src/vnet/ip/ip4_forward.h - fdio/vpp - Gitiles

 /*
  * Copyright (c) 2015-2019 Cisco and/or its affiliates.
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at:
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 /*
  * ip/ip4_forward.h: IP v4 forwarding
  *
  * Copyright (c) 2008 Eliot Dresselhaus
  *
  * Permission is hereby granted, free of charge, to any person obtaining
  * a copy of this software and associated documentation files (the
  * "Software"), to deal in the Software without restriction, including
  * without limitation the rights to use, copy, modify, merge, publish,
  * distribute, sublicense, and/or sell copies of the Software, and to
  * permit persons to whom the Software is furnished to do so, subject to
  * the following conditions:
  *
  * The above copyright notice and this permission notice shall be
  * included in all copies or substantial portions of the Software.
  *
  *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  *  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  *  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  *  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  *  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  *  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  *  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */

 #ifndef __included_ip4_forward_h__
 #define __included_ip4_forward_h__

 #include <vppinfra/cache.h>
 #include <vnet/fib/ip4_fib.h>
 #include <vnet/dpo/load_balance_map.h>

 /**
  * @file
  * @brief IPv4 Forwarding.
  *
  * This file contains the source code for IPv4 forwarding.
  */

 always_inline uword
 ip4_lookup_inline (vlib_main_t * vm,
 		   vlib_node_runtime_t * node, vlib_frame_t * frame)
 {
   ip4_main_t *im = &ip4_main;
   vlib_combined_counter_main_t *cm = &load_balance_main.lbm_to_counters;
   u32 n_left, *from;
   u32 thread_index = vm->thread_index;
   vlib_buffer_t *bufs[VLIB_FRAME_SIZE];
   vlib_buffer_t **b = bufs;
   u16 nexts[VLIB_FRAME_SIZE], *next;

   from = vlib_frame_vector_args (frame);
   n_left = frame->n_vectors;
   next = nexts;
   vlib_get_buffers (vm, from, bufs, n_left);

 #if (CLIB_N_PREFETCHES >= 8)
   while (n_left >= 4)
     {
       ip4_header_t *ip0, *ip1, *ip2, *ip3;
       const load_balance_t *lb0, *lb1, *lb2, *lb3;
       ip4_fib_mtrie_t *mtrie0, *mtrie1, *mtrie2, *mtrie3;
       ip4_fib_mtrie_leaf_t leaf0, leaf1, leaf2, leaf3;
       ip4_address_t *dst_addr0, *dst_addr1, *dst_addr2, *dst_addr3;
       u32 lb_index0, lb_index1, lb_index2, lb_index3;
       flow_hash_config_t flow_hash_config0, flow_hash_config1;
       flow_hash_config_t flow_hash_config2, flow_hash_config3;
       u32 hash_c0, hash_c1, hash_c2, hash_c3;
       const dpo_id_t *dpo0, *dpo1, *dpo2, *dpo3;

       /* Prefetch next iteration. */
       if (n_left >= 8)
 	{
 	  vlib_prefetch_buffer_header (b[4], LOAD);
 	  vlib_prefetch_buffer_header (b[5], LOAD);
 	  vlib_prefetch_buffer_header (b[6], LOAD);
 	  vlib_prefetch_buffer_header (b[7], LOAD);

 	  CLIB_PREFETCH (b[4]->data, sizeof (ip0[0]), LOAD);
 	  CLIB_PREFETCH (b[5]->data, sizeof (ip0[0]), LOAD);
 	  CLIB_PREFETCH (b[6]->data, sizeof (ip0[0]), LOAD);
 	  CLIB_PREFETCH (b[7]->data, sizeof (ip0[0]), LOAD);
 	}

       ip0 = vlib_buffer_get_current (b[0]);
       ip1 = vlib_buffer_get_current (b[1]);
       ip2 = vlib_buffer_get_current (b[2]);
       ip3 = vlib_buffer_get_current (b[3]);

       dst_addr0 = &ip0->dst_address;
       dst_addr1 = &ip1->dst_address;
       dst_addr2 = &ip2->dst_address;
       dst_addr3 = &ip3->dst_address;

       ip_lookup_set_buffer_fib_index (im->fib_index_by_sw_if_index, b[0]);
       ip_lookup_set_buffer_fib_index (im->fib_index_by_sw_if_index, b[1]);
       ip_lookup_set_buffer_fib_index (im->fib_index_by_sw_if_index, b[2]);
       ip_lookup_set_buffer_fib_index (im->fib_index_by_sw_if_index, b[3]);

       mtrie0 = &ip4_fib_get (vnet_buffer (b[0])->ip.fib_index)->mtrie;
       mtrie1 = &ip4_fib_get (vnet_buffer (b[1])->ip.fib_index)->mtrie;
       mtrie2 = &ip4_fib_get (vnet_buffer (b[2])->ip.fib_index)->mtrie;
       mtrie3 = &ip4_fib_get (vnet_buffer (b[3])->ip.fib_index)->mtrie;

