nat: nat44 split slow and fast path

Type: improvement

Change-Id: I07c7e1c154583906ac9af958f22ed9a1be382f4a
Signed-off-by: Filip Varga <fivarga@cisco.com>

2 files changed, 339 insertions, 1080 deletions

diff --git a/src/plugins/nat/in2out_ed.c b/src/plugins/nat/in2out_ed.c
index e52411094c2..581d7b4ef60 100644
--- a/src/plugins/nat/in2out_ed.c
+++ b/src/plugins/nat/in2out_ed.c
@@ -818,10 +818,10 @@ nat44_ed_in2out_unknown_proto (snat_main_t * sm,
 }
 
 static inline uword
-nat44_ed_in2out_node_fn_inline (vlib_main_t * vm,
-				vlib_node_runtime_t * node,
-				vlib_frame_t * frame, int is_slow_path,
-				int is_output_feature)
+nat44_ed_in2out_fast_path_node_fn_inline (vlib_main_t * vm,
+					  vlib_node_runtime_t * node,
+					  vlib_frame_t * frame,
+					  int is_output_feature)
 {
   u32 n_left_from, *from, *to_next, pkts_processed = 0, stats_node_index;
   nat_next_t next_index;
@@ -835,8 +835,7 @@ nat44_ed_in2out_node_fn_inline (vlib_main_t * vm,
   def_slow = is_output_feature ? NAT_NEXT_IN2OUT_ED_OUTPUT_SLOW_PATH :
     NAT_NEXT_IN2OUT_ED_SLOW_PATH;
 
-  stats_node_index = is_slow_path ? sm->ed_in2out_slowpath_node_index :
-    sm->ed_in2out_node_index;
+  stats_node_index = sm->ed_in2out_node_index;
 
   from = vlib_frame_vector_args (frame);
   n_left_from = frame->n_vectors;
@@ -848,64 +847,37 @@ nat44_ed_in2out_node_fn_inline (vlib_main_t * vm,
 
       vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
 
-      while (n_left_from >= 4 && n_left_to_next >= 2)
+      while (n_left_from > 0 && n_left_to_next > 0)
 	{
-	  u32 bi0, bi1;
-	  vlib_buffer_t *b0, *b1;
+	  u32 bi0;
+	  vlib_buffer_t *b0;
 	  u32 next0, sw_if_index0, rx_fib_index0, iph_offset0 = 0, proto0,
 	    new_addr0, old_addr0;
-	  u32 next1, sw_if_index1, rx_fib_index1, iph_offset1 = 0, proto1,
-	    new_addr1, old_addr1;
-	  u16 old_port0, new_port0, old_port1, new_port1;
-	  ip4_header_t *ip0, *ip1;
-	  udp_header_t *udp0, *udp1;
-	  tcp_header_t *tcp0, *tcp1;
-	  icmp46_header_t *icmp0, *icmp1;
-	  snat_session_t *s0 = 0, *s1 = 0;
-	  clib_bihash_kv_16_8_t kv0, value0, kv1, value1;
-	  ip_csum_t sum0, sum1;
-
-	  /* Prefetch next iteration. */
-	  {
-	    vlib_buffer_t *p2, *p3;
-
-	    p2 = vlib_get_buffer (vm, from[2]);
-	    p3 = vlib_get_buffer (vm, from[3]);
-
-	    vlib_prefetch_buffer_header (p2, LOAD);
-	    vlib_prefetch_buffer_header (p3, LOAD);
-
-	    CLIB_PREFETCH (p2->data, CLIB_CACHE_LINE_BYTES, STORE);
-	    CLIB_PREFETCH (p3->data, CLIB_CACHE_LINE_BYTES, STORE);
-	  }
-
-	  /* speculatively enqueue b0 and b1 to the current next frame */
-	  to_next[0] = bi0 = from[0];
-	  to_next[1] = bi1 = from[1];
-	  from += 2;
-	  to_next += 2;
-	  n_left_from -= 2;
-	  n_left_to_next -= 2;
+	  u16 old_port0, new_port0;
+	  ip4_header_t *ip0;
+	  udp_header_t *udp0;
+	  tcp_header_t *tcp0;
+	  snat_session_t *s0 = 0;
+	  clib_bihash_kv_16_8_t kv0, value0;
+	  ip_csum_t sum0;
+
+	  /* speculatively enqueue b0 to the current next frame */
+	  bi0 = from[0];
+	  to_next[0] = bi0;
+	  from += 1;
+	  to_next += 1;
+	  n_left_from -= 1;
+	  n_left_to_next -= 1;
 
 	  b0 = vlib_get_buffer (vm, bi0);
-	  b1 = vlib_get_buffer (vm, bi1);
 
 	  if (is_output_feature)
 	    {
-	      // output feature fast path is enabled on the arc
-	      // we need new arc_next feature
-	      if (PREDICT_TRUE (!is_slow_path))
-		{
-		  vnet_feature_next (&nat_buffer_opaque (b0)->arc_next, b0);
-		  vnet_feature_next (&nat_buffer_opaque (b1)->arc_next, b1);
-		}
-
+	      vnet_feature_next (&nat_buffer_opaque (b0)->arc_next, b0);
 	      iph_offset0 = vnet_buffer (b0)->ip.reass.save_rewrite_length;
-	      iph_offset1 = vnet_buffer (b1)->ip.reass.save_rewrite_length;
 	    }
 
 	  next0 = nat_buffer_opaque (b0)->arc_next;
-	  next1 = nat_buffer_opaque (b1)->arc_next;
 
 	  ip0 = (ip4_header_t *) ((u8 *) vlib_buffer_get_current (b0) +
 				  iph_offset0);
@@ -922,58 +894,30 @@ nat44_ed_in2out_node_fn_inline (vlib_main_t * vm,
 					   ICMP4_time_exceeded_ttl_exceeded_in_transit,
 					   0);
 	      next0 = NAT_NEXT_ICMP_ERROR;
-	      goto trace00;
+	      goto trace0;
 	    }
 
 	  udp0 = ip4_next_header (ip0);
 	  tcp0 = (tcp_header_t *) udp0;
-	  icmp0 = (icmp46_header_t *) udp0;
 	  proto0 = ip_proto_to_snat_proto (ip0->protocol);
 
-	  if (is_slow_path)
+	  if (PREDICT_FALSE (proto0 == ~0))
 	    {
-	      if (PREDICT_FALSE (proto0 == ~0))
-		{
-		  s0 = nat44_ed_in2out_unknown_proto (sm, b0, ip0,
-						      rx_fib_index0,
-						      thread_index, now, vm,
-						      node);
-		  if (!s0)
-		    next0 = NAT_NEXT_DROP;
-		  other_packets++;
-		  goto trace00;
-		}
-
-	      if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
-		{
-		  next0 = icmp_in2out_ed_slow_path
-		    (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, node,
-		     next0, now, thread_index, &s0);
-		  icmp_packets++;
-		  goto trace00;
-		}
+	      next0 = def_slow;
+	      goto trace0;
 	    }
-	  else
-	    {
-	      if (PREDICT_FALSE (proto0 == ~0))
-		{
-		  next0 = def_slow;
-		  goto trace00;
-		}
 
-	      if (is_output_feature)
-		{
-		  if (PREDICT_FALSE
-		      (nat_not_translate_output_feature_fwd
-		       (sm, ip0, thread_index, now, vm, b0)))
-		    goto trace00;
-		}
+	  if (is_output_feature)
+	    {
+	      if (PREDICT_FALSE (nat_not_translate_output_feature_fwd
+				 (sm, ip0, thread_index, now, vm, b0)))
+		goto trace0;
+	    }
 
-	      if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
-		{
-		  next0 = def_slow;
-		  goto trace00;
-		}
+	  if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
+	    {
+	      next0 = def_slow;
+	      goto trace0;
 	    }
 
 	  make_ed_kv (&kv0, &ip0->src_address, &ip0->dst_address,
@@ -981,64 +925,16 @@ nat44_ed_in2out_node_fn_inline (vlib_main_t * vm,
 		      vnet_buffer (b0)->ip.reass.l4_src_port,
 		      vnet_buffer (b0)->ip.reass.l4_dst_port);
 
