ip: use IPv6 flowlabel in flow hash computation
[vpp.git] / src / vnet / ip / ip4_forward.c
index 985db21..332c483 100644 (file)
 #include <vnet/fib/fib_entry.h>        /* for FIB table and entry creation */
 #include <vnet/fib/fib_urpf_list.h>    /* for FIB uRPF check */
 #include <vnet/fib/ip4_fib.h>
+#include <vnet/mfib/ip4_mfib.h>
 #include <vnet/dpo/load_balance.h>
 #include <vnet/dpo/load_balance_map.h>
 #include <vnet/dpo/classify_dpo.h>
 #include <vnet/mfib/mfib_table.h>      /* for mFIB table and entry creation */
+#include <vnet/adj/adj_dp.h>
 
 #include <vnet/ip/ip4_forward.h>
 #include <vnet/interface_output.h>
+#include <vnet/classify/vnet_classify.h>
 
 /** @brief IPv4 lookup node.
     @node ip4-lookup
 VLIB_NODE_FN (ip4_lookup_node) (vlib_main_t * vm, vlib_node_runtime_t * node,
                                vlib_frame_t * frame)
 {
-  return ip4_lookup_inline (vm, node, frame,
-                           /* lookup_for_responses_to_locally_received_packets */
-                           0);
-
+  return ip4_lookup_inline (vm, node, frame);
 }
 
 static u8 *format_ip4_lookup_trace (u8 * s, va_list * args);
@@ -116,182 +116,149 @@ VLIB_NODE_FN (ip4_load_balance_node) (vlib_main_t * vm,
                                      vlib_frame_t * frame)
 {
   vlib_combined_counter_main_t *cm = &load_balance_main.lbm_via_counters;
-  u32 n_left_from, n_left_to_next, *from, *to_next;
-  ip_lookup_next_t next;
+  u32 n_left, *from;
   u32 thread_index = vm->thread_index;
+  vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b = bufs;
+  u16 nexts[VLIB_FRAME_SIZE], *next;
 
   from = vlib_frame_vector_args (frame);
-  n_left_from = frame->n_vectors;
-  next = node->cached_next_index;
-
-  while (n_left_from > 0)
-    {
-      vlib_get_next_frame (vm, node, next, to_next, n_left_to_next);
-
-
-      while (n_left_from >= 4 && n_left_to_next >= 2)
-       {
-         ip_lookup_next_t next0, next1;
-         const load_balance_t *lb0, *lb1;
-         vlib_buffer_t *p0, *p1;
-         u32 pi0, lbi0, hc0, pi1, lbi1, hc1;
-         const ip4_header_t *ip0, *ip1;
-         const dpo_id_t *dpo0, *dpo1;
-
-         /* 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, STORE);
-           vlib_prefetch_buffer_header (p3, STORE);
+  n_left = frame->n_vectors;
+  next = nexts;
 
-           CLIB_PREFETCH (p2->data, sizeof (ip0[0]), STORE);
-           CLIB_PREFETCH (p3->data, sizeof (ip0[0]), STORE);
-         }
+  vlib_get_buffers (vm, from, bufs, n_left);
 
-         pi0 = to_next[0] = from[0];
-         pi1 = to_next[1] = from[1];
+  while (n_left >= 4)
+    {
+      const load_balance_t *lb0, *lb1;
+      const ip4_header_t *ip0, *ip1;
+      u32 lbi0, hc0, lbi1, hc1;
+      const dpo_id_t *dpo0, *dpo1;
 
-         from += 2;
-         n_left_from -= 2;
-         to_next += 2;
-         n_left_to_next -= 2;
+      /* Prefetch next iteration. */
+      {
+       vlib_prefetch_buffer_header (b[2], LOAD);
+       vlib_prefetch_buffer_header (b[3], LOAD);
 
-         p0 = vlib_get_buffer (vm, pi0);
-         p1 = vlib_get_buffer (vm, pi1);
+       CLIB_PREFETCH (b[2]->data, sizeof (ip0[0]), LOAD);
+       CLIB_PREFETCH (b[3]->data, sizeof (ip0[0]), LOAD);
+      }
 
-         ip0 = vlib_buffer_get_current (p0);
-         ip1 = vlib_buffer_get_current (p1);
-         lbi0 = vnet_buffer (p0)->ip.adj_index[VLIB_TX];
-         lbi1 = vnet_buffer (p1)->ip.adj_index[VLIB_TX];
+      ip0 = vlib_buffer_get_current (b[0]);
+      ip1 = vlib_buffer_get_current (b[1]);
+      lbi0 = vnet_buffer (b[0])->ip.adj_index[VLIB_TX];
+      lbi1 = vnet_buffer (b[1])->ip.adj_index[VLIB_TX];
 
-         lb0 = load_balance_get (lbi0);
-         lb1 = load_balance_get (lbi1);
+      lb0 = load_balance_get (lbi0);
+      lb1 = load_balance_get (lbi1);
 
-         /*
-          * this node is for via FIBs we can re-use the hash value from the
-          * to node if present.
-          * We don't want to use the same hash value at each level in the recursion
-          * graph as that would lead to polarisation
-          */
-         hc0 = hc1 = 0;
+      /*
+       * this node is for via FIBs we can re-use the hash value from the
+       * to node if present.
+       * We don't want to use the same hash value at each level in the recursion
+       * graph as that would lead to polarisation
+       */
+      hc0 = hc1 = 0;
 
-         if (PREDICT_FALSE (lb0->lb_n_buckets > 1))
+      if (PREDICT_FALSE (lb0->lb_n_buckets > 1))
+       {
+         if (PREDICT_TRUE (vnet_buffer (b[0])->ip.flow_hash))
            {
-             if (PREDICT_TRUE (vnet_buffer (p0)->ip.flow_hash))
-               {
-                 hc0 = vnet_buffer (p0)->ip.flow_hash =
-                   vnet_buffer (p0)->ip.flow_hash >> 1;
-               }
-             else
-               {
-                 hc0 = vnet_buffer (p0)->ip.flow_hash =
-                   ip4_compute_flow_hash (ip0, lb0->lb_hash_config);
-               }
-             dpo0 = load_balance_get_fwd_bucket
-               (lb0, (hc0 & (lb0->lb_n_buckets_minus_1)));
+             hc0 = vnet_buffer (b[0])->ip.flow_hash =
+               vnet_buffer (b[0])->ip.flow_hash >> 1;
            }
          else
            {
-             dpo0 = load_balance_get_bucket_i (lb0, 0);
+             hc0 = vnet_buffer (b[0])->ip.flow_hash =
+               ip4_compute_flow_hash (ip0, lb0->lb_hash_config);
            }
-         if (PREDICT_FALSE (lb1->lb_n_buckets > 1))
+         dpo0 = load_balance_get_fwd_bucket
+           (lb0, (hc0 & (lb0->lb_n_buckets_minus_1)));
+       }
+      else
+       {
+         dpo0 = load_balance_get_bucket_i (lb0, 0);
+       }
+      if (PREDICT_FALSE (lb1->lb_n_buckets > 1))
+       {
+         if (PREDICT_TRUE (vnet_buffer (b[1])->ip.flow_hash))
            {
-             if (PREDICT_TRUE (vnet_buffer (p1)->ip.flow_hash))
-               {
-                 hc1 = vnet_buffer (p1)->ip.flow_hash =
-                   vnet_buffer (p1)->ip.flow_hash >> 1;
-               }
-             else
-               {
-                 hc1 = vnet_buffer (p1)->ip.flow_hash =
-                   ip4_compute_flow_hash (ip1, lb1->lb_hash_config);
-               }
-             dpo1 = load_balance_get_fwd_bucket
-               (lb1, (hc1 & (lb1->lb_n_buckets_minus_1)));
+             hc1 = vnet_buffer (b[1])->ip.flow_hash =
+               vnet_buffer (b[1])->ip.flow_hash >> 1;
            }
          else
            {
-             dpo1 = load_balance_get_bucket_i (lb1, 0);
+             hc1 = vnet_buffer (b[1])->ip.flow_hash =
+               ip4_compute_flow_hash (ip1, lb1->lb_hash_config);
            }
+         dpo1 = load_balance_get_fwd_bucket
+           (lb1, (hc1 & (lb1->lb_n_buckets_minus_1)));
+       }
+      else
+       {
+         dpo1 = load_balance_get_bucket_i (lb1, 0);
+       }
 
-         next0 = dpo0->dpoi_next_node;
-         next1 = dpo1->dpoi_next_node;
-
-         vnet_buffer (p0)->ip.adj_index[VLIB_TX] = dpo0->dpoi_index;
-         vnet_buffer (p1)->ip.adj_index[VLIB_TX] = dpo1->dpoi_index;
-
-         vlib_increment_combined_counter
-           (cm, thread_index, lbi0, 1, vlib_buffer_length_in_chain (vm, p0));
-         vlib_increment_combined_counter
-           (cm, thread_index, lbi1, 1, vlib_buffer_length_in_chain (vm, p1));
+      next[0] = dpo0->dpoi_next_node;
+      next[1] = dpo1->dpoi_next_node;
 
-         vlib_validate_buffer_enqueue_x2 (vm, node, next,
-                                          to_next, n_left_to_next,
-                                          pi0, pi1, next0, next1);
-       }
+      vnet_buffer (b[0])->ip.adj_index[VLIB_TX] = dpo0->dpoi_index;
+      vnet_buffer (b[1])->ip.adj_index[VLIB_TX] = dpo1->dpoi_index;
 
-      while (n_left_from > 0 && n_left_to_next > 0)
-       {
-         ip_lookup_next_t next0;
-         const load_balance_t *lb0;
-         vlib_buffer_t *p0;
-         u32 pi0, lbi0, hc0;
-         const ip4_header_t *ip0;
-         const dpo_id_t *dpo0;
+      vlib_increment_combined_counter
+       (cm, thread_index, lbi0, 1, vlib_buffer_length_in_chain (vm, b[0]));
+      vlib_increment_combined_counter
+       (cm, thread_index, lbi1, 1, vlib_buffer_length_in_chain (vm, b[1]));
 
-         pi0 = from[0];
-         to_next[0] = pi0;
-         from += 1;
-         to_next += 1;
-         n_left_to_next -= 1;
-         n_left_from -= 1;
+      b += 2;
+      next += 2;
+      n_left -= 2;
+    }
 
-         p0 = vlib_get_buffer (vm, pi0);
+  while (n_left > 0)
+    {
+      const load_balance_t *lb0;
+      const ip4_header_t *ip0;
+      const dpo_id_t *dpo0;
+      u32 lbi0, hc0;
 
-         ip0 = vlib_buffer_get_current (p0);
-         lbi0 = vnet_buffer (p0)->ip.adj_index[VLIB_TX];
+      ip0 = vlib_buffer_get_current (b[0]);
+      lbi0 = vnet_buffer (b[0])->ip.adj_index[VLIB_TX];
 
-         lb0 = load_balance_get (lbi0);
+      lb0 = load_balance_get (lbi0);
 
