_index0,
+                                                   ip0->dst_address.as_u32)))
+               {
+                 dont_translate = 1;
+                 goto out;
+               }
+             b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+             next0 = SNAT_OUT2IN_NEXT_DROP;
+             goto out;
+           }
+         else
+           {
+             dont_translate = 1;
+             goto out;
+           }
+       }
 
+      if (PREDICT_FALSE (icmp0->type != ICMP4_echo_reply &&
+                        (icmp0->type != ICMP4_echo_request
+                         || !is_addr_only)))
+       {
+         b0->error = node->errors[SNAT_OUT2IN_ERROR_BAD_ICMP_TYPE];
+         next0 = SNAT_OUT2IN_NEXT_DROP;
+         goto out;
+       }
+
+      if (PREDICT_FALSE (identity_nat))
+       {
+         dont_translate = 1;
+         goto out;
+       }
       /* Create session initiated by host from external network */
-      s0 = create_session_for_static_mapping(sm, b0, sm0, key0,
-                                             node, thread_index);
+      s0 = create_session_for_static_mapping (sm, b0, sm0, key0,
+                                             node, thread_index,
+                                             vlib_time_now (sm->vlib_main));
 
       if (!s0)
-        {
-          next0 = SNAT_OUT2IN_NEXT_DROP;
-          goto out;
-        }
+       {
+         next0 = SNAT_OUT2IN_NEXT_DROP;
+         goto out;
+       }
     }
   else
     {
-      if (PREDICT_FALSE(icmp0->type != ICMP4_echo_reply &&
-                        icmp0->type != ICMP4_echo_request &&
-                        !icmp_is_error_message (icmp0)))
-        {
-          b0->error = node->errors[SNAT_OUT2IN_ERROR_BAD_ICMP_TYPE];
-          next0 = SNAT_OUT2IN_NEXT_DROP;
-          goto out;
-        }
+      if (PREDICT_FALSE (icmp0->type != ICMP4_echo_reply &&
+                        icmp0->type != ICMP4_echo_request &&
+                        !icmp_is_error_message (icmp0)))
+       {
+         b0->error = node->errors[SNAT_OUT2IN_ERROR_BAD_ICMP_TYPE];
+         next0 = SNAT_OUT2IN_NEXT_DROP;
+         goto out;
+       }
 
       s0 = pool_elt_at_index (sm->per_thread_data[thread_index].sessions,
-                              value0.value);
+                             value0.value);
     }
 
 out:
@@ -389,10 +432,12 @@ out:
     *p_value = s0->in2out;
   *p_dont_translate = dont_translate;
   if (d)
-    *(snat_session_t**)d = s0;
+    *(snat_session_t **) d = s0;
   return next0;
 }
+#endif
 
+#ifndef CLIB_MARCH_VARIANT
 /**
  * Get address and port values to be used for ICMP packet translation
  *
@@ -406,11 +451,12 @@ out:
  * @param d                      optional parameter
  * @param e                      optional parameter
  */
-u32 icmp_match_out2in_fast(snat_main_t *sm, vlib_node_runtime_t *node,
-                           u32 thread_index, vlib_buffer_t *b0,
-                           ip4_header_t *ip0, u8 *p_proto,
-                           snat_session_key_t *p_value,
-                           u8 *p_dont_translate, void *d, void *e)
+u32
+icmp_match_out2in_fast (snat_main_t * sm, vlib_node_runtime_t * node,
+                       u32 thread_index, vlib_buffer_t * b0,
+                       ip4_header_t * ip0, u8 * p_proto,
+                       snat_session_key_t * p_value,
+                       u8 * p_dont_translate, void *d, void *e)
 {
   icmp46_header_t *icmp0;
   u32 sw_if_index0;
@@ -423,7 +469,7 @@ u32 icmp_match_out2in_fast(snat_main_t *sm, vlib_node_runtime_t *node,
   int err;
 
   icmp0 = (icmp46_header_t *) ip4_next_header (ip0);
-  sw_if_index0 = vnet_buffer(b0)->sw_if_index[VLIB_RX];
+  sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
   rx_fib_index0 = ip4_fib_table_get_index_for_sw_if_index (sw_if_index0);
 
   err = icmp_get_key (ip0, &key0);
@@ -435,22 +481,23 @@ u32 icmp_match_out2in_fast(snat_main_t *sm, vlib_node_runtime_t *node,
     }
   key0.fib_index = rx_fib_index0;
 
-  if (snat_static_mapping_match(sm, key0, &sm0, 1, &is_addr_only))
+  if (snat_static_mapping_match
+      (sm, key0, &sm0, 1, &is_addr_only, 0, 0, 0, 0))
     {
       /* Don't NAT packet aimed at the intfc address */
-      if (is_interface_addr(sm, node, sw_if_index0, ip0->dst_address.as_u32))
-        {
-          dont_translate = 1;
-          goto out;
-        }
+      if (is_interface_addr (sm, node, sw_if_index0, ip0->dst_address.as_u32))
+       {
+         dont_translate = 1;
+         goto out;
+       }
       b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
       next0 = SNAT_OUT2IN_NEXT_DROP;
       goto out;
     }
 
-  if (PREDICT_FALSE(icmp0->type != ICMP4_echo_reply &&
-                    (icmp0->type != ICMP4_echo_request || !is_addr_only) &&
-                    !icmp_is_error_message (icmp0)))
+  if (PREDICT_FALSE (icmp0->type != ICMP4_echo_reply &&
+                    (icmp0->type != ICMP4_echo_request || !is_addr_only) &&
+                    !icmp_is_error_message (icmp0)))
     {
       b0->error = node->errors[SNAT_OUT2IN_ERROR_BAD_ICMP_TYPE];
       next0 = SNAT_OUT2IN_NEXT_DROP;
@@ -464,18 +511,18 @@ out2:
   *p_dont_translate = dont_translate;
   return next0;
 }
-
-static inline u32 icmp_out2in (snat_main_t *sm,
-                               vlib_buffer_t * b0,
-                               ip4_header_t * ip0,
-                               icmp46_header_t * icmp0,
-                               u32 sw_if_index0,
-                               u32 rx_fib_index0,
-                               vlib_node_runtime_t * node,
-                               u32 next0,
-                               u32 thread_index,
-                               void *d,
-                               void *e)
+#endif
+
+#ifndef CLIB_MARCH_VARIANT
+u32
+icmp_out2in (snat_main_t * sm,
+            vlib_buffer_t * b0,
+            ip4_header_t * ip0,
+            icmp46_header_t * icmp0,
+            u32 sw_if_index0,
+            u32 rx_fib_index0,
+            vlib_node_runtime_t * node,
+            u32 next0, u32 thread_index, void *d, void *e)
 {
   snat_session_key_t sm0;
   u8 protocol;
@@ -490,58 +537,68 @@ static inline u32 icmp_out2in (snat_main_t *sm,
   u16 checksum0;
   u32 next0_tmp;
 
-  echo0 = (icmp_echo_header_t *)(icmp0+1);
+  echo0 = (icmp_echo_header_t *) (icmp0 + 1);
 
-  next0_tmp = sm->icmp_match_out2in_cb(sm, node, thread_index, b0, ip0,
-                                       &protocol, &sm0, &dont_translate, d, e);
+  next0_tmp = sm->icmp_match_out2in_cb (sm, node, thread_index, b0, ip0,
+                                       &protocol, &sm0, &dont_translate, d,
+                                       e);
   if (next0_tmp != ~0)
     next0 = next0_tmp;
   if (next0 == SNAT_OUT2IN_NEXT_DROP || dont_translate)
     goto out;
 
-  sum0 = ip_incremental_checksum (0, icmp0,
-                                  ntohs(ip0->length) - ip4_header_bytes (ip0));
-  checksum0 = ~ip_csum_fold (sum0);
-  if (checksum0 != 0 && checksum0 != 0xffff)
+  if (PREDICT_TRUE (!ip4_is_fragment (ip0)))
     {
-      next0 = SNAT_OUT2IN_NEXT_DROP;
-      goto out;
+      sum0 = ip_incremental_checksum_buffer (sm->vlib_main, b0, (u8 *) icmp0 -
+                                            (u8 *)
+                                            vlib_buffer_get_current (b0),
+                                            ntohs (ip0->length) -
+                                            ip4_header_bytes (ip0), 0);
+      checksum0 = ~ip_csum_fold (sum0);
+      if (checksum0 != 0 && checksum0 != 0xffff)
+       {
+         next0 = SNAT_OUT2IN_NEXT_DROP;
+         goto out;
+       }
     }
 
   old_addr0 = ip0->dst_address.as_u32;
   new_addr0 = ip0->dst_address.as_u32 = sm0.addr.as_u32;
-  vnet_buffer(b0)->sw_if_index[VLIB_TX] = sm0.fib_index;
+  vnet_buffer (b0)->sw_if_index[VLIB_TX] = sm0.fib_index;
 
   sum0 = ip0->checksum;
   sum0 = ip_csum_update (sum0, old_addr0, new_addr0, ip4_header_t,
-                         dst_address /* changed member */);
+                        dst_address /* changed member */ );
   ip0->checksum = ip_csum_fold (sum0);
 
+  if (icmp0->checksum == 0)
+    icmp0->checksum = 0xffff;
+
   if (!icmp_is_error_message (icmp0))
     {
       new_id0 = sm0.port;
-      if (PREDICT_FALSE(new_id0 != echo0->identifier))
-        {
-          old_id0 = echo0->identifier;
-          new_id0 = sm0.port;
-          echo0->identifier = new_id0;
-
-          sum0 = icmp0->checksum;
-          sum0 = ip_csum_update (sum0, old_id0, new_id0, icmp_echo_header_t,
-                                 identifier /* changed member */);
-          icmp0->checksum = ip_csum_fold (sum0);
-        }
+      if (PREDICT_FALSE (new_id0 != echo0->identifier))
+       {
+         old_id0 = echo0->identifier;
+         new_id0 = sm0.port;
+         echo0->identifier = new_id0;
+
+         sum0 = icmp0->checksum;
+         sum0 = ip_csum_update (sum0, old_id0, new_id0, icmp_echo_header_t,
+                                identifier /* changed member */ );
+         icmp0->checksum = ip_csum_fold (sum0);
+       }
     }
   else
     {
-      inner_ip0 = (ip4_header_t *)(echo0+1);
+      inner_ip0 = (ip4_header_t *) (echo0 + 1);
       l4_header = ip4_next_header (inner_ip0);
 
       if (!ip4_header_checksum_is_valid (inner_ip0))
-        {
-          next0 = SNAT_OUT2IN_NEXT_DROP;
-          goto out;
-        }
+       {
+         next0 = SNAT_OUT2IN_NEXT_DROP;
+         goto out;
+       }
 
       old_addr0 = inner_ip0->src_address.as_u32;
       inner_ip0->src_address = sm0.addr;
@@ -549,390 +606,114 @@ static inline u32 icmp_out2in (snat_main_t *sm,
 
       sum0 = icmp0->checksum;
       sum0 = ip_csum_update (sum0, old_addr0, new_addr0, ip4_header_t,
-                             src_address /* changed member */);
+                            src_address /* changed member */ );
       icmp0->checksum = ip_csum_fold (sum0);
 
       switch (protocol)
-        {
-        case SNAT_PROTOCOL_ICMP:
-          inner_icmp0 = (icmp46_header_t*)l4_header;
-          inner_echo0 = (icmp_echo_header_t *)(inner_icmp0+1);
-
-          old_id0 = inner_echo0->identifier;
-          new_id0 = sm0.port;
-          inner_echo0->identifier = new_id0;
-
-          sum0 = icmp0->checksum;
-          sum0 = ip_csum_update (sum0, old_id0, new_id0, icmp_echo_header_t,
-                                 identifier);
-          icmp0->checksum = ip_csum_fold (sum0);
-          break;
-        case SNAT_PROTOCOL_UDP:
-        case SNAT_PROTOCOL_TCP:
-          old_id0 = ((tcp_udp_header_t*)l4_header)->src_port;
-          new_id0 = sm0.port;
-          ((tcp_udp_header_t*)l4_header)->src_port = new_id0;
-
-          sum0 = icmp0->checksum;
-          sum0 = ip_csum_update (sum0, old_id0, new_id0, tcp_udp_header_t,
-                                 src_port);
-          icmp0->checksum = ip_csum_fold (sum0);
-          break;
-        default:
-          ASSERT(0);
-        }
+       {
+       case SNAT_PROTOCOL_ICMP:
+         inner_icmp0 = (icmp46_header_t *) l4_header;
+         inner_echo0 = (icmp_echo_header_t *) (inner_icmp0 + 1);
+
+         old_id0 = inner_echo0->identifier;
+         new_id0 = sm0.port;
+         inner_echo0->identifier = new_id0;
+
+         sum0 = icmp0->checksum;
+         sum0 = ip_csum_update (sum0, old_id0, new_id0, icmp_echo_header_t,
+                                identifier);
+         icmp0->checksum = ip_csum_fold (sum0);
+         break;
+       case SNAT_PROTOCOL_UDP:
+       case SNAT_PROTOCOL_TCP:
+         old_id0 = ((tcp_udp_header_t *) l4_header)->src_port;
+         new_id0 = sm0.port;
+         ((tcp_udp_header_t *) l4_header)->src_port = new_id0;
+
+         sum0 = icmp0->checksum;
+         sum0 = ip_csum_update (sum0, old_id0, new_id0, tcp_udp_header_t,
+                                src_port);
+         icmp0->checksum = ip_csum_fold (sum0);
+         break;
+       default:
+         ASSERT (0);
+       }
     }
 
 out:
   return next0;
 }
-
-
-static inline u32 icmp_out2in_slow_path (snat_main_t *sm,
-                                         vlib_buffer_t * b0,
-                                         ip4_header_t * ip0,
-                                         icmp46_header_t * icmp0,
-                                         u32 sw_if_index0,
-                                         u32 rx_fib_index0,
-                                         vlib_node_runtime_t * node,
-                                         u32 next0, f64 now,
-                                         u32 thread_index,
-                                         snat_session_t ** p_s0)
+#endif
+
+static inline u32
+icmp_out2in_slow_path (snat_main_t * sm,
+                      vlib_buffer_t * b0,
+                      ip4_header_t * ip0,
+                      icmp46_header_t * icmp0,
+                      u32 sw_if_index0,
+                      u32 rx_fib_index0,
+                      vlib_node_runtime_t * node,
+                      u32 next0, f64 now,
+                      u32 thread_index, snat_session_t ** p_s0)
 {
-  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 != SNAT_OUT2IN_NEXT_DROP && s0))
+  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 != SNAT_OUT2IN_NEXT_DROP && s0))
     {
       /* Accounting */
-      s0->last_heard = now;
-      s0->total_pkts++;
-      s0->total_bytes += vlib_buffer_length_in_chain (sm->vlib_main, b0);
-      /* Per-user LRU list maintenance for dynamic translation */
-      if (!snat_is_session_static (s0))
-        {
-          clib_dlist_remove (sm->per_thread_data[thread_index].list_pool,
-                             s0->per_user_index);
-          clib_dlist_addtail (sm->per_thread_data[thread_index].list_pool,
-                              s0->per_user_list_head_index,
-                              s0->per_user_index);
-        }
+      nat44_session_update_counters (s0, now,
+                                    vlib_buffer_length_in_chain
+                                    (sm->vlib_main, b0), thread_index);
+      /* Per-user LRU list maintenance */
+      nat44_session_update_lru (sm, s0, thread_index);
     }
   return next0;
 }
 