+	  // lookup for session
 	  if (clib_bihash_search_16_8 (&tsm->in2out_ed, &kv0, &value0))
 	    {
-	      if (is_slow_path)
-		{
-		  if (is_output_feature)
-		    {
-		      if (PREDICT_FALSE
-			  (nat44_ed_not_translate_output_feature
-			   (sm, ip0, ip0->protocol,
-			    vnet_buffer (b0)->ip.reass.l4_src_port,
-			    vnet_buffer (b0)->ip.reass.l4_dst_port,
-			    thread_index, sw_if_index0,
-			    vnet_buffer (b0)->sw_if_index[VLIB_TX])))
-			goto trace00;
-
-		      /*
-		       * Send DHCP packets to the ipv4 stack, or we won't
-		       * be able to use dhcp client on the outside interface
-		       */
-		      if (PREDICT_FALSE
-			  (proto0 == SNAT_PROTOCOL_UDP
-			   && (vnet_buffer (b0)->ip.reass.l4_dst_port ==
-			       clib_host_to_net_u16
-			       (UDP_DST_PORT_dhcp_to_server))
-			   && ip0->dst_address.as_u32 == 0xffffffff))
-			goto trace00;
-		    }
-		  else
-		    {
-		      if (PREDICT_FALSE (nat44_ed_not_translate (sm, node,
-								 sw_if_index0,
-								 ip0, proto0,
-								 rx_fib_index0,
-								 thread_index)))
-			goto trace00;
-		    }
-
-		  next0 =
-		    slow_path_ed (sm, b0, rx_fib_index0, &kv0, &s0, node,
-				  next0, thread_index, now);
-
-		  if (PREDICT_FALSE (next0 == NAT_NEXT_DROP))
-		    goto trace00;
-
-		  if (PREDICT_FALSE (!s0))
-		    goto trace00;
-		}
-	      else
-		{
-		  next0 = def_slow;
-		  goto trace00;
-		}
-	    }
-	  else
-	    {
-	      s0 = pool_elt_at_index (tsm->sessions, value0.value);
+	      // session does not exist go slow path
+	      next0 = def_slow;
+	      goto trace0;
 	    }
 
+	  s0 = pool_elt_at_index (tsm->sessions, value0.value);
+
 	  b0->flags |= VNET_BUFFER_F_IS_NATED;
 
 	  if (!is_output_feature)
@@ -1064,16 +960,17 @@ nat44_ed_in2out_node_fn_inline (vlib_main_t * vm,
 		  new_port0 = udp0->src_port = s0->out2in.port;
 		  sum0 = tcp0->checksum;
 		  sum0 =
-		    ip_csum_update (sum0, old_addr0, new_addr0, ip4_header_t,
-				    dst_address);
+		    ip_csum_update (sum0, old_addr0, new_addr0,
+				    ip4_header_t, dst_address);
 		  sum0 =
-		    ip_csum_update (sum0, old_port0, new_port0, ip4_header_t,
-				    length);
+		    ip_csum_update (sum0, old_port0, new_port0,
+				    ip4_header_t, length);
 		  if (PREDICT_FALSE (is_twice_nat_session (s0)))
 		    {
-		      sum0 = ip_csum_update (sum0, ip0->dst_address.as_u32,
-					     s0->ext_host_addr.as_u32,
-					     ip4_header_t, dst_address);
+		      sum0 =
+			ip_csum_update (sum0, ip0->dst_address.as_u32,
+					s0->ext_host_addr.as_u32,
+					ip4_header_t, dst_address);
 		      sum0 =
 			ip_csum_update (sum0,
 					vnet_buffer (b0)->ip.
@@ -1087,17 +984,19 @@ nat44_ed_in2out_node_fn_inline (vlib_main_t * vm,
 		}
 	      tcp_packets++;
 	      if (nat44_set_tcp_session_state_i2o (sm, s0, b0, thread_index))
-		goto trace00;
+		goto trace0;
 	    }
 	  else if (!vnet_buffer (b0)->ip.reass.is_non_first_fragment
 		   && udp0->checksum)
 	    {
 	      new_port0 = udp0->src_port = s0->out2in.port;
 	      sum0 = udp0->checksum;
-	      sum0 = ip_csum_update (sum0, old_addr0, new_addr0, ip4_header_t,
-				     dst_address);
-	      sum0 = ip_csum_update (sum0, old_port0, new_port0, ip4_header_t,
-				     length);
+	      sum0 =
+		ip_csum_update (sum0, old_addr0, new_addr0, ip4_header_t,
+				dst_address);
+	      sum0 =
+		ip_csum_update (sum0, old_port0, new_port0, ip4_header_t,
+				length);
 	      if (PREDICT_FALSE (is_twice_nat_session (s0)))
 		{
 		  sum0 = ip_csum_update (sum0, ip0->dst_address.as_u32,
@@ -1129,283 +1028,78 @@ nat44_ed_in2out_node_fn_inline (vlib_main_t * vm,
 
 	  /* Accounting */
 	  nat44_session_update_counters (s0, now,
-					 vlib_buffer_length_in_chain (vm,
-								      b0),
-					 thread_index);
+					 vlib_buffer_length_in_chain
+					 (vm, b0), thread_index);
 	  /* Per-user LRU list maintenance */
 	  nat44_session_update_lru (sm, s0, thread_index);
 
-	trace00:
+	trace0:
 	  if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
 			     && (b0->flags & VLIB_BUFFER_IS_TRACED)))
 	    {
 	      nat_in2out_ed_trace_t *t =
 		vlib_add_trace (vm, node, b0, sizeof (*t));
-	      t->is_slow_path = is_slow_path;
 	      t->sw_if_index = sw_if_index0;
 	      t->next_index = next0;
-	      t->session_index = ~0;
+	      t->is_slow_path = 0;
+
 	      if (s0)
 		t->session_index = s0 - tsm->sessions;
-	    }
-
-	  pkts_processed += next0 == nat_buffer_opaque (b0)->arc_next;
-
-	  ip1 = (ip4_header_t *) ((u8 *) vlib_buffer_get_current (b1) +
-				  iph_offset1);
-
-	  sw_if_index1 = vnet_buffer (b1)->sw_if_index[VLIB_RX];
-	  rx_fib_index1 =
-	    fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP4,
-						 sw_if_index1);
-
-	  if (PREDICT_FALSE (ip1->ttl == 1))
-	    {
-	      vnet_buffer (b1)->sw_if_index[VLIB_TX] = (u32) ~ 0;
-	      icmp4_error_set_vnet_buffer (b1, ICMP4_time_exceeded,
-					   ICMP4_time_exceeded_ttl_exceeded_in_transit,
-					   0);
-	      next1 = NAT_NEXT_ICMP_ERROR;
-	      goto trace01;
-	    }
-
-	  udp1 = ip4_next_header (ip1);
-	  tcp1 = (tcp_header_t *) udp1;
-	  icmp1 = (icmp46_header_t *) udp1;
-	  proto1 = ip_proto_to_snat_proto (ip1->protocol);
-
-	  if (is_slow_path)
-	    {
-	      if (PREDICT_FALSE (proto1 == ~0))
-		{
-		  s1 = nat44_ed_in2out_unknown_proto (sm, b1, ip1,
-						      rx_fib_index1,
-						      thread_index, now,
-						      vm, node);
-		  if (!s1)
-		    next1 = NAT_NEXT_DROP;
-		  other_packets++;
-		  goto trace01;
-		}
-
-	      if (PREDICT_FALSE (proto1 == SNAT_PROTOCOL_ICMP))
-		{
-		  next1 = icmp_in2out_ed_slow_path
-		    (sm, b1, ip1, icmp1, sw_if_index1, rx_fib_index1,
-		     node, next1, now, thread_index, &s1);
-		  icmp_packets++;
-		  goto trace01;
-		}
-	    }
-	  else
-	    {
-	      if (PREDICT_FALSE (proto1 == ~0))
-		{
-		  next1 = def_slow;
-		  goto trace01;
-		}
-
-	      if (is_output_feature)
-		{
-		  if (PREDICT_FALSE
-		      (nat_not_translate_output_feature_fwd
-		       (sm, ip1, thread_index, now, vm, b1)))
-		    goto trace01;
-		}
-
-	      if (PREDICT_FALSE (proto1 == SNAT_PROTOCOL_ICMP))
-		{
-		  next1 = def_slow;
-		  goto trace01;
-		}
-	    }
-
-	  make_ed_kv (&kv1, &ip1->src_address, &ip1->dst_address,
-		      ip1->protocol, rx_fib_index1,
-		      vnet_buffer (b1)->ip.reass.l4_src_port,
-		      vnet_buffer (b1)->ip.reass.l4_dst_port);
-
-	  if (clib_bihash_search_16_8 (&tsm->in2out_ed, &kv1, &value1))
-	    {
-	      if (is_slow_path)
-		{
-		  if (is_output_feature)
-		    {
-		      if (PREDICT_FALSE
-			  (nat44_ed_not_translate_output_feature
-			   (sm, ip1, ip1->protocol,
-			    vnet_buffer (b1)->ip.reass.l4_src_port,
-			    vnet_buffer (b1)->ip.reass.l4_dst_port,
-			    thread_index, sw_if_index1,
-			    vnet_buffer (b1)->sw_if_index[VLIB_TX])))
-			goto trace01;
-
-		      /*
-		       * 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
-			   && (vnet_buffer (b1)->ip.reass.l4_dst_port ==
-			       clib_host_to_net_u16
-			       (UDP_DST_PORT_dhcp_to_server))
-			   && ip1->dst_address.as_u32 == 0xffffffff))
-			goto trace01;
-		    }
-		  else
-		    {
-		      if (PREDICT_FALSE (nat44_ed_not_translate (sm, node,
-								 sw_if_index1,
-								 ip1,
-								 proto1,
-								 rx_fib_index1,
-								 thread_index)))
-			goto trace01;
-		    }
-
-		  next1 =
-		    slow_path_ed (sm, b1, rx_fib_index1, &kv1, &s1, node,
-				  next1, thread_index, now);
-
-		  if (PREDICT_FALSE (next1 == NAT_NEXT_DROP))
-		    goto trace01;
-
-		  if (PREDICT_FALSE (!s1))
-		    goto trace01;
-		}
 	      else
-		{
-		  next1 = def_slow;
-		  goto trace01;
-		}
+		t->session_index = ~0;
 	    }
-	  else
-	    {
-	      s1 = pool_elt_at_index (tsm->sessions, value1.value);
-	    }
-
-	  b1->flags |= VNET_BUFFER_F_IS_NATED;
-
-	  if (!is_output_feature)
-	    vnet_buffer (b1)->sw_if_index[VLIB_TX] = s1->out2in.fib_index;
-
-	  old_addr1 = ip1->src_address.as_u32;
-	  new_addr1 = ip1->src_address.as_u32 = s1->out2in.addr.as_u32;
-	  sum1 = ip1->checksum;
-	  sum1 = ip_csum_update (sum1, old_addr1, new_addr1, ip4_header_t,
-				 src_address);
-	  if (PREDICT_FALSE (is_twice_nat_session (s1)))
-	    sum1 = ip_csum_update (sum1, ip1->dst_address.as_u32,
-				   s1->ext_host_addr.as_u32, ip4_header_t,
-				   dst_address);
-	  ip1->checksum = ip_csum_fold (sum1);
 