       leaf0 = ip4_fib_mtrie_lookup_step_one (mtrie0, dst_addr0);
       leaf1 = ip4_fib_mtrie_lookup_step_one (mtrie1, dst_addr1);
       leaf2 = ip4_fib_mtrie_lookup_step_one (mtrie2, dst_addr2);
       leaf3 = ip4_fib_mtrie_lookup_step_one (mtrie3, dst_addr3);

       leaf0 = ip4_fib_mtrie_lookup_step (mtrie0, leaf0, dst_addr0, 2);
       leaf1 = ip4_fib_mtrie_lookup_step (mtrie1, leaf1, dst_addr1, 2);
       leaf2 = ip4_fib_mtrie_lookup_step (mtrie2, leaf2, dst_addr2, 2);
       leaf3 = ip4_fib_mtrie_lookup_step (mtrie3, leaf3, dst_addr3, 2);

       leaf0 = ip4_fib_mtrie_lookup_step (mtrie0, leaf0, dst_addr0, 3);
       leaf1 = ip4_fib_mtrie_lookup_step (mtrie1, leaf1, dst_addr1, 3);
       leaf2 = ip4_fib_mtrie_lookup_step (mtrie2, leaf2, dst_addr2, 3);
       leaf3 = ip4_fib_mtrie_lookup_step (mtrie3, leaf3, dst_addr3, 3);

       lb_index0 = ip4_fib_mtrie_leaf_get_adj_index (leaf0);
       lb_index1 = ip4_fib_mtrie_leaf_get_adj_index (leaf1);
       lb_index2 = ip4_fib_mtrie_leaf_get_adj_index (leaf2);
       lb_index3 = ip4_fib_mtrie_leaf_get_adj_index (leaf3);

       ASSERT (lb_index0 && lb_index1 && lb_index2 && lb_index3);
       lb0 = load_balance_get (lb_index0);
       lb1 = load_balance_get (lb_index1);
       lb2 = load_balance_get (lb_index2);
       lb3 = load_balance_get (lb_index3);

       ASSERT (lb0->lb_n_buckets > 0);
       ASSERT (is_pow2 (lb0->lb_n_buckets));
       ASSERT (lb1->lb_n_buckets > 0);
       ASSERT (is_pow2 (lb1->lb_n_buckets));
       ASSERT (lb2->lb_n_buckets > 0);
       ASSERT (is_pow2 (lb2->lb_n_buckets));
       ASSERT (lb3->lb_n_buckets > 0);
       ASSERT (is_pow2 (lb3->lb_n_buckets));

       /* Use flow hash to compute multipath adjacency. */
       hash_c0 = vnet_buffer (b[0])->ip.flow_hash = 0;
       hash_c1 = vnet_buffer (b[1])->ip.flow_hash = 0;
       hash_c2 = vnet_buffer (b[2])->ip.flow_hash = 0;
       hash_c3 = vnet_buffer (b[3])->ip.flow_hash = 0;
       if (PREDICT_FALSE (lb0->lb_n_buckets > 1))
 	{
 	  flow_hash_config0 = lb0->lb_hash_config;
 	  hash_c0 = vnet_buffer (b[0])->ip.flow_hash =
 	    ip4_compute_flow_hash (ip0, flow_hash_config0);
 	  dpo0 =
 	    load_balance_get_fwd_bucket (lb0,
 					 (hash_c0 &
 					  (lb0->lb_n_buckets_minus_1)));
 	}
       else
 	{
 	  dpo0 = load_balance_get_bucket_i (lb0, 0);
 	}
       if (PREDICT_FALSE (lb1->lb_n_buckets > 1))
 	{
 	  flow_hash_config1 = lb1->lb_hash_config;
 	  hash_c1 = vnet_buffer (b[1])->ip.flow_hash =
 	    ip4_compute_flow_hash (ip1, flow_hash_config1);
 	  dpo1 =
 	    load_balance_get_fwd_bucket (lb1,
 					 (hash_c1 &
 					  (lb1->lb_n_buckets_minus_1)));
 	}
       else
 	{
 	  dpo1 = load_balance_get_bucket_i (lb1, 0);
 	}
       if (PREDICT_FALSE (lb2->lb_n_buckets > 1))
 	{
 	  flow_hash_config2 = lb2->lb_hash_config;
 	  hash_c2 = vnet_buffer (b[2])->ip.flow_hash =
 	    ip4_compute_flow_hash (ip2, flow_hash_config2);
 	  dpo2 =
 	    load_balance_get_fwd_bucket (lb2,
 					 (hash_c2 &
 					  (lb2->lb_n_buckets_minus_1)));
 	}
       else
 	{
 	  dpo2 = load_balance_get_bucket_i (lb2, 0);
 	}
       if (PREDICT_FALSE (lb3->lb_n_buckets > 1))
 	{
 	  flow_hash_config3 = lb3->lb_hash_config;
 	  hash_c3 = vnet_buffer (b[3])->ip.flow_hash =
 	    ip4_compute_flow_hash (ip3, flow_hash_config3);
 	  dpo3 =
 	    load_balance_get_fwd_bucket (lb3,
 					 (hash_c3 &
 					  (lb3->lb_n_buckets_minus_1)));
 	}
       else
 	{
 	  dpo3 = load_balance_get_bucket_i (lb3, 0);
 	}