-static snat_session_t *
-snat_out2in_unknown_proto (snat_main_t *sm,
-                           vlib_buffer_t * b,
-                           ip4_header_t * ip,
-                           u32 rx_fib_index,
-                           u32 thread_index,
-                           f64 now,
-                           vlib_main_t * vm,
-                           vlib_node_runtime_t * node)
+static int
+nat_out2in_sm_unknown_proto (snat_main_t * sm,
+                            vlib_buffer_t * b,
+                            ip4_header_t * ip, u32 rx_fib_index)
 {
   clib_bihash_kv_8_8_t kv, value;
-  clib_bihash_kv_16_8_t s_kv, s_value;
   snat_static_mapping_t *m;
   snat_session_key_t m_key;
   u32 old_addr, new_addr;
   ip_csum_t sum;
-  nat_ed_ses_key_t key;
-  snat_session_t * s;
-  snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
-  snat_user_key_t u_key;
-  snat_user_t *u;
-  dlist_elt_t *head, *elt;
-
-  old_addr = ip->dst_address.as_u32;
 
-  key.l_addr = ip->dst_address;
-  key.r_addr = ip->src_address;
-  key.fib_index = rx_fib_index;
-  key.proto = ip->protocol;
-  key.rsvd = 0;
-  key.l_port = 0;
-  s_kv.key[0] = key.as_u64[0];
-  s_kv.key[1] = key.as_u64[1];
+  m_key.addr = ip->dst_address;
+  m_key.port = 0;
+  m_key.protocol = 0;
+  m_key.fib_index = 0;
+  kv.key = m_key.as_u64;
+  if (clib_bihash_search_8_8 (&sm->static_mapping_by_external, &kv, &value))
+    return 1;
 
-  if (!clib_bihash_search_16_8 (&sm->out2in_ed, &s_kv, &s_value))
-    {
-      s = pool_elt_at_index (tsm->sessions, s_value.value);
-      new_addr = ip->dst_address.as_u32 = s->in2out.addr.as_u32;
-    }
-  else
-    {
-      if (PREDICT_FALSE (maximum_sessions_exceeded(sm, thread_index)))
-        {
-          b->error = node->errors[SNAT_OUT2IN_ERROR_MAX_SESSIONS_EXCEEDED];
-          return 0;
-        }
-
-      m_key.addr = ip->dst_address;
-      m_key.port = 0;
-      m_key.protocol = 0;
-      m_key.fib_index = rx_fib_index;
-      kv.key = m_key.as_u64;
-      if (clib_bihash_search_8_8 (&sm->static_mapping_by_external, &kv, &value))
-        {
-          b->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
-          return 0;
-        }
-
-      m = pool_elt_at_index (sm->static_mappings, value.value);
-
-      new_addr = ip->dst_address.as_u32 = m->local_addr.as_u32;
-
-      u_key.addr = ip->src_address;
-      u_key.fib_index = m->fib_index;
-      kv.key = u_key.as_u64;
-
-      /* Ever heard of the "user" = src ip4 address before? */
-      if (clib_bihash_search_8_8 (&tsm->user_hash, &kv, &value))
-        {
-          /* no, make a new one */
-          pool_get (tsm->users, u);
-          memset (u, 0, sizeof (*u));
-          u->addr = ip->src_address;
-          u->fib_index = rx_fib_index;
-
-          pool_get (tsm->list_pool, head);
-          u->sessions_per_user_list_head_index = head - tsm->list_pool;
-
-          clib_dlist_init (tsm->list_pool,
-                           u->sessions_per_user_list_head_index);
-
-          kv.value = u - tsm->users;
-
-          /* add user */
-          clib_bihash_add_del_8_8 (&tsm->user_hash, &kv, 1);
-        }
-      else
-        {
-          u = pool_elt_at_index (tsm->users, value.value);
-        }
-
-      /* Create a new session */
-      pool_get (tsm->sessions, s);
-      memset (s, 0, sizeof (*s));
-
-      s->ext_host_addr.as_u32 = ip->src_address.as_u32;
-      s->flags |= SNAT_SESSION_FLAG_UNKNOWN_PROTO;
-      s->flags |= SNAT_SESSION_FLAG_STATIC_MAPPING;
-      s->outside_address_index = ~0;
-      s->out2in.addr.as_u32 = old_addr;
-      s->out2in.fib_index = rx_fib_index;
-      s->in2out.addr.as_u32 = new_addr;
-      s->in2out.fib_index = m->fib_index;
-      s->in2out.port = s->out2in.port = ip->protocol;
-      u->nstaticsessions++;
-
-      /* Create list elts */
-      pool_get (tsm->list_pool, elt);
-      clib_dlist_init (tsm->list_pool, elt - tsm->list_pool);
-      elt->value = s - tsm->sessions;
-      s->per_user_index = elt - tsm->list_pool;
-      s->per_user_list_head_index = u->sessions_per_user_list_head_index;
-      clib_dlist_addtail (tsm->list_pool, s->per_user_list_head_index,
-                          s->per_user_index);
-
-      /* Add to lookup tables */
-      s_kv.value = s - tsm->sessions;
-      if (clib_bihash_add_del_16_8 (&sm->out2in_ed, &s_kv, 1))
-        clib_warning ("out2in key add failed");
-
-      key.l_addr = ip->dst_address;
-      key.fib_index = m->fib_index;
-      s_kv.key[0] = key.as_u64[0];
-      s_kv.key[1] = key.as_u64[1];
-      if (clib_bihash_add_del_16_8 (&sm->in2out_ed, &s_kv, 1))
-        clib_warning ("in2out key add failed");
-   }
-
-  /* Update IP checksum */
-  sum = ip->checksum;
-  sum = ip_csum_update (sum, old_addr, new_addr, ip4_header_t, dst_address);
-  ip->checksum = ip_csum_fold (sum);
-
-  vnet_buffer(b)->sw_if_index[VLIB_TX] = s->in2out.fib_index;
-
-  /* Accounting */
-  s->last_heard = now;
-  s->total_pkts++;
-  s->total_bytes += vlib_buffer_length_in_chain (vm, b);
-  /* Per-user LRU list maintenance */
-  clib_dlist_remove (tsm->list_pool, s->per_user_index);
-  clib_dlist_addtail (tsm->list_pool, s->per_user_list_head_index,
-                      s->per_user_index);
-
-  return s;
-}
-
-static snat_session_t *
-snat_out2in_lb (snat_main_t *sm,
-                vlib_buffer_t * b,
-                ip4_header_t * ip,
-                u32 rx_fib_index,
-                u32 thread_index,
-                f64 now,
-                vlib_main_t * vm,
-                vlib_node_runtime_t * node)
-{
-  nat_ed_ses_key_t key;
-  clib_bihash_kv_16_8_t s_kv, s_value;
-  udp_header_t *udp = ip4_next_header (ip);
-  tcp_header_t *tcp = (tcp_header_t *) udp;
-  snat_session_t *s = 0;
-  snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
-  snat_session_key_t e_key, l_key;
-  clib_bihash_kv_8_8_t kv, value;
-  u32 old_addr, new_addr;
-  u32 proto = ip_proto_to_snat_proto (ip->protocol);
-  u16 new_port, old_port;
-  ip_csum_t sum;
-  snat_user_key_t u_key;
-  snat_user_t *u;
-  dlist_elt_t *head, *elt;
+  m = pool_elt_at_index (sm->static_mappings, value.value);
 
   old_addr = ip->dst_address.as_u32;
-
-  key.l_addr = ip->dst_address;
-  key.r_addr = ip->src_address;
-  key.fib_index = rx_fib_index;
-  key.proto = ip->protocol;
-  key.rsvd = 0;
-  key.l_port = udp->dst_port;
-  s_kv.key[0] = key.as_u64[0];
-  s_kv.key[1] = key.as_u64[1];
-
-  if (!clib_bihash_search_16_8 (&sm->out2in_ed, &s_kv, &s_value))
-    {
-      s = pool_elt_at_index (tsm->sessions, s_value.value);
-    }
-  else
-    {
-      if (PREDICT_FALSE (maximum_sessions_exceeded(sm, thread_index)))
-        {
-          b->error = node->errors[SNAT_OUT2IN_ERROR_MAX_SESSIONS_EXCEEDED];
-          return 0;
-        }
-
-      e_key.addr = ip->dst_address;
-      e_key.port = udp->dst_port;
-      e_key.protocol = proto;
-      e_key.fib_index = rx_fib_index;
-      if (snat_static_mapping_match(sm, e_key, &l_key, 1, 0))
-        return 0;
-
-      u_key.addr = l_key.addr;
-      u_key.fib_index = l_key.fib_index;
-      kv.key = u_key.as_u64;
-
-      /* Ever heard of the "user" = src ip4 address before? */
-      if (clib_bihash_search_8_8 (&tsm->user_hash, &kv, &value))
-        {
-          /* no, make a new one */
-          pool_get (tsm->users, u);
-          memset (u, 0, sizeof (*u));
-          u->addr = l_key.addr;
-          u->fib_index = l_key.fib_index;
-
-          pool_get (tsm->list_pool, head);
-          u->sessions_per_user_list_head_index = head - tsm->list_pool;
-
-          clib_dlist_init (tsm->list_pool,
-                           u->sessions_per_user_list_head_index);
-
-          kv.value = u - tsm->users;
-
-          /* add user */
-          if (clib_bihash_add_del_8_8 (&tsm->user_hash, &kv, 1))
-            clib_warning ("user key add failed");
-        }
-      else
-        {
-          u = pool_elt_at_index (tsm->users, value.value);
-        }
-
-      /* Create a new session */
-      pool_get (tsm->sessions, s);
-      memset (s, 0, sizeof (*s));
-
-      s->ext_host_addr.as_u32 = ip->src_address.as_u32;
-      s->flags |= SNAT_SESSION_FLAG_STATIC_MAPPING;
-      s->flags |= SNAT_SESSION_FLAG_LOAD_BALANCING;
-      s->outside_address_index = ~0;
-      s->out2in = e_key;
-      s->in2out = l_key;
-      u->nstaticsessions++;
-
-      /* Create list elts */
-      pool_get (tsm->list_pool, elt);
-      clib_dlist_init (tsm->list_pool, elt - tsm->list_pool);
-      elt->value = s - tsm->sessions;
-      s->per_user_index = elt - tsm->list_pool;
-      s->per_user_list_head_index = u->sessions_per_user_list_head_index;
-      clib_dlist_addtail (tsm->list_pool, s->per_user_list_head_index,
-                          s->per_user_index);
-
-      /* Add to lookup tables */
-      s_kv.value = s - tsm->sessions;
-      if (clib_bihash_add_del_16_8 (&sm->out2in_ed, &s_kv, 1))
-        clib_warning ("out2in-ed key add failed");
-
-      key.l_addr = l_key.addr;
-      key.fib_index = l_key.fib_index;
-      key.l_port = l_key.port;
-      s_kv.key[0] = key.as_u64[0];
-      s_kv.key[1] = key.as_u64[1];
-      if (clib_bihash_add_del_16_8 (&sm->in2out_ed, &s_kv, 1))
-        clib_warning ("in2out-ed key add failed");
-    }
-
-  new_addr = ip->dst_address.as_u32 = s->in2out.addr.as_u32;
-
-  /* Update IP checksum */
+  new_addr = ip->dst_address.as_u32 = m->local_addr.as_u32;
   sum = ip->checksum;
   sum = ip_csum_update (sum, old_addr, new_addr, ip4_header_t, dst_address);
   ip->checksum = ip_csum_fold (sum);
 
-  if (PREDICT_TRUE(proto == SNAT_PROTOCOL_TCP))
-    {
-      old_port = tcp->dst_port;
-      tcp->dst_port = s->in2out.port;
-      new_port = tcp->dst_port;
-
-      sum = tcp->checksum;
-      sum = ip_csum_update (sum, old_addr, new_addr, ip4_header_t, dst_address);
-      sum = ip_csum_update (sum, old_port, new_port, ip4_header_t, length);
-      tcp->checksum = ip_csum_fold(sum);
-    }
-  else
-    {
-      udp->dst_port = s->in2out.port;
-      udp->checksum = 0;
-    }
-
-  vnet_buffer(b)->sw_if_index[VLIB_TX] = s->in2out.fib_index;
-
-  /* Accounting */
-  s->last_heard = now;
-  s->total_pkts++;
-  s->total_bytes += vlib_buffer_length_in_chain (vm, b);
-  return s;
+  vnet_buffer (b)->sw_if_index[VLIB_TX] = m->fib_index;
+  return 0;
 }
 