-	  old_port1 = vnet_buffer (b1)->ip.reass.l4_src_port;
+	  pkts_processed += next0 == nat_buffer_opaque (b0)->arc_next;
+	  /* verify speculative enqueue, maybe switch current next frame */
+	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
+					   to_next, n_left_to_next,
+					   bi0, next0);
+	}
 
-	  if (PREDICT_TRUE (proto1 == SNAT_PROTOCOL_TCP))
-	    {
-	      if (!vnet_buffer (b0)->ip.reass.is_non_first_fragment)
-		{
-		  new_port1 = udp1->src_port = s1->out2in.port;
-		  sum1 = tcp1->checksum;
-		  sum1 =
-		    ip_csum_update (sum1, old_addr1, new_addr1,
-				    ip4_header_t, dst_address);
-		  sum1 =
-		    ip_csum_update (sum1, old_port1, new_port1,
-				    ip4_header_t, length);
-		  if (PREDICT_FALSE (is_twice_nat_session (s1)))
-		    {
-		      sum1 =
-			ip_csum_update (sum1, ip1->dst_address.as_u32,
-					s1->ext_host_addr.as_u32,
-					ip4_header_t, dst_address);
-		      sum1 =
-			ip_csum_update (sum1,
-					vnet_buffer (b1)->ip.
-					reass.l4_dst_port, s1->ext_host_port,
-					ip4_header_t, length);
-		      tcp1->dst_port = s1->ext_host_port;
-		      ip1->dst_address.as_u32 = s1->ext_host_addr.as_u32;
-		    }
-		  tcp1->checksum = ip_csum_fold (sum1);
-		  mss_clamping (sm, tcp1, &sum1);
-		}
-	      tcp_packets++;
-	      if (nat44_set_tcp_session_state_i2o (sm, s1, b1, thread_index))
-		goto trace01;
-	    }
-	  else if (!vnet_buffer (b1)->ip.reass.is_non_first_fragment
-		   && udp1->checksum)
-	    {
-	      new_port1 = udp1->src_port = s1->out2in.port;
-	      sum1 = udp1->checksum;
-	      sum1 =
-		ip_csum_update (sum1, old_addr1, new_addr1, ip4_header_t,
-				dst_address);
-	      sum1 =
-		ip_csum_update (sum1, old_port1, new_port1, ip4_header_t,
-				length);
+      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
+    }
 
-	      if (PREDICT_FALSE (is_twice_nat_session (s1)))
-		{
-		  sum1 = ip_csum_update (sum1, ip1->dst_address.as_u32,
-					 s1->ext_host_addr.as_u32,
-					 ip4_header_t, dst_address);
-		  sum1 =
-		    ip_csum_update (sum1,
-				    vnet_buffer (b1)->ip.reass.l4_dst_port,
-				    s1->ext_host_port, ip4_header_t, length);
-		  udp1->dst_port = s1->ext_host_port;
-		  ip1->dst_address.as_u32 = s1->ext_host_addr.as_u32;
-		}
-	      udp1->checksum = ip_csum_fold (sum1);
-	      udp_packets++;
-	    }
-	  else
-	    {
-	      if (!vnet_buffer (b1)->ip.reass.is_non_first_fragment)
-		{
-		  new_port1 = udp1->src_port = s1->out2in.port;
-		  if (PREDICT_FALSE (is_twice_nat_session (s1)))
-		    {
-		      udp1->dst_port = s1->ext_host_port;
-		      ip1->dst_address.as_u32 = s1->ext_host_addr.as_u32;
-		    }
-		}
-	      udp_packets++;
-	    }
+  vlib_node_increment_counter (vm, stats_node_index,
+			       NAT_IN2OUT_ED_ERROR_IN2OUT_PACKETS,
+			       pkts_processed);
+  vlib_node_increment_counter (vm, stats_node_index,
+			       NAT_IN2OUT_ED_ERROR_TCP_PACKETS, tcp_packets);
+  vlib_node_increment_counter (vm, stats_node_index,
+			       NAT_IN2OUT_ED_ERROR_UDP_PACKETS, udp_packets);
+  vlib_node_increment_counter (vm, stats_node_index,
+			       NAT_IN2OUT_ED_ERROR_ICMP_PACKETS,
+			       icmp_packets);
+  vlib_node_increment_counter (vm, stats_node_index,
+			       NAT_IN2OUT_ED_ERROR_OTHER_PACKETS,
+			       other_packets);
+  return frame->n_vectors;
+}
 
-	  /* 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);
+static inline uword
+nat44_ed_in2out_slow_path_node_fn_inline (vlib_main_t * vm,
+					  vlib_node_runtime_t * node,
+					  vlib_frame_t * frame,
+					  int is_output_feature)
+{
+  u32 n_left_from, *from, *to_next, pkts_processed = 0, stats_node_index;
+  nat_next_t next_index;
+  snat_main_t *sm = &snat_main;
+  f64 now = vlib_time_now (vm);
+  u32 thread_index = vm->thread_index;
+  snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
+  u32 tcp_packets = 0, udp_packets = 0, icmp_packets = 0, other_packets = 0;
 
-	trace01:
-	  if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
-			     && (b1->flags & VLIB_BUFFER_IS_TRACED)))
-	    {
-	      nat_in2out_ed_trace_t *t =
-		vlib_add_trace (vm, node, b1, sizeof (*t));
-	      t->is_slow_path = is_slow_path;
-	      t->sw_if_index = sw_if_index1;
-	      t->next_index = next1;
-	      t->session_index = ~0;
-	      if (s1)
-		t->session_index = s1 - tsm->sessions;
-	    }
+  stats_node_index = sm->ed_in2out_slowpath_node_index;
 
-	  pkts_processed += next1 == nat_buffer_opaque (b1)->arc_next;
+  from = vlib_frame_vector_args (frame);
+  n_left_from = frame->n_vectors;
+  next_index = node->cached_next_index;
 
+  while (n_left_from > 0)
+    {
+      u32 n_left_to_next;
 
-	  /* verify speculative enqueues, maybe switch current next frame */
-	  vlib_validate_buffer_enqueue_x2 (vm, node, next_index,
-					   to_next, n_left_to_next,
-					   bi0, bi1, next0, next1);
-	}
+      vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
 
       while (n_left_from > 0 && n_left_to_next > 0)
 	{
@@ -1433,14 +1127,7 @@ nat44_ed_in2out_node_fn_inline (vlib_main_t * vm,
 	  b0 = vlib_get_buffer (vm, bi0);
 
 	  if (is_output_feature)
-	    {
-	      // output feature fast path is enabled on the arc
-	      // we need new arc_next feature
-	      if (PREDICT_TRUE (!is_slow_path))
-		vnet_feature_next (&nat_buffer_opaque (b0)->arc_next, b0);
-
-	      iph_offset0 = vnet_buffer (b0)->ip.reass.save_rewrite_length;
-	    }
+	    iph_offset0 = vnet_buffer (b0)->ip.reass.save_rewrite_length;
 
 	  next0 = nat_buffer_opaque (b0)->arc_next;
 