       next[0] = dpo0->dpoi_next_node;
       vnet_buffer (b[0])->ip.adj_index[VLIB_TX] = dpo0->dpoi_index;
       next[1] = dpo1->dpoi_next_node;
       vnet_buffer (b[1])->ip.adj_index[VLIB_TX] = dpo1->dpoi_index;
       next[2] = dpo2->dpoi_next_node;
       vnet_buffer (b[2])->ip.adj_index[VLIB_TX] = dpo2->dpoi_index;
       next[3] = dpo3->dpoi_next_node;
       vnet_buffer (b[3])->ip.adj_index[VLIB_TX] = dpo3->dpoi_index;

       vlib_increment_combined_counter
 	(cm, thread_index, lb_index0, 1,
 	 vlib_buffer_length_in_chain (vm, b[0]));
       vlib_increment_combined_counter
 	(cm, thread_index, lb_index1, 1,
 	 vlib_buffer_length_in_chain (vm, b[1]));
       vlib_increment_combined_counter
 	(cm, thread_index, lb_index2, 1,
 	 vlib_buffer_length_in_chain (vm, b[2]));
       vlib_increment_combined_counter
 	(cm, thread_index, lb_index3, 1,
 	 vlib_buffer_length_in_chain (vm, b[3]));

       b += 4;
       next += 4;
       n_left -= 4;
     }
 #elif (CLIB_N_PREFETCHES >= 4)
   while (n_left >= 4)
     {
       ip4_header_t *ip0, *ip1;
       const load_balance_t *lb0, *lb1;
       ip4_fib_mtrie_t *mtrie0, *mtrie1;
       ip4_fib_mtrie_leaf_t leaf0, leaf1;
       ip4_address_t *dst_addr0, *dst_addr1;
       u32 lb_index0, lb_index1;
       flow_hash_config_t flow_hash_config0, flow_hash_config1;
       u32 hash_c0, hash_c1;
       const dpo_id_t *dpo0, *dpo1;

       /* Prefetch next iteration. */
       {
 	vlib_prefetch_buffer_header (b[2], LOAD);
 	vlib_prefetch_buffer_header (b[3], LOAD);

 	CLIB_PREFETCH (b[2]->data, sizeof (ip0[0]), LOAD);
 	CLIB_PREFETCH (b[3]->data, sizeof (ip0[0]), LOAD);
       }

       ip0 = vlib_buffer_get_current (b[0]);
       ip1 = vlib_buffer_get_current (b[1]);

       dst_addr0 = &ip0->dst_address;
       dst_addr1 = &ip1->dst_address;

       ip_lookup_set_buffer_fib_index (im->fib_index_by_sw_if_index, b[0]);
       ip_lookup_set_buffer_fib_index (im->fib_index_by_sw_if_index, b[1]);

       if (!lookup_for_responses_to_locally_received_packets)
 	{
 	  mtrie0 = &ip4_fib_get (vnet_buffer (b[0])->ip.fib_index)->mtrie;
 	  mtrie1 = &ip4_fib_get (vnet_buffer (b[1])->ip.fib_index)->mtrie;

 	  leaf0 = ip4_fib_mtrie_lookup_step_one (mtrie0, dst_addr0);
 	  leaf1 = ip4_fib_mtrie_lookup_step_one (mtrie1, dst_addr1);
 	}

       if (!lookup_for_responses_to_locally_received_packets)
 	{
 	  leaf0 = ip4_fib_mtrie_lookup_step (mtrie0, leaf0, dst_addr0, 2);
 	  leaf1 = ip4_fib_mtrie_lookup_step (mtrie1, leaf1, dst_addr1, 2);
 	}

       if (!lookup_for_responses_to_locally_received_packets)
 	{
 	  leaf0 = ip4_fib_mtrie_lookup_step (mtrie0, leaf0, dst_addr0, 3);
 	  leaf1 = ip4_fib_mtrie_lookup_step (mtrie1, leaf1, dst_addr1, 3);
 	}

       if (lookup_for_responses_to_locally_received_packets)
 	{
 	  lb_index0 = vnet_buffer (b[0])->ip.adj_index[VLIB_RX];
 	  lb_index1 = vnet_buffer (b[1])->ip.adj_index[VLIB_RX];
 	}
       else
 	{
 	  lb_index0 = ip4_fib_mtrie_leaf_get_adj_index (leaf0);
 	  lb_index1 = ip4_fib_mtrie_leaf_get_adj_index (leaf1);
 	}