-static uword
-snat_out2in_node_fn (vlib_main_t * vm,
-                 vlib_node_runtime_t * node,
-                 vlib_frame_t * frame)
+VLIB_NODE_FN (snat_out2in_node) (vlib_main_t * vm,
+                                vlib_node_runtime_t * node,
+                                vlib_frame_t * frame)
 {
-  u32 n_left_from, * from, * to_next;
+  u32 n_left_from, *from, *to_next;
   snat_out2in_next_t next_index;
   u32 pkts_processed = 0;
-  snat_main_t * sm = &snat_main;
+  snat_main_t *sm = &snat_main;
   f64 now = vlib_time_now (vm);
-  u32 thread_index = vlib_get_thread_index ();
+  u32 thread_index = vm->thread_index;
+  u32 tcp_packets = 0, udp_packets = 0, icmp_packets = 0, other_packets =
+    0, fragments = 0;
 
   from = vlib_frame_vector_args (frame);
   n_left_from = frame->n_vectors;
@@ -942,34 +723,34 @@ snat_out2in_node_fn (vlib_main_t * vm,
     {
       u32 n_left_to_next;
 
-      vlib_get_next_frame (vm, node, next_index,
-                          to_next, n_left_to_next);
+      vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
 
       while (n_left_from >= 4 && n_left_to_next >= 2)
        {
-          u32 bi0, bi1;
-         vlib_buffer_t * b0, * b1;
-          u32 next0 = SNAT_OUT2IN_NEXT_LOOKUP;
-          u32 next1 = SNAT_OUT2IN_NEXT_LOOKUP;
-          u32 sw_if_index0, sw_if_index1;
-          ip4_header_t * ip0, *ip1;
-          ip_csum_t sum0, sum1;
-          u32 new_addr0, old_addr0;
-          u16 new_port0, old_port0;
-          u32 new_addr1, old_addr1;
-          u16 new_port1, old_port1;
-          udp_header_t * udp0, * udp1;
-          tcp_header_t * tcp0, * tcp1;
-          icmp46_header_t * icmp0, * icmp1;
-          snat_session_key_t key0, key1, sm0, sm1;
-          u32 rx_fib_index0, rx_fib_index1;
-          u32 proto0, proto1;
-          snat_session_t * s0 = 0, * s1 = 0;
-          clib_bihash_kv_8_8_t kv0, kv1, value0, value1;
+         u32 bi0, bi1;
+         vlib_buffer_t *b0, *b1;
+         u32 next0 = SNAT_OUT2IN_NEXT_LOOKUP;
+         u32 next1 = SNAT_OUT2IN_NEXT_LOOKUP;
+         u32 sw_if_index0, sw_if_index1;
+         ip4_header_t *ip0, *ip1;
+         ip_csum_t sum0, sum1;
+         u32 new_addr0, old_addr0;
+         u16 new_port0, old_port0;
+         u32 new_addr1, old_addr1;
+         u16 new_port1, old_port1;
+         udp_header_t *udp0, *udp1;
+         tcp_header_t *tcp0, *tcp1;
+         icmp46_header_t *icmp0, *icmp1;
+         snat_session_key_t key0, key1, sm0, sm1;
+         u32 rx_fib_index0, rx_fib_index1;
+         u32 proto0, proto1;
+         snat_session_t *s0 = 0, *s1 = 0;
+         clib_bihash_kv_8_8_t kv0, kv1, value0, value1;
+         u8 identity_nat0, identity_nat1;
 
          /* Prefetch next iteration. */
          {
-           vlib_buffer_t * p2, * p3;
+           vlib_buffer_t *p2, *p3;
 
            p2 = vlib_get_buffer (vm, from[2]);
            p3 = vlib_get_buffer (vm, from[3]);
@@ -981,7 +762,7 @@ snat_out2in_node_fn (vlib_main_t * vm,
            CLIB_PREFETCH (p3->data, CLIB_CACHE_LINE_BYTES, STORE);
          }
 
-          /* speculatively enqueue b0 and b1 to the current next frame */
+         /* speculatively enqueue b0 and b1 to the current next frame */
          to_next[0] = bi0 = from[0];
          to_next[1] = bi1 = from[1];
          from += 2;
@@ -992,874 +773,367 @@ snat_out2in_node_fn (vlib_main_t * vm,
          b0 = vlib_get_buffer (vm, bi0);
          b1 = vlib_get_buffer (vm, bi1);
 
-          vnet_buffer (b0)->snat.flags = 0;
-          vnet_buffer (b1)->snat.flags = 0;
+         vnet_buffer (b0)->snat.flags = 0;
+         vnet_buffer (b1)->snat.flags = 0;
 
-          ip0 = vlib_buffer_get_current (b0);
-          udp0 = ip4_next_header (ip0);
-          tcp0 = (tcp_header_t *) udp0;
-          icmp0 = (icmp46_header_t *) udp0;
+         ip0 = vlib_buffer_get_current (b0);
+         udp0 = ip4_next_header (ip0);
+         tcp0 = (tcp_header_t *) udp0;
+         icmp0 = (icmp46_header_t *) udp0;
 
-          sw_if_index0 = vnet_buffer(b0)->sw_if_index[VLIB_RX];
+         sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
          rx_fib_index0 = vec_elt (sm->ip4_main->fib_index_by_sw_if_index,
-                                   sw_if_index0);
-
-          if (PREDICT_FALSE(ip0->ttl == 1))
-            {
-              vnet_buffer (b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
-              icmp4_error_set_vnet_buffer (b0, ICMP4_time_exceeded,
-                                           ICMP4_time_exceeded_ttl_exceeded_in_transit,
-                                           0);
-              next0 = SNAT_OUT2IN_NEXT_ICMP_ERROR;
-              goto trace0;
-            }
-
-          proto0 = ip_proto_to_snat_proto (ip0->protocol);
-
-          if (PREDICT_FALSE (proto0 == ~0))
-            {
-              s0 = snat_out2in_unknown_proto(sm, b0, ip0, rx_fib_index0,
-                                             thread_index, now, vm, node);
-              if (!s0)
-                next0 = SNAT_OUT2IN_NEXT_DROP;
-              goto trace0;
-            }
-
-          if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
-            {
-              next0 = icmp_out2in_slow_path
-                (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, node,
-                 next0, now, thread_index, &s0);
-              goto trace0;
-            }
-
-          key0.addr = ip0->dst_address;
-          key0.port = udp0->dst_port;
-          key0.protocol = proto0;
-          key0.fib_index = rx_fib_index0;
-
-          kv0.key = key0.as_u64;
-
-          if (clib_bihash_search_8_8 (&sm->per_thread_data[thread_index].out2in,
-                                      &kv0, &value0))
-            {
-              /* Try to match static mapping by external address and port,
-                 destination address and port in packet */
-              if (snat_static_mapping_match(sm, key0, &sm0, 1, 0))
-                {
-                  b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
-                  /*
-                   * Send DHCP packets to the ipv4 stack, or we won't
-                   * be able to use dhcp client on the outside interface
-                   */
-                  if (proto0 != SNAT_PROTOCOL_UDP
-                      || (udp0->dst_port
-                          != clib_host_to_net_u16(UDP_DST_PORT_dhcp_to_client)))
-                    next0 = SNAT_OUT2IN_NEXT_DROP;
-                  goto trace0;
-                }
-
-              /* Create session initiated by host from external network */
-              s0 = create_session_for_static_mapping(sm, b0, sm0, key0, node,
-                                                     thread_index);
-              if (!s0)
-                {
-                  next0 = SNAT_OUT2IN_NEXT_DROP;
-                  goto trace0;
-                }
-            }
-          else
-            {
-              if (PREDICT_FALSE (value0.value == ~0ULL))
-                {
-                  s0 = snat_out2in_lb(sm, b0, ip0, rx_fib_index0, thread_index,
-                                      now, vm, node);
-                  if (!s0)
-                    next0 = SNAT_OUT2IN_NEXT_DROP;
-                  goto trace0;
-                }
-              else
-                {
-                  s0 = pool_elt_at_index (
-                    sm->per_thread_data[thread_index].sessions,
-                    value0.value);
-                }
-            }
-
-          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 */);
-          ip0->checksum = ip_csum_fold (sum0);
-
-          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 */);
-              tcp0->checksum = ip_csum_fold(sum0);
-            }
-          else
-            {
-              old_port0 = udp0->dst_port;
-              udp0->dst_port = s0->in2out.port;
-              udp0->checksum = 0;
-            }
-
-          /* Accounting */
-          s0->last_heard = now;
-          s0->total_pkts++;
-          s0->total_bytes += vlib_buffer_length_in_chain (vm, b0);
-          /* Per-user LRU list maintenance for dynamic translation */
-          if (!snat_is_session_static (s0))
-            {
-              clib_dlist_remove (sm->per_thread_data[thread_index].list_pool,
-                                 s0->per_user_index);
-              clib_dlist_addtail (sm->per_thread_data[thread_index].list_pool,
-                                  s0->per_user_list_head_index,
-                                  s0->per_user_index);
-            }
-        trace0:
-
-          if (PREDICT_FALSE((node->flags & VLIB_NODE_FLAG_TRACE)
-                            && (b0->flags & VLIB_BUFFER_IS_TRACED)))
-            {
-              snat_out2in_trace_t *t =
-                 vlib_add_trace (vm, node, b0, sizeof (*t));
-              t->sw_if_index = sw_if_index0;
-              t->next_index = next0;
-              t->session_index = ~0;
-              if (s0)
-                t->session_index = s0 - sm->per_thread_data[thread_index].sessions;
-            }
-
-          pkts_processed += next0 != SNAT_OUT2IN_NEXT_DROP;
-
-
-          ip1 = vlib_buffer_get_current (b1);
-          udp1 = ip4_next_header (ip1);
-          tcp1 = (tcp_header_t *) udp1;
-          icmp1 = (icmp46_header_t *) udp1;
-
-          sw_if_index1 = vnet_buffer(b1)->sw_if_index[VLIB_RX];
-         rx_fib_index1 = vec_elt (sm->ip4_main->fib_index_by_sw_if_index,
-                                   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 = SNAT_OUT2IN_NEXT_ICMP_ERROR;
-              goto trace1;
-            }
-
-          proto1 = ip_proto_to_snat_proto (ip1->protocol);
-
-          if (PREDICT_FALSE (proto1 == ~0))
-            {
-              s1 = snat_out2in_unknown_proto(sm, b1, ip1, rx_fib_index1,
-                                             thread_index, now, vm, node);
-              if (!s1)
-                next1 = SNAT_OUT2IN_NEXT_DROP;
-              goto trace1;
-            }
-
-          if (PREDICT_FALSE (proto1 == SNAT_PROTOCOL_ICMP))
-            {
-              next1 = icmp_out2in_slow_path
-                (sm, b1, ip1, icmp1, sw_if_index1, rx_fib_index1, node,
-                 next1, now, thread_index, &s1);
-              goto trace1;
-            }
-
-          key1.addr = ip1->dst_address;
-          key1.port = udp1->dst_port;
-          key1.protocol = proto1;
-          key1.fib_index = rx_fib_index1;
-
-          kv1.key = key1.as_u64;
-
-          if (clib_bihash_search_8_8 (&sm->per_thread_data[thread_index].out2in,
-                                      &kv1, &value1))
-            {
-              /* Try to match static mapping by external address and port,
-                 destination address and port in packet */
-              if (snat_static_mapping_match(sm, key1, &sm1, 1, 0))
-                {
-                  b1->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
-                  /*
-                   * Send DHCP packets to the ipv4 stack, or we won't
-                   * be able to use dhcp client on the outside interface
-                   */
-                  if (proto1 != SNAT_PROTOCOL_UDP
-                      || (udp1->dst_port
-                          != clib_host_to_net_u16(UDP_DST_PORT_dhcp_to_client)))
-                    next1 = SNAT_OUT2IN_NEXT_DROP;
-                  goto trace1;
-                }
-
-              /* Create session initiated by host from external network */
-              s1 = create_session_for_static_mapping(sm, b1, sm1, key1, node,
-                                                     thread_index);
-              if (!s1)
-                {
-                  next1 = SNAT_OUT2IN_NEXT_DROP;
-                  goto trace1;
-                }
-            }
-          else
-            {
-              if (PREDICT_FALSE (value1.value == ~0ULL))
-                {
-                  s1 = snat_out2in_lb(sm, b1, ip1, rx_fib_index1, thread_index,
-                                      now, vm, node);
-                  if (!s1)
-                    next1 = SNAT_OUT2IN_NEXT_DROP;
-                  goto trace1;
-                }
-              else
-                {
-                  s1 = pool_elt_at_index (
-                    sm->per_thread_data[thread_index].sessions,
-                    value1.value);
-                }
-            }
-
-          old_addr1 = ip1->dst_address.as_u32;
-          ip1->dst_address = s1->in2out.addr;
-          new_addr1 = ip1->dst_address.as_u32;
-          vnet_buffer(b1)->sw_if_index[VLIB_TX] = s1->in2out.fib_index;
-
-          sum1 = ip1->checksum;
-          sum1 = ip_csum_update (sum1, old_addr1, new_addr1,
-                                 ip4_header_t,
-                                 dst_address /* changed member */);
-          ip1->checksum = ip_csum_fold (sum1);
-
-          if (PREDICT_TRUE(proto1 == SNAT_PROTOCOL_TCP))
-            {
-              old_port1 = tcp1->dst_port;
-              tcp1->dst_port = s1->in2out.port;
-              new_port1 = tcp1->dst_port;
-
-              sum1 = tcp1->checksum;
-              sum1 = ip_csum_update (sum1, old_addr1, new_addr1,
-                                     ip4_header_t,
-                                     dst_address /* changed member */);
-
-              sum1 = ip_csum_update (sum1, old_port1, new_port1,
-                                     ip4_header_t /* cheat */,
-                                     length /* changed member */);
-              tcp1->checksum = ip_csum_fold(sum1);
-            }
-          else
-            {
-              old_port1 = udp1->dst_port;
-              udp1->dst_port = s1->in2out.port;
-              udp1->checksum = 0;
-            }
-
-          /* Accounting */
-          s1->last_heard = now;
-          s1->total_pkts++;
-          s1->total_bytes += vlib_buffer_length_in_chain (vm, b1);
-          /* Per-user LRU list maintenance for dynamic translation */
-          if (!snat_is_session_static (s1))
-            {
-              clib_dlist_remove (sm->per_thread_data[thread_index].list_pool,
-                                 s1->per_user_index);
-              clib_dlist_addtail (sm->per_thread_data[thread_index].list_pool,
-                                  s1->per_user_list_head_index,
-                                  s1->per_user_index);
-            }
-        trace1:
-
-          if (PREDICT_FALSE((node->flags & VLIB_NODE_FLAG_TRACE)
-                            && (b1->flags & VLIB_BUFFER_IS_TRACED)))
-            {
-              snat_out2in_trace_t *t =
-                 vlib_add_trace (vm, node, b1, sizeof (*t));
-              t->sw_if_index = sw_if_index1;
-              t->next_index = next1;
-              t->session_index = ~0;
-              if (s1)
-                t->session_index = s1 - sm->per_thread_data[thread_index].sessions;
-            }
-
-          pkts_processed += next1 != SNAT_OUT2IN_NEXT_DROP;
-
-          /* 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);
-        }
+                                  sw_if_index0);
 