@@ -1467,52 +1154,29 @@ nat44_ed_in2out_node_fn_inline (vlib_main_t * vm,
 	  icmp0 = (icmp46_header_t *) udp0;
 	  proto0 = ip_proto_to_snat_proto (ip0->protocol);
 
-	  if (is_slow_path)
+	  if (PREDICT_FALSE (proto0 == ~0))
 	    {
-	      if (PREDICT_FALSE (proto0 == ~0))
-		{
-		  s0 = nat44_ed_in2out_unknown_proto (sm, b0, ip0,
-						      rx_fib_index0,
-						      thread_index, now,
-						      vm, node);
-		  if (!s0)
-		    next0 = NAT_NEXT_DROP;
-		  other_packets++;
-		  goto trace0;
-		}
-
-	      if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
-		{
-		  next0 = icmp_in2out_ed_slow_path
-		    (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0,
-		     node, next0, now, thread_index, &s0);
-		  icmp_packets++;
-		  goto trace0;
-		}
+	      s0 = nat44_ed_in2out_unknown_proto (sm, b0, ip0,
+						  rx_fib_index0,
+						  thread_index, now,
+						  vm, node);
+	      if (!s0)
+		next0 = NAT_NEXT_DROP;
+
+	      other_packets++;
+	      goto trace0;
 	    }
-	  else
-	    {
-	      if (PREDICT_FALSE (proto0 == ~0))
-		{
-		  next0 = def_slow;
-		  goto trace0;
-		}
-
-	      if (is_output_feature)
-		{
-		  if (PREDICT_FALSE
-		      (nat_not_translate_output_feature_fwd
-		       (sm, ip0, thread_index, now, vm, b0)))
-		    goto trace0;
-		}
 
-	      if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
-		{
-		  next0 = def_slow;
-		  goto trace0;
-		}
+	  if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
+	    {
+	      next0 = icmp_in2out_ed_slow_path
+		(sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0,
+		 node, next0, now, thread_index, &s0);
+	      icmp_packets++;
+	      goto trace0;
 	    }
 
+	  // move down
 	  make_ed_kv (&kv0, &ip0->src_address, &ip0->dst_address,
 		      ip0->protocol, rx_fib_index0,
 		      vnet_buffer (b0)->ip.reass.l4_src_port,
@@ -1520,63 +1184,54 @@ nat44_ed_in2out_node_fn_inline (vlib_main_t * vm,
 
 	  if (clib_bihash_search_16_8 (&tsm->in2out_ed, &kv0, &value0))
 	    {
-	      if (is_slow_path)
-		{
-		  if (is_output_feature)
-		    {
-		      if (PREDICT_FALSE
-			  (nat44_ed_not_translate_output_feature
-			   (sm, ip0, ip0->protocol,
-			    vnet_buffer (b0)->ip.reass.l4_src_port,
-			    vnet_buffer (b0)->ip.reass.l4_dst_port,
-			    thread_index, sw_if_index0,
-			    vnet_buffer (b0)->sw_if_index[VLIB_TX])))
-			goto trace0;
-
-		      /*
-		       * Send DHCP packets to the ipv4 stack, or we won't
-		       * be able to use dhcp client on the outside interface
-		       */
-		      if (PREDICT_FALSE
-			  (proto0 == SNAT_PROTOCOL_UDP
-			   && (vnet_buffer (b0)->ip.reass.l4_dst_port ==
-			       clib_host_to_net_u16
-			       (UDP_DST_PORT_dhcp_to_server))
-			   && ip0->dst_address.as_u32 == 0xffffffff))
-			goto trace0;
-		    }
-		  else
-		    {
-		      if (PREDICT_FALSE (nat44_ed_not_translate (sm, node,
-								 sw_if_index0,
-								 ip0,
-								 proto0,
-								 rx_fib_index0,
-								 thread_index)))
-			goto trace0;
-		    }
 
-		  next0 =
-		    slow_path_ed (sm, b0, rx_fib_index0, &kv0, &s0, node,
-				  next0, thread_index, now);
-
-		  if (PREDICT_FALSE (next0 == NAT_NEXT_DROP))
+	      if (is_output_feature)
+		{
+		  if (PREDICT_FALSE
+		      (nat44_ed_not_translate_output_feature
+		       (sm, ip0, ip0->protocol,
+			vnet_buffer (b0)->ip.reass.l4_src_port,
+			vnet_buffer (b0)->ip.reass.l4_dst_port,
+			thread_index, sw_if_index0,
+			vnet_buffer (b0)->sw_if_index[VLIB_TX])))
 		    goto trace0;
 
-		  if (PREDICT_FALSE (!s0))
+		  /*
+		   * Send DHCP packets to the ipv4 stack, or we won't
+		   * be able to use dhcp client on the outside interface
+		   */
+		  if (PREDICT_FALSE
+		      (proto0 == SNAT_PROTOCOL_UDP
+		       && (vnet_buffer (b0)->ip.reass.l4_dst_port ==
+			   clib_host_to_net_u16 (UDP_DST_PORT_dhcp_to_server))
+		       && ip0->dst_address.as_u32 == 0xffffffff))
 		    goto trace0;
 		}
 	      else
 		{
-		  next0 = def_slow;
-		  goto trace0;
+		  if (PREDICT_FALSE
+		      (nat44_ed_not_translate
+		       (sm, node, sw_if_index0, ip0, proto0, rx_fib_index0,
+			thread_index)))
+		    goto trace0;
 		}
+
+	      next0 = slow_path_ed (sm, b0, rx_fib_index0, &kv0, &s0, node,
+				    next0, thread_index, now);
+
+	      if (PREDICT_FALSE (next0 == NAT_NEXT_DROP))
+		goto trace0;
+
+	      if (PREDICT_FALSE (!s0))
+		goto trace0;
+
 	    }
 	  else
 	    {
 	      s0 = pool_elt_at_index (tsm->sessions, value0.value);
 	    }
 
+
 	  b0->flags |= VNET_BUFFER_F_IS_NATED;
 
 	  if (!is_output_feature)
@@ -1681,12 +1336,14 @@ nat44_ed_in2out_node_fn_inline (vlib_main_t * vm,
 	    {
 	      nat_in2out_ed_trace_t *t =
 		vlib_add_trace (vm, node, b0, sizeof (*t));
-	      t->is_slow_path = is_slow_path;
 	      t->sw_if_index = sw_if_index0;
 	      t->next_index = next0;
-	      t->session_index = ~0;
+	      t->is_slow_path = 1;
+
 	      if (s0)
 		t->session_index = s0 - tsm->sessions;
+	      else
+		t->session_index = ~0;
 	    }
 
 	  pkts_processed += next0 == nat_buffer_opaque (b0)->arc_next;
@@ -1720,7 +1377,7 @@ VLIB_NODE_FN (nat44_ed_in2out_node) (vlib_main_t * vm,
 				     vlib_node_runtime_t * node,
 				     vlib_frame_t * frame)
 {
-  return nat44_ed_in2out_node_fn_inline (vm, node, frame, 0, 0);
+  return nat44_ed_in2out_fast_path_node_fn_inline (vm, node, frame, 0);
 }
 
 /* *INDENT-OFF* */
@@ -1740,7 +1397,7 @@ VLIB_NODE_FN (nat44_ed_in2out_output_node) (vlib_main_t * vm,
 					    vlib_node_runtime_t * node,
 					    vlib_frame_t * frame)
 {
-  return nat44_ed_in2out_node_fn_inline (vm, node, frame, 0, 1);
+  return nat44_ed_in2out_fast_path_node_fn_inline (vm, node, frame, 1);
 }
 
 /* *INDENT-OFF* */
@@ -1760,7 +1417,7 @@ VLIB_NODE_FN (nat44_ed_in2out_slowpath_node) (vlib_main_t * vm,
 					      vlib_node_runtime_t *
 					      node, vlib_frame_t * frame)
 {
-  return nat44_ed_in2out_node_fn_inline (vm, node, frame, 1, 0);
+  return nat44_ed_in2out_slow_path_node_fn_inline (vm, node, frame, 0);
 }
 
 /* *INDENT-OFF* */
@@ -1781,7 +1438,7 @@ VLIB_NODE_FN (nat44_ed_in2out_output_slowpath_node) (vlib_main_t * vm,
 						     * node,
 						     vlib_frame_t * frame)
 {
-  return nat44_ed_in2out_node_fn_inline (vm, node, frame, 1, 1);
+  return nat44_ed_in2out_slow_path_node_fn_inline (vm, node, frame, 1);
 }
 