       ASSERT (lb_index0 && lb_index1);
       lb0 = load_balance_get (lb_index0);
       lb1 = load_balance_get (lb_index1);

       ASSERT (lb0->lb_n_buckets > 0);
       ASSERT (is_pow2 (lb0->lb_n_buckets));
       ASSERT (lb1->lb_n_buckets > 0);
       ASSERT (is_pow2 (lb1->lb_n_buckets));

       /* Use flow hash to compute multipath adjacency. */
       hash_c0 = vnet_buffer (b[0])->ip.flow_hash = 0;
       hash_c1 = vnet_buffer (b[1])->ip.flow_hash = 0;
       if (PREDICT_FALSE (lb0->lb_n_buckets > 1))
 	{
 	  flow_hash_config0 = lb0->lb_hash_config;
 	  hash_c0 = vnet_buffer (b[0])->ip.flow_hash =
 	    ip4_compute_flow_hash (ip0, flow_hash_config0);
 	  dpo0 =
 	    load_balance_get_fwd_bucket (lb0,
 					 (hash_c0 &
 					  (lb0->lb_n_buckets_minus_1)));
 	}
       else
 	{
 	  dpo0 = load_balance_get_bucket_i (lb0, 0);
 	}
       if (PREDICT_FALSE (lb1->lb_n_buckets > 1))
 	{
 	  flow_hash_config1 = lb1->lb_hash_config;
 	  hash_c1 = vnet_buffer (b[1])->ip.flow_hash =
 	    ip4_compute_flow_hash (ip1, flow_hash_config1);
 	  dpo1 =
 	    load_balance_get_fwd_bucket (lb1,
 					 (hash_c1 &
 					  (lb1->lb_n_buckets_minus_1)));
 	}
       else
 	{
 	  dpo1 = load_balance_get_bucket_i (lb1, 0);
 	}

       next[0] = dpo0->dpoi_next_node;
       vnet_buffer (b[0])->ip.adj_index[VLIB_TX] = dpo0->dpoi_index;
       next[1] = dpo1->dpoi_next_node;
       vnet_buffer (b[1])->ip.adj_index[VLIB_TX] = dpo1->dpoi_index;

       vlib_increment_combined_counter
 	(cm, thread_index, lb_index0, 1,
 	 vlib_buffer_length_in_chain (vm, b[0]));
       vlib_increment_combined_counter
 	(cm, thread_index, lb_index1, 1,
 	 vlib_buffer_length_in_chain (vm, b[1]));

       b += 2;
       next += 2;
       n_left -= 2;
     }
 #endif
   while (n_left > 0)
     {
       ip4_header_t *ip0;
       const load_balance_t *lb0;
       ip4_fib_mtrie_t *mtrie0;
       ip4_fib_mtrie_leaf_t leaf0;
       ip4_address_t *dst_addr0;
       u32 lbi0;
       flow_hash_config_t flow_hash_config0;
       const dpo_id_t *dpo0;
       u32 hash_c0;

       ip0 = vlib_buffer_get_current (b[0]);
       dst_addr0 = &ip0->dst_address;
       ip_lookup_set_buffer_fib_index (im->fib_index_by_sw_if_index, b[0]);

       mtrie0 = &ip4_fib_get (vnet_buffer (b[0])->ip.fib_index)->mtrie;
       leaf0 = ip4_fib_mtrie_lookup_step_one (mtrie0, dst_addr0);
       leaf0 = ip4_fib_mtrie_lookup_step (mtrie0, leaf0, dst_addr0, 2);
       leaf0 = ip4_fib_mtrie_lookup_step (mtrie0, leaf0, dst_addr0, 3);
       lbi0 = ip4_fib_mtrie_leaf_get_adj_index (leaf0);

       ASSERT (lbi0);
       lb0 = load_balance_get (lbi0);

       ASSERT (lb0->lb_n_buckets > 0);
       ASSERT (is_pow2 (lb0->lb_n_buckets));

       /* Use flow hash to compute multipath adjacency. */
       hash_c0 = vnet_buffer (b[0])->ip.flow_hash = 0;
       if (PREDICT_FALSE (lb0->lb_n_buckets > 1))
 	{
 	  flow_hash_config0 = lb0->lb_hash_config;

 	  hash_c0 = vnet_buffer (b[0])->ip.flow_hash =
 	    ip4_compute_flow_hash (ip0, flow_hash_config0);
 	  dpo0 =
 	    load_balance_get_fwd_bucket (lb0,
 					 (hash_c0 &
 					  (lb0->lb_n_buckets_minus_1)));
 	}
       else
 	{
 	  dpo0 = load_balance_get_bucket_i (lb0, 0);
 	}

       next[0] = dpo0->dpoi_next_node;
       vnet_buffer (b[0])->ip.adj_index[VLIB_TX] = dpo0->dpoi_index;

       vlib_increment_combined_counter (cm, thread_index, lbi0, 1,
 				       vlib_buffer_length_in_chain (vm,
 								    b[0]));