-      while (n_left_from > 0 && n_left_to_next > 0)
-       {
-          u32 bi0;
-         vlib_buffer_t * b0;
-          u32 next0 = SNAT_OUT2IN_NEXT_LOOKUP;
-          u32 sw_if_index0;
-          ip4_header_t * ip0;
-          ip_csum_t sum0;
-          u32 new_addr0, old_addr0;
-          u16 new_port0, old_port0;
-          udp_header_t * udp0;
-          tcp_header_t * tcp0;
-          icmp46_header_t * icmp0;
-          snat_session_key_t key0, sm0;
-          u32 rx_fib_index0;
-          u32 proto0;
-          snat_session_t * s0 = 0;
-          clib_bihash_kv_8_8_t kv0, value0;
-
-          /* 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;
+         if (PREDICT_FALSE (ip0->ttl == 1))
+           {
+             vnet_buffer (b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
+             icmp4_error_set_vnet_buffer (b0, ICMP4_time_exceeded,
+                                          ICMP4_time_exceeded_ttl_exceeded_in_transit,
+                                          0);
+             next0 = SNAT_OUT2IN_NEXT_ICMP_ERROR;
+             goto trace0;
+           }
 
-         b0 = vlib_get_buffer (vm, bi0);
+         proto0 = ip_proto_to_snat_proto (ip0->protocol);
 
-          vnet_buffer (b0)->snat.flags = 0;
+         if (PREDICT_FALSE (proto0 == ~0))
+           {
+             if (nat_out2in_sm_unknown_proto (sm, b0, ip0, rx_fib_index0))
+               {
+                 if (!sm->forwarding_enabled)
+                   {
+                     b0->error =
+                       node->errors[SNAT_OUT2IN_ERROR_UNSUPPORTED_PROTOCOL];
+                     next0 = SNAT_OUT2IN_NEXT_DROP;
+                   }
+               }
+             other_packets++;
+             goto trace0;
+           }
 
-          ip0 = vlib_buffer_get_current (b0);
-          udp0 = ip4_next_header (ip0);
-          tcp0 = (tcp_header_t *) udp0;
-          icmp0 = (icmp46_header_t *) udp0;
+         if (PREDICT_FALSE (ip4_is_fragment (ip0)))
+           {
+             next0 = SNAT_OUT2IN_NEXT_REASS;
+             fragments++;
+             goto trace0;
+           }
 
-          sw_if_index0 = vnet_buffer(b0)->sw_if_index[VLIB_RX];
-         rx_fib_index0 = vec_elt (sm->ip4_main->fib_index_by_sw_if_index,
-                                   sw_if_index0);
-
-          proto0 = ip_proto_to_snat_proto (ip0->protocol);
-
-          if (PREDICT_FALSE (proto0 == ~0))
-            {
-              s0 = snat_out2in_unknown_proto(sm, b0, ip0, rx_fib_index0,
-                                             thread_index, now, vm, node);
-              if (!s0)
-                next0 = SNAT_OUT2IN_NEXT_DROP;
-              goto trace00;
-            }
-
-          if (PREDICT_FALSE(ip0->ttl == 1))
-            {
-              vnet_buffer (b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
-              icmp4_error_set_vnet_buffer (b0, ICMP4_time_exceeded,
-                                           ICMP4_time_exceeded_ttl_exceeded_in_transit,
-                                           0);
-              next0 = SNAT_OUT2IN_NEXT_ICMP_ERROR;
-              goto trace00;
-            }
-
-          if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
-            {
-              next0 = icmp_out2in_slow_path
-                (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, node,
-                 next0, now, thread_index, &s0);
-              goto trace00;
-            }
-
-          key0.addr = ip0->dst_address;
-          key0.port = udp0->dst_port;
-          key0.protocol = proto0;
-          key0.fib_index = rx_fib_index0;
-
-          kv0.key = key0.as_u64;
-
-          if (clib_bihash_search_8_8 (&sm->per_thread_data[thread_index].out2in,
-                                      &kv0, &value0))
-            {
-              /* Try to match static mapping by external address and port,
-                 destination address and port in packet */
-              if (snat_static_mapping_match(sm, key0, &sm0, 1, 0))
-                {
-                  b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
-                  /*
-                   * Send DHCP packets to the ipv4 stack, or we won't
-                   * be able to use dhcp client on the outside interface
-                   */
-                  if (proto0 != SNAT_PROTOCOL_UDP
-                      || (udp0->dst_port
-                          != clib_host_to_net_u16(UDP_DST_PORT_dhcp_to_client)))
-
-                    next0 = SNAT_OUT2IN_NEXT_DROP;
-                  goto trace00;
-                }
-
-              /* Create session initiated by host from external network */
-              s0 = create_session_for_static_mapping(sm, b0, sm0, key0, node,
-                                                     thread_index);
-              if (!s0)
-                {
-                  next0 = SNAT_OUT2IN_NEXT_DROP;
-                  goto trace00;
-                }
-            }
-          else
-            {
-              if (PREDICT_FALSE (value0.value == ~0ULL))
-                {
-                  s0 = snat_out2in_lb(sm, b0, ip0, rx_fib_index0, thread_index,
-                                      now, vm, node);
-                  if (!s0)
-                    next0 = SNAT_OUT2IN_NEXT_DROP;
-                  goto trace00;
-                }
-              else
-                {
-                  s0 = pool_elt_at_index (
-                    sm->per_thread_data[thread_index].sessions,
-                    value0.value);
-                }
-            }
-
-          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 */);
-          ip0->checksum = ip_csum_fold (sum0);
-
-          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 */);
-              tcp0->checksum = ip_csum_fold(sum0);
-            }
-          else
-            {
-              old_port0 = udp0->dst_port;
-              udp0->dst_port = s0->in2out.port;
-              udp0->checksum = 0;
-            }
-
-          /* Accounting */
-          s0->last_heard = now;
-          s0->total_pkts++;
-          s0->total_bytes += vlib_buffer_length_in_chain (vm, b0);
-          /* Per-user LRU list maintenance for dynamic translation */
-          if (!snat_is_session_static (s0))
-            {
-              clib_dlist_remove (sm->per_thread_data[thread_index].list_pool,
-                                 s0->per_user_index);
-              clib_dlist_addtail (sm->per_thread_data[thread_index].list_pool,
-                                  s0->per_user_list_head_index,
-                                  s0->per_user_index);
-            }
-        trace00:
-
-          if (PREDICT_FALSE((node->flags & VLIB_NODE_FLAG_TRACE)
-                            && (b0->flags & VLIB_BUFFER_IS_TRACED)))
-            {
-              snat_out2in_trace_t *t =
-                 vlib_add_trace (vm, node, b0, sizeof (*t));
-              t->sw_if_index = sw_if_index0;
-              t->next_index = next0;
-              t->session_index = ~0;
-              if (s0)
-                t->session_index = s0 - sm->per_thread_data[thread_index].sessions;
-            }
-
-          pkts_processed += next0 != SNAT_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 (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
+           {
+             next0 = icmp_out2in_slow_path
+               (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, node,
+                next0, now, thread_index, &s0);
+             icmp_packets++;
+             goto trace0;
+           }
 
-      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
-    }
+         key0.addr = ip0->dst_address;
+         key0.port = udp0->dst_port;
+         key0.protocol = proto0;
+         key0.fib_index = rx_fib_index0;
 
-  vlib_node_increment_counter (vm, snat_out2in_node.index,
-                               SNAT_OUT2IN_ERROR_OUT2IN_PACKETS,
-                               pkts_processed);
-  return frame->n_vectors;
-}
+         kv0.key = key0.as_u64;
 
-VLIB_REGISTER_NODE (snat_out2in_node) = {
-  .function = snat_out2in_node_fn,
-  .name = "nat44-out2in",
-  .vector_size = sizeof (u32),
-  .format_trace = format_snat_out2in_trace,
-  .type = VLIB_NODE_TYPE_INTERNAL,
+         if (clib_bihash_search_8_8
+             (&sm->per_thread_data[thread_index].out2in, &kv0, &value0))
+           {
+             /* Try to match static mapping by external address and port,
+                destination address and port in packet */
+             if (snat_static_mapping_match
+                 (sm, key0, &sm0, 1, 0, 0, 0, 0, &identity_nat0))
+               {
+                 /*
+                  * 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[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+                     next0 = SNAT_OUT2IN_NEXT_DROP;
+                   }
+                 goto trace0;
+               }
+
+             if (PREDICT_FALSE (identity_nat0))
+               goto trace0;
+
+             /* Create session initiated by host from external network */
+             s0 = create_session_for_static_mapping (sm, b0, sm0, key0, node,
+                                                     thread_index, now);
+             if (!s0)
+               {
+                 next0 = SNAT_OUT2IN_NEXT_DROP;
+                 goto trace0;
+               }
+           }
+         else
+           s0 =
+             pool_elt_at_index (sm->per_thread_data[thread_index].sessions,
+                                value0.value);
+
+         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 */ );
+         ip0->checksum = ip_csum_fold (sum0);
+
+         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 */ );
+             tcp0->checksum = ip_csum_fold (sum0);
+             tcp_packets++;
+           }
+         else
+           {
+             old_port0 = udp0->dst_port;
+             udp0->dst_port = s0->in2out.port;
+             udp0->checksum = 0;
+             udp_packets++;
+           }
 
-  .n_errors = ARRAY_LEN(snat_out2in_error_strings),
-  .error_strings = snat_out2in_error_strings,
+         /* Accounting */
+         nat44_session_update_counters (s0, now,
+                                        vlib_buffer_length_in_chain (vm, b0),
+                                        thread_index);
+         /* Per-user LRU list maintenance */
+         nat44_session_update_lru (sm, s0, thread_index);
+       trace0:
 
-  .runtime_data_bytes = sizeof (snat_runtime_t),
+         if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
+                            && (b0->flags & VLIB_BUFFER_IS_TRACED)))
+           {
+             snat_out2in_trace_t *t =
+               vlib_add_trace (vm, node, b0, sizeof (*t));
+             t->sw_if_index = sw_if_index0;
+             t->next_index = next0;
+             t->session_index = ~0;
+             if (s0)
+               t->session_index =
+                 s0 - sm->per_thread_data[thread_index].sessions;
+           }
 
-  .n_next_nodes = SNAT_OUT2IN_N_NEXT,
+         pkts_processed += next0 == SNAT_OUT2IN_NEXT_LOOKUP;
 
-  /* edit / add dispositions here */
-  .next_nodes = {
-    [SNAT_OUT2IN_NEXT_DROP] = "error-drop",
-    [SNAT_OUT2IN_NEXT_LOOKUP] = "ip4-lookup",
-    [SNAT_OUT2IN_NEXT_ICMP_ERROR] = "ip4-icmp-error",
-  },
-};
-VLIB_NODE_FUNCTION_MULTIARCH (snat_out2in_node, snat_out2in_node_fn);
-
-/**************************/
-/*** deterministic mode ***/
-/**************************/
-static uword
-snat_det_out2in_node_fn (vlib_main_t * vm,
-                         vlib_node_runtime_t * node,
-                         vlib_frame_t * frame)
-{
-  u32 n_left_from, * from, * to_next;
-  snat_out2in_next_t next_index;
-  u32 pkts_processed = 0;
-  snat_main_t * sm = &snat_main;
-  u32 thread_index = vlib_get_thread_index ();
 
-  from = vlib_frame_vector_args (frame);
-  n_left_from = frame->n_vectors;
-  next_index = node->cached_next_index;
+         ip1 = vlib_buffer_get_current (b1);
+         udp1 = ip4_next_header (ip1);
+         tcp1 = (tcp_header_t *) udp1;
+         icmp1 = (icmp46_header_t *) udp1;
 
-  while (n_left_from > 0)
-    {
-      u32 n_left_to_next;
+         sw_if_index1 = vnet_buffer (b1)->sw_if_index[VLIB_RX];
+         rx_fib_index1 = vec_elt (sm->ip4_main->fib_index_by_sw_if_index,
+                                  sw_if_index1);
 
-      vlib_get_next_frame (vm, node, next_index,
-                          to_next, n_left_to_next);
+         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 = SNAT_OUT2IN_NEXT_ICMP_ERROR;
+             goto trace1;
+           }
 
-      while (n_left_from >= 4 && n_left_to_next >= 2)
-        {
-          u32 bi0, bi1;
-         vlib_buffer_t * b0, * b1;
-          u32 next0 = SNAT_OUT2IN_NEXT_LOOKUP;
-          u32 next1 = SNAT_OUT2IN_NEXT_LOOKUP;
-          u32 sw_if_index0, sw_if_index1;
-          ip4_header_t * ip0, * ip1;
-          ip_csum_t sum0, sum1;
-          ip4_address_t new_addr0, old_addr0, new_addr1, old_addr1;
-          u16 new_port0, old_port0, old_port1, new_port1;
-          udp_header_t * udp0, * udp1;
-          tcp_header_t * tcp0, * tcp1;
-          u32 proto0, proto1;
-          snat_det_out_key_t key0, key1;
-          snat_det_map_t * dm0, * dm1;
-          snat_det_session_t * ses0 = 0, * ses1 = 0;
-          u32 rx_fib_index0, rx_fib_index1;
-          icmp46_header_t * icmp0, * icmp1;
+         proto1 = ip_proto_to_snat_proto (ip1->protocol);
 