 /* *INDENT-OFF* */
diff --git a/src/plugins/nat/out2in_ed.c b/src/plugins/nat/out2in_ed.c
index 7cb205f6d6f..91b8d5a8aae 100644
--- a/src/plugins/nat/out2in_ed.c
+++ b/src/plugins/nat/out2in_ed.c
@@ -668,9 +668,9 @@ nat44_ed_out2in_unknown_proto (snat_main_t * sm,
 }
 
 static inline uword
-nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
-				vlib_node_runtime_t * node,
-				vlib_frame_t * frame, int is_slow_path)
+nat44_ed_out2in_fast_path_node_fn_inline (vlib_main_t * vm,
+					  vlib_node_runtime_t * node,
+					  vlib_frame_t * frame)
 {
   u32 n_left_from, *from, *to_next, pkts_processed = 0, stats_node_index;
   nat_next_t next_index;
@@ -681,8 +681,7 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
   u32 tcp_packets = 0, udp_packets = 0, icmp_packets = 0, other_packets =
     0, fragments = 0;
 
-  stats_node_index = is_slow_path ? sm->ed_out2in_slowpath_node_index :
-    sm->ed_out2in_node_index;
+  stats_node_index = sm->ed_out2in_node_index;
 
   from = vlib_frame_vector_args (frame);
   n_left_from = frame->n_vectors;
@@ -694,54 +693,30 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
 
       vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
 
-      while (n_left_from >= 4 && n_left_to_next >= 2)
+      while (n_left_from > 0 && n_left_to_next > 0)
 	{
-	  u32 bi0, bi1;
-	  vlib_buffer_t *b0, *b1;
+	  u32 bi0;
+	  vlib_buffer_t *b0;
 	  u32 next0, sw_if_index0, rx_fib_index0, proto0, old_addr0,
 	    new_addr0;
-	  u32 next1, sw_if_index1, rx_fib_index1, proto1, old_addr1,
-	    new_addr1;
-	  u16 old_port0, new_port0, old_port1, new_port1;
-	  ip4_header_t *ip0, *ip1;
-	  udp_header_t *udp0, *udp1;
-	  tcp_header_t *tcp0, *tcp1;
-	  icmp46_header_t *icmp0, *icmp1;
-	  snat_session_t *s0 = 0, *s1 = 0;
-	  clib_bihash_kv_16_8_t kv0, value0, kv1, value1;
-	  ip_csum_t sum0, sum1;
-	  snat_session_key_t e_key0, l_key0, e_key1, l_key1;
-	  lb_nat_type_t lb_nat0, lb_nat1;
-	  twice_nat_type_t twice_nat0, twice_nat1;
-	  u8 identity_nat0, identity_nat1;
-
-	  /* Prefetch next iteration. */
-	  {
-	    vlib_buffer_t *p2, *p3;
-
-	    p2 = vlib_get_buffer (vm, from[2]);
-	    p3 = vlib_get_buffer (vm, from[3]);
-
-	    vlib_prefetch_buffer_header (p2, LOAD);
-	    vlib_prefetch_buffer_header (p3, LOAD);
-
-	    CLIB_PREFETCH (p2->data, CLIB_CACHE_LINE_BYTES, STORE);
-	    CLIB_PREFETCH (p3->data, CLIB_CACHE_LINE_BYTES, STORE);
-	  }
-
-	  /* speculatively enqueue b0 and b1 to the current next frame */
-	  to_next[0] = bi0 = from[0];
-	  to_next[1] = bi1 = from[1];
-	  from += 2;
-	  to_next += 2;
-	  n_left_from -= 2;
-	  n_left_to_next -= 2;
+	  u16 old_port0, new_port0;
+	  ip4_header_t *ip0;
+	  udp_header_t *udp0;
+	  tcp_header_t *tcp0;
+	  snat_session_t *s0 = 0;
+	  clib_bihash_kv_16_8_t kv0, value0;
+	  ip_csum_t sum0;
 
-	  b0 = vlib_get_buffer (vm, bi0);
-	  b1 = vlib_get_buffer (vm, bi1);
+	  /* speculatively enqueue b0 to the current next frame */
+	  bi0 = from[0];
+	  to_next[0] = bi0;
+	  from += 1;
+	  to_next += 1;
+	  n_left_from -= 1;
+	  n_left_to_next -= 1;
 
+	  b0 = vlib_get_buffer (vm, bi0);
 	  next0 = nat_buffer_opaque (b0)->arc_next;
-	  next1 = nat_buffer_opaque (b1)->arc_next;
 
 	  vnet_buffer (b0)->snat.flags = 0;
 	  ip0 = vlib_buffer_get_current (b0);
@@ -758,53 +733,23 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
 					   ICMP4_time_exceeded_ttl_exceeded_in_transit,
 					   0);
 	      next0 = NAT_NEXT_ICMP_ERROR;
-	      goto trace00;
+	      goto trace0;
 	    }
 
 	  udp0 = ip4_next_header (ip0);
 	  tcp0 = (tcp_header_t *) udp0;
-	  icmp0 = (icmp46_header_t *) udp0;
 	  proto0 = ip_proto_to_snat_proto (ip0->protocol);
 
-	  if (is_slow_path)
+	  if (PREDICT_FALSE (proto0 == ~0))
 	    {
-	      if (PREDICT_FALSE (proto0 == ~0))
-		{
-		  s0 =
-		    nat44_ed_out2in_unknown_proto (sm, b0, ip0, rx_fib_index0,
-						   thread_index, now, vm,
-						   node);
-		  other_packets++;
-		  if (!sm->forwarding_enabled)
-		    {
-		      if (!s0)
-			next0 = NAT_NEXT_DROP;
-		      goto trace00;
-		    }
-		}
-
-	      if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
-		{
-		  next0 = icmp_out2in_ed_slow_path
-		    (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, node,
-		     next0, now, thread_index, &s0);
-		  icmp_packets++;
-		  goto trace00;
-		}
+	      next0 = NAT_NEXT_OUT2IN_ED_SLOW_PATH;
+	      goto trace0;
 	    }
-	  else
-	    {
-	      if (PREDICT_FALSE (proto0 == ~0))
-		{
-		  next0 = NAT_NEXT_OUT2IN_ED_SLOW_PATH;
-		  goto trace00;
-		}
 
-	      if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
-		{
-		  next0 = NAT_NEXT_OUT2IN_ED_SLOW_PATH;
-		  goto trace00;
-		}
+	  if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
+	    {
+	      next0 = NAT_NEXT_OUT2IN_ED_SLOW_PATH;
+	      goto trace0;
 	    }
 
 	  make_ed_kv (&kv0, &ip0->dst_address, &ip0->src_address,
@@ -814,94 +759,10 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
 
 	  if (clib_bihash_search_16_8 (&tsm->out2in_ed, &kv0, &value0))
 	    {
-	      if (is_slow_path)
-		{
-		  /* Try to match static mapping by external address and port,
-		     destination address and port in packet */
-		  e_key0.addr = ip0->dst_address;
-		  e_key0.port = vnet_buffer (b0)->ip.reass.l4_dst_port;
-		  e_key0.protocol = proto0;
-		  e_key0.fib_index = rx_fib_index0;
-		  if (snat_static_mapping_match (sm, e_key0, &l_key0, 1, 0,
-						 &twice_nat0, &lb_nat0,
-						 &ip0->src_address,
-						 &identity_nat0))
-		    {
-		      /*
-		       * Send DHCP packets to the ipv4 stack, or we won't
-		       * be able to use dhcp client on the outside interface
-		       */
-		      if (PREDICT_FALSE
-			  (proto0 == SNAT_PROTOCOL_UDP
-			   && (vnet_buffer (b0)->ip.reass.l4_dst_port ==
-			       clib_host_to_net_u16
-			       (UDP_DST_PORT_dhcp_to_client))))
-			{
-			  goto trace00;
-			}
-
-		      if (!sm->forwarding_enabled)
-			{
-			  b0->error =
-			    node->errors[NAT_OUT2IN_ED_ERROR_NO_TRANSLATION];
-			  next0 = NAT_NEXT_DROP;
-			}
-		      else
-			{
-			  if (next_src_nat
-			      (sm, ip0, ip0->protocol,
-			       vnet_buffer (b0)->ip.reass.l4_src_port,
-			       vnet_buffer (b0)->ip.reass.l4_dst_port,
-			       thread_index, rx_fib_index0))
-			    {
-			      next0 = NAT_NEXT_IN2OUT_ED_FAST_PATH;
-			      goto trace00;
-			    }
-			  if (sm->num_workers > 1)
-			    create_bypass_for_fwd_worker (sm, b0, ip0,
-							  rx_fib_index0);
-			  else
-			    create_bypass_for_fwd (sm, b0, ip0, rx_fib_index0,
-						   thread_index);
-			}
-		      goto trace00;
-		    }
-
-		  if (PREDICT_FALSE (identity_nat0))
-		    goto trace00;
-
-		  if ((proto0 == SNAT_PROTOCOL_TCP)
-		      && !tcp_flags_is_init (vnet_buffer (b0)->ip.
-					     reass.icmp_type_or_tcp_flags))
-		    {
-		      b0->error = node->errors[NAT_OUT2IN_ED_ERROR_NON_SYN];
-		      next0 = NAT_NEXT_DROP;
-		      goto trace00;
-		    }
-
-		  /* Create session initiated by host from external network */
-		  s0 = create_session_for_static_mapping_ed (sm, b0, l_key0,
-							     e_key0, node,
-							     thread_index,
-							     twice_nat0,
-							     lb_nat0, now);
-
-		  if (!s0)
-		    {
-		      next0 = NAT_NEXT_DROP;
-		      goto trace00;
-		    }
-		}
-	      else
-		{
-		  next0 = NAT_NEXT_OUT2IN_ED_SLOW_PATH;
-		  goto trace00;
-		}
-	    }
-	  else
-	    {
-	      s0 = pool_elt_at_index (tsm->sessions, value0.value);
+	      next0 = NAT_NEXT_OUT2IN_ED_SLOW_PATH;
+	      goto trace0;
 	    }
+	  s0 = pool_elt_at_index (tsm->sessions, value0.value);
 
 	  old_addr0 = ip0->dst_address.as_u32;
 	  new_addr0 = ip0->dst_address.as_u32 = s0->in2out.addr.as_u32;
@@ -951,7 +812,7 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
 		  (sm, s0, vnet_buffer (b0)->ip.reass.icmp_type_or_tcp_flags,
 		   vnet_buffer (b0)->ip.reass.tcp_ack_number,
 		   vnet_buffer (b0)->ip.reass.tcp_seq_number, thread_index))
-		goto trace00;
+		goto trace0;
 	    }
 	  else if (!vnet_buffer (b0)->ip.reass.is_non_first_fragment
 		   && udp0->checksum)
@@ -985,14 +846,8 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
 		  new_port0 = udp0->dst_port = s0->in2out.port;
 		  if (PREDICT_FALSE (is_twice_nat_session (s0)))
 		    {
-		      udp0->dst_port = s0->in2out.port;
-		      if (is_twice_nat_session (s0))
-			{
-			  udp0->src_port = s0->ext_host_nat_port;
-			  ip0->src_address.as_u32 =
-			    s0->ext_host_nat_addr.as_u32;
-			}
-		      udp0->checksum = 0;
+		      udp0->src_port = s0->ext_host_nat_port;
+		      ip0->src_address.as_u32 = s0->ext_host_nat_addr.as_u32;
 		    }
 		}
 	      udp_packets++;
@@ -1005,305 +860,75 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
 	  /* Per-user LRU list maintenance */
 	  nat44_session_update_lru (sm, s0, thread_index);
 
-	trace00:
+	trace0:
 	  if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
 			     && (b0->flags & VLIB_BUFFER_IS_TRACED)))
 	    {
 	      nat44_ed_out2in_trace_t *t =
 		vlib_add_trace (vm, node, b0, sizeof (*t));
-	      t->is_slow_path = is_slow_path;
 	      t->sw_if_index = sw_if_index0;
 	      t->next_index = next0;
-	      t->session_index = ~0;
+	      t->is_slow_path = 0;
+
 	      if (s0)
 		t->session_index = s0 - tsm->sessions;
-	    }
-
-	  pkts_processed += next0 == nat_buffer_opaque (b0)->arc_next;
-
-	  vnet_buffer (b1)->snat.flags = 0;
-	  ip1 = vlib_buffer_get_current (b1);
-
-	  sw_if_index1 = vnet_buffer (b1)->sw_if_index[VLIB_RX];
-	  rx_fib_index1 =
-	    fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP4,
-						 sw_if_index1);
-
-	  if (PREDICT_FALSE (ip1->ttl == 1))
-	    {
-	      vnet_buffer (b1)->sw_if_index[VLIB_TX] = (u32) ~ 0;
-	      icmp4_error_set_vnet_buffer (b1, ICMP4_time_exceeded,
-					   ICMP4_time_exceeded_ttl_exceeded_in_transit,
-					   0);
-	      next1 = NAT_NEXT_ICMP_ERROR;
-	      goto trace01;
-	    }
-
-	  udp1 = ip4_next_header (ip1);
-	  tcp1 = (tcp_header_t *) udp1;
-	  icmp1 = (icmp46_header_t *) udp1;
-	  proto1 = ip_proto_to_snat_proto (ip1->protocol);
-
-	  if (is_slow_path)
-	    {
-	      if (PREDICT_FALSE (proto1 == ~0))
-		{
-		  s1 =
-		    nat44_ed_out2in_unknown_proto (sm, b1, ip1, rx_fib_index1,
-						   thread_index, now, vm,
-						   node);
-		  other_packets++;
-		  if (!sm->forwarding_enabled)
-		    {
-		      if (!s1)
-			next1 = NAT_NEXT_DROP;
-		      goto trace01;
-		    }
-		}
-
-	      if (PREDICT_FALSE (proto1 == SNAT_PROTOCOL_ICMP))
-		{
-		  next1 = icmp_out2in_ed_slow_path
-		    (sm, b1, ip1, icmp1, sw_if_index1, rx_fib_index1, node,
-		     next1, now, thread_index, &s1);
-		  icmp_packets++;
-		  goto trace01;
-		}
-	    }
-	  else
-	    {
-	      if (PREDICT_FALSE (proto1 == ~0))
-		{
-		  next1 = NAT_NEXT_OUT2IN_ED_SLOW_PATH;
-		  goto trace01;
-		}
-
-	      if (PREDICT_FALSE (proto1 == SNAT_PROTOCOL_ICMP))
-		{
-		  next1 = NAT_NEXT_OUT2IN_ED_SLOW_PATH;
-		  goto trace01;
-		}
-	    }
-
-	  make_ed_kv (&kv1, &ip1->dst_address, &ip1->src_address,
-		      ip1->protocol, rx_fib_index1,
-		      vnet_buffer (b1)->ip.reass.l4_dst_port,
-		      vnet_buffer (b1)->ip.reass.l4_src_port);
-
-	  if (clib_bihash_search_16_8 (&tsm->out2in_ed, &kv1, &value1))
-	    {
-	      if (is_slow_path)
-		{
-		  /* Try to match static mapping by external address and port,
-		     destination address and port in packet */
-		  e_key1.addr = ip1->dst_address;
-		  e_key1.port = vnet_buffer (b1)->ip.reass.l4_dst_port;
-		  e_key1.protocol = proto1;
-		  e_key1.fib_index = rx_fib_index1;
-		  if (snat_static_mapping_match (sm, e_key1, &l_key1, 1, 0,
-						 &twice_nat1, &lb_nat1,
-						 &ip1->src_address,
-						 &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
-			   && (vnet_buffer (b1)->ip.reass.l4_dst_port ==
-			       clib_host_to_net_u16
-			       (UDP_DST_PORT_dhcp_to_client))))
-			{
-			  goto trace01;
-			}
-
-		      if (!sm->forwarding_enabled)
-			{
-			  b1->error =
-			    node->errors[NAT_OUT2IN_ED_ERROR_NO_TRANSLATION];
-			  next1 = NAT_NEXT_DROP;
-			}
-		      else
-			{
-			  if (next_src_nat
-			      (sm, ip1, ip1->protocol,
-			       vnet_buffer (b1)->ip.reass.l4_src_port,
-			       vnet_buffer (b1)->ip.reass.l4_dst_port,
-			       thread_index, rx_fib_index1))
-			    {
-			      next1 = NAT_NEXT_IN2OUT_ED_FAST_PATH;
-			      goto trace01;
-			    }
-			  if (sm->num_workers > 1)
-			    create_bypass_for_fwd_worker (sm, b1, ip1,
-							  rx_fib_index1);
-			  else
-			    create_bypass_for_fwd (sm, b1, ip1, rx_fib_index1,
-						   thread_index);
-			}
-		      goto trace01;
-		    }
-
-		  if (PREDICT_FALSE (identity_nat1))
-		    goto trace01;
-
-		  if ((proto1 == SNAT_PROTOCOL_TCP)
-		      && !tcp_flags_is_init (vnet_buffer (b1)->ip.
-					     reass.icmp_type_or_tcp_flags))
-		    {
-		      b1->error = node->errors[NAT_OUT2IN_ED_ERROR_NON_SYN];
-		      next1 = NAT_NEXT_DROP;
-		      goto trace01;
-		    }
-
-		  /* Create session initiated by host from external network */
-		  s1 = create_session_for_static_mapping_ed (sm, b1, l_key1,
-							     e_key1, node,
-							     thread_index,
-							     twice_nat1,
-							     lb_nat1, now);
-
-		  if (!s1)
-		    {
-		      next1 = NAT_NEXT_DROP;
-		      goto trace01;
-		    }
-		}
 	      else
-		{
-		  next1 = NAT_NEXT_OUT2IN_ED_SLOW_PATH;
-		  goto trace01;
-		}
-	    }
-	  else
-	    {
-	      s1 = pool_elt_at_index (tsm->sessions, value1.value);
+		t->session_index = ~0;
 	    }
 
-	  old_addr1 = ip1->dst_address.as_u32;
-	  new_addr1 = ip1->dst_address.as_u32 = s1->in2out.addr.as_u32;
-	  vnet_buffer (b1)->sw_if_index[VLIB_TX] = s1->in2out.fib_index;
-
-	  sum1 = ip1->checksum;
-	  sum1 = ip_csum_update (sum1, old_addr1, new_addr1, ip4_header_t,
-				 dst_address);
-	  if (PREDICT_FALSE (is_twice_nat_session (s1)))
-	    sum1 = ip_csum_update (sum1, ip1->src_address.as_u32,
-				   s1->ext_host_nat_addr.as_u32, ip4_header_t,
-				   src_address);
-	  ip1->checksum = ip_csum_fold (sum1);
+	  pkts_processed += next0 == nat_buffer_opaque (b0)->arc_next;
+	  /* verify speculative enqueue, maybe switch current next frame */
+	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
+					   to_next, n_left_to_next,
+					   bi0, next0);
+	}
 
-	  old_port1 = vnet_buffer (b1)->ip.reass.l4_dst_port;
+      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
+    }
 
-	  if (PREDICT_TRUE (proto1 == SNAT_PROTOCOL_TCP))
-	    {
-	      if (!vnet_buffer (b1)->ip.reass.is_non_first_fragment)
-		{
-		  new_port1 = udp1->dst_port = s1->in2out.port;
+  vlib_node_increment_counter (vm, stats_node_index,
+			       NAT_OUT2IN_ED_ERROR_OUT2IN_PACKETS,
+			       pkts_processed);
+  vlib_node_increment_counter (vm, stats_node_index,
+			       NAT_OUT2IN_ED_ERROR_TCP_PACKETS, tcp_packets);
+  vlib_node_increment_counter (vm, stats_node_index,
+			       NAT_OUT2IN_ED_ERROR_UDP_PACKETS, udp_packets);
+  vlib_node_increment_counter (vm, stats_node_index,
+			       NAT_OUT2IN_ED_ERROR_ICMP_PACKETS,
+			       icmp_packets);
+  vlib_node_increment_counter (vm, stats_node_index,
+			       NAT_OUT2IN_ED_ERROR_OTHER_PACKETS,
+			       other_packets);
+  vlib_node_increment_counter (vm, stats_node_index,
+			       NAT_OUT2IN_ED_ERROR_FRAGMENTS, fragments);
+  return frame->n_vectors;
+}
 
-		  sum1 = tcp1->checksum;
-		  sum1 =
-		    ip_csum_update (sum1, old_addr1, new_addr1, ip4_header_t,
-				    dst_address);
-		  sum1 =
-		    ip_csum_update (sum1, old_port1, new_port1, ip4_header_t,
-				    length);
-		  if (is_twice_nat_session (s1))
-		    {
-		      sum1 = ip_csum_update (sum1, ip1->src_address.as_u32,
-					     s1->ext_host_nat_addr.as_u32,
-					     ip4_header_t, dst_address);
-		      sum1 =
-			ip_csum_update (sum1,
-					vnet_buffer (b1)->ip.
-					reass.l4_src_port,
-					s1->ext_host_nat_port, ip4_header_t,
-					length);
-		      tcp1->src_port = s1->ext_host_nat_port;
-		      ip1->src_address.as_u32 = s1->ext_host_nat_addr.as_u32;
-		    }
-		  tcp1->checksum = ip_csum_fold (sum1);
-		}
-	      tcp_packets++;
-	      if (nat44_set_tcp_session_state_o2i
-		  (sm, s1, vnet_buffer (b1)->ip.reass.icmp_type_or_tcp_flags,
-		   vnet_buffer (b1)->ip.reass.tcp_ack_number,
-		   vnet_buffer (b1)->ip.reass.tcp_seq_number, thread_index))
-		goto trace01;
-	    }
-	  else if (!vnet_buffer (b1)->ip.reass.is_non_first_fragment
-		   && udp1->checksum)
-	    {
-	      new_port1 = udp1->dst_port = s1->in2out.port;
-	      sum1 = udp1->checksum;
-	      sum1 = ip_csum_update (sum1, old_addr1, new_addr1, ip4_header_t,
-				     dst_address);
-	      sum1 = ip_csum_update (sum1, old_port1, new_port1, ip4_header_t,
-				     length);
-	      if (PREDICT_FALSE (is_twice_nat_session (s1)))
-		{
-		  sum1 = ip_csum_update (sum1, ip1->src_address.as_u32,
-					 s1->ext_host_nat_addr.as_u32,
-					 ip4_header_t, dst_address);
-		  sum1 =
-		    ip_csum_update (sum1,
-				    vnet_buffer (b1)->ip.reass.l4_src_port,
-				    s1->ext_host_nat_port, ip4_header_t,
-				    length);
-		  udp1->src_port = s1->ext_host_nat_port;
-		  ip1->src_address.as_u32 = s1->ext_host_nat_addr.as_u32;
-		}
-	      udp1->checksum = ip_csum_fold (sum1);
-	      udp_packets++;
-	    }
-	  else
-	    {
-	      if (!vnet_buffer (b1)->ip.reass.is_non_first_fragment)
-		{
-		  if (PREDICT_FALSE (is_twice_nat_session (s1)))
-		    {
-		      udp1->dst_port = s1->in2out.port;
-		      if (is_twice_nat_session (s1))
-			{
-			  udp1->src_port = s1->ext_host_nat_port;
-			  ip1->src_address.as_u32 =
-			    s1->ext_host_nat_addr.as_u32;
-			}
-		      udp1->checksum = 0;
-		    }
-		}
-	      udp_packets++;
-	    }
+static inline uword
+nat44_ed_out2in_slow_path_node_fn_inline (vlib_main_t * vm,
+					  vlib_node_runtime_t * node,
+					  vlib_frame_t * frame)
+{
+  u32 n_left_from, *from, *to_next, pkts_processed = 0, stats_node_index;
+  nat_next_t next_index;
+  snat_main_t *sm = &snat_main;
+  f64 now = vlib_time_now (vm);
+  u32 thread_index = vm->thread_index;
+  snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
+  u32 tcp_packets = 0, udp_packets = 0, icmp_packets = 0, other_packets =
+    0, fragments = 0;
 
-	  /* Accounting */
-	  nat44_session_update_counters (s1, now,
-					 vlib_buffer_length_in_chain (vm, b1),
-					 thread_index);
-	  /* Per-user LRU list maintenance */
-	  nat44_session_update_lru (sm, s1, thread_index);
+  stats_node_index = sm->ed_out2in_slowpath_node_index;
 
-	trace01:
-	  if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
-			     && (b1->flags & VLIB_BUFFER_IS_TRACED)))
-	    {
-	      nat44_ed_out2in_trace_t *t =
-		vlib_add_trace (vm, node, b1, sizeof (*t));
-	      t->is_slow_path = is_slow_path;
-	      t->sw_if_index = sw_if_index1;
-	      t->next_index = next1;
-	      t->session_index = ~0;
-	      if (s1)
-		t->session_index = s1 - tsm->sessions;
-	    }
+  from = vlib_frame_vector_args (frame);
+  n_left_from = frame->n_vectors;
+  next_index = node->cached_next_index;
 
-	  pkts_processed += next1 == nat_buffer_opaque (b1)->arc_next;
+  while (n_left_from > 0)
+    {
+      u32 n_left_to_next;
 
-	  /* verify speculative enqueues, maybe switch current next frame */
-	  vlib_validate_buffer_enqueue_x2 (vm, node, next_index,
-					   to_next, n_left_to_next,
-					   bi0, bi1, next0, next1);
-	}
+      vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
 
       while (n_left_from > 0 && n_left_to_next > 0)
 	{
@@ -1358,45 +983,27 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
 	  icmp0 = (icmp46_header_t *) udp0;
 	  proto0 = ip_proto_to_snat_proto (ip0->protocol);
 
-	  if (is_slow_path)
+	  if (PREDICT_FALSE (proto0 == ~0))
 	    {
-	      if (PREDICT_FALSE (proto0 == ~0))
-		{
-		  s0 =
-		    nat44_ed_out2in_unknown_proto (sm, b0, ip0, rx_fib_index0,
-						   thread_index, now, vm,
-						   node);
-		  other_packets++;
-		  if (!sm->forwarding_enabled)
-		    {
-		      if (!s0)
-			next0 = NAT_NEXT_DROP;
-		      goto trace0;
-		    }
-		}
-
-	      if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
+	      s0 =
+		nat44_ed_out2in_unknown_proto (sm, b0, ip0, rx_fib_index0,
+					       thread_index, now, vm, node);
+	      other_packets++;
+	      if (!sm->forwarding_enabled)
 		{
-		  next0 = icmp_out2in_ed_slow_path
-		    (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, node,
-		     next0, now, thread_index, &s0);
-		  icmp_packets++;
+		  if (!s0)
+		    next0 = NAT_NEXT_DROP;
 		  goto trace0;
 		}
 	    }
-	  else
-	    {
-	      if (PREDICT_FALSE (proto0 == ~0))
-		{
-		  next0 = NAT_NEXT_OUT2IN_ED_SLOW_PATH;
-		  goto trace0;
-		}
 
-	      if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
-		{
-		  next0 = NAT_NEXT_OUT2IN_ED_SLOW_PATH;
-		  goto trace0;
-		}
+	  if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
+	    {
+	      next0 = icmp_out2in_ed_slow_path
+		(sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, node,
+		 next0, now, thread_index, &s0);
+	      icmp_packets++;
+	      goto trace0;
 	    }
 
 	  make_ed_kv (&kv0, &ip0->dst_address, &ip0->src_address,
@@ -1406,87 +1013,80 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
 
 	  if (clib_bihash_search_16_8 (&tsm->out2in_ed, &kv0, &value0))
 	    {
-	      if (is_slow_path)
+	      /* Try to match static mapping by external address and port,
+	         destination address and port in packet */
+	      e_key0.addr = ip0->dst_address;
+	      e_key0.port = vnet_buffer (b0)->ip.reass.l4_dst_port;
+	      e_key0.protocol = proto0;
+	      e_key0.fib_index = rx_fib_index0;
+
+	      if (snat_static_mapping_match (sm, e_key0, &l_key0, 1, 0,
+					     &twice_nat0, &lb_nat0,
+					     &ip0->src_address,
+					     &identity_nat0))
 		{
-		  /* Try to match static mapping by external address and port,
-		     destination address and port in packet */
-		  e_key0.addr = ip0->dst_address;
-		  e_key0.port = vnet_buffer (b0)->ip.reass.l4_dst_port;
-		  e_key0.protocol = proto0;
-		  e_key0.fib_index = rx_fib_index0;
-		  if (snat_static_mapping_match (sm, e_key0, &l_key0, 1, 0,
-						 &twice_nat0, &lb_nat0,
-						 &ip0->src_address,
-						 &identity_nat0))
+		  /*
+		   * Send DHCP packets to the ipv4 stack, or we won't
+		   * be able to use dhcp client on the outside interface
+		   */
+		  if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_UDP
+				     && (vnet_buffer (b0)->ip.
+					 reass.l4_dst_port ==
+					 clib_host_to_net_u16
+					 (UDP_DST_PORT_dhcp_to_client))))
 		    {
-		      /*
-		       * Send DHCP packets to the ipv4 stack, or we won't
-		       * be able to use dhcp client on the outside interface
-		       */
-		      if (PREDICT_FALSE
-			  (proto0 == SNAT_PROTOCOL_UDP
-			   && (vnet_buffer (b0)->ip.reass.l4_dst_port ==
-			       clib_host_to_net_u16
-			       (UDP_DST_PORT_dhcp_to_client))))
-			{
-			  goto trace0;
-			}
-
-		      if (!sm->forwarding_enabled)
-			{
-			  b0->error =
-			    node->errors[NAT_OUT2IN_ED_ERROR_NO_TRANSLATION];
-			  next0 = NAT_NEXT_DROP;
-			}
-		      else
-			{
-			  if (next_src_nat
-			      (sm, ip0, ip0->protocol,
-			       vnet_buffer (b0)->ip.reass.l4_src_port,
-			       vnet_buffer (b0)->ip.reass.l4_dst_port,
-			       thread_index, rx_fib_index0))
-			    {
-			      next0 = NAT_NEXT_IN2OUT_ED_FAST_PATH;
-			      goto trace0;
-			    }
-			  if (sm->num_workers > 1)
-			    create_bypass_for_fwd_worker (sm, b0, ip0,
-							  rx_fib_index0);
-			  else
-			    create_bypass_for_fwd (sm, b0, ip0, rx_fib_index0,
-						   thread_index);
-			}
 		      goto trace0;
 		    }
 
-		  if (PREDICT_FALSE (identity_nat0))
-		    goto trace0;
-
-		  if ((proto0 == SNAT_PROTOCOL_TCP)
-		      && !tcp_flags_is_init (vnet_buffer (b0)->ip.
-					     reass.icmp_type_or_tcp_flags))
+		  if (!sm->forwarding_enabled)
 		    {
-		      b0->error = node->errors[NAT_OUT2IN_ED_ERROR_NON_SYN];
+		      b0->error =
+			node->errors[NAT_OUT2IN_ED_ERROR_NO_TRANSLATION];
 		      next0 = NAT_NEXT_DROP;
-		      goto trace0;
 		    }
-
-		  /* Create session initiated by host from external network */
-		  s0 = create_session_for_static_mapping_ed (sm, b0, l_key0,
-							     e_key0, node,
-							     thread_index,
-							     twice_nat0,
-							     lb_nat0, now);
-
-		  if (!s0)
+		  else
 		    {
-		      next0 = NAT_NEXT_DROP;
-		      goto trace0;
+		      if (next_src_nat (sm, ip0, ip0->protocol,
+					vnet_buffer (b0)->ip.
+					reass.l4_src_port,
+					vnet_buffer (b0)->ip.
+					reass.l4_dst_port, thread_index,
+					rx_fib_index0))
+			{
+			  next0 = NAT_NEXT_IN2OUT_ED_FAST_PATH;
+			  goto trace0;
+			}
+		      if (sm->num_workers > 1)
+			create_bypass_for_fwd_worker (sm, b0, ip0,
+						      rx_fib_index0);
+		      else
+			create_bypass_for_fwd (sm, b0, ip0, rx_fib_index0,
+					       thread_index);
 		    }
+		  goto trace0;
 		}
-	      else
+
+	      if (PREDICT_FALSE (identity_nat0))
+		goto trace0;
+
+	      if ((proto0 == SNAT_PROTOCOL_TCP)
+		  && !tcp_flags_is_init (vnet_buffer (b0)->ip.
+					 reass.icmp_type_or_tcp_flags))
+		{
+		  b0->error = node->errors[NAT_OUT2IN_ED_ERROR_NON_SYN];
+		  next0 = NAT_NEXT_DROP;
+		  goto trace0;
+		}
+
+	      /* Create session initiated by host from external network */
+	      s0 = create_session_for_static_mapping_ed (sm, b0, l_key0,
+							 e_key0, node,
+							 thread_index,
+							 twice_nat0,
+							 lb_nat0, now);
+	      if (!s0)
 		{
-		  next0 = NAT_NEXT_OUT2IN_ED_SLOW_PATH;
+		  next0 = NAT_NEXT_DROP;
 		  goto trace0;
 		}
 	    }
@@ -1597,12 +1197,14 @@ nat44_ed_out2in_node_fn_inline (vlib_main_t * vm,
 	    {
 	      nat44_ed_out2in_trace_t *t =
 		vlib_add_trace (vm, node, b0, sizeof (*t));
-	      t->is_slow_path = is_slow_path;
 	      t->sw_if_index = sw_if_index0;
 	      t->next_index = next0;
-	      t->session_index = ~0;
+	      t->is_slow_path = 1;
+
 	      if (s0)
 		t->session_index = s0 - tsm->sessions;
+	      else
+		t->session_index = ~0;
 	    }
 
 	  pkts_processed += next0 == nat_buffer_opaque (b0)->arc_next;
@@ -1637,7 +1239,7 @@ VLIB_NODE_FN (nat44_ed_out2in_node) (vlib_main_t * vm,
 				     vlib_node_runtime_t * node,
 				     vlib_frame_t * frame)
 {
-  return nat44_ed_out2in_node_fn_inline (vm, node, frame, 0);
+  return nat44_ed_out2in_fast_path_node_fn_inline (vm, node, frame);
 }
 
 /* *INDENT-OFF* */
@@ -1657,7 +1259,7 @@ VLIB_NODE_FN (nat44_ed_out2in_slowpath_node) (vlib_main_t * vm,
 					      vlib_node_runtime_t * node,
 					      vlib_frame_t * frame)
 {
-  return nat44_ed_out2in_node_fn_inline (vm, node, frame, 1);
+  return nat44_ed_out2in_slow_path_node_fn_inline (vm, node, frame);
 }
 
 /* *INDENT-OFF* */