       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);

   return frame->n_vectors;
 }

 #endif /* __included_ip4_forward_h__ */

 /*
  * fd.io coding-style-patch-verification: ON
  *
  * Local Variables:
  * eval: (c-set-style "gnu")
  * End:
  */
	/*
	* Copyright (c) 2015-2019 Cisco and/or its affiliates.
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at:
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/
	/*
	* ip/ip4_forward.h: IP v4 forwarding
	*
	* Copyright (c) 2008 Eliot Dresselhaus
	*
	* Permission is hereby granted, free of charge, to any person obtaining
	* a copy of this software and associated documentation files (the
	* "Software"), to deal in the Software without restriction, including
	* without limitation the rights to use, copy, modify, merge, publish,
	* distribute, sublicense, and/or sell copies of the Software, and to
	* permit persons to whom the Software is furnished to do so, subject to
	* the following conditions:
	*
	* The above copyright notice and this permission notice shall be
	* included in all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
	* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
	* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
	* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
	* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
	* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
	* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
	*/

	#ifndef __included_ip4_forward_h__
	#define __included_ip4_forward_h__

	#include <vppinfra/cache.h>
	#include <vnet/fib/ip4_fib.h>
	#include <vnet/dpo/load_balance_map.h>

	/**
	* @file
	* @brief IPv4 Forwarding.
	*
	* This file contains the source code for IPv4 forwarding.
	*/

	always_inline uword
	ip4_lookup_inline (vlib_main_t * vm,
	vlib_node_runtime_t * node, vlib_frame_t * frame)
	{
	ip4_main_t *im = &ip4_main;
	vlib_combined_counter_main_t *cm = &load_balance_main.lbm_to_counters;
	u32 n_left, *from;
	u32 thread_index = vm->thread_index;
	vlib_buffer_t *bufs[VLIB_FRAME_SIZE];
	vlib_buffer_t **b = bufs;
	u16 nexts[VLIB_FRAME_SIZE], *next;

	from = vlib_frame_vector_args (frame);
	n_left = frame->n_vectors;
	next = nexts;
	vlib_get_buffers (vm, from, bufs, n_left);

	#if (CLIB_N_PREFETCHES >= 8)
	while (n_left >= 4)
	{
	ip4_header_t ip0, ip1, ip2, ip3;
	const load_balance_t lb0, lb1, lb2, lb3;
	ip4_fib_mtrie_t mtrie0, mtrie1, mtrie2, mtrie3;
	ip4_fib_mtrie_leaf_t leaf0, leaf1, leaf2, leaf3;
	ip4_address_t dst_addr0, dst_addr1, dst_addr2, dst_addr3;
	u32 lb_index0, lb_index1, lb_index2, lb_index3;
	flow_hash_config_t flow_hash_config0, flow_hash_config1;
	flow_hash_config_t flow_hash_config2, flow_hash_config3;
	u32 hash_c0, hash_c1, hash_c2, hash_c3;
	const dpo_id_t dpo0, dpo1, dpo2, dpo3;

	/* Prefetch next iteration. */
	if (n_left >= 8)
	{
	vlib_prefetch_buffer_header (b[4], LOAD);
	vlib_prefetch_buffer_header (b[5], LOAD);
	vlib_prefetch_buffer_header (b[6], LOAD);
	vlib_prefetch_buffer_header (b[7], LOAD);

	CLIB_PREFETCH (b[4]->data, sizeof (ip0[0]), LOAD);
	CLIB_PREFETCH (b[5]->data, sizeof (ip0[0]), LOAD);
	CLIB_PREFETCH (b[6]->data, sizeof (ip0[0]), LOAD);
	CLIB_PREFETCH (b[7]->data, sizeof (ip0[0]), LOAD);
	}

	ip0 = vlib_buffer_get_current (b[0]);
	ip1 = vlib_buffer_get_current (b[1]);
	ip2 = vlib_buffer_get_current (b[2]);
	ip3 = vlib_buffer_get_current (b[3]);

	dst_addr0 = &ip0->dst_address;
	dst_addr1 = &ip1->dst_address;
	dst_addr2 = &ip2->dst_address;
	dst_addr3 = &ip3->dst_address;

	ip_lookup_set_buffer_fib_index (im->fib_index_by_sw_if_index, b[0]);
	ip_lookup_set_buffer_fib_index (im->fib_index_by_sw_if_index, b[1]);
	ip_lookup_set_buffer_fib_index (im->fib_index_by_sw_if_index, b[2]);
	ip_lookup_set_buffer_fib_index (im->fib_index_by_sw_if_index, b[3]);