-         /* Prefetch next iteration. */
-         {
-           vlib_buffer_t * p2, * p3;
+         if (PREDICT_FALSE (proto1 == ~0))
+           {
+             if (nat_out2in_sm_unknown_proto (sm, b1, ip1, rx_fib_index1))
+               {
+                 if (!sm->forwarding_enabled)
+                   {
+                     b1->error =
+                       node->errors[SNAT_OUT2IN_ERROR_UNSUPPORTED_PROTOCOL];
+                     next1 = SNAT_OUT2IN_NEXT_DROP;
+                   }
+               }
+             other_packets++;
+             goto trace1;
+           }
 
-           p2 = vlib_get_buffer (vm, from[2]);
-           p3 = vlib_get_buffer (vm, from[3]);
+         if (PREDICT_FALSE (ip4_is_fragment (ip1)))
+           {
+             next1 = SNAT_OUT2IN_NEXT_REASS;
+             fragments++;
+             goto trace1;
+           }
 
-           vlib_prefetch_buffer_header (p2, LOAD);
-           vlib_prefetch_buffer_header (p3, LOAD);
+         if (PREDICT_FALSE (proto1 == SNAT_PROTOCOL_ICMP))
+           {
+             next1 = icmp_out2in_slow_path
+               (sm, b1, ip1, icmp1, sw_if_index1, rx_fib_index1, node,
+                next1, now, thread_index, &s1);
+             icmp_packets++;
+             goto trace1;
+           }
 
-           CLIB_PREFETCH (p2->data, CLIB_CACHE_LINE_BYTES, STORE);
-           CLIB_PREFETCH (p3->data, CLIB_CACHE_LINE_BYTES, STORE);
-         }
+         key1.addr = ip1->dst_address;
+         key1.port = udp1->dst_port;
+         key1.protocol = proto1;
+         key1.fib_index = rx_fib_index1;
 
-          /* 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;
+         kv1.key = key1.as_u64;
 
-         b0 = vlib_get_buffer (vm, bi0);
-         b1 = vlib_get_buffer (vm, bi1);
+         if (clib_bihash_search_8_8
+             (&sm->per_thread_data[thread_index].out2in, &kv1, &value1))
+           {
+             /* Try to match static mapping by external address and port,
+                destination address and port in packet */
+             if (snat_static_mapping_match
+                 (sm, key1, &sm1, 1, 0, 0, 0, 0, &identity_nat1))
+               {
+                 /*
+                  * 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 trace1;
+                   }
+
+                 if (!sm->forwarding_enabled)
+                   {
+                     b1->error =
+                       node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+                     next1 = SNAT_OUT2IN_NEXT_DROP;
+                   }
+                 goto trace1;
+               }
+
+             if (PREDICT_FALSE (identity_nat1))
+               goto trace1;
+
+             /* Create session initiated by host from external network */
+             s1 = create_session_for_static_mapping (sm, b1, sm1, key1, node,
+                                                     thread_index, now);
+             if (!s1)
+               {
+                 next1 = SNAT_OUT2IN_NEXT_DROP;
+                 goto trace1;
+               }
+           }
+         else
+           s1 =
+             pool_elt_at_index (sm->per_thread_data[thread_index].sessions,
+                                value1.value);
+
+         old_addr1 = ip1->dst_address.as_u32;
+         ip1->dst_address = s1->in2out.addr;
+         new_addr1 = ip1->dst_address.as_u32;
+         vnet_buffer (b1)->sw_if_index[VLIB_TX] = s1->in2out.fib_index;
+
+         sum1 = ip1->checksum;
+         sum1 = ip_csum_update (sum1, old_addr1, new_addr1,
+                                ip4_header_t,
+                                dst_address /* changed member */ );
+         ip1->checksum = ip_csum_fold (sum1);
+
+         if (PREDICT_TRUE (proto1 == SNAT_PROTOCOL_TCP))
+           {
+             old_port1 = tcp1->dst_port;
+             tcp1->dst_port = s1->in2out.port;
+             new_port1 = tcp1->dst_port;
+
+             sum1 = tcp1->checksum;
+             sum1 = ip_csum_update (sum1, old_addr1, new_addr1,
+                                    ip4_header_t,
+                                    dst_address /* changed member */ );
+
+             sum1 = ip_csum_update (sum1, old_port1, new_port1,
+                                    ip4_header_t /* cheat */ ,
+                                    length /* changed member */ );
+             tcp1->checksum = ip_csum_fold (sum1);
+             tcp_packets++;
+           }
+         else
+           {
+             old_port1 = udp1->dst_port;
+             udp1->dst_port = s1->in2out.port;
+             udp1->checksum = 0;
+             udp_packets++;
+           }
 
-          ip0 = vlib_buffer_get_current (b0);
-          udp0 = ip4_next_header (ip0);
-          tcp0 = (tcp_header_t *) udp0;
-
-          sw_if_index0 = vnet_buffer(b0)->sw_if_index[VLIB_RX];
-
-          if (PREDICT_FALSE(ip0->ttl == 1))
-            {
-              vnet_buffer (b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
-              icmp4_error_set_vnet_buffer (b0, ICMP4_time_exceeded,
-                                           ICMP4_time_exceeded_ttl_exceeded_in_transit,
-                                           0);
-              next0 = SNAT_OUT2IN_NEXT_ICMP_ERROR;
-              goto trace0;
-            }
-
-          proto0 = ip_proto_to_snat_proto (ip0->protocol);
-
-          if (PREDICT_FALSE(proto0 == SNAT_PROTOCOL_ICMP))
-            {
-              rx_fib_index0 = ip4_fib_table_get_index_for_sw_if_index(sw_if_index0);
-              icmp0 = (icmp46_header_t *) udp0;
-
-              next0 = icmp_out2in(sm, b0, ip0, icmp0, sw_if_index0,
-                                  rx_fib_index0, node, next0, thread_index,
-                                  &ses0, &dm0);
-              goto trace0;
-            }
-
-          key0.ext_host_addr = ip0->src_address;
-          key0.ext_host_port = tcp0->src;
-          key0.out_port = tcp0->dst;
-
-          dm0 = snat_det_map_by_out(sm, &ip0->dst_address);
-          if (PREDICT_FALSE(!dm0))
-            {
-              clib_warning("unknown dst address:  %U",
-                           format_ip4_address, &ip0->dst_address);
-              next0 = SNAT_OUT2IN_NEXT_DROP;
-              b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
-              goto trace0;
-            }
-
-          snat_det_reverse(dm0, &ip0->dst_address,
-                           clib_net_to_host_u16(tcp0->dst), &new_addr0);
-
-          ses0 = snat_det_get_ses_by_out (dm0, &new_addr0, key0.as_u64);
-          if (PREDICT_FALSE(!ses0))
-            {
-              clib_warning("no match src %U:%d dst %U:%d for user %U",
-                           format_ip4_address, &ip0->src_address,
-                           clib_net_to_host_u16 (tcp0->src),
-                           format_ip4_address, &ip0->dst_address,
-                           clib_net_to_host_u16 (tcp0->dst),
-                           format_ip4_address, &new_addr0);
-              next0 = SNAT_OUT2IN_NEXT_DROP;
-              b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
-              goto trace0;
-            }
-          new_port0 = ses0->in_port;
-
-          old_addr0 = ip0->dst_address;
-          ip0->dst_address = new_addr0;
-          vnet_buffer(b0)->sw_if_index[VLIB_TX] = sm->inside_fib_index;
-
-          sum0 = ip0->checksum;
-          sum0 = ip_csum_update (sum0, old_addr0.as_u32, new_addr0.as_u32,
-                                 ip4_header_t,
-                                 dst_address /* changed member */);
-          ip0->checksum = ip_csum_fold (sum0);
-
-          if (PREDICT_TRUE(proto0 == SNAT_PROTOCOL_TCP))
-            {
-              if (tcp0->flags & TCP_FLAG_FIN && ses0->state == SNAT_SESSION_TCP_ESTABLISHED)
-                ses0->state = SNAT_SESSION_TCP_CLOSE_WAIT;
-              else if (tcp0->flags & TCP_FLAG_ACK && ses0->state == SNAT_SESSION_TCP_LAST_ACK)
-                snat_det_ses_close(dm0, ses0);
-
-              old_port0 = tcp0->dst;
-              tcp0->dst = new_port0;
-
-              sum0 = tcp0->checksum;
-              sum0 = ip_csum_update (sum0, old_addr0.as_u32, new_addr0.as_u32,
-                                     ip4_header_t,
-                                     dst_address /* changed member */);
-
-              sum0 = ip_csum_update (sum0, old_port0, new_port0,
-                                     ip4_header_t /* cheat */,
-                                     length /* changed member */);
-              tcp0->checksum = ip_csum_fold(sum0);
-            }
-          else
-            {
-              old_port0 = udp0->dst_port;
-              udp0->dst_port = new_port0;
-              udp0->checksum = 0;
-            }
-
-        trace0:
-
-          if (PREDICT_FALSE((node->flags & VLIB_NODE_FLAG_TRACE)
-                            && (b0->flags & VLIB_BUFFER_IS_TRACED)))
-            {
-              snat_out2in_trace_t *t =
-                 vlib_add_trace (vm, node, b0, sizeof (*t));
-              t->sw_if_index = sw_if_index0;
-              t->next_index = next0;
-              t->session_index = ~0;
-              if (ses0)
-                t->session_index = ses0 - dm0->sessions;
-            }
-
-          pkts_processed += next0 != SNAT_OUT2IN_NEXT_DROP;
+         /* Accounting */
+         nat44_session_update_counters (s1, now,
+                                        vlib_buffer_length_in_chain (vm, b1),
+                                        thread_index);
+         /* Per-user LRU list maintenance */
+         nat44_session_update_lru (sm, s1, thread_index);
+       trace1:
 
-         b1 = vlib_get_buffer (vm, bi1);
+         if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
+                            && (b1->flags & VLIB_BUFFER_IS_TRACED)))
+           {
+             snat_out2in_trace_t *t =
+               vlib_add_trace (vm, node, b1, sizeof (*t));
+             t->sw_if_index = sw_if_index1;
+             t->next_index = next1;
+             t->session_index = ~0;
+             if (s1)
+               t->session_index =
+                 s1 - sm->per_thread_data[thread_index].sessions;
+           }
+
+         pkts_processed += next1 == SNAT_OUT2IN_NEXT_LOOKUP;
 
-          ip1 = vlib_buffer_get_current (b1);
-          udp1 = ip4_next_header (ip1);
-          tcp1 = (tcp_header_t *) udp1;
-
-          sw_if_index1 = vnet_buffer(b1)->sw_if_index[VLIB_RX];
-
-          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 = SNAT_OUT2IN_NEXT_ICMP_ERROR;
-              goto trace1;
-            }
-
-          proto1 = ip_proto_to_snat_proto (ip1->protocol);
-
-          if (PREDICT_FALSE(proto1 == SNAT_PROTOCOL_ICMP))
-            {
-              rx_fib_index1 = ip4_fib_table_get_index_for_sw_if_index(sw_if_index1);
-              icmp1 = (icmp46_header_t *) udp1;
-
-              next1 = icmp_out2in(sm, b1, ip1, icmp1, sw_if_index1,
-                                  rx_fib_index1, node, next1, thread_index,
-                                  &ses1, &dm1);
-              goto trace1;
-            }
-
-          key1.ext_host_addr = ip1->src_address;
-          key1.ext_host_port = tcp1->src;
-          key1.out_port = tcp1->dst;
-
-          dm1 = snat_det_map_by_out(sm, &ip1->dst_address);
-          if (PREDICT_FALSE(!dm1))
-            {
-              clib_warning("unknown dst address:  %U",
-                           format_ip4_address, &ip1->dst_address);
-              next1 = SNAT_OUT2IN_NEXT_DROP;
-              b1->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
-              goto trace1;
-            }
-
-          snat_det_reverse(dm1, &ip1->dst_address,
-                           clib_net_to_host_u16(tcp1->dst), &new_addr1);
-
-          ses1 = snat_det_get_ses_by_out (dm1, &new_addr1, key1.as_u64);
-          if (PREDICT_FALSE(!ses1))
-            {
-              clib_warning("no match src %U:%d dst %U:%d for user %U",
-                           format_ip4_address, &ip1->src_address,
-                           clib_net_to_host_u16 (tcp1->src),
-                           format_ip4_address, &ip1->dst_address,
-                           clib_net_to_host_u16 (tcp1->dst),
-                           format_ip4_address, &new_addr1);
-              next1 = SNAT_OUT2IN_NEXT_DROP;
-              b1->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
-              goto trace1;
-            }
-          new_port1 = ses1->in_port;
-
-          old_addr1 = ip1->dst_address;
-          ip1->dst_address = new_addr1;
-          vnet_buffer(b1)->sw_if_index[VLIB_TX] = sm->inside_fib_index;
-
-          sum1 = ip1->checksum;
-          sum1 = ip_csum_update (sum1, old_addr1.as_u32, new_addr1.as_u32,
-                                 ip4_header_t,
-                                 dst_address /* changed member */);
-          ip1->checksum = ip_csum_fold (sum1);
-
-          if (PREDICT_TRUE(proto1 == SNAT_PROTOCOL_TCP))
-            {
-              if (tcp1->flags & TCP_FLAG_FIN && ses1->state == SNAT_SESSION_TCP_ESTABLISHED)
-                ses1->state = SNAT_SESSION_TCP_CLOSE_WAIT;
-              else if (tcp1->flags & TCP_FLAG_ACK && ses1->state == SNAT_SESSION_TCP_LAST_ACK)
-                snat_det_ses_close(dm1, ses1);
-
-              old_port1 = tcp1->dst;
-              tcp1->dst = new_port1;
-
-              sum1 = tcp1->checksum;
-              sum1 = ip_csum_update (sum1, old_addr1.as_u32, new_addr1.as_u32,
-                                     ip4_header_t,
-                                     dst_address /* changed member */);
-
-              sum1 = ip_csum_update (sum1, old_port1, new_port1,
-                                     ip4_header_t /* cheat */,
-                                     length /* changed member */);
-              tcp1->checksum = ip_csum_fold(sum1);
-            }
-          else
-            {
-              old_port1 = udp1->dst_port;
-              udp1->dst_port = new_port1;
-              udp1->checksum = 0;
-            }
-
-        trace1:
-
-          if (PREDICT_FALSE((node->flags & VLIB_NODE_FLAG_TRACE)
-                            && (b1->flags & VLIB_BUFFER_IS_TRACED)))
-            {
-              snat_out2in_trace_t *t =
-                 vlib_add_trace (vm, node, b1, sizeof (*t));
-              t->sw_if_index = sw_if_index1;
-              t->next_index = next1;
-              t->session_index = ~0;
-              if (ses1)
-                t->session_index = ses1 - dm1->sessions;
-            }
-
-          pkts_processed += next1 != SNAT_OUT2IN_NEXT_DROP;
-
-          /* 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);
-         }
+         /* 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);
+       }
 