-         hc0 = 0;
-         if (PREDICT_FALSE (lb0->lb_n_buckets > 1))
+      hc0 = 0;
+      if (PREDICT_FALSE (lb0->lb_n_buckets > 1))
+       {
+         if (PREDICT_TRUE (vnet_buffer (b[0])->ip.flow_hash))
            {
-             if (PREDICT_TRUE (vnet_buffer (p0)->ip.flow_hash))
-               {
-                 hc0 = vnet_buffer (p0)->ip.flow_hash =
-                   vnet_buffer (p0)->ip.flow_hash >> 1;
-               }
-             else
-               {
-                 hc0 = vnet_buffer (p0)->ip.flow_hash =
-                   ip4_compute_flow_hash (ip0, lb0->lb_hash_config);
-               }
-             dpo0 = load_balance_get_fwd_bucket
-               (lb0, (hc0 & (lb0->lb_n_buckets_minus_1)));
+             hc0 = vnet_buffer (b[0])->ip.flow_hash =
+               vnet_buffer (b[0])->ip.flow_hash >> 1;
            }
          else
            {
-             dpo0 = load_balance_get_bucket_i (lb0, 0);
+             hc0 = vnet_buffer (b[0])->ip.flow_hash =
+               ip4_compute_flow_hash (ip0, lb0->lb_hash_config);
            }
+         dpo0 = load_balance_get_fwd_bucket
+           (lb0, (hc0 & (lb0->lb_n_buckets_minus_1)));
+       }
+      else
+       {
+         dpo0 = load_balance_get_bucket_i (lb0, 0);
+       }
 
-         next0 = dpo0->dpoi_next_node;
-         vnet_buffer (p0)->ip.adj_index[VLIB_TX] = dpo0->dpoi_index;
-
-         vlib_increment_combined_counter
-           (cm, thread_index, lbi0, 1, vlib_buffer_length_in_chain (vm, p0));
+      next[0] = dpo0->dpoi_next_node;
+      vnet_buffer (b[0])->ip.adj_index[VLIB_TX] = dpo0->dpoi_index;
 
-         vlib_validate_buffer_enqueue_x1 (vm, node, next,
-                                          to_next, n_left_to_next,
-                                          pi0, next0);
-       }
+      vlib_increment_combined_counter
+       (cm, thread_index, lbi0, 1, vlib_buffer_length_in_chain (vm, b[0]));
 
-      vlib_put_next_frame (vm, node, next, n_left_to_next);
+      b += 1;
+      next += 1;
+      n_left -= 1;
     }
 
+  vlib_buffer_enqueue_to_next (vm, node, from, nexts, frame->n_vectors);
   if (node->flags & VLIB_NODE_FLAG_TRACE)
     ip4_forward_next_trace (vm, node, frame, VLIB_TX);
 
@@ -333,6 +300,7 @@ ip4_interface_first_address (ip4_main_t * im, u32 sw_if_index,
     *result_ia = result ? ia : 0;
   return result;
 }
+#endif
 
 static void
 ip4_add_subnet_bcast_route (u32 fib_index,
@@ -374,74 +342,122 @@ ip4_add_subnet_bcast_route (u32 fib_index,
 }
 
 static void
-ip4_add_interface_routes (u32 sw_if_index,
-                         ip4_main_t * im, u32 fib_index,
-                         ip_interface_address_t * a)
+ip4_add_interface_prefix_routes (ip4_main_t *im,
+                                u32 sw_if_index,
+                                u32 fib_index,
+                                ip_interface_address_t * a)
 {
   ip_lookup_main_t *lm = &im->lookup_main;
+  ip_interface_prefix_t *if_prefix;
   ip4_address_t *address = ip_interface_address_get_address (lm, a);
-  fib_prefix_t pfx = {
-    .fp_len = a->address_length,
+
+  ip_interface_prefix_key_t key = {
+    .prefix = {
+      .fp_len = a->address_length,
+      .fp_proto = FIB_PROTOCOL_IP4,
+      .fp_addr.ip4.as_u32 = address->as_u32 & im->fib_masks[a->address_length],
+    },
+    .sw_if_index = sw_if_index,
+  };
+
+  fib_prefix_t pfx_special = {
     .fp_proto = FIB_PROTOCOL_IP4,
-    .fp_addr.ip4 = *address,
   };
 
-  if (pfx.fp_len <= 30)
+  /* If prefix already set on interface, just increment ref count & return */
+  if_prefix = ip_get_interface_prefix (lm, &key);
+  if (if_prefix)
     {
-      /* a /30 or shorter - add a glean for the network address */
-      fib_table_entry_update_one_path (fib_index, &pfx,
-                                       FIB_SOURCE_INTERFACE,
-                                       (FIB_ENTRY_FLAG_CONNECTED |
-                                        FIB_ENTRY_FLAG_ATTACHED),
-                                       DPO_PROTO_IP4,
-                                       /* No next-hop address */
-                                       NULL,
-                                       sw_if_index,
-                                       // invalid FIB index
-                                       ~0,
-                                       1,
-                                       // no out-label stack
-                                       NULL,
-                                       FIB_ROUTE_PATH_FLAG_NONE);
-
-      /* Add the two broadcast addresses as drop */
-      fib_prefix_t net_pfx = {
-        .fp_len = 32,
-        .fp_proto = FIB_PROTOCOL_IP4,
-        .fp_addr.ip4.as_u32 = address->as_u32 & im->fib_masks[pfx.fp_len],
-      };
-      if (net_pfx.fp_addr.ip4.as_u32 != pfx.fp_addr.ip4.as_u32)
-        fib_table_entry_special_add(fib_index,
-                                    &net_pfx,
-                                    FIB_SOURCE_INTERFACE,
-                                    (FIB_ENTRY_FLAG_DROP |
-                                     FIB_ENTRY_FLAG_LOOSE_URPF_EXEMPT));
-      net_pfx.fp_addr.ip4.as_u32 |= ~im->fib_masks[pfx.fp_len];
-      if (net_pfx.fp_addr.ip4.as_u32 != pfx.fp_addr.ip4.as_u32)
-        ip4_add_subnet_bcast_route(fib_index, &net_pfx, sw_if_index);
+      if_prefix->ref_count += 1;
+      return;
     }
-  else if (pfx.fp_len == 31)
+
+  /* New prefix - allocate a pool entry, initialize it, add to the hash */
+  pool_get (lm->if_prefix_pool, if_prefix);
+  if_prefix->ref_count = 1;
+  if_prefix->src_ia_index = a - lm->if_address_pool;
+  clib_memcpy (&if_prefix->key, &key, sizeof (key));
+  mhash_set (&lm->prefix_to_if_prefix_index, &key,
+            if_prefix - lm->if_prefix_pool, 0 /* old value */);
+
+  pfx_special.fp_len = a->address_length;
+  pfx_special.fp_addr.ip4.as_u32 = address->as_u32;
+
+  /* set the glean route for the prefix */
+  fib_table_entry_update_one_path (fib_index, &pfx_special,
+                                   FIB_SOURCE_INTERFACE,
+                                   (FIB_ENTRY_FLAG_CONNECTED |
+                                    FIB_ENTRY_FLAG_ATTACHED),
+                                   DPO_PROTO_IP4,
+                                   /* No next-hop address */
+                                   NULL,
+                                   sw_if_index,
+                                   /* invalid FIB index */
+                                   ~0,
+                                   1,
+                                   /* no out-label stack */
+                                   NULL,
+                                   FIB_ROUTE_PATH_FLAG_NONE);
+
+  /* length <= 30 - add glean, drop first address, maybe drop bcast address */
+  if (a->address_length <= 30)
     {
-      u32 mask = clib_host_to_net_u32(1);
-      fib_prefix_t net_pfx = pfx;
+      /* set a drop route for the base address of the prefix */
+      pfx_special.fp_len = 32;
+      pfx_special.fp_addr.ip4.as_u32 =
+       address->as_u32 & im->fib_masks[a->address_length];
 
-      net_pfx.fp_len = 32;
-      net_pfx.fp_addr.ip4.as_u32 ^= mask;
+      if (pfx_special.fp_addr.ip4.as_u32 != address->as_u32)
+       fib_table_entry_special_add (fib_index, &pfx_special,
+                                    FIB_SOURCE_INTERFACE,
+                                    (FIB_ENTRY_FLAG_DROP |
+                                     FIB_ENTRY_FLAG_LOOSE_URPF_EXEMPT));
 
-      /* a /31 - add the other end as an attached host */
-      fib_table_entry_update_one_path (fib_index, &net_pfx,
-                                       FIB_SOURCE_INTERFACE,
-                                       (FIB_ENTRY_FLAG_ATTACHED),
-                                       DPO_PROTO_IP4,
-                                       &net_pfx.fp_addr,
-                                       sw_if_index,
-                                       // invalid FIB index
+      /* set a route for the broadcast address of the prefix */
+      pfx_special.fp_len = 32;
+      pfx_special.fp_addr.ip4.as_u32 =
+       address->as_u32 | ~im->fib_masks[a->address_length];
+      if (pfx_special.fp_addr.ip4.as_u32 != address->as_u32)
+       ip4_add_subnet_bcast_route (fib_index, &pfx_special, sw_if_index);
+
+
+    }
+  /* length == 31 - add an attached route for the other address */
+  else if (a->address_length == 31)
+    {
+      pfx_special.fp_len = 32;
+      pfx_special.fp_addr.ip4.as_u32 =
+       address->as_u32 ^ clib_host_to_net_u32(1);
+
+      fib_table_entry_update_one_path (fib_index, &pfx_special,
+                                      FIB_SOURCE_INTERFACE,
+                                      (FIB_ENTRY_FLAG_ATTACHED),
+                                      DPO_PROTO_IP4,
+                                      &pfx_special.fp_addr,
+                                      sw_if_index,
+                                       /* invalid FIB index */
                                        ~0,
                                        1,
                                        NULL,
                                        FIB_ROUTE_PATH_FLAG_NONE);
     }
-  pfx.fp_len = 32;
+}
+
+static void
+ip4_add_interface_routes (u32 sw_if_index,
+                         ip4_main_t * im, u32 fib_index,
+                         ip_interface_address_t * a)
+{
+  ip_lookup_main_t *lm = &im->lookup_main;
+  ip4_address_t *address = ip_interface_address_get_address (lm, a);
+  fib_prefix_t pfx = {
+    .fp_len = 32,
+    .fp_proto = FIB_PROTOCOL_IP4,
+    .fp_addr.ip4 = *address,
+  };
+
+  /* set special routes for the prefix if needed */
+  ip4_add_interface_prefix_routes (im, sw_if_index, fib_index, a);
 
   if (sw_if_index < vec_len (lm->classify_table_index_by_sw_if_index))
     {
@@ -478,53 +494,115 @@ ip4_add_interface_routes (u32 sw_if_index,
 }
 
 static void
-ip4_del_interface_routes (ip4_main_t * im,
-                         u32 fib_index,
-                         ip4_address_t * address, u32 address_length)
+ip4_del_interface_prefix_routes (ip4_main_t * im,
+                                u32 sw_if_index,
+                                u32 fib_index,
+                                ip4_address_t * address,
+                                u32 address_length)
 {
-  fib_prefix_t pfx = {
-    .fp_len = address_length,
+  ip_lookup_main_t *lm = &im->lookup_main;
+  ip_interface_prefix_t *if_prefix;
+
+  ip_interface_prefix_key_t key = {
+    .prefix = {
+      .fp_len = address_length,
+      .fp_proto = FIB_PROTOCOL_IP4,
+      .fp_addr.ip4.as_u32 = address->as_u32 & im->fib_masks[address_length],
+    },
+    .sw_if_index = sw_if_index,
+  };
+
+  fib_prefix_t pfx_special = {
+    .fp_len = 32,
     .fp_proto = FIB_PROTOCOL_IP4,
-    .fp_addr.ip4 = *address,
   };
 