	mtrie0 = &ip4_fib_get (vnet_buffer (b[0])->ip.fib_index)->mtrie;
	mtrie1 = &ip4_fib_get (vnet_buffer (b[1])->ip.fib_index)->mtrie;
	mtrie2 = &ip4_fib_get (vnet_buffer (b[2])->ip.fib_index)->mtrie;
	mtrie3 = &ip4_fib_get (vnet_buffer (b[3])->ip.fib_index)->mtrie;

	leaf0 = ip4_fib_mtrie_lookup_step_one (mtrie0, dst_addr0);
	leaf1 = ip4_fib_mtrie_lookup_step_one (mtrie1, dst_addr1);
	leaf2 = ip4_fib_mtrie_lookup_step_one (mtrie2, dst_addr2);
	leaf3 = ip4_fib_mtrie_lookup_step_one (mtrie3, dst_addr3);

	leaf0 = ip4_fib_mtrie_lookup_step (mtrie0, leaf0, dst_addr0, 2);
	leaf1 = ip4_fib_mtrie_lookup_step (mtrie1, leaf1, dst_addr1, 2);
	leaf2 = ip4_fib_mtrie_lookup_step (mtrie2, leaf2, dst_addr2, 2);
	leaf3 = ip4_fib_mtrie_lookup_step (mtrie3, leaf3, dst_addr3, 2);

	leaf0 = ip4_fib_mtrie_lookup_step (mtrie0, leaf0, dst_addr0, 3);
	leaf1 = ip4_fib_mtrie_lookup_step (mtrie1, leaf1, dst_addr1, 3);
	leaf2 = ip4_fib_mtrie_lookup_step (mtrie2, leaf2, dst_addr2, 3);
	leaf3 = ip4_fib_mtrie_lookup_step (mtrie3, leaf3, dst_addr3, 3);

	lb_index0 = ip4_fib_mtrie_leaf_get_adj_index (leaf0);
	lb_index1 = ip4_fib_mtrie_leaf_get_adj_index (leaf1);
	lb_index2 = ip4_fib_mtrie_leaf_get_adj_index (leaf2);
	lb_index3 = ip4_fib_mtrie_leaf_get_adj_index (leaf3);

	ASSERT (lb_index0 && lb_index1 && lb_index2 && lb_index3);
	lb0 = load_balance_get (lb_index0);
	lb1 = load_balance_get (lb_index1);
	lb2 = load_balance_get (lb_index2);
	lb3 = load_balance_get (lb_index3);

	ASSERT (lb0->lb_n_buckets > 0);
	ASSERT (is_pow2 (lb0->lb_n_buckets));
	ASSERT (lb1->lb_n_buckets > 0);
	ASSERT (is_pow2 (lb1->lb_n_buckets));
	ASSERT (lb2->lb_n_buckets > 0);
	ASSERT (is_pow2 (lb2->lb_n_buckets));
	ASSERT (lb3->lb_n_buckets > 0);
	ASSERT (is_pow2 (lb3->lb_n_buckets));

	/* Use flow hash to compute multipath adjacency. */
	hash_c0 = vnet_buffer (b[0])->ip.flow_hash = 0;
	hash_c1 = vnet_buffer (b[1])->ip.flow_hash = 0;
	hash_c2 = vnet_buffer (b[2])->ip.flow_hash = 0;
	hash_c3 = vnet_buffer (b[3])->ip.flow_hash = 0;
	if (PREDICT_FALSE (lb0->lb_n_buckets > 1))
	{
	flow_hash_config0 = lb0->lb_hash_config;
	hash_c0 = vnet_buffer (b[0])->ip.flow_hash =
	ip4_compute_flow_hash (ip0, flow_hash_config0);
	dpo0 =
	load_balance_get_fwd_bucket (lb0,
	(hash_c0 &
	(lb0->lb_n_buckets_minus_1)));
	}
	else
	{
	dpo0 = load_balance_get_bucket_i (lb0, 0);
	}
	if (PREDICT_FALSE (lb1->lb_n_buckets > 1))
	{
	flow_hash_config1 = lb1->lb_hash_config;
	hash_c1 = vnet_buffer (b[1])->ip.flow_hash =
	ip4_compute_flow_hash (ip1, flow_hash_config1);
	dpo1 =
	load_balance_get_fwd_bucket (lb1,
	(hash_c1 &
	(lb1->lb_n_buckets_minus_1)));
	}
	else
	{
	dpo1 = load_balance_get_bucket_i (lb1, 0);
	}
	if (PREDICT_FALSE (lb2->lb_n_buckets > 1))
	{
	flow_hash_config2 = lb2->lb_hash_config;
	hash_c2 = vnet_buffer (b[2])->ip.flow_hash =
	ip4_compute_flow_hash (ip2, flow_hash_config2);
	dpo2 =
	load_balance_get_fwd_bucket (lb2,
	(hash_c2 &
	(lb2->lb_n_buckets_minus_1)));
	}
	else
	{
	dpo2 = load_balance_get_bucket_i (lb2, 0);
	}
	if (PREDICT_FALSE (lb3->lb_n_buckets > 1))
	{
	flow_hash_config3 = lb3->lb_hash_config;
	hash_c3 = vnet_buffer (b[3])->ip.flow_hash =
	ip4_compute_flow_hash (ip3, flow_hash_config3);
	dpo3 =
	load_balance_get_fwd_bucket (lb3,
	(hash_c3 &
	(lb3->lb_n_buckets_minus_1)));
	}
	else
	{
	dpo3 = load_balance_get_bucket_i (lb3, 0);
	}

	next[0] = dpo0->dpoi_next_node;
	vnet_buffer (b[0])->ip.adj_index[VLIB_TX] = dpo0->dpoi_index;
	next[1] = dpo1->dpoi_next_node;
	vnet_buffer (b[1])->ip.adj_index[VLIB_TX] = dpo1->dpoi_index;
	next[2] = dpo2->dpoi_next_node;
	vnet_buffer (b[2])->ip.adj_index[VLIB_TX] = dpo2->dpoi_index;
	next[3] = dpo3->dpoi_next_node;
	vnet_buffer (b[3])->ip.adj_index[VLIB_TX] = dpo3->dpoi_index;

	vlib_increment_combined_counter
	(cm, thread_index, lb_index0, 1,
	vlib_buffer_length_in_chain (vm, b[0]));
	vlib_increment_combined_counter
	(cm, thread_index, lb_index1, 1,
	vlib_buffer_length_in_chain (vm, b[1]));
	vlib_increment_combined_counter
	(cm, thread_index, lb_index2, 1,
	vlib_buffer_length_in_chain (vm, b[2]));
	vlib_increment_combined_counter
	(cm, thread_index, lb_index3, 1,
	vlib_buffer_length_in_chain (vm, b[3]));

	b += 4;
	next += 4;
	n_left -= 4;
	}
	#elif (CLIB_N_PREFETCHES >= 4)
	while (n_left >= 4)
	{
	ip4_header_t ip0, ip1;
	const load_balance_t lb0, lb1;
	ip4_fib_mtrie_t mtrie0, mtrie1;
	ip4_fib_mtrie_leaf_t leaf0, leaf1;
	ip4_address_t dst_addr0, dst_addr1;
	u32 lb_index0, lb_index1;
	flow_hash_config_t flow_hash_config0, flow_hash_config1;
	u32 hash_c0, hash_c1;
	const dpo_id_t dpo0, dpo1;

	/* Prefetch next iteration. */
	{
	vlib_prefetch_buffer_header (b[2], LOAD);
	vlib_prefetch_buffer_header (b[3], LOAD);

	CLIB_PREFETCH (b[2]->data, sizeof (ip0[0]), LOAD);
	CLIB_PREFETCH (b[3]->data, sizeof (ip0[0]), LOAD);
	}

	ip0 = vlib_buffer_get_current (b[0]);
	ip1 = vlib_buffer_get_current (b[1]);

	dst_addr0 = &ip0->dst_address;
	dst_addr1 = &ip1->dst_address;

	ip_lookup_set_buffer_fib_index (im->fib_index_by_sw_if_index, b[0]);
	ip_lookup_set_buffer_fib_index (im->fib_index_by_sw_if_index, b[1]);

	if (!lookup_for_responses_to_locally_received_packets)
	{
	mtrie0 = &ip4_fib_get (vnet_buffer (b[0])->ip.fib_index)->mtrie;
	mtrie1 = &ip4_fib_get (vnet_buffer (b[1])->ip.fib_index)->mtrie;

	leaf0 = ip4_fib_mtrie_lookup_step_one (mtrie0, dst_addr0);
	leaf1 = ip4_fib_mtrie_lookup_step_one (mtrie1, dst_addr1);
	}

	if (!lookup_for_responses_to_locally_received_packets)
	{
	leaf0 = ip4_fib_mtrie_lookup_step (mtrie0, leaf0, dst_addr0, 2);
	leaf1 = ip4_fib_mtrie_lookup_step (mtrie1, leaf1, dst_addr1, 2);
	}

	if (!lookup_for_responses_to_locally_received_packets)
	{
	leaf0 = ip4_fib_mtrie_lookup_step (mtrie0, leaf0, dst_addr0, 3);
	leaf1 = ip4_fib_mtrie_lookup_step (mtrie1, leaf1, dst_addr1, 3);
	}

	if (lookup_for_responses_to_locally_received_packets)
	{
	lb_index0 = vnet_buffer (b[0])->ip.adj_index[VLIB_RX];
	lb_index1 = vnet_buffer (b[1])->ip.adj_index[VLIB_RX];
	}
	else
	{
	lb_index0 = ip4_fib_mtrie_leaf_get_adj_index (leaf0);
	lb_index1 = ip4_fib_mtrie_leaf_get_adj_index (leaf1);
	}

	ASSERT (lb_index0 && lb_index1);
	lb0 = load_balance_get (lb_index0);
	lb1 = load_balance_get (lb_index1);

	ASSERT (lb0->lb_n_buckets > 0);
	ASSERT (is_pow2 (lb0->lb_n_buckets));
	ASSERT (lb1->lb_n_buckets > 0);
	ASSERT (is_pow2 (lb1->lb_n_buckets));

	/* Use flow hash to compute multipath adjacency. */
	hash_c0 = vnet_buffer (b[0])->ip.flow_hash = 0;
	hash_c1 = vnet_buffer (b[1])->ip.flow_hash = 0;
	if (PREDICT_FALSE (lb0->lb_n_buckets > 1))
	{
	flow_hash_config0 = lb0->lb_hash_config;
	hash_c0 = vnet_buffer (b[0])->ip.flow_hash =
	ip4_compute_flow_hash (ip0, flow_hash_config0);
	dpo0 =
	load_balance_get_fwd_bucket (lb0,
	(hash_c0 &
	(lb0->lb_n_buckets_minus_1)));
	}
	else
	{
	dpo0 = load_balance_get_bucket_i (lb0, 0);
	}
	if (PREDICT_FALSE (lb1->lb_n_buckets > 1))
	{
	flow_hash_config1 = lb1->lb_hash_config;
	hash_c1 = vnet_buffer (b[1])->ip.flow_hash =
	ip4_compute_flow_hash (ip1, flow_hash_config1);
	dpo1 =
	load_balance_get_fwd_bucket (lb1,
	(hash_c1 &
	(lb1->lb_n_buckets_minus_1)));
	}
	else
	{
	dpo1 = load_balance_get_bucket_i (lb1, 0);
	}

	next[0] = dpo0->dpoi_next_node;
	vnet_buffer (b[0])->ip.adj_index[VLIB_TX] = dpo0->dpoi_index;
	next[1] = dpo1->dpoi_next_node;
	vnet_buffer (b[1])->ip.adj_index[VLIB_TX] = dpo1->dpoi_index;

	vlib_increment_combined_counter
	(cm, thread_index, lb_index0, 1,
	vlib_buffer_length_in_chain (vm, b[0]));
	vlib_increment_combined_counter
	(cm, thread_index, lb_index1, 1,
	vlib_buffer_length_in_chain (vm, b[1]));

	b += 2;
	next += 2;
	n_left -= 2;
	}
	#endif
	while (n_left > 0)
	{
	ip4_header_t *ip0;
	const load_balance_t *lb0;
	ip4_fib_mtrie_t *mtrie0;
	ip4_fib_mtrie_leaf_t leaf0;
	ip4_address_t *dst_addr0;
	u32 lbi0;
	flow_hash_config_t flow_hash_config0;
	const dpo_id_t *dpo0;
	u32 hash_c0;

	ip0 = vlib_buffer_get_current (b[0]);
	dst_addr0 = &ip0->dst_address;
	ip_lookup_set_buffer_fib_index (im->fib_index_by_sw_if_index, b[0]);

	mtrie0 = &ip4_fib_get (vnet_buffer (b[0])->ip.fib_index)->mtrie;
	leaf0 = ip4_fib_mtrie_lookup_step_one (mtrie0, dst_addr0);
	leaf0 = ip4_fib_mtrie_lookup_step (mtrie0, leaf0, dst_addr0, 2);
	leaf0 = ip4_fib_mtrie_lookup_step (mtrie0, leaf0, dst_addr0, 3);
	lbi0 = ip4_fib_mtrie_leaf_get_adj_index (leaf0);

	ASSERT (lbi0);
	lb0 = load_balance_get (lbi0);

	ASSERT (lb0->lb_n_buckets > 0);
	ASSERT (is_pow2 (lb0->lb_n_buckets));

	/* Use flow hash to compute multipath adjacency. */
	hash_c0 = vnet_buffer (b[0])->ip.flow_hash = 0;
	if (PREDICT_FALSE (lb0->lb_n_buckets > 1))
	{
	flow_hash_config0 = lb0->lb_hash_config;

	hash_c0 = vnet_buffer (b[0])->ip.flow_hash =
	ip4_compute_flow_hash (ip0, flow_hash_config0);
	dpo0 =
	load_balance_get_fwd_bucket (lb0,
	(hash_c0 &
	(lb0->lb_n_buckets_minus_1)));
	}
	else
	{
	dpo0 = load_balance_get_bucket_i (lb0, 0);
	}

	next[0] = dpo0->dpoi_next_node;
	vnet_buffer (b[0])->ip.adj_index[VLIB_TX] = dpo0->dpoi_index;

	vlib_increment_combined_counter (cm, thread_index, lbi0, 1,
	vlib_buffer_length_in_chain (vm,
	b[0]));

	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);

	return frame->n_vectors;
	}

	#endif /* __included_ip4_forward_h__ */

	/*
	* fd.io coding-style-patch-verification: ON
	*
	* Local Variables:
	* eval: (c-set-style "gnu")
	* End:
	*/