       while (n_left_from > 0 && n_left_to_next > 0)
        {
-          u32 bi0;
-         vlib_buffer_t * b0;
-          u32 next0 = SNAT_OUT2IN_NEXT_LOOKUP;
-          u32 sw_if_index0;
-          ip4_header_t * ip0;
-          ip_csum_t sum0;
-          ip4_address_t new_addr0, old_addr0;
-          u16 new_port0, old_port0;
-          udp_header_t * udp0;
-          tcp_header_t * tcp0;
-          u32 proto0;
-          snat_det_out_key_t key0;
-          snat_det_map_t * dm0;
-          snat_det_session_t * ses0 = 0;
-          u32 rx_fib_index0;
-          icmp46_header_t * icmp0;
-
-          /* speculatively enqueue b0 to the current next frame */
+         u32 bi0;
+         vlib_buffer_t *b0;
+         u32 next0 = SNAT_OUT2IN_NEXT_LOOKUP;
+         u32 sw_if_index0;
+         ip4_header_t *ip0;
+         ip_csum_t sum0;
+         u32 new_addr0, old_addr0;
+         u16 new_port0, old_port0;
+         udp_header_t *udp0;
+         tcp_header_t *tcp0;
+         icmp46_header_t *icmp0;
+         snat_session_key_t key0, sm0;
+         u32 rx_fib_index0;
+         u32 proto0;
+         snat_session_t *s0 = 0;
+         clib_bihash_kv_8_8_t kv0, value0;
+         u8 identity_nat0;
+
+         /* speculatively enqueue b0 to the current next frame */
          bi0 = from[0];
          to_next[0] = bi0;
          from += 1;
@@ -1869,121 +1143,174 @@ snat_det_out2in_node_fn (vlib_main_t * vm,
 
          b0 = vlib_get_buffer (vm, bi0);
 
-          ip0 = vlib_buffer_get_current (b0);
-          udp0 = ip4_next_header (ip0);
-          tcp0 = (tcp_header_t *) udp0;
-
-          sw_if_index0 = vnet_buffer(b0)->sw_if_index[VLIB_RX];
-
-          if (PREDICT_FALSE(ip0->ttl == 1))
-            {
-              vnet_buffer (b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
-              icmp4_error_set_vnet_buffer (b0, ICMP4_time_exceeded,
-                                           ICMP4_time_exceeded_ttl_exceeded_in_transit,
-                                           0);
-              next0 = SNAT_OUT2IN_NEXT_ICMP_ERROR;
-              goto trace00;
-            }
-
-          proto0 = ip_proto_to_snat_proto (ip0->protocol);
-
-          if (PREDICT_FALSE(proto0 == SNAT_PROTOCOL_ICMP))
-            {
-              rx_fib_index0 = ip4_fib_table_get_index_for_sw_if_index(sw_if_index0);
-              icmp0 = (icmp46_header_t *) udp0;
-
-              next0 = icmp_out2in(sm, b0, ip0, icmp0, sw_if_index0,
-                                  rx_fib_index0, node, next0, thread_index,
-                                  &ses0, &dm0);
-              goto trace00;
-            }
-
-          key0.ext_host_addr = ip0->src_address;
-          key0.ext_host_port = tcp0->src;
-          key0.out_port = tcp0->dst;
-
-          dm0 = snat_det_map_by_out(sm, &ip0->dst_address);
-          if (PREDICT_FALSE(!dm0))
-            {
-              clib_warning("unknown dst address:  %U",
-                           format_ip4_address, &ip0->dst_address);
-              next0 = SNAT_OUT2IN_NEXT_DROP;
-              b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
-              goto trace00;
-            }
-
-          snat_det_reverse(dm0, &ip0->dst_address,
-                           clib_net_to_host_u16(tcp0->dst), &new_addr0);
-
-          ses0 = snat_det_get_ses_by_out (dm0, &new_addr0, key0.as_u64);
-          if (PREDICT_FALSE(!ses0))
-            {
-              clib_warning("no match src %U:%d dst %U:%d for user %U",
-                           format_ip4_address, &ip0->src_address,
-                           clib_net_to_host_u16 (tcp0->src),
-                           format_ip4_address, &ip0->dst_address,
-                           clib_net_to_host_u16 (tcp0->dst),
-                           format_ip4_address, &new_addr0);
-              next0 = SNAT_OUT2IN_NEXT_DROP;
-              b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
-              goto trace00;
-            }
-          new_port0 = ses0->in_port;
-
-          old_addr0 = ip0->dst_address;
-          ip0->dst_address = new_addr0;
-          vnet_buffer(b0)->sw_if_index[VLIB_TX] = sm->inside_fib_index;
-
-          sum0 = ip0->checksum;
-          sum0 = ip_csum_update (sum0, old_addr0.as_u32, new_addr0.as_u32,
-                                 ip4_header_t,
-                                 dst_address /* changed member */);
-          ip0->checksum = ip_csum_fold (sum0);
-
-          if (PREDICT_TRUE(proto0 == SNAT_PROTOCOL_TCP))
-            {
-              if (tcp0->flags & TCP_FLAG_FIN && ses0->state == SNAT_SESSION_TCP_ESTABLISHED)
-                ses0->state = SNAT_SESSION_TCP_CLOSE_WAIT;
-              else if (tcp0->flags & TCP_FLAG_ACK && ses0->state == SNAT_SESSION_TCP_LAST_ACK)
-                snat_det_ses_close(dm0, ses0);
-
-              old_port0 = tcp0->dst;
-              tcp0->dst = new_port0;
-
-              sum0 = tcp0->checksum;
-              sum0 = ip_csum_update (sum0, old_addr0.as_u32, new_addr0.as_u32,
-                                     ip4_header_t,
-                                     dst_address /* changed member */);
-
-              sum0 = ip_csum_update (sum0, old_port0, new_port0,
-                                     ip4_header_t /* cheat */,
-                                     length /* changed member */);
-              tcp0->checksum = ip_csum_fold(sum0);
-            }
-          else
-            {
-              old_port0 = udp0->dst_port;
-              udp0->dst_port = new_port0;
-              udp0->checksum = 0;
-            }
-
-        trace00:
-
-          if (PREDICT_FALSE((node->flags & VLIB_NODE_FLAG_TRACE)
-                            && (b0->flags & VLIB_BUFFER_IS_TRACED)))
-            {
-              snat_out2in_trace_t *t =
-                 vlib_add_trace (vm, node, b0, sizeof (*t));
-              t->sw_if_index = sw_if_index0;
-              t->next_index = next0;
-              t->session_index = ~0;
-              if (ses0)
-                t->session_index = ses0 - dm0->sessions;
-            }
-
-          pkts_processed += next0 != SNAT_OUT2IN_NEXT_DROP;
-
-          /* verify speculative enqueue, maybe switch current next frame */
+         vnet_buffer (b0)->snat.flags = 0;
+
+         ip0 = vlib_buffer_get_current (b0);
+         udp0 = ip4_next_header (ip0);
+         tcp0 = (tcp_header_t *) udp0;
+         icmp0 = (icmp46_header_t *) udp0;
+
+         sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
+         rx_fib_index0 = vec_elt (sm->ip4_main->fib_index_by_sw_if_index,
+                                  sw_if_index0);
+
+         proto0 = ip_proto_to_snat_proto (ip0->protocol);
+
+         if (PREDICT_FALSE (proto0 == ~0))
+           {
+             if (nat_out2in_sm_unknown_proto (sm, b0, ip0, rx_fib_index0))
+               {
+                 if (!sm->forwarding_enabled)
+                   {
+                     b0->error =
+                       node->errors[SNAT_OUT2IN_ERROR_UNSUPPORTED_PROTOCOL];
+                     next0 = SNAT_OUT2IN_NEXT_DROP;
+                   }
+               }
+             other_packets++;
+             goto trace00;
+           }
+
+         if (PREDICT_FALSE (ip0->ttl == 1))
+           {
+             vnet_buffer (b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
+             icmp4_error_set_vnet_buffer (b0, ICMP4_time_exceeded,
+                                          ICMP4_time_exceeded_ttl_exceeded_in_transit,
+                                          0);
+             next0 = SNAT_OUT2IN_NEXT_ICMP_ERROR;
+             goto trace00;
+           }
+
+         if (PREDICT_FALSE (ip4_is_fragment (ip0)))
+           {
+             next0 = SNAT_OUT2IN_NEXT_REASS;
+             fragments++;
+             goto trace00;
+           }
+
+         if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
+           {
+             next0 = icmp_out2in_slow_path
+               (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, node,
+                next0, now, thread_index, &s0);
+             icmp_packets++;
+             goto trace00;
+           }
+
+         key0.addr = ip0->dst_address;
+         key0.port = udp0->dst_port;
+         key0.protocol = proto0;
+         key0.fib_index = rx_fib_index0;
+
+         kv0.key = key0.as_u64;
+
+         if (clib_bihash_search_8_8
+             (&sm->per_thread_data[thread_index].out2in, &kv0, &value0))
+           {
+             /* Try to match static mapping by external address and port,
+                destination address and port in packet */
+             if (snat_static_mapping_match
+                 (sm, key0, &sm0, 1, 0, 0, 0, 0, &identity_nat0))
+               {
+                 /*
+                  * 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[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+                     next0 = SNAT_OUT2IN_NEXT_DROP;
+                   }
+                 goto trace00;
+               }
+
+             if (PREDICT_FALSE (identity_nat0))
+               goto trace00;
+
+             /* Create session initiated by host from external network */
+             s0 = create_session_for_static_mapping (sm, b0, sm0, key0, node,
+                                                     thread_index, now);
+             if (!s0)
+               {
+                 next0 = SNAT_OUT2IN_NEXT_DROP;
+                 goto trace00;
+               }
+           }
+         else
+           s0 =
+             pool_elt_at_index (sm->per_thread_data[thread_index].sessions,
+                                value0.value);
+
+         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 */ );
+         ip0->checksum = ip_csum_fold (sum0);
+
+         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 */ );
+             tcp0->checksum = ip_csum_fold (sum0);
+             tcp_packets++;
+           }
+         else
+           {
+             old_port0 = udp0->dst_port;
+             udp0->dst_port = s0->in2out.port;
+             udp0->checksum = 0;
+             udp_packets++;
+           }
+
+         /* Accounting */
+         nat44_session_update_counters (s0, now,
+                                        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)
+                            && (b0->flags & VLIB_BUFFER_IS_TRACED)))
+           {
+             snat_out2in_trace_t *t =
+               vlib_add_trace (vm, node, b0, sizeof (*t));
+             t->sw_if_index = sw_if_index0;
+             t->next_index = next0;
+             t->session_index = ~0;
+             if (s0)
+               t->session_index =
+                 s0 - sm->per_thread_data[thread_index].sessions;
+           }
+
+         pkts_processed += next0 == SNAT_OUT2IN_NEXT_LOOKUP;
+
+         /* 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);
@@ -1992,15 +1319,27 @@ snat_det_out2in_node_fn (vlib_main_t * vm,
       vlib_put_next_frame (vm, node, next_index, n_left_to_next);
     }
 
-  vlib_node_increment_counter (vm, snat_det_out2in_node.index,
-                               SNAT_OUT2IN_ERROR_OUT2IN_PACKETS,
-                               pkts_processed);
+  vlib_node_increment_counter (vm, sm->out2in_node_index,
+                              SNAT_OUT2IN_ERROR_OUT2IN_PACKETS,
+                              pkts_processed);
+  vlib_node_increment_counter (vm, sm->out2in_node_index,
+                              SNAT_OUT2IN_ERROR_TCP_PACKETS, tcp_packets);
+  vlib_node_increment_counter (vm, sm->out2in_node_index,
+                              SNAT_OUT2IN_ERROR_UDP_PACKETS, udp_packets);
+  vlib_node_increment_counter (vm, sm->out2in_node_index,
+                              SNAT_OUT2IN_ERROR_ICMP_PACKETS, icmp_packets);
+  vlib_node_increment_counter (vm, sm->out2in_node_index,
+                              SNAT_OUT2IN_ERROR_OTHER_PACKETS,
+                              other_packets);
+  vlib_node_increment_counter (vm, sm->out2in_node_index,
+                              SNAT_OUT2IN_ERROR_FRAGMENTS, fragments);
+
   return frame->n_vectors;
 }
 
-VLIB_REGISTER_NODE (snat_det_out2in_node) = {
-  .function = snat_det_out2in_node_fn,
-  .name = "nat44-det-out2in",
+/* *INDENT-OFF* */
+VLIB_REGISTER_NODE (snat_out2in_node) = {
+  .name = "nat44-out2in",
   .vector_size = sizeof (u32),
   .format_trace = format_snat_out2in_trace,
   .type = VLIB_NODE_TYPE_INTERNAL,
@@ -2017,321 +1356,352 @@ VLIB_REGISTER_NODE (snat_det_out2in_node) = {
     [SNAT_OUT2IN_NEXT_DROP] = "error-drop",
     [SNAT_OUT2IN_NEXT_LOOKUP] = "ip4-lookup",
     [SNAT_OUT2IN_NEXT_ICMP_ERROR] = "ip4-icmp-error",
+    [SNAT_OUT2IN_NEXT_REASS] = "nat44-out2in-reass",
   },
 };
-VLIB_NODE_FUNCTION_MULTIARCH (snat_det_out2in_node, snat_det_out2in_node_fn);
+/* *INDENT-ON* */
 