-  if (pfx.fp_len <= 30)
+  if_prefix = ip_get_interface_prefix (lm, &key);
+  if (!if_prefix)
     {
-      fib_prefix_t net_pfx = {
-        .fp_len = 32,
-        .fp_proto = FIB_PROTOCOL_IP4,
-        .fp_addr.ip4.as_u32 = address->as_u32 & im->fib_masks[pfx.fp_len],
-      };
-      if (net_pfx.fp_addr.ip4.as_u32 != pfx.fp_addr.ip4.as_u32)
-        fib_table_entry_special_remove(fib_index,
-                                       &net_pfx,
-                                       FIB_SOURCE_INTERFACE);
-      net_pfx.fp_addr.ip4.as_u32 |= ~im->fib_masks[pfx.fp_len];
-      if (net_pfx.fp_addr.ip4.as_u32 != pfx.fp_addr.ip4.as_u32)
-        fib_table_entry_special_remove(fib_index,
-                                       &net_pfx,
-                                       FIB_SOURCE_INTERFACE);
-      fib_table_entry_delete (fib_index, &pfx, FIB_SOURCE_INTERFACE);
+      clib_warning ("Prefix not found while deleting %U",
+                   format_ip4_address_and_length, address, address_length);
+      return;
     }
-    else if (pfx.fp_len == 31)
-    {
-      u32 mask = clib_host_to_net_u32(1);
-      fib_prefix_t net_pfx = pfx;
 
-      net_pfx.fp_len = 32;
-      net_pfx.fp_addr.ip4.as_u32 ^= mask;
+  if_prefix->ref_count -= 1;
+
+  /*
+   * Routes need to be adjusted if deleting last intf addr in prefix
+   *
+   * We're done now otherwise
+   */
+  if (if_prefix->ref_count > 0)
+    return;
+
+  /* length <= 30, delete glean route, first address, last address */
+  if (address_length <= 30)
+    {
+      /* Less work to do in FIB if we remove the covered /32s first */
+
+      /* first address in prefix */
+      pfx_special.fp_addr.ip4.as_u32 =
+        address->as_u32 & im->fib_masks[address_length];
+      pfx_special.fp_len = 32;
+
+      if (pfx_special.fp_addr.ip4.as_u32 != address->as_u32)
+        fib_table_entry_special_remove (fib_index,
+                                        &pfx_special,
+                                        FIB_SOURCE_INTERFACE);
+
+      /* prefix broadcast address */
+      pfx_special.fp_addr.ip4.as_u32 =
+        address->as_u32 | ~im->fib_masks[address_length];
+      pfx_special.fp_len = 32;
+
+      if (pfx_special.fp_addr.ip4.as_u32 != address->as_u32)
+        fib_table_entry_special_remove (fib_index,
+                                        &pfx_special,
+                                        FIB_SOURCE_INTERFACE);
+    }
+  else if (address_length == 31)
+    {
+      /* length == 31, delete attached route for the other address */
+      pfx_special.fp_addr.ip4.as_u32 =
+       address->as_u32 ^ clib_host_to_net_u32(1);
 
-      fib_table_entry_delete (fib_index, &net_pfx, FIB_SOURCE_INTERFACE);
+      fib_table_entry_delete (fib_index, &pfx_special, FIB_SOURCE_INTERFACE);
     }
 
-  pfx.fp_len = 32;
+  /* remove glean route for prefix */
+  pfx_special.fp_addr.ip4 = *address;
+  pfx_special.fp_len = address_length;
+  fib_table_entry_delete (fib_index, &pfx_special, FIB_SOURCE_INTERFACE);
+
+  mhash_unset (&lm->prefix_to_if_prefix_index, &key, 0 /* old_value */);
+  pool_put (lm->if_prefix_pool, if_prefix);
+}
+
+static void
+ip4_del_interface_routes (u32 sw_if_index,
+                         ip4_main_t * im,
+                         u32 fib_index,
+                         ip4_address_t * address, u32 address_length)
+{
+  fib_prefix_t pfx = {
+    .fp_len = 32,
+    .fp_proto = FIB_PROTOCOL_IP4,
+    .fp_addr.ip4 = *address,
+  };
+
   fib_table_entry_delete (fib_index, &pfx, FIB_SOURCE_INTERFACE);
+
+  ip4_del_interface_prefix_routes (im, sw_if_index, fib_index,
+                                  address, address_length);
 }
 
+#ifndef CLIB_MARCH_VARIANT
 void
 ip4_sw_interface_enable_disable (u32 sw_if_index, u32 is_enable)
 {
   ip4_main_t *im = &ip4_main;
+  vnet_main_t *vnm = vnet_get_main ();
+  vnet_hw_interface_t *hi = vnet_get_sup_hw_interface (vnm, sw_if_index);
 
   vec_validate_init_empty (im->ip_enabled_by_sw_if_index, sw_if_index, 0);
 
@@ -548,6 +626,17 @@ ip4_sw_interface_enable_disable (u32 sw_if_index, u32 is_enable)
 
   vnet_feature_enable_disable ("ip4-multicast", "ip4-not-enabled",
                               sw_if_index, !is_enable, 0, 0);
+
+  if (is_enable)
+    hi->l3_if_count++;
+  else if (hi->l3_if_count)
+    hi->l3_if_count--;
+
+  {
+    ip4_enable_disable_interface_callback_t *cb;
+    vec_foreach (cb, im->enable_disable_interface_callbacks)
+      cb->function (im, cb->function_opaque, sw_if_index, is_enable);
+  }
 }
 
 static clib_error_t *
@@ -560,7 +649,7 @@ ip4_add_del_interface_address_internal (vlib_main_t * vm,
   ip4_main_t *im = &ip4_main;
   ip_lookup_main_t *lm = &im->lookup_main;
   clib_error_t *error = 0;
-  u32 if_address_index, elts_before;
+  u32 if_address_index;
   ip4_address_fib_t ip4_af, *addr_fib = 0;
 
   /* local0 interface doesn't support IP addressing  */
@@ -588,8 +677,8 @@ ip4_add_del_interface_address_internal (vlib_main_t * vm,
       ip_interface_address_t *ia;
       vnet_sw_interface_t *sif;
 
-      pool_foreach(sif, vnm->interface_main.sw_interfaces,
-      ({
+      pool_foreach (sif, vnm->interface_main.sw_interfaces)
+       {
           if (im->fib_index_by_sw_if_index[sw_if_index] ==
               im->fib_index_by_sw_if_index[sif->sw_if_index])
             {
@@ -600,6 +689,7 @@ ip4_add_del_interface_address_internal (vlib_main_t * vm,
                    ip4_address_t * x =
                      ip_interface_address_get_address
                      (&im->lookup_main, ia);
+
                    if (ip4_destination_matches_route
                        (im, address, x, ia->address_length) ||
                        ip4_destination_matches_route (im,
@@ -607,50 +697,133 @@ ip4_add_del_interface_address_internal (vlib_main_t * vm,
                                                       address,
                                                       address_length))
                      {
-                       vnm->api_errno = VNET_API_ERROR_DUPLICATE_IF_ADDRESS;
-
-                       return
-                         clib_error_create
-                         ("failed to add %U which conflicts with %U for interface %U",
+                      /* an intf may have >1 addr from the same prefix */
+                      if ((sw_if_index == sif->sw_if_index) &&
+                          (ia->address_length == address_length) &&
+                          (x->as_u32 != address->as_u32))
+                        continue;
+
+                       if (ia->flags & IP_INTERFACE_ADDRESS_FLAG_STALE)
+                         /* if the address we're comparing against is stale
+                          * then the CP has not added this one back yet, maybe
+                          * it never will, so we have to assume it won't and
+                          * ignore it. if it does add it back, then it will fail
+                          * because this one is now present */
+                         continue;
+
+                      /* error if the length or intf was different */
+                       vnm->api_errno = VNET_API_ERROR_ADDRESS_IN_USE;
+
+                       error = clib_error_create
+                         ("failed to add %U on %U which conflicts with %U for interface %U",
                           format_ip4_address_and_length, address,
                           address_length,
+                         format_vnet_sw_if_index_name, vnm,
+                         sw_if_index,
                           format_ip4_address_and_length, x,
                           ia->address_length,
                           format_vnet_sw_if_index_name, vnm,
                           sif->sw_if_index);
+                       goto done;
                      }
                  }));
             }
-      }));
+      }
     }
   /* *INDENT-ON* */
 
-  elts_before = pool_elts (lm->if_address_pool);
+  if_address_index = ip_interface_address_find (lm, addr_fib, address_length);
+
+  if (is_del)
+    {
+      if (~0 == if_address_index)
+       {
+         vnm->api_errno = VNET_API_ERROR_ADDRESS_NOT_FOUND_FOR_INTERFACE;
+         error = clib_error_create ("%U not found for interface %U",
+                                    lm->format_address_and_length,
+                                    addr_fib, address_length,
+                                    format_vnet_sw_if_index_name, vnm,
+                                    sw_if_index);
+         goto done;
+       }
+
+      error = ip_interface_address_del (lm, vnm, if_address_index, addr_fib,
+                                       address_length, sw_if_index);
+      if (error)
+       goto done;
+    }
+  else
+    {
+      if (~0 != if_address_index)
+       {
+         ip_interface_address_t *ia;
+
+         ia = pool_elt_at_index (lm->if_address_pool, if_address_index);
+
+         if (ia->flags & IP_INTERFACE_ADDRESS_FLAG_STALE)
+           {
+             if (ia->sw_if_index == sw_if_index)
+               {
+                 /* re-adding an address during the replace action.
+                  * consdier this the update. clear the flag and
+                  * we're done */
+                 ia->flags &= ~IP_INTERFACE_ADDRESS_FLAG_STALE;
+                 goto done;
+               }
+             else
+               {
+                 /* The prefix is moving from one interface to another.
+                  * delete the stale and add the new */
+                 ip4_add_del_interface_address_internal (vm,
+                                                         ia->sw_if_index,
+                                                         address,
+                                                         address_length, 1);
+                 ia = NULL;
+                 error = ip_interface_address_add (lm, sw_if_index,
+                                                   addr_fib, address_length,
+                                                   &if_address_index);
+               }
+           }
+         else
+           {
+             vnm->api_errno = VNET_API_ERROR_DUPLICATE_IF_ADDRESS;
+             error = clib_error_create
+               ("Prefix %U already found on interface %U",
+                lm->format_address_and_length, addr_fib, address_length,
+                format_vnet_sw_if_index_name, vnm, ia->sw_if_index);
+           }
+       }
+      else
+       error = ip_interface_address_add (lm, sw_if_index,
+                                         addr_fib, address_length,
+                                         &if_address_index);
+    }
 
-  error = ip_interface_address_add_del
-    (lm, sw_if_index, addr_fib, address_length, is_del, &if_address_index);
   if (error)
     goto done;
 
   ip4_sw_interface_enable_disable (sw_if_index, !is_del);
+  ip4_mfib_interface_enable_disable (sw_if_index, !is_del);
 
-  if (is_del)
-    ip4_del_interface_routes (im, ip4_af.fib_index, address, address_length);
-  else
-    ip4_add_interface_routes (sw_if_index,
-                             im, ip4_af.fib_index,
-                             pool_elt_at_index
-                             (lm->if_address_pool, if_address_index));
-
-  /* If pool did not grow/shrink: add duplicate address. */
-  if (elts_before != pool_elts (lm->if_address_pool))
+  /* intf addr routes are added/deleted on admin up/down */
+  if (vnet_sw_interface_is_admin_up (vnm, sw_if_index))
     {
-      ip4_add_del_interface_address_callback_t *cb;
-      vec_foreach (cb, im->add_del_interface_address_callbacks)
-       cb->function (im, cb->function_opaque, sw_if_index,
-                     address, address_length, if_address_index, is_del);
+      if (is_del)
+       ip4_del_interface_routes (sw_if_index,
+                                 im, ip4_af.fib_index, address,
+                                 address_length);
+      else
+       ip4_add_interface_routes (sw_if_index,
+                                 im, ip4_af.fib_index,
+                                 pool_elt_at_index
+                                 (lm->if_address_pool, if_address_index));
     }
 
+  ip4_add_del_interface_address_callback_t *cb;
+  vec_foreach (cb, im->add_del_interface_address_callbacks)
+    cb->function (im, cb->function_opaque, sw_if_index,
+                 address, address_length, if_address_index, is_del);
+
 done:
   vec_free (addr_fib);
   return error;
@@ -706,6 +879,46 @@ ip4_directed_broadcast (u32 sw_if_index, u8 enable)
 }
 #endif
 
+static clib_error_t *
+ip4_sw_interface_admin_up_down (vnet_main_t * vnm, u32 sw_if_index, u32 flags)
+{
+  ip4_main_t *im = &ip4_main;
+  ip_interface_address_t *ia;
+  ip4_address_t *a;
+  u32 is_admin_up, fib_index;
+
+  /* Fill in lookup tables with default table (0). */
+  vec_validate (im->fib_index_by_sw_if_index, sw_if_index);
+
+  vec_validate_init_empty (im->
+                          lookup_main.if_address_pool_index_by_sw_if_index,
+                          sw_if_index, ~0);
+
+  is_admin_up = (flags & VNET_SW_INTERFACE_FLAG_ADMIN_UP) != 0;
+
+  fib_index = vec_elt (im->fib_index_by_sw_if_index, sw_if_index);
+
+  /* *INDENT-OFF* */
+  foreach_ip_interface_address (&im->lookup_main, ia, sw_if_index,
+                                0 /* honor unnumbered */,
+  ({
+    a = ip_interface_address_get_address (&im->lookup_main, ia);
+    if (is_admin_up)
+      ip4_add_interface_routes (sw_if_index,
+                               im, fib_index,
+                               ia);
+    else
+      ip4_del_interface_routes (sw_if_index,
+                               im, fib_index,
+                               a, ia->address_length);
+  }));
+  /* *INDENT-ON* */
+
+  return 0;
+}
+
+VNET_SW_INTERFACE_ADMIN_UP_DOWN_FUNCTION (ip4_sw_interface_admin_up_down);
+
 /* Built-in ip4 unicast rx feature path definition */
 /* *INDENT-OFF* */
 VNET_FEATURE_ARC_INIT (ip4_unicast, static) =
@@ -727,20 +940,6 @@ VNET_FEATURE_INIT (ip4_inacl, static) =
 {
   .arc_name = "ip4-unicast",
   .node_name = "ip4-inacl",
-  .runs_before = VNET_FEATURES ("ip4-source-check-via-rx"),
-};
-
-VNET_FEATURE_INIT (ip4_source_check_1, static) =
-{
-  .arc_name = "ip4-unicast",
-  .node_name = "ip4-source-check-via-rx",
-  .runs_before = VNET_FEATURES ("ip4-source-check-via-any"),
-};
-
-VNET_FEATURE_INIT (ip4_source_check_2, static) =
-{
-  .arc_name = "ip4-unicast",
-  .node_name = "ip4-source-check-via-any",
   .runs_before = VNET_FEATURES ("ip4-policer-classify"),
 };
 
@@ -887,6 +1086,7 @@ ip4_sw_interface_add_del (vnet_main_t * vnm, u32 sw_if_index, u32 is_add)
         ip4_add_del_interface_address(vm, sw_if_index, address, ia->address_length, 1);
       }));
       /* *INDENT-ON* */
+      ip4_mfib_interface_enable_disable (sw_if_index, 0);
     }
 
   vnet_feature_enable_disable ("ip4-unicast", "ip4-not-enabled", sw_if_index,
@@ -1030,7 +1230,7 @@ format_ip4_rewrite_trace (u8 * s, va_list * args)
   s = format (s, "\n%U%U",
              format_white_space, indent,
              format_ip_adjacency_packet_data,
-             t->dpo_index, t->packet_data, sizeof (t->packet_data));
+             t->packet_data, sizeof (t->packet_data));
   return s;
 }
 
@@ -1130,9 +1330,6 @@ ip4_tcp_udp_compute_checksum (vlib_main_t * vm, vlib_buffer_t * p0,
 {
   ip_csum_t sum0;
   u32 ip_header_length, payload_length_host_byte_order;
-  u32 n_this_buffer, n_bytes_left, n_ip_bytes_this_buffer;
-  u16 sum16;
-  void *data_this_buffer;
 
   /* Initialize checksum with ip header. */
   ip_header_length = ip4_header_bytes (ip0);
@@ -1155,31 +1352,9 @@ ip4_tcp_udp_compute_checksum (vlib_main_t * vm, vlib_buffer_t * p0,
     sum0 =
       ip_csum_with_carry (sum0, clib_mem_unaligned (&ip0->src_address, u64));
 
-  n_bytes_left = n_this_buffer = payload_length_host_byte_order;
-  data_this_buffer = (void *) ip0 + ip_header_length;
-  n_ip_bytes_this_buffer =
-    p0->current_length - (((u8 *) ip0 - p0->data) - p0->current_data);
-  if (n_this_buffer + ip_header_length > n_ip_bytes_this_buffer)
-    {
-      n_this_buffer = n_ip_bytes_this_buffer > ip_header_length ?
-       n_ip_bytes_this_buffer - ip_header_length : 0;
-    }
-  while (1)
-    {
-      sum0 = ip_incremental_checksum (sum0, data_this_buffer, n_this_buffer);
-      n_bytes_left -= n_this_buffer;
-      if (n_bytes_left == 0)
-       break;
-
-      ASSERT (p0->flags & VLIB_BUFFER_NEXT_PRESENT);
-      p0 = vlib_get_buffer (vm, p0->next_buffer);
-      data_this_buffer = vlib_buffer_get_current (p0);
-      n_this_buffer = p0->current_length;
-    }
-
-  sum16 = ~ip_csum_fold (sum0);
-
-  return sum16;
+  return ip_calculate_l4_checksum (vm, p0, sum0,
+                                  payload_length_host_byte_order, (u8 *) ip0,
+                                  ip_header_length, NULL);
 }
 
 u32
@@ -1350,8 +1525,14 @@ ip4_local_check_src (vlib_buffer_t * b, ip4_header_t * ip0,
     vnet_buffer (b)->sw_if_index[VLIB_TX] != ~0 ?
     vnet_buffer (b)->sw_if_index[VLIB_TX] : vnet_buffer (b)->ip.fib_index;
 
-  if (PREDICT_FALSE (last_check->first ||
-                    (last_check->src.as_u32 != ip0->src_address.as_u32)))
+  /*
+   * vnet_buffer()->ip.adj_index[VLIB_RX] will be set to the index of the
+   *  adjacency for the destination address (the local interface address).
+   * vnet_buffer()->ip.adj_index[VLIB_TX] will be set to the index of the
+   *  adjacency for the source address (the remote sender's address)
+   */
+  if (PREDICT_TRUE (last_check->src.as_u32 != ip0->src_address.as_u32) ||
+      last_check->first)
     {
       mtrie0 = &ip4_fib_get (vnet_buffer (b)->ip.fib_index)->mtrie;
       leaf0 = ip4_fib_mtrie_lookup_step_one (mtrie0, &ip0->src_address);
@@ -1359,8 +1540,9 @@ ip4_local_check_src (vlib_buffer_t * b, ip4_header_t * ip0,
       leaf0 = ip4_fib_mtrie_lookup_step (mtrie0, leaf0, &ip0->src_address, 3);
       lbi0 = ip4_fib_mtrie_leaf_get_adj_index (leaf0);
 
+      vnet_buffer (b)->ip.adj_index[VLIB_RX] =
+       vnet_buffer (b)->ip.adj_index[VLIB_TX];
       vnet_buffer (b)->ip.adj_index[VLIB_TX] = lbi0;
-      vnet_buffer (b)->ip.adj_index[VLIB_RX] = lbi0;
 
       lb0 = load_balance_get (lbi0);
       dpo0 = load_balance_get_bucket_i (lb0, 0);
@@ -1387,13 +1569,14 @@ ip4_local_check_src (vlib_buffer_t * b, ip4_header_t * ip0,
       last_check->src.as_u32 = ip0->src_address.as_u32;
       last_check->lbi = lbi0;
       last_check->error = *error0;
+      last_check->first = 0;
     }
   else
     {
+      vnet_buffer (b)->ip.adj_index[VLIB_RX] =
+       vnet_buffer (b)->ip.adj_index[VLIB_TX];
       vnet_buffer (b)->ip.adj_index[VLIB_TX] = last_check->lbi;
-      vnet_buffer (b)->ip.adj_index[VLIB_RX] = last_check->lbi;
       *error0 = last_check->error;
-      last_check->first = 0;
     }
 }
 
@@ -1422,7 +1605,13 @@ ip4_local_check_src_x2 (vlib_buffer_t ** b, ip4_header_t ** ip,
     vnet_buffer (b[1])->sw_if_index[VLIB_TX] :
     vnet_buffer (b[1])->ip.fib_index;
 
-  if (PREDICT_FALSE (not_last_hit))
+  /*
+   * vnet_buffer()->ip.adj_index[VLIB_RX] will be set to the index of the
+   *  adjacency for the destination address (the local interface address).
+   * vnet_buffer()->ip.adj_index[VLIB_TX] will be set to the index of the
+   *  adjacency for the source address (the remote sender's address)
+   */
+  if (PREDICT_TRUE (not_last_hit))
     {
       mtrie[0] = &ip4_fib_get (vnet_buffer (b[0])->ip.fib_index)->mtrie;
       mtrie[1] = &ip4_fib_get (vnet_buffer (b[1])->ip.fib_index)->mtrie;
@@ -1443,11 +1632,13 @@ ip4_local_check_src_x2 (vlib_buffer_t ** b, ip4_header_t ** ip,
       lbi[0] = ip4_fib_mtrie_leaf_get_adj_index (leaf[0]);
       lbi[1] = ip4_fib_mtrie_leaf_get_adj_index (leaf[1]);
 
+      vnet_buffer (b[0])->ip.adj_index[VLIB_RX] =
+       vnet_buffer (b[0])->ip.adj_index[VLIB_TX];
       vnet_buffer (b[0])->ip.adj_index[VLIB_TX] = lbi[0];
-      vnet_buffer (b[0])->ip.adj_index[VLIB_RX] = lbi[0];
 
+      vnet_buffer (b[1])->ip.adj_index[VLIB_RX] =
+       vnet_buffer (b[1])->ip.adj_index[VLIB_TX];
       vnet_buffer (b[1])->ip.adj_index[VLIB_TX] = lbi[1];
-      vnet_buffer (b[1])->ip.adj_index[VLIB_RX] = lbi[1];
 
       lb[0] = load_balance_get (lbi[0]);
       lb[1] = load_balance_get (lbi[1]);
@@ -1474,18 +1665,20 @@ ip4_local_check_src_x2 (vlib_buffer_t ** b, ip4_header_t ** ip,
       last_check->src.as_u32 = ip[1]->src_address.as_u32;
       last_check->lbi = lbi[1];
       last_check->error = error[1];
+      last_check->first = 0;
     }
   else
     {
+      vnet_buffer (b[0])->ip.adj_index[VLIB_RX] =
+       vnet_buffer (b[0])->ip.adj_index[VLIB_TX];
       vnet_buffer (b[0])->ip.adj_index[VLIB_TX] = last_check->lbi;
-      vnet_buffer (b[0])->ip.adj_index[VLIB_RX] = last_check->lbi;
 
+      vnet_buffer (b[1])->ip.adj_index[VLIB_RX] =
+       vnet_buffer (b[1])->ip.adj_index[VLIB_TX];
       vnet_buffer (b[1])->ip.adj_index[VLIB_TX] = last_check->lbi;
-      vnet_buffer (b[1])->ip.adj_index[VLIB_RX] = last_check->lbi;
 
       error[0] = last_check->error;
       error[1] = last_check->error;
-      last_check->first = 0;
     }
 }
 
@@ -1529,7 +1722,7 @@ ip4_local_inline (vlib_main_t * vm,
 {
   u32 *from, n_left_from;
   vlib_node_runtime_t *error_node =
-    vlib_node_get_runtime (vm, ip4_input_node.index);
+    vlib_node_get_runtime (vm, ip4_local_node.index);
   u16 nexts[VLIB_FRAME_SIZE], *next;
   vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b;
   ip4_header_t *ip[2];
@@ -1658,6 +1851,8 @@ VLIB_REGISTER_NODE (ip4_local_node) =
   .name = "ip4-local",
   .vector_size = sizeof (u32),
   .format_trace = format_ip4_forward_next_trace,
+  .n_errors = IP4_N_ERROR,
+  .error_strings = ip4_error_strings,
   .n_next_nodes = IP_LOCAL_N_NEXT,
   .next_nodes =
   {
@@ -1665,7 +1860,7 @@ VLIB_REGISTER_NODE (ip4_local_node) =
     [IP_LOCAL_NEXT_PUNT] = "ip4-punt",
     [IP_LOCAL_NEXT_UDP_LOOKUP] = "ip4-udp-lookup",
     [IP_LOCAL_NEXT_ICMP] = "ip4-icmp-input",
-    [IP_LOCAL_NEXT_REASSEMBLY] = "ip4-reassembly",
+    [IP_LOCAL_NEXT_REASSEMBLY] = "ip4-full-reassembly",
   },
 };
 /* *INDENT-ON* */
@@ -1706,6 +1901,16 @@ ip4_register_protocol (u32 protocol, u32 node_index)
   lm->local_next_by_ip_protocol[protocol] =
     vlib_node_add_next (vm, ip4_local_node.index, node_index);
 }
+
+void
+ip4_unregister_protocol (u32 protocol)
+{
+  ip4_main_t *im = &ip4_main;
+  ip_lookup_main_t *lm = &im->lookup_main;
+
+  ASSERT (protocol < ARRAY_LEN (lm->local_next_by_ip_protocol));
+  lm->local_next_by_ip_protocol[protocol] = IP_LOCAL_NEXT_PUNT;
+}
 #endif
 
 static clib_error_t *
@@ -1724,8 +1929,8 @@ show_ip_local_command_fn (vlib_main_t * vm,
          u32 node_index = vlib_get_node (vm,
                                          ip4_local_node.index)->
            next_nodes[lm->local_next_by_ip_protocol[i]];
-         vlib_cli_output (vm, "%d: %U", i, format_vlib_node_name, vm,
-                          node_index);
+         vlib_cli_output (vm, "%U: %U", format_ip_protocol, i,
+                          format_vlib_node_name, vm, node_index);
        }
     }
   return 0;
@@ -1754,349 +1959,6 @@ VLIB_CLI_COMMAND (show_ip_local, static) =
 };
 /* *INDENT-ON* */
 
-always_inline uword
-ip4_arp_inline (vlib_main_t * vm,
-               vlib_node_runtime_t * node,
-               vlib_frame_t * frame, int is_glean)
-{
-  vnet_main_t *vnm = vnet_get_main ();
-  ip4_main_t *im = &ip4_main;
-  ip_lookup_main_t *lm = &im->lookup_main;
-  u32 *from, *to_next_drop;
-  uword n_left_from, n_left_to_next_drop, next_index;
-  u32 thread_index = vm->thread_index;
-  u64 seed;
-
-  if (node->flags & VLIB_NODE_FLAG_TRACE)
-    ip4_forward_next_trace (vm, node, frame, VLIB_TX);
-
-  seed = throttle_seed (&im->arp_throttle, thread_index, vlib_time_now (vm));
-
-  from = vlib_frame_vector_args (frame);
-  n_left_from = frame->n_vectors;
-  next_index = node->cached_next_index;
-  if (next_index == IP4_ARP_NEXT_DROP)
-    next_index = IP4_ARP_N_NEXT;       /* point to first interface */
-
-  while (n_left_from > 0)
-    {
-      vlib_get_next_frame (vm, node, IP4_ARP_NEXT_DROP,
-                          to_next_drop, n_left_to_next_drop);
-
-      while (n_left_from > 0 && n_left_to_next_drop > 0)
-       {
-         u32 pi0, bi0, adj_index0, sw_if_index0;
-         ip_adjacency_t *adj0;
-         vlib_buffer_t *p0, *b0;
-         ip4_address_t resolve0;
-         ethernet_arp_header_t *h0;
-         vnet_hw_interface_t *hw_if0;
-         u64 r0;
-
-         pi0 = from[0];
-         p0 = vlib_get_buffer (vm, pi0);
-
-         from += 1;
-         n_left_from -= 1;
-         to_next_drop[0] = pi0;
-         to_next_drop += 1;
-         n_left_to_next_drop -= 1;
-
-         adj_index0 = vnet_buffer (p0)->ip.adj_index[VLIB_TX];
-         adj0 = adj_get (adj_index0);
-
-         if (is_glean)
-           {
-             /* resolve the packet's destination */
-             ip4_header_t *ip0 = vlib_buffer_get_current (p0);
-             resolve0 = ip0->dst_address;
-           }
-         else
-           {
-             /* resolve the incomplete adj */
-             resolve0 = adj0->sub_type.nbr.next_hop.ip4;
-           }
-
-         /* combine the address and interface for the hash key */
-         sw_if_index0 = adj0->rewrite_header.sw_if_index;
-         r0 = (u64) resolve0.data_u32 << 32;
-         r0 |= sw_if_index0;
-
-         if (throttle_check (&im->arp_throttle, thread_index, r0, seed))
-           {
-             p0->error = node->errors[IP4_ARP_ERROR_THROTTLED];
-             continue;
-           }
-
-         /*
-          * the adj has been updated to a rewrite but the node the DPO that got
-          * us here hasn't - yet. no big deal. we'll drop while we wait.
-          */
-         if (IP_LOOKUP_NEXT_REWRITE == adj0->lookup_next_index)
-           {
-             p0->error = node->errors[IP4_ARP_ERROR_RESOLVED];
-             continue;
-           }
-
-         /*
-          * Can happen if the control-plane is programming tables
-          * with traffic flowing; at least that's today's lame excuse.
-          */
-         if ((is_glean && adj0->lookup_next_index != IP_LOOKUP_NEXT_GLEAN)
-             || (!is_glean && adj0->lookup_next_index != IP_LOOKUP_NEXT_ARP))
-           {
-             p0->error = node->errors[IP4_ARP_ERROR_NON_ARP_ADJ];
-             continue;
-           }
-         /* Send ARP request. */
-         h0 =
-           vlib_packet_template_get_packet (vm,
-                                            &im->ip4_arp_request_packet_template,
-                                            &bi0);
-         b0 = vlib_get_buffer (vm, bi0);
-
-         /* copy the persistent fields from the original */
-         clib_memcpy_fast (b0->opaque2, p0->opaque2, sizeof (p0->opaque2));
-
-         /* Seems we're out of buffers */
-         if (PREDICT_FALSE (!h0))
-           {
-             p0->error = node->errors[IP4_ARP_ERROR_NO_BUFFERS];
-             continue;
-           }
-
-         /* Add rewrite/encap string for ARP packet. */
-         vnet_rewrite_one_header (adj0[0], h0, sizeof (ethernet_header_t));
-
-         hw_if0 = vnet_get_sup_hw_interface (vnm, sw_if_index0);
-
-         /* Src ethernet address in ARP header. */
-         mac_address_from_bytes (&h0->ip4_over_ethernet[0].mac,
-                                 hw_if0->hw_address);
-         if (is_glean)
-           {
-             /* The interface's source address is stashed in the Glean Adj */
-             h0->ip4_over_ethernet[0].ip4 =
-               adj0->sub_type.glean.receive_addr.ip4;
-           }
-         else
-           {
-             /* Src IP address in ARP header. */
-             if (ip4_src_address_for_packet (lm, sw_if_index0,
-                                             &h0->ip4_over_ethernet[0].ip4))
-               {
-                 /* No source address available */
-                 p0->error = node->errors[IP4_ARP_ERROR_NO_SOURCE_ADDRESS];
-                 vlib_buffer_free (vm, &bi0, 1);
-                 continue;
-               }
-           }
-         h0->ip4_over_ethernet[1].ip4 = resolve0;
-
-         p0->error = node->errors[IP4_ARP_ERROR_REQUEST_SENT];
-
-         vlib_buffer_copy_trace_flag (vm, p0, bi0);
-         VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b0);
-         vnet_buffer (b0)->sw_if_index[VLIB_TX] = sw_if_index0;
-
-         vlib_buffer_advance (b0, -adj0->rewrite_header.data_bytes);
-
-         vlib_set_next_frame_buffer (vm, node,
-                                     adj0->rewrite_header.next_index, bi0);
-       }
-
-      vlib_put_next_frame (vm, node, IP4_ARP_NEXT_DROP, n_left_to_next_drop);
-    }
-
-  return frame->n_vectors;
-}
-
-VLIB_NODE_FN (ip4_arp_node) (vlib_main_t * vm, vlib_node_runtime_t * node,
-                            vlib_frame_t * frame)
-{
-  return (ip4_arp_inline (vm, node, frame, 0));
-}
-
-VLIB_NODE_FN (ip4_glean_node) (vlib_main_t * vm, vlib_node_runtime_t * node,
-                              vlib_frame_t * frame)
-{
-  return (ip4_arp_inline (vm, node, frame, 1));
-}
-
-static char *ip4_arp_error_strings[] = {
-  [IP4_ARP_ERROR_THROTTLED] = "ARP requests throttled",
-  [IP4_ARP_ERROR_RESOLVED] = "ARP requests resolved",
-  [IP4_ARP_ERROR_NO_BUFFERS] = "ARP requests out of buffer",
-  [IP4_ARP_ERROR_REQUEST_SENT] = "ARP requests sent",
-  [IP4_ARP_ERROR_NON_ARP_ADJ] = "ARPs to non-ARP adjacencies",
-  [IP4_ARP_ERROR_NO_SOURCE_ADDRESS] = "no source address for ARP request",
-};
-
-/* *INDENT-OFF* */
-VLIB_REGISTER_NODE (ip4_arp_node) =
-{
-  .name = "ip4-arp",
-  .vector_size = sizeof (u32),
-  .format_trace = format_ip4_forward_next_trace,
-  .n_errors = ARRAY_LEN (ip4_arp_error_strings),
-  .error_strings = ip4_arp_error_strings,
-  .n_next_nodes = IP4_ARP_N_NEXT,
-  .next_nodes =
-  {
-    [IP4_ARP_NEXT_DROP] = "error-drop",
-  },
-};
-
-VLIB_REGISTER_NODE (ip4_glean_node) =
-{
-  .name = "ip4-glean",
-  .vector_size = sizeof (u32),
-  .format_trace = format_ip4_forward_next_trace,
-  .n_errors = ARRAY_LEN (ip4_arp_error_strings),
-  .error_strings = ip4_arp_error_strings,
-  .n_next_nodes = IP4_ARP_N_NEXT,
-  .next_nodes = {
-  [IP4_ARP_NEXT_DROP] = "error-drop",
-  },
-};
-/* *INDENT-ON* */
-
-#define foreach_notrace_ip4_arp_error           \
-_(THROTTLED)                                    \
-_(RESOLVED)                                     \
-_(NO_BUFFERS)                                   \
-_(REQUEST_SENT)                                 \
-_(NON_ARP_ADJ)                                  \
-_(NO_SOURCE_ADDRESS)
-
-static clib_error_t *
-arp_notrace_init (vlib_main_t * vm)
-{
-  vlib_node_runtime_t *rt = vlib_node_get_runtime (vm, ip4_arp_node.index);
-
-  /* don't trace ARP request packets */
-#define _(a)                                    \
-    vnet_pcap_drop_trace_filter_add_del         \
-        (rt->errors[IP4_ARP_ERROR_##a],         \
-         1 /* is_add */);
-  foreach_notrace_ip4_arp_error;
-#undef _
-  return 0;
-}
-
-VLIB_INIT_FUNCTION (arp_notrace_init);
-
-
-#ifndef CLIB_MARCH_VARIANT
-/* Send an ARP request to see if given destination is reachable on given interface. */
-clib_error_t *
-ip4_probe_neighbor (vlib_main_t * vm, ip4_address_t * dst, u32 sw_if_index,
-                   u8 refresh)
-{
-  vnet_main_t *vnm = vnet_get_main ();
-  ip4_main_t *im = &ip4_main;
-  ethernet_arp_header_t *h;
-  ip4_address_t *src;
-  ip_interface_address_t *ia;
-  ip_adjacency_t *adj;
-  vnet_hw_interface_t *hi;
-  vnet_sw_interface_t *si;
-  vlib_buffer_t *b;
-  adj_index_t ai;
-  u32 bi = 0;
-  u8 unicast_rewrite = 0;
-
-  si = vnet_get_sw_interface (vnm, sw_if_index);
-
-  if (!(si->flags & VNET_SW_INTERFACE_FLAG_ADMIN_UP))
-    {
-      return clib_error_return (0, "%U: interface %U down",
-                               format_ip4_address, dst,
-                               format_vnet_sw_if_index_name, vnm,
-                               sw_if_index);
-    }
-
-  src =
-    ip4_interface_address_matching_destination (im, dst, sw_if_index, &ia);
-  if (!src)
-    {
-      vnm->api_errno = VNET_API_ERROR_NO_MATCHING_INTERFACE;
-      return clib_error_return
-       (0,
-        "no matching interface address for destination %U (interface %U)",
-        format_ip4_address, dst, format_vnet_sw_if_index_name, vnm,
-        sw_if_index);
-    }
-
-  h = vlib_packet_template_get_packet (vm,
-                                      &im->ip4_arp_request_packet_template,
-                                      &bi);
-
-  if (!h)
-    return clib_error_return (0, "ARP request packet allocation failed");
-
-  hi = vnet_get_sup_hw_interface (vnm, sw_if_index);
-  if (PREDICT_FALSE (!hi->hw_address))
-    {
-      return clib_error_return (0, "%U: interface %U do not support ip probe",
-                               format_ip4_address, dst,
-                               format_vnet_sw_if_index_name, vnm,
-                               sw_if_index);
-    }
-
-  mac_address_from_bytes (&h->ip4_over_ethernet[0].mac, hi->hw_address);
-
-  h->ip4_over_ethernet[0].ip4 = src[0];
-  h->ip4_over_ethernet[1].ip4 = dst[0];
-
-  b = vlib_get_buffer (vm, bi);
-  vnet_buffer (b)->sw_if_index[VLIB_RX] =
-    vnet_buffer (b)->sw_if_index[VLIB_TX] = sw_if_index;
-
-  ip46_address_t nh = {
-    .ip4 = *dst,
-  };
-
-  ai = adj_nbr_add_or_lock (FIB_PROTOCOL_IP4,
-                           VNET_LINK_IP4, &nh, sw_if_index);
-  adj = adj_get (ai);
-
-  /* Peer has been previously resolved, retrieve glean adj instead */
-  if (adj->lookup_next_index == IP_LOOKUP_NEXT_REWRITE)
-    {
-      if (refresh)
-       unicast_rewrite = 1;
-      else
-       {
-         adj_unlock (ai);
-         ai = adj_glean_add_or_lock (FIB_PROTOCOL_IP4,
-                                     VNET_LINK_IP4, sw_if_index, &nh);
-         adj = adj_get (ai);
-       }
-    }
-
-  /* Add encapsulation string for software interface (e.g. ethernet header). */
-  vnet_rewrite_one_header (adj[0], h, sizeof (ethernet_header_t));
-  if (unicast_rewrite)
-    {
-      u16 *etype = vlib_buffer_get_current (b) - 2;
-      etype[0] = clib_host_to_net_u16 (ETHERNET_TYPE_ARP);
-    }
-  vlib_buffer_advance (b, -adj->rewrite_header.data_bytes);
-
-  {
-    vlib_frame_t *f = vlib_get_frame_to_node (vm, hi->output_node_index);
-    u32 *to_next = vlib_frame_vector_args (f);
-    to_next[0] = bi;
-    f->n_vectors = 1;
-    vlib_put_frame_to_node (vm, hi->output_node_index, f);
-  }
-
-  adj_unlock (ai);
-  return /* no error */ 0;
-}
-#endif
-
 typedef enum
 {
   IP4_REWRITE_NEXT_DROP,
@@ -2117,7 +1979,8 @@ typedef enum
 
 always_inline void
 ip4_mtu_check (vlib_buffer_t * b, u16 packet_len,
-              u16 adj_packet_bytes, bool df, u16 * next, u32 * error)
+              u16 adj_packet_bytes, bool df, u16 * next,
+              u8 is_midchain, u32 * error)
 {
   if (packet_len > adj_packet_bytes)
     {
@@ -2134,12 +1997,36 @@ ip4_mtu_check (vlib_buffer_t * b, u16 packet_len,
        {
          /* IP fragmentation */
          ip_frag_set_vnet_buffer (b, adj_packet_bytes,
-                                  IP4_FRAG_NEXT_IP4_REWRITE, 0);
+                                  (is_midchain ?
+                                   IP_FRAG_NEXT_IP_REWRITE_MIDCHAIN :
+                                   IP_FRAG_NEXT_IP_REWRITE), 0);
          *next = IP4_REWRITE_NEXT_FRAGMENT;
        }
     }
 }
 
+/* increment TTL & update checksum.
+   Works either endian, so no need for byte swap. */
+static_always_inline void
+ip4_ttl_inc (vlib_buffer_t * b, ip4_header_t * ip)
+{
+  i32 ttl;
+  u32 checksum;
+  if (PREDICT_FALSE (b->flags & VNET_BUFFER_F_LOCALLY_ORIGINATED))
+    return;
+
+  ttl = ip->ttl;
+
+  checksum = ip->checksum - clib_host_to_net_u16 (0x0100);
+  checksum += checksum >= 0xffff;
+
+  ip->checksum = checksum;
+  ttl += 1;
+  ip->ttl = ttl;
+
+  ASSERT (ip4_header_checksum_is_valid (ip));
+}
+
 /* Decrement TTL & update checksum.
    Works either endian, so no need for byte swap. */
 static_always_inline void
@@ -2149,10 +2036,7 @@ ip4_ttl_and_checksum_check (vlib_buffer_t * b, ip4_header_t * ip, u16 * next,
   i32 ttl;
   u32 checksum;
   if (PREDICT_FALSE (b->flags & VNET_BUFFER_F_LOCALLY_ORIGINATED))
-    {
-      b->flags &= ~VNET_BUFFER_F_LOCALLY_ORIGINATED;
-      return;
-    }
+    return;
 
   ttl = ip->ttl;
 
@@ -2181,7 +2065,7 @@ ip4_ttl_and_checksum_check (vlib_buffer_t * b, ip4_header_t * ip, u16 * next,
     }
 
   /* Verify checksum. */
-  ASSERT ((ip->checksum == ip4_header_checksum (ip)) ||
+  ASSERT (ip4_header_checksum_is_valid (ip) ||
          (b->flags & VNET_BUFFER_F_OFFLOAD_IP_CKSUM));
 }
 
@@ -2190,8 +2074,7 @@ always_inline uword
 ip4_rewrite_inline_with_gso (vlib_main_t * vm,
                             vlib_node_runtime_t * node,
                             vlib_frame_t * frame,
-                            int do_counters, int is_midchain, int is_mcast,
-                            int do_gso)
+                            int do_counters, int is_midchain, int is_mcast)
 {
   ip_lookup_main_t *lm = &ip4_main.lookup_main;
   u32 *from = vlib_frame_vector_args (frame);
@@ -2207,6 +2090,7 @@ ip4_rewrite_inline_with_gso (vlib_main_t * vm,
   vlib_get_buffers (vm, from, bufs, n_left_from);
   clib_memset_u16 (nexts, IP4_REWRITE_NEXT_DROP, n_left_from);
 
+#if (CLIB_N_PREFETCHES >= 8)
   if (n_left_from >= 6)
     {
       int i;
@@ -2218,15 +2102,18 @@ ip4_rewrite_inline_with_gso (vlib_main_t * vm,
   b = bufs;
   while (n_left_from >= 8)
     {
-      ip_adjacency_t *adj0, *adj1;
+      const ip_adjacency_t *adj0, *adj1;
       ip4_header_t *ip0, *ip1;
       u32 rw_len0, error0, adj_index0;
       u32 rw_len1, error1, adj_index1;
       u32 tx_sw_if_index0, tx_sw_if_index1;
       u8 *p;
 
-      vlib_prefetch_buffer_header (b[6], LOAD);
-      vlib_prefetch_buffer_header (b[7], LOAD);
+      if (is_midchain)
+       {
+         vlib_prefetch_buffer_header (b[6], LOAD);
+         vlib_prefetch_buffer_header (b[7], LOAD);
+       }
 
       adj_index0 = vnet_buffer (b[0])->ip.adj_index[VLIB_TX];
       adj_index1 = vnet_buffer (b[1])->ip.adj_index[VLIB_TX];
@@ -2272,21 +2159,21 @@ ip4_rewrite_inline_with_gso (vlib_main_t * vm,
       u16 ip0_len = clib_net_to_host_u16 (ip0->length);
       u16 ip1_len = clib_net_to_host_u16 (ip1->length);
 
-      if (do_gso && (b[0]->flags & VNET_BUFFER_F_GSO))
+      if (b[0]->flags & VNET_BUFFER_F_GSO)
        ip0_len = gso_mtu_sz (b[0]);
-      if (do_gso && (b[1]->flags & VNET_BUFFER_F_GSO))
+      if (b[1]->flags & VNET_BUFFER_F_GSO)
        ip1_len = gso_mtu_sz (b[1]);
 
       ip4_mtu_check (b[0], ip0_len,
                     adj0[0].rewrite_header.max_l3_packet_bytes,
                     ip0->flags_and_fragment_offset &
                     clib_host_to_net_u16 (IP4_HEADER_FLAG_DONT_FRAGMENT),
-                    next + 0, &error0);
+                    next + 0, is_midchain, &error0);
       ip4_mtu_check (b[1], ip1_len,
                     adj1[0].rewrite_header.max_l3_packet_bytes,
                     ip1->flags_and_fragment_offset &
                     clib_host_to_net_u16 (IP4_HEADER_FLAG_DONT_FRAGMENT),
-                    next + 1, &error1);
+                    next + 1, is_midchain, &error1);
 
       if (is_mcast)
        {
@@ -2299,96 +2186,242 @@ ip4_rewrite_inline_with_gso (vlib_main_t * vm,
        }
 
       /* Don't adjust the buffer for ttl issue; icmp-error node wants
-       * to see the IP headerr */
+       * to see the IP header */
       if (PREDICT_TRUE (error0 == IP4_ERROR_NONE))
        {
          u32 next_index = adj0[0].rewrite_header.next_index;
-         b[0]->current_data -= rw_len0;
-         b[0]->current_length += rw_len0;
+         vlib_buffer_advance (b[0], -(word) rw_len0);
+
          tx_sw_if_index0 = adj0[0].rewrite_header.sw_if_index;
          vnet_buffer (b[0])->sw_if_index[VLIB_TX] = tx_sw_if_index0;
 
          if (PREDICT_FALSE
              (adj0[0].rewrite_header.flags & VNET_REWRITE_HAS_FEATURES))
-           vnet_feature_arc_start (lm->output_feature_arc_index,
-                                   tx_sw_if_index0, &next_index, b[0]);
+           vnet_feature_arc_start_w_cfg_index (lm->output_feature_arc_index,
+                                               tx_sw_if_index0,
+                                               &next_index, b[0],
+                                               adj0->ia_cfg_index);
+
          next[0] = next_index;
+         if (is_midchain)
+           vnet_calc_checksums_inline (vm, b[0], 1 /* is_ip4 */ ,
+                                       0 /* is_ip6 */ );
        }
       else
        {
          b[0]->error = error_node->errors[error0];
+         if (error0 == IP4_ERROR_MTU_EXCEEDED)
+           ip4_ttl_inc (b[0], ip0);
        }
       if (PREDICT_TRUE (error1 == IP4_ERROR_NONE))
        {
          u32 next_index = adj1[0].rewrite_header.next_index;
-         b[1]->current_data -= rw_len1;
-         b[1]->current_length += rw_len1;
+         vlib_buffer_advance (b[1], -(word) rw_len1);
 
          tx_sw_if_index1 = adj1[0].rewrite_header.sw_if_index;
          vnet_buffer (b[1])->sw_if_index[VLIB_TX] = tx_sw_if_index1;
 
          if (PREDICT_FALSE
              (adj1[0].rewrite_header.flags & VNET_REWRITE_HAS_FEATURES))
-           vnet_feature_arc_start (lm->output_feature_arc_index,
-                                   tx_sw_if_index1, &next_index, b[1]);
+           vnet_feature_arc_start_w_cfg_index (lm->output_feature_arc_index,
+                                               tx_sw_if_index1,
+                                               &next_index, b[1],
+                                               adj1->ia_cfg_index);
          next[1] = next_index;
+         if (is_midchain)
+           vnet_calc_checksums_inline (vm, b[1], 1 /* is_ip4 */ ,
+                                       0 /* is_ip6 */ );
        }
       else
        {
          b[1]->error = error_node->errors[error1];
+         if (error1 == IP4_ERROR_MTU_EXCEEDED)
+           ip4_ttl_inc (b[1], ip1);
        }
+
       if (is_midchain)
+       /* Guess we are only writing on ipv4 header. */
+       vnet_rewrite_two_headers (adj0[0], adj1[0],
+                                 ip0, ip1, sizeof (ip4_header_t));
+      else
+       /* Guess we are only writing on simple Ethernet header. */
+       vnet_rewrite_two_headers (adj0[0], adj1[0],
+                                 ip0, ip1, sizeof (ethernet_header_t));
+
+      if (do_counters)
+       {
+         if (error0 == IP4_ERROR_NONE)
+           vlib_increment_combined_counter
+             (&adjacency_counters,
+              thread_index,
+              adj_index0, 1,
+              vlib_buffer_length_in_chain (vm, b[0]) + rw_len0);
+
+         if (error1 == IP4_ERROR_NONE)
+           vlib_increment_combined_counter
+             (&adjacency_counters,
+              thread_index,
+              adj_index1, 1,
+              vlib_buffer_length_in_chain (vm, b[1]) + rw_len1);
+       }
+
+      if (is_midchain)
+       {
+         if (error0 == IP4_ERROR_NONE)
+           adj_midchain_fixup (vm, adj0, b[0], VNET_LINK_IP4);
+         if (error1 == IP4_ERROR_NONE)
+           adj_midchain_fixup (vm, adj1, b[1], VNET_LINK_IP4);
+       }
+
+      if (is_mcast)
+       {
+         /* copy bytes from the IP address into the MAC rewrite */
+         if (error0 == IP4_ERROR_NONE)
+           vnet_ip_mcast_fixup_header (IP4_MCAST_ADDR_MASK,
+                                       adj0->rewrite_header.dst_mcast_offset,
+                                       &ip0->dst_address.as_u32, (u8 *) ip0);
+         if (error1 == IP4_ERROR_NONE)
+           vnet_ip_mcast_fixup_header (IP4_MCAST_ADDR_MASK,
+                                       adj1->rewrite_header.dst_mcast_offset,
+                                       &ip1->dst_address.as_u32, (u8 *) ip1);
+       }
+
+      next += 2;
+      b += 2;
+      n_left_from -= 2;
+    }
+#elif (CLIB_N_PREFETCHES >= 4)
+  next = nexts;
+  b = bufs;
+  while (n_left_from >= 1)
+    {
+      ip_adjacency_t *adj0;
+      ip4_header_t *ip0;
+      u32 rw_len0, error0, adj_index0;
+      u32 tx_sw_if_index0;
+      u8 *p;
+
+      /* Prefetch next iteration */
+      if (PREDICT_TRUE (n_left_from >= 4))
        {
-         calc_checksums (vm, b[0]);
-         calc_checksums (vm, b[1]);
+         ip_adjacency_t *adj2;
+         u32 adj_index2;
+
+         vlib_prefetch_buffer_header (b[3], LOAD);
+         vlib_prefetch_buffer_data (b[2], LOAD);
+
+         /* Prefetch adj->rewrite_header */
+         adj_index2 = vnet_buffer (b[2])->ip.adj_index[VLIB_TX];
+         adj2 = adj_get (adj_index2);
+         p = (u8 *) adj2;
+         CLIB_PREFETCH (p + CLIB_CACHE_LINE_BYTES, CLIB_CACHE_LINE_BYTES,
+                        LOAD);
        }
-      /* Guess we are only writing on simple Ethernet header. */
-      vnet_rewrite_two_headers (adj0[0], adj1[0],
-                               ip0, ip1, sizeof (ethernet_header_t));
+
+      adj_index0 = vnet_buffer (b[0])->ip.adj_index[VLIB_TX];
 
       /*
-       * Bump the per-adjacency counters
+       * Prefetch the per-adjacency counters
        */
       if (do_counters)
        {
-         vlib_increment_combined_counter
-           (&adjacency_counters,
-            thread_index,
-            adj_index0, 1, vlib_buffer_length_in_chain (vm, b[0]) + rw_len0);
-
-         vlib_increment_combined_counter
-           (&adjacency_counters,
-            thread_index,
-            adj_index1, 1, vlib_buffer_length_in_chain (vm, b[1]) + rw_len1);
+         vlib_prefetch_combined_counter (&adjacency_counters,
+                                         thread_index, adj_index0);
        }
 
-      if (is_midchain)
+      ip0 = vlib_buffer_get_current (b[0]);
+
+      error0 = IP4_ERROR_NONE;
+
+      ip4_ttl_and_checksum_check (b[0], ip0, next + 0, &error0);
+
+      /* Rewrite packet header and updates lengths. */
+      adj0 = adj_get (adj_index0);
+
+      /* Rewrite header was prefetched. */
+      rw_len0 = adj0[0].rewrite_header.data_bytes;
+      vnet_buffer (b[0])->ip.save_rewrite_length = rw_len0;
+
+      /* Check MTU of outgoing interface. */
+      u16 ip0_len = clib_net_to_host_u16 (ip0->length);
+
+      if (b[0]->flags & VNET_BUFFER_F_GSO)
+       ip0_len = gso_mtu_sz (b[0]);
+
+      ip4_mtu_check (b[0], ip0_len,
+                    adj0[0].rewrite_header.max_l3_packet_bytes,
+                    ip0->flags_and_fragment_offset &
+                    clib_host_to_net_u16 (IP4_HEADER_FLAG_DONT_FRAGMENT),
+                    next + 0, is_midchain, &error0);
+
+      if (is_mcast)
        {
-         if (adj0->sub_type.midchain.fixup_func)
-           adj0->sub_type.midchain.fixup_func
-             (vm, adj0, b[0], adj0->sub_type.midchain.fixup_data);
-         if (adj1->sub_type.midchain.fixup_func)
-           adj1->sub_type.midchain.fixup_func
-             (vm, adj1, b[1], adj1->sub_type.midchain.fixup_data);
+         error0 = ((adj0[0].rewrite_header.sw_if_index ==
+                    vnet_buffer (b[0])->sw_if_index[VLIB_RX]) ?
+                   IP4_ERROR_SAME_INTERFACE : error0);
        }
 
-      if (is_mcast)
+      /* Don't adjust the buffer for ttl issue; icmp-error node wants
+       * to see the IP header */
+      if (PREDICT_TRUE (error0 == IP4_ERROR_NONE))
        {
+         u32 next_index = adj0[0].rewrite_header.next_index;
+         vlib_buffer_advance (b[0], -(word) rw_len0);
+         tx_sw_if_index0 = adj0[0].rewrite_header.sw_if_index;
+         vnet_buffer (b[0])->sw_if_index[VLIB_TX] = tx_sw_if_index0;
+
+         if (PREDICT_FALSE
+             (adj0[0].rewrite_header.flags & VNET_REWRITE_HAS_FEATURES))
+           vnet_feature_arc_start_w_cfg_index (lm->output_feature_arc_index,
+                                               tx_sw_if_index0,
+                                               &next_index, b[0],
+                                               adj0->ia_cfg_index);
+         next[0] = next_index;
+
+         if (is_midchain)
+           {
+             vnet_calc_checksums_inline (vm, b[0], 1 /* is_ip4 */ ,
+                                         0 /* is_ip6 */ );
+
+             /* Guess we are only writing on ipv4 header. */
+             vnet_rewrite_one_header (adj0[0], ip0, sizeof (ip4_header_t));
+           }
+         else
+           /* Guess we are only writing on simple Ethernet header. */
+           vnet_rewrite_one_header (adj0[0], ip0,
+                                    sizeof (ethernet_header_t));
+
          /*
-          * copy bytes from the IP address into the MAC rewrite
+          * Bump the per-adjacency counters
           */
-         vnet_ip_mcast_fixup_header (IP4_MCAST_ADDR_MASK,
-                                     adj0->rewrite_header.dst_mcast_offset,
-                                     &ip0->dst_address.as_u32, (u8 *) ip0);
-         vnet_ip_mcast_fixup_header (IP4_MCAST_ADDR_MASK,
-                                     adj1->rewrite_header.dst_mcast_offset,
-                                     &ip1->dst_address.as_u32, (u8 *) ip1);
+         if (do_counters)
+           vlib_increment_combined_counter
+             (&adjacency_counters,
+              thread_index,
+              adj_index0, 1, vlib_buffer_length_in_chain (vm,
+                                                          b[0]) + rw_len0);
+
+         if (is_midchain)
+           adj_midchain_fixup (vm, adj0, b[0], VNET_LINK_IP4);
+
+         if (is_mcast)
+           /* copy bytes from the IP address into the MAC rewrite */
+           vnet_ip_mcast_fixup_header (IP4_MCAST_ADDR_MASK,
+                                       adj0->rewrite_header.dst_mcast_offset,
+                                       &ip0->dst_address.as_u32, (u8 *) ip0);
+       }
+      else
+       {
+         b[0]->error = error_node->errors[error0];
+         if (error0 == IP4_ERROR_MTU_EXCEEDED)
+           ip4_ttl_inc (b[0], ip0);
        }
 
-      next += 2;
-      b += 2;
-      n_left_from -= 2;
+      next += 1;
+      b += 1;
+      n_left_from -= 1;
     }
+#endif
 
   while (n_left_from > 0)
     {
@@ -2418,14 +2451,14 @@ ip4_rewrite_inline_with_gso (vlib_main_t * vm,
 
       /* Check MTU of outgoing interface. */
       u16 ip0_len = clib_net_to_host_u16 (ip0->length);
-      if (do_gso && (b[0]->flags & VNET_BUFFER_F_GSO))
+      if (b[0]->flags & VNET_BUFFER_F_GSO)
        ip0_len = gso_mtu_sz (b[0]);
 
       ip4_mtu_check (b[0], ip0_len,
                     adj0[0].rewrite_header.max_l3_packet_bytes,
                     ip0->flags_and_fragment_offset &
                     clib_host_to_net_u16 (IP4_HEADER_FLAG_DONT_FRAGMENT),
-                    next + 0, &error0);
+                    next + 0, is_midchain, &error0);
 
       if (is_mcast)
        {
@@ -2435,53 +2468,57 @@ ip4_rewrite_inline_with_gso (vlib_main_t * vm,
        }
 
       /* Don't adjust the buffer for ttl issue; icmp-error node wants
-       * to see the IP headerr */
+       * to see the IP header */
       if (PREDICT_TRUE (error0 == IP4_ERROR_NONE))
        {
          u32 next_index = adj0[0].rewrite_header.next_index;
-         b[0]->current_data -= rw_len0;
-         b[0]->current_length += rw_len0;
+         vlib_buffer_advance (b[0], -(word) rw_len0);
          tx_sw_if_index0 = adj0[0].rewrite_header.sw_if_index;
          vnet_buffer (b[0])->sw_if_index[VLIB_TX] = tx_sw_if_index0;
 
          if (PREDICT_FALSE
              (adj0[0].rewrite_header.flags & VNET_REWRITE_HAS_FEATURES))
-           vnet_feature_arc_start (lm->output_feature_arc_index,
-                                   tx_sw_if_index0, &next_index, b[0]);
+           vnet_feature_arc_start_w_cfg_index (lm->output_feature_arc_index,
+                                               tx_sw_if_index0,
+                                               &next_index, b[0],
+                                               adj0->ia_cfg_index);
          next[0] = next_index;
-       }
-      else
-       {
-         b[0]->error = error_node->errors[error0];
-       }
-      if (is_midchain)
-       {
-         calc_checksums (vm, b[0]);
-       }
-      /* Guess we are only writing on simple Ethernet header. */
-      vnet_rewrite_one_header (adj0[0], ip0, sizeof (ethernet_header_t));
 
-      if (do_counters)
-       vlib_increment_combined_counter
-         (&adjacency_counters,
-          thread_index, adj_index0, 1,
-          vlib_buffer_length_in_chain (vm, b[0]) + rw_len0);
+         if (is_midchain)
+           {
+             /* this acts on the packet that is about to be encapped */
+             vnet_calc_checksums_inline (vm, b[0], 1 /* is_ip4 */ ,
+                                         0 /* is_ip6 */ );
 
-      if (is_midchain)
-       {
-         if (adj0->sub_type.midchain.fixup_func)
-           adj0->sub_type.midchain.fixup_func
-             (vm, adj0, b[0], adj0->sub_type.midchain.fixup_data);
+             /* Guess we are only writing on ipv4 header. */
+             vnet_rewrite_one_header (adj0[0], ip0, sizeof (ip4_header_t));
+           }
+         else
+           /* Guess we are only writing on simple Ethernet header. */
+           vnet_rewrite_one_header (adj0[0], ip0,
+                                    sizeof (ethernet_header_t));
+
+         if (do_counters)
+           vlib_increment_combined_counter
+             (&adjacency_counters,
+              thread_index, adj_index0, 1,
+              vlib_buffer_length_in_chain (vm, b[0]) + rw_len0);
+
+         if (is_midchain)
+           adj_midchain_fixup (vm, adj0, b[0], VNET_LINK_IP4);
+
+         if (is_mcast)
+           /* copy bytes from the IP address into the MAC rewrite */
+           vnet_ip_mcast_fixup_header (IP4_MCAST_ADDR_MASK,
+                                       adj0->rewrite_header.dst_mcast_offset,
+                                       &ip0->dst_address.as_u32, (u8 *) ip0);
        }
-
-      if (is_mcast)
+      else
        {
-         /*
-          * copy bytes from the IP address into the MAC rewrite
-          */
-         vnet_ip_mcast_fixup_header (IP4_MCAST_ADDR_MASK,
-                                     adj0->rewrite_header.dst_mcast_offset,
-                                     &ip0->dst_address.as_u32, (u8 *) ip0);
+         b[0]->error = error_node->errors[error0];
+         /* undo the TTL decrement - we'll be back to do it again */
+         if (error0 == IP4_ERROR_MTU_EXCEEDED)
+           ip4_ttl_inc (b[0], ip0);
        }
 
       next += 1;
@@ -2504,15 +2541,8 @@ ip4_rewrite_inline (vlib_main_t * vm,
                    vlib_frame_t * frame,
                    int do_counters, int is_midchain, int is_mcast)
 {
-  vnet_main_t *vnm = vnet_get_main ();
-  if (PREDICT_FALSE (vnm->interface_main.gso_interface_count > 0))
-    return ip4_rewrite_inline_with_gso (vm, node, frame, do_counters,
-                                       is_midchain, is_mcast,
-                                       1 /* do_gso */ );
-  else
-    return ip4_rewrite_inline_with_gso (vm, node, frame, do_counters,
-                                       is_midchain, is_mcast,
-                                       0 /* no do_gso */ );
+  return ip4_rewrite_inline_with_gso (vm, node, frame, do_counters,
+                                     is_midchain, is_mcast);
 }
 
 
@@ -2639,8 +2669,8 @@ VLIB_REGISTER_NODE (ip4_mcast_midchain_node) = {
 VLIB_REGISTER_NODE (ip4_midchain_node) = {
   .name = "ip4-midchain",
   .vector_size = sizeof (u32),
-  .format_trace = format_ip4_forward_next_trace,
-  .sibling_of =  "ip4-rewrite",
+  .format_trace = format_ip4_rewrite_trace,
+  .sibling_of = "ip4-rewrite",
 };
 /* *INDENT-ON */
 
@@ -2741,24 +2771,6 @@ VLIB_CLI_COMMAND (lookup_test_command, static) =
 };
 /* *INDENT-ON* */
 
-#ifndef CLIB_MARCH_VARIANT
-int
-vnet_set_ip4_flow_hash (u32 table_id, u32 flow_hash_config)
-{
-  u32 fib_index;
-
-  fib_index = fib_table_find (FIB_PROTOCOL_IP4, table_id);
-
-  if (~0 == fib_index)
-    return VNET_API_ERROR_NO_SUCH_FIB;
-
-  fib_table_set_flow_hash_config (fib_index, FIB_PROTOCOL_IP4,
-                                 flow_hash_config);
-
-  return 0;
-}
-#endif
-
 static clib_error_t *
 set_ip_flow_hash_command_fn (vlib_main_t * vm,
                             unformat_input_t * input,
@@ -2773,8 +2785,12 @@ set_ip_flow_hash_command_fn (vlib_main_t * vm,
     {
       if (unformat (input, "table %d", &table_id))
        matched = 1;
-#define _(a,v) \
-    else if (unformat (input, #a)) { flow_hash_config |= v; matched=1;}
+#define _(a, b, v)                                                            \
+  else if (unformat (input, #a))                                              \
+  {                                                                           \
+    flow_hash_config |= v;                                                    \
+    matched = 1;                                                              \
+  }
       foreach_flow_hash_bit
 #undef _
        else
@@ -2785,7 +2801,7 @@ set_ip_flow_hash_command_fn (vlib_main_t * vm,
     return clib_error_return (0, "unknown input `%U'",
                              format_unformat_error, input);
 
-  rv = vnet_set_ip4_flow_hash (table_id, flow_hash_config);
+  rv = ip_flow_hash_set (AF_IP4, table_id, flow_hash_config);
   switch (rv)
     {
     case 0:
@@ -3020,29 +3036,6 @@ VLIB_CLI_COMMAND (set_ip_classify_command, static) =
 };
 /* *INDENT-ON* */
 
-static clib_error_t *
-ip4_config (vlib_main_t * vm, unformat_input_t * input)
-{
-  ip4_main_t *im = &ip4_main;
-  uword heapsize = 0;
-
-  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
-    {
-      if (unformat (input, "heap-size %U", unformat_memory_size, &heapsize))
-       ;
-      else
-       return clib_error_return (0,
-                                 "invalid heap-size parameter `%U'",
-                                 format_unformat_error, input);
-    }
-
-  im->mtrie_heap_size = heapsize;
-
-  return 0;
-}
-
-VLIB_EARLY_CONFIG_FUNCTION (ip4_config, "ip");
-
 /*
  * fd.io coding-style-patch-verification: ON
  *