-/**
- * Get address and port values to be used for ICMP packet translation
- * and create session if needed
- *
- * @param[in,out] sm             NAT main
- * @param[in,out] node           NAT node runtime
- * @param[in] thread_index       thread index
- * @param[in,out] b0             buffer containing packet to be translated
- * @param[out] p_proto           protocol used for matching
- * @param[out] p_value           address and port after NAT translation
- * @param[out] p_dont_translate  if packet should not be translated
- * @param d                      optional parameter
- * @param e                      optional parameter
- */
-u32 icmp_match_out2in_det(snat_main_t *sm, vlib_node_runtime_t *node,
-                          u32 thread_index, vlib_buffer_t *b0,
-                          ip4_header_t *ip0, u8 *p_proto,
-                          snat_session_key_t *p_value,
-                          u8 *p_dont_translate, void *d, void *e)
+VLIB_NODE_FN (nat44_out2in_reass_node) (vlib_main_t * vm,
+                                       vlib_node_runtime_t * node,
+                                       vlib_frame_t * frame)
 {
-  icmp46_header_t *icmp0;
-  u32 sw_if_index0;
-  u8 protocol;
-  snat_det_out_key_t key0;
-  u8 dont_translate = 0;
-  u32 next0 = ~0;
-  icmp_echo_header_t *echo0, *inner_echo0 = 0;
-  ip4_header_t *inner_ip0;
-  void *l4_header = 0;
-  icmp46_header_t *inner_icmp0;
-  snat_det_map_t * dm0 = 0;
-  ip4_address_t new_addr0 = {{0}};
-  snat_det_session_t * ses0 = 0;
-  ip4_address_t out_addr;
+  u32 n_left_from, *from, *to_next;
+  snat_out2in_next_t next_index;
+  u32 pkts_processed = 0, cached_fragments = 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;
 
-  icmp0 = (icmp46_header_t *) ip4_next_header (ip0);
-  echo0 = (icmp_echo_header_t *)(icmp0+1);
-  sw_if_index0 = vnet_buffer(b0)->sw_if_index[VLIB_RX];
+  from = vlib_frame_vector_args (frame);
+  n_left_from = frame->n_vectors;
+  next_index = node->cached_next_index;
 
-  if (!icmp_is_error_message (icmp0))
-    {
-      protocol = SNAT_PROTOCOL_ICMP;
-      key0.ext_host_addr = ip0->src_address;
-      key0.ext_host_port = 0;
-      key0.out_port = echo0->identifier;
-      out_addr = ip0->dst_address;
-    }
-  else
+  while (n_left_from > 0)
     {
-      inner_ip0 = (ip4_header_t *)(echo0+1);
-      l4_header = ip4_next_header (inner_ip0);
-      protocol = ip_proto_to_snat_proto (inner_ip0->protocol);
-      key0.ext_host_addr = inner_ip0->dst_address;
-      out_addr = inner_ip0->src_address;
-      switch (protocol)
-        {
-        case SNAT_PROTOCOL_ICMP:
-          inner_icmp0 = (icmp46_header_t*)l4_header;
-          inner_echo0 = (icmp_echo_header_t *)(inner_icmp0+1);
-          key0.ext_host_port = 0;
-          key0.out_port = inner_echo0->identifier;
-          break;
-        case SNAT_PROTOCOL_UDP:
-        case SNAT_PROTOCOL_TCP:
-          key0.ext_host_port = ((tcp_udp_header_t*)l4_header)->dst_port;
-          key0.out_port = ((tcp_udp_header_t*)l4_header)->src_port;
-          break;
-        default:
-          b0->error = node->errors[SNAT_OUT2IN_ERROR_UNSUPPORTED_PROTOCOL];
-          next0 = SNAT_OUT2IN_NEXT_DROP;
-          goto out;
-        }
-    }
+      u32 n_left_to_next;
 
-  dm0 = snat_det_map_by_out(sm, &out_addr);
-  if (PREDICT_FALSE(!dm0))
-    {
-      /* Don't NAT packet aimed at the intfc address */
-      if (PREDICT_FALSE(is_interface_addr(sm, node, sw_if_index0,
-                                          ip0->dst_address.as_u32)))
-        {
-          dont_translate = 1;
-          goto out;
-        }
-      clib_warning("unknown dst address:  %U",
-                   format_ip4_address, &ip0->dst_address);
-      goto out;
-    }
+      vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
 
-  snat_det_reverse(dm0, &ip0->dst_address,
-                   clib_net_to_host_u16(key0.out_port), &new_addr0);
+      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;
+         snat_session_key_t key0, sm0;
+         clib_bihash_kv_8_8_t kv0, value0;
+         snat_session_t *s0 = 0;
+         u16 old_port0, new_port0;
+         ip_csum_t sum0;
+         u8 identity_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;
 
-  ses0 = snat_det_get_ses_by_out (dm0, &new_addr0, key0.as_u64);
-  if (PREDICT_FALSE(!ses0))
-    {
-      /* Don't NAT packet aimed at the intfc address */
-      if (PREDICT_FALSE(is_interface_addr(sm, node, sw_if_index0,
-                                          ip0->dst_address.as_u32)))
-        {
-          dont_translate = 1;
-          goto out;
-        }
-      clib_warning("no match src %U:%d dst %U:%d for user %U",
-                   format_ip4_address, &key0.ext_host_addr,
-                   clib_net_to_host_u16 (key0.ext_host_port),
-                   format_ip4_address, &out_addr,
-                   clib_net_to_host_u16 (key0.out_port),
-                   format_ip4_address, &new_addr0);
-      b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
-      next0 = SNAT_OUT2IN_NEXT_DROP;
-      goto out;
-    }
+         b0 = vlib_get_buffer (vm, bi0);
+         next0 = SNAT_OUT2IN_NEXT_LOOKUP;
 
-  if (PREDICT_FALSE(icmp0->type != ICMP4_echo_reply &&
-                    !icmp_is_error_message (icmp0)))
-    {
-      b0->error = node->errors[SNAT_OUT2IN_ERROR_BAD_ICMP_TYPE];
-      next0 = SNAT_OUT2IN_NEXT_DROP;
-      goto out;
-    }
+         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);
 
-  goto out;
+         if (PREDICT_FALSE (nat_reass_is_drop_frag (0)))
+           {
+             next0 = SNAT_OUT2IN_NEXT_DROP;
+             b0->error = node->errors[SNAT_OUT2IN_ERROR_DROP_FRAGMENT];
+             goto trace0;
+           }
 
-out:
-  *p_proto = protocol;
-  if (ses0)
-    {
-      p_value->addr = new_addr0;
-      p_value->fib_index = sm->inside_fib_index;
-      p_value->port = ses0->in_port;
-    }
-  *p_dont_translate = dont_translate;
-  if (d)
-    *(snat_det_session_t**)d = ses0;
-  if (e)
-    *(snat_det_map_t**)e = dm0;
-  return next0;
-}
+         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);
 
-/**********************/
-/*** worker handoff ***/
-/**********************/
-static uword
-snat_out2in_worker_handoff_fn (vlib_main_t * vm,
-                               vlib_node_runtime_t * node,
-                               vlib_frame_t * frame)
-{
-  snat_main_t *sm = &snat_main;
-  vlib_thread_main_t *tm = vlib_get_thread_main ();
-  u32 n_left_from, *from, *to_next = 0;
-  static __thread vlib_frame_queue_elt_t **handoff_queue_elt_by_worker_index;
-  static __thread vlib_frame_queue_t **congested_handoff_queue_by_worker_index
-    = 0;
-  vlib_frame_queue_elt_t *hf = 0;
-  vlib_frame_t *f = 0;
-  int i;
-  u32 n_left_to_next_worker = 0, *to_next_worker = 0;
-  u32 next_worker_index = 0;
-  u32 current_worker_index = ~0;
-  u32 thread_index = vlib_get_thread_index ();
-
-  ASSERT (vec_len (sm->workers));
-
-  if (PREDICT_FALSE (handoff_queue_elt_by_worker_index == 0))
-    {
-      vec_validate (handoff_queue_elt_by_worker_index, tm->n_vlib_mains - 1);
+         reass0 = nat_ip4_reass_find_or_create (ip0->src_address,
+                                                ip0->dst_address,
+                                                ip0->fragment_id,
+                                                ip0->protocol,
+                                                1, &fragments_to_drop);
 
-      vec_validate_init_empty (congested_handoff_queue_by_worker_index,
-                              sm->first_worker_index + sm->num_workers - 1,
-                              (vlib_frame_queue_t *) (~0));
-    }
+         if (PREDICT_FALSE (!reass0))
+           {
+             next0 = SNAT_OUT2IN_NEXT_DROP;
+             b0->error = node->errors[SNAT_OUT2IN_ERROR_MAX_REASS];
+             nat_log_notice ("maximum reassemblies exceeded");
+             goto trace0;
+           }
 
-  from = vlib_frame_vector_args (frame);
-  n_left_from = frame->n_vectors;
+         if (PREDICT_FALSE (ip4_is_first_fragment (ip0)))
+           {
+             if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
+               {
+                 next0 = icmp_out2in_slow_path
+                   (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, node,
+                    next0, now, thread_index, &s0);
+
+                 if (PREDICT_TRUE (next0 != SNAT_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;
+               }
+
+             key0.addr = ip0->dst_address;
+             key0.port = udp0->dst_port;
+             key0.protocol = proto0;
+             key0.fib_index = rx_fib_index0;
+             kv0.key = key0.as_u64;
+
+             if (clib_bihash_search_8_8
+                 (&per_thread_data->out2in, &kv0, &value0))
+               {
+                 /* Try to match static mapping by external address and port,
+                    destination address and port in packet */
+                 if (snat_static_mapping_match
+                     (sm, key0, &sm0, 1, 0, 0, 0, 0, &identity_nat0))
+                   {
+                     /*
+                      * 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[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+                         next0 = SNAT_OUT2IN_NEXT_DROP;
+                       }
+                     else
+                       {
+                         reass0->flags |= NAT_REASS_FLAG_ED_DONT_TRANSLATE;
+                         nat_ip4_reass_get_frags (reass0,
+                                                  &fragments_to_loopback);
+                       }
+                     goto trace0;
+                   }
+
+                 if (PREDICT_FALSE (identity_nat0))
+                   goto trace0;
+
+                 /* Create session initiated by host from external network */
+                 s0 =
+                   create_session_for_static_mapping (sm, b0, sm0, key0,
+                                                      node, thread_index,
+                                                      now);
+                 if (!s0)
+                   {
+                     b0->error =
+                       node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+                     next0 = SNAT_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
+                     (thread_index, reass0, bi0, &fragments_to_drop))
+                   {
+                     b0->error = node->errors[SNAT_OUT2IN_ERROR_MAX_FRAG];
+                     nat_log_notice
+                       ("maximum fragments per reassembly exceeded");
+                     next0 = SNAT_OUT2IN_NEXT_DROP;
+                     goto trace0;
+                   }
+                 cached0 = 1;
+                 goto trace0;
+               }
+             s0 = pool_elt_at_index (per_thread_data->sessions,
+                                     reass0->sess_index);
+           }
 
-  while (n_left_from > 0)
-    {
-      u32 bi0;
-      vlib_buffer_t *b0;
-      u32 sw_if_index0;
-      u32 rx_fib_index0;
-      ip4_header_t * ip0;
-      u8 do_handoff;
-
-      bi0 = from[0];
-      from += 1;
-      n_left_from -= 1;
-
-      b0 = vlib_get_buffer (vm, bi0);
-
-      sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
-      rx_fib_index0 = ip4_fib_table_get_index_for_sw_if_index(sw_if_index0);
-
-      ip0 = vlib_buffer_get_current (b0);
-
-      next_worker_index = sm->worker_out2in_cb(ip0, rx_fib_index0);
-
-      if (PREDICT_FALSE (next_worker_index != thread_index))
-        {
-          do_handoff = 1;
-
-          if (next_worker_index != current_worker_index)
-            {
-              if (hf)
-                hf->n_vectors = VLIB_FRAME_SIZE - n_left_to_next_worker;
-
-              hf = vlib_get_worker_handoff_queue_elt (sm->fq_out2in_index,
-                                                      next_worker_index,
-                                                      handoff_queue_elt_by_worker_index);
-
-              n_left_to_next_worker = VLIB_FRAME_SIZE - hf->n_vectors;
-              to_next_worker = &hf->buffer_index[hf->n_vectors];
-              current_worker_index = next_worker_index;
-            }
-
-          /* enqueue to correct worker thread */
-          to_next_worker[0] = bi0;
-          to_next_worker++;
-          n_left_to_next_worker--;
-
-          if (n_left_to_next_worker == 0)
-            {
-              hf->n_vectors = VLIB_FRAME_SIZE;
-              vlib_put_frame_queue_elt (hf);
-              current_worker_index = ~0;
-              handoff_queue_elt_by_worker_index[next_worker_index] = 0;
-              hf = 0;
-            }
-        }
-      else
-        {
-          do_handoff = 0;
-          /* if this is 1st frame */
-          if (!f)
-            {
-              f = vlib_get_frame_to_node (vm, sm->out2in_node_index);
-              to_next = vlib_frame_vector_args (f);
-            }
-
-          to_next[0] = bi0;
-          to_next += 1;
-          f->n_vectors++;
-        }
-
-      if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
-                        && (b0->flags & VLIB_BUFFER_IS_TRACED)))
-       {
-          snat_out2in_worker_handoff_trace_t *t =
-            vlib_add_trace (vm, node, b0, sizeof (*t));
-          t->next_worker_index = next_worker_index;
-          t->do_handoff = do_handoff;
-        }
-    }
+         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 */ );
+         ip0->checksum = ip_csum_fold (sum0);
 
-  if (f)
-    vlib_put_frame_to_node (vm, sm->out2in_node_index, f);
+         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 */ );
+                 tcp0->checksum = ip_csum_fold (sum0);
+               }
+             else
+               {
+                 old_port0 = udp0->dst_port;
+                 udp0->dst_port = s0->in2out.port;
+                 udp0->checksum = 0;
+               }
+           }
 
-  if (hf)
-    hf->n_vectors = VLIB_FRAME_SIZE - n_left_to_next_worker;
+         /* Accounting */
+         nat44_session_update_counters (s0, now,
+                                        vlib_buffer_length_in_chain (vm, b0),
+                                        thread_index);
+         /* Per-user LRU list maintenance */
+         nat44_session_update_lru (sm, s0, thread_index);
 
-  /* Ship frames to the worker nodes */
-  for (i = 0; i < vec_len (handoff_queue_elt_by_worker_index); i++)
-    {
-      if (handoff_queue_elt_by_worker_index[i])
-       {
-         hf = handoff_queue_elt_by_worker_index[i];
-         /*
-          * It works better to let the handoff node
-          * rate-adapt, always ship the handoff queue element.
-          */
-         if (1 || hf->n_vectors == hf->last_n_vectors)
+       trace0:
+         if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
+                            && (b0->flags & VLIB_BUFFER_IS_TRACED)))
            {
-             vlib_put_frame_queue_elt (hf);
-             handoff_queue_elt_by_worker_index[i] = 0;
+             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--;
+             cached_fragments++;
            }
          else
-           hf->last_n_vectors = hf->n_vectors;
+           {
+             pkts_processed += next0 != SNAT_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_fast (from, fragments_to_loopback,
+                                   sizeof (u32) * len);
+                 n_left_from = len;
+                 vec_reset_length (fragments_to_loopback);
+               }
+             else
+               {
+                 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;
+               }
+           }
        }
-      congested_handoff_queue_by_worker_index[i] =
-       (vlib_frame_queue_t *) (~0);
+
+      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
     }
-  hf = 0;
-  current_worker_index = ~0;
+
+  vlib_node_increment_counter (vm, sm->out2in_reass_node_index,
+                              SNAT_OUT2IN_ERROR_PROCESSED_FRAGMENTS,
+                              pkts_processed);
+  vlib_node_increment_counter (vm, sm->out2in_reass_node_index,
+                              SNAT_OUT2IN_ERROR_CACHED_FRAGMENTS,
+                              cached_fragments);
+
+  nat_send_all_to_node (vm, fragments_to_drop, node,
+                       &node->errors[SNAT_OUT2IN_ERROR_DROP_FRAGMENT],
+                       SNAT_OUT2IN_NEXT_DROP);
+
+  vec_free (fragments_to_drop);
+  vec_free (fragments_to_loopback);
   return frame->n_vectors;
 }
 
-VLIB_REGISTER_NODE (snat_out2in_worker_handoff_node) = {
-  .function = snat_out2in_worker_handoff_fn,
-  .name = "nat44-out2in-worker-handoff",
+/* *INDENT-OFF* */
+VLIB_REGISTER_NODE (nat44_out2in_reass_node) = {
+  .name = "nat44-out2in-reass",
   .vector_size = sizeof (u32),
-  .format_trace = format_snat_out2in_worker_handoff_trace,
+  .format_trace = format_nat44_reass_trace,
   .type = VLIB_NODE_TYPE_INTERNAL,
 
-  .n_next_nodes = 1,
+  .n_errors = ARRAY_LEN(snat_out2in_error_strings),
+  .error_strings = snat_out2in_error_strings,
+
+  .n_next_nodes = SNAT_OUT2IN_N_NEXT,
 
+  /* edit / add dispositions here */
   .next_nodes = {
-    [0] = "error-drop",
+    [SNAT_OUT2IN_NEXT_DROP] = "error-drop",
+    [SNAT_OUT2IN_NEXT_LOOKUP] = "ip4-lookup",
+    [SNAT_OUT2IN_NEXT_ICMP_ERROR] = "ip4-icmp-error",
+    [SNAT_OUT2IN_NEXT_REASS] = "nat44-out2in-reass",
   },
 };
+/* *INDENT-ON* */
 
-VLIB_NODE_FUNCTION_MULTIARCH (snat_out2in_worker_handoff_node, snat_out2in_worker_handoff_fn);
-
-static uword
-snat_out2in_fast_node_fn (vlib_main_t * vm,
-                          vlib_node_runtime_t * node,
-                         vlib_frame_t * frame)
+VLIB_NODE_FN (snat_out2in_fast_node) (vlib_main_t * vm,
+                                     vlib_node_runtime_t * node,
+                                     vlib_frame_t * frame)
 {
-  u32 n_left_from, * from, * to_next;
+  u32 n_left_from, *from, *to_next;
   snat_out2in_next_t next_index;
   u32 pkts_processed = 0;
-  snat_main_t * sm = &snat_main;
+  snat_main_t *sm = &snat_main;
 
   from = vlib_frame_vector_args (frame);
   n_left_from = frame->n_vectors;
@@ -2341,27 +1711,26 @@ snat_out2in_fast_node_fn (vlib_main_t * vm,
     {
       u32 n_left_to_next;
 
-      vlib_get_next_frame (vm, node, next_index,
-                          to_next, 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;
-         vlib_buffer_t * b0;
-          u32 next0 = SNAT_OUT2IN_NEXT_DROP;
-          u32 sw_if_index0;
-          ip4_header_t * ip0;
-          ip_csum_t sum0;
-          u32 new_addr0, old_addr0;
-          u16 new_port0, old_port0;
-          udp_header_t * udp0;
-          tcp_header_t * tcp0;
-          icmp46_header_t * icmp0;
-          snat_session_key_t key0, sm0;
-          u32 proto0;
-          u32 rx_fib_index0;
-
-          /* speculatively enqueue b0 to the current next frame */
+         u32 bi0;
+         vlib_buffer_t *b0;
+         u32 next0 = SNAT_OUT2IN_NEXT_DROP;
+         u32 sw_if_index0;
+         ip4_header_t *ip0;
+         ip_csum_t sum0;
+         u32 new_addr0, old_addr0;
+         u16 new_port0, old_port0;
+         udp_header_t *udp0;
+         tcp_header_t *tcp0;
+         icmp46_header_t *icmp0;
+         snat_session_key_t key0, sm0;
+         u32 proto0;
+         u32 rx_fib_index0;
+
+         /* speculatively enqueue b0 to the current next frame */
          bi0 = from[0];
          to_next[0] = bi0;
          from += 1;
@@ -2371,111 +1740,112 @@ snat_out2in_fast_node_fn (vlib_main_t * vm,
 
          b0 = vlib_get_buffer (vm, bi0);
 
-          ip0 = vlib_buffer_get_current (b0);
-          udp0 = ip4_next_header (ip0);
-          tcp0 = (tcp_header_t *) udp0;
-          icmp0 = (icmp46_header_t *) udp0;
-
-          sw_if_index0 = vnet_buffer(b0)->sw_if_index[VLIB_RX];
-         rx_fib_index0 = ip4_fib_table_get_index_for_sw_if_index(sw_if_index0);
-
-         vnet_feature_next (sw_if_index0, &next0, b0);
-
-          if (PREDICT_FALSE(ip0->ttl == 1))
-            {
-              vnet_buffer (b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
-              icmp4_error_set_vnet_buffer (b0, ICMP4_time_exceeded,
-                                           ICMP4_time_exceeded_ttl_exceeded_in_transit,
-                                           0);
-              next0 = SNAT_OUT2IN_NEXT_ICMP_ERROR;
-              goto trace00;
-            }
-
-          proto0 = ip_proto_to_snat_proto (ip0->protocol);
-
-          if (PREDICT_FALSE (proto0 == ~0))
-              goto trace00;
-
-          if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
-            {
-              next0 = icmp_out2in(sm, b0, ip0, icmp0, sw_if_index0,
-                                  rx_fib_index0, node, next0, ~0, 0, 0);
-              goto trace00;
-            }
-
-          key0.addr = ip0->dst_address;
-          key0.port = udp0->dst_port;
-          key0.fib_index = rx_fib_index0;
-
-          if (snat_static_mapping_match(sm, key0, &sm0, 1, 0))
-            {
-              b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
-              goto trace00;
-            }
-
-          new_addr0 = sm0.addr.as_u32;
-          new_port0 = sm0.port;
-          vnet_buffer(b0)->sw_if_index[VLIB_TX] = sm0.fib_index;
-          old_addr0 = ip0->dst_address.as_u32;
-          ip0->dst_address.as_u32 = new_addr0;
-
-          sum0 = ip0->checksum;
-          sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
-                                 ip4_header_t,
-                                 dst_address /* changed member */);
-          ip0->checksum = ip_csum_fold (sum0);
-
-          if (PREDICT_FALSE(new_port0 != udp0->dst_port))
-            {
-               if (PREDICT_TRUE(proto0 == SNAT_PROTOCOL_TCP))
-                {
-                  old_port0 = tcp0->dst_port;
-                  tcp0->dst_port = new_port0;
-
-                  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 */);
-                  tcp0->checksum = ip_csum_fold(sum0);
-                }
-              else
-                {
-                  old_port0 = udp0->dst_port;
-                  udp0->dst_port = new_port0;
-                  udp0->checksum = 0;
-                }
-            }
-          else
-            {
-              if (PREDICT_TRUE(proto0 == SNAT_PROTOCOL_TCP))
-                {
-                  sum0 = tcp0->checksum;
-                  sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
-                                         ip4_header_t,
-                                         dst_address /* changed member */);
-
-                  tcp0->checksum = ip_csum_fold(sum0);
-                }
-            }
-
-        trace00:
-
-          if (PREDICT_FALSE((node->flags & VLIB_NODE_FLAG_TRACE)
-                            && (b0->flags & VLIB_BUFFER_IS_TRACED)))
-            {
-              snat_out2in_trace_t *t =
-                 vlib_add_trace (vm, node, b0, sizeof (*t));
-              t->sw_if_index = sw_if_index0;
-              t->next_index = next0;
-            }
-
-          pkts_processed += next0 != SNAT_OUT2IN_NEXT_DROP;
-
-          /* verify speculative enqueue, maybe switch current next frame */
+         ip0 = vlib_buffer_get_current (b0);
+         udp0 = ip4_next_header (ip0);
+         tcp0 = (tcp_header_t *) udp0;
+         icmp0 = (icmp46_header_t *) udp0;
+
+         sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
+         rx_fib_index0 =
+           ip4_fib_table_get_index_for_sw_if_index (sw_if_index0);
+
+         vnet_feature_next (&next0, b0);
+
+         if (PREDICT_FALSE (ip0->ttl == 1))
+           {
+             vnet_buffer (b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
+             icmp4_error_set_vnet_buffer (b0, ICMP4_time_exceeded,
+                                          ICMP4_time_exceeded_ttl_exceeded_in_transit,
+                                          0);
+             next0 = SNAT_OUT2IN_NEXT_ICMP_ERROR;
+             goto trace00;
+           }
+
+         proto0 = ip_proto_to_snat_proto (ip0->protocol);
+
+         if (PREDICT_FALSE (proto0 == ~0))
+           goto trace00;
+
+         if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
+           {
+             next0 = icmp_out2in (sm, b0, ip0, icmp0, sw_if_index0,
+                                  rx_fib_index0, node, next0, ~0, 0, 0);
+             goto trace00;
+           }
+
+         key0.addr = ip0->dst_address;
+         key0.port = udp0->dst_port;
+         key0.fib_index = rx_fib_index0;
+
+         if (snat_static_mapping_match (sm, key0, &sm0, 1, 0, 0, 0, 0, 0))
+           {
+             b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+             goto trace00;
+           }
+
+         new_addr0 = sm0.addr.as_u32;
+         new_port0 = sm0.port;
+         vnet_buffer (b0)->sw_if_index[VLIB_TX] = sm0.fib_index;
+         old_addr0 = ip0->dst_address.as_u32;
+         ip0->dst_address.as_u32 = new_addr0;
+
+         sum0 = ip0->checksum;
+         sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
+                                ip4_header_t,
+                                dst_address /* changed member */ );
+         ip0->checksum = ip_csum_fold (sum0);
+
+         if (PREDICT_FALSE (new_port0 != udp0->dst_port))
+           {
+             if (PREDICT_TRUE (proto0 == SNAT_PROTOCOL_TCP))
+               {
+                 old_port0 = tcp0->dst_port;
+                 tcp0->dst_port = new_port0;
+
+                 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 */ );
+                 tcp0->checksum = ip_csum_fold (sum0);
+               }
+             else
+               {
+                 old_port0 = udp0->dst_port;
+                 udp0->dst_port = new_port0;
+                 udp0->checksum = 0;
+               }
+           }
+         else
+           {
+             if (PREDICT_TRUE (proto0 == SNAT_PROTOCOL_TCP))
+               {
+                 sum0 = tcp0->checksum;
+                 sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
+                                        ip4_header_t,
+                                        dst_address /* changed member */ );
+
+                 tcp0->checksum = ip_csum_fold (sum0);
+               }
+           }
+
+       trace00:
+
+         if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
+                            && (b0->flags & VLIB_BUFFER_IS_TRACED)))
+           {
+             snat_out2in_trace_t *t =
+               vlib_add_trace (vm, node, b0, sizeof (*t));
+             t->sw_if_index = sw_if_index0;
+             t->next_index = next0;
+           }
+
+         pkts_processed += next0 != SNAT_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);
@@ -2484,14 +1854,14 @@ snat_out2in_fast_node_fn (vlib_main_t * vm,
       vlib_put_next_frame (vm, node, next_index, n_left_to_next);
     }
 
-  vlib_node_increment_counter (vm, snat_out2in_fast_node.index,
-                               SNAT_OUT2IN_ERROR_OUT2IN_PACKETS,
-                               pkts_processed);
+  vlib_node_increment_counter (vm, sm->out2in_fast_node_index,
+                              SNAT_OUT2IN_ERROR_OUT2IN_PACKETS,
+                              pkts_processed);
   return frame->n_vectors;
 }
 
+/* *INDENT-OFF* */
 VLIB_REGISTER_NODE (snat_out2in_fast_node) = {
-  .function = snat_out2in_fast_node_fn,
   .name = "nat44-out2in-fast",
   .vector_size = sizeof (u32),
   .format_trace = format_snat_out2in_fast_trace,
@@ -2509,6 +1879,15 @@ VLIB_REGISTER_NODE (snat_out2in_fast_node) = {
     [SNAT_OUT2IN_NEXT_LOOKUP] = "ip4-lookup",
     [SNAT_OUT2IN_NEXT_DROP] = "error-drop",
     [SNAT_OUT2IN_NEXT_ICMP_ERROR] = "ip4-icmp-error",
+    [SNAT_OUT2IN_NEXT_REASS] = "nat44-out2in-reass",
   },
 };
-VLIB_NODE_FUNCTION_MULTIARCH (snat_out2in_fast_node, snat_out2in_fast_node_fn);
+/* *INDENT-ON* */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */