src/vnet/mpls/mpls_lookup.c - fdio/vpp - Gitiles

 /*
  * mpls_lookup.c: MPLS lookup
  *
  * Copyright (c) 2012-2014 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.
  */

 #include <vlib/vlib.h>
 #include <vnet/pg/pg.h>
 #include <vnet/mpls/mpls.h>
 #include <vnet/fib/mpls_fib.h>
 #include <vnet/dpo/load_balance.h>

 vlib_node_registration_t mpls_lookup_node;

 typedef struct {
   u32 next_index;
   u32 lb_index;
   u32 lfib_index;
   u32 label_net_byte_order;
   u32 hash;
 } mpls_lookup_trace_t;

 static u8 *
 format_mpls_lookup_trace (u8 * s, va_list * args)
 {
   CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
   CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
   mpls_lookup_trace_t * t = va_arg (*args, mpls_lookup_trace_t *);

   s = format (s, "MPLS: next [%d], lookup fib index %d, LB index %d hash %d"
               "label %d eos %d",
               t->next_index, t->lfib_index, t->lb_index, t->hash,
               vnet_mpls_uc_get_label(
                   clib_net_to_host_u32(t->label_net_byte_order)),
               vnet_mpls_uc_get_s(t->label_net_byte_order));
   return s;
 }

 /*
  * Compute flow hash.
  * We'll use it to select which adjacency to use for this flow.  And other things.
  */
 always_inline u32
 mpls_compute_flow_hash (const mpls_unicast_header_t * hdr,
                         flow_hash_config_t flow_hash_config)
 {
     // FIXME
     return (vnet_mpls_uc_get_label(hdr->label_exp_s_ttl));
 }

 static inline uword
 mpls_lookup (vlib_main_t * vm,
              vlib_node_runtime_t * node,
              vlib_frame_t * from_frame)
 {
   vlib_combined_counter_main_t * cm = &load_balance_main.lbm_to_counters;
   u32 n_left_from, next_index, * from, * to_next;
   mpls_main_t * mm = &mpls_main;
   u32 cpu_index = os_get_cpu_number();

   from = vlib_frame_vector_args (from_frame);
   n_left_from = from_frame->n_vectors;
   next_index = node->cached_next_index;

   while (n_left_from > 0)
     {
       u32 n_left_to_next;

       vlib_get_next_frame (vm, node, next_index,
                            to_next, n_left_to_next);

       while (n_left_from >= 4 && n_left_to_next >= 2)
         {
           u32 lbi0, next0, lfib_index0, bi0, hash_c0;
           const mpls_unicast_header_t * h0;
           const load_balance_t *lb0;
           const dpo_id_t *dpo0;
           vlib_buffer_t * b0;
           u32 lbi1, next1, lfib_index1, bi1, hash_c1;
           const mpls_unicast_header_t * h1;
           const load_balance_t *lb1;
           const dpo_id_t *dpo1;
           vlib_buffer_t * b1;

            /* 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);

             CLIB_PREFETCH (p2->data, sizeof (h0[0]), STORE);
             CLIB_PREFETCH (p3->data, sizeof (h0[0]), STORE);
           }

           bi0 = to_next[0] = from[0];
           bi1 = to_next[1] = from[1];

           from += 2;
           n_left_from -= 2;
           to_next += 2;
           n_left_to_next -= 2;

           b0 = vlib_get_buffer (vm, bi0);
           b1 = vlib_get_buffer (vm, bi1);
           h0 = vlib_buffer_get_current (b0);
           h1 = vlib_buffer_get_current (b1);

           lfib_index0 = vec_elt(mm->fib_index_by_sw_if_index,
                                 vnet_buffer(b0)->sw_if_index[VLIB_RX]);
           lfib_index1 = vec_elt(mm->fib_index_by_sw_if_index,
                                 vnet_buffer(b1)->sw_if_index[VLIB_RX]);

           lbi0 = mpls_fib_table_forwarding_lookup (lfib_index0, h0);
           lbi1 = mpls_fib_table_forwarding_lookup (lfib_index1, h1);
           lb0 = load_balance_get(lbi0);
           lb1 = load_balance_get(lbi1);

           hash_c0 = vnet_buffer(b0)->ip.flow_hash = 0;
           hash_c1 = vnet_buffer(b1)->ip.flow_hash = 0;

           if (PREDICT_FALSE(lb0->lb_n_buckets > 1))
           {
               hash_c0 = vnet_buffer (b0)->ip.flow_hash =
                   mpls_compute_flow_hash(h0, lb0->lb_hash_config);
           }
           if (PREDICT_FALSE(lb1->lb_n_buckets > 1))
           {
               hash_c1 = vnet_buffer (b1)->ip.flow_hash =
                   mpls_compute_flow_hash(h1, lb1->lb_hash_config);
           }

           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));

           dpo0 = load_balance_get_bucket_i(lb0,
                                            (hash_c0 &
                                             (lb0->lb_n_buckets_minus_1)));
           dpo1 = load_balance_get_bucket_i(lb1,
                                            (hash_c1 &
                                             (lb1->lb_n_buckets_minus_1)));

           next0 = dpo0->dpoi_next_node;
           next1 = dpo1->dpoi_next_node;

           vnet_buffer (b0)->ip.adj_index[VLIB_TX] = dpo0->dpoi_index;
           vnet_buffer (b1)->ip.adj_index[VLIB_TX] = dpo1->dpoi_index;

           vlib_increment_combined_counter
               (cm, cpu_index, lbi0, 1,
                vlib_buffer_length_in_chain (vm, b0));
           vlib_increment_combined_counter
               (cm, cpu_index, lbi1, 1,
                vlib_buffer_length_in_chain (vm, b1));

           /*
            * before we pop the label copy th values we need to maintain.
            * The label header is in network byte order.
            *  last byte is the TTL.
            *  bits 2 to 4 inclusive are the EXP bits
            */
           vnet_buffer (b0)->mpls.ttl = ((char*)h0)[3];
           vnet_buffer (b0)->mpls.exp = (((char*)h0)[2] & 0xe) >> 1;
           vnet_buffer (b0)->mpls.first = 1;
           vnet_buffer (b1)->mpls.ttl = ((char*)h1)[3];
           vnet_buffer (b1)->mpls.exp = (((char*)h1)[2] & 0xe) >> 1;
           vnet_buffer (b1)->mpls.first = 1;

           /*
            * pop the label that was just used in the lookup
            */
           vlib_buffer_advance(b0, sizeof(*h0));
           vlib_buffer_advance(b1, sizeof(*h1));

           if (PREDICT_FALSE(b0->flags & VLIB_BUFFER_IS_TRACED))
           {
               mpls_lookup_trace_t *tr = vlib_add_trace (vm, node,
                                                         b0, sizeof (*tr));
               tr->next_index = next0;
               tr->lb_index = lbi0;
               tr->lfib_index = lfib_index0;
               tr->hash = hash_c0;
               tr->label_net_byte_order = h0->label_exp_s_ttl;
           }

           if (PREDICT_FALSE(b1->flags & VLIB_BUFFER_IS_TRACED))
           {
               mpls_lookup_trace_t *tr = vlib_add_trace (vm, node,
                                                         b1, sizeof (*tr));
               tr->next_index = next1;
               tr->lb_index = lbi1;
               tr->lfib_index = lfib_index1;
               tr->hash = hash_c1;
               tr->label_net_byte_order = h1->label_exp_s_ttl;
           }

           vlib_validate_buffer_enqueue_x2 (vm, node, next_index,
                                            to_next, n_left_to_next,
                                            bi0, bi1, next0, next1);
         }

       while (n_left_from > 0 && n_left_to_next > 0)
       {
           u32 lbi0, next0, lfib_index0, bi0, hash_c0;
           const mpls_unicast_header_t * h0;
           const load_balance_t *lb0;
           const dpo_id_t *dpo0;
           vlib_buffer_t * b0;

           bi0 = from[0];
           to_next[0] = bi0;
           from += 1;
           to_next += 1;
           n_left_from -= 1;
           n_left_to_next -= 1;

           b0 = vlib_get_buffer (vm, bi0);
           h0 = vlib_buffer_get_current (b0);

           lfib_index0 = vec_elt(mm->fib_index_by_sw_if_index,
                                 vnet_buffer(b0)->sw_if_index[VLIB_RX]);

           lbi0 = mpls_fib_table_forwarding_lookup(lfib_index0, h0);
 	  lb0 = load_balance_get(lbi0);

           hash_c0 = vnet_buffer(b0)->ip.flow_hash = 0;
           if (PREDICT_FALSE(lb0->lb_n_buckets > 1))
           {
               hash_c0 = vnet_buffer (b0)->ip.flow_hash =
                   mpls_compute_flow_hash(h0, lb0->lb_hash_config);
           }

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

           dpo0 = load_balance_get_bucket_i(lb0,
                                            (hash_c0 &
                                             (lb0->lb_n_buckets_minus_1)));

           next0 = dpo0->dpoi_next_node;
           vnet_buffer (b0)->ip.adj_index[VLIB_TX] = dpo0->dpoi_index;

           vlib_increment_combined_counter
               (cm, cpu_index, lbi0, 1,
                vlib_buffer_length_in_chain (vm, b0));

           /*
            * before we pop the label copy th values we need to maintain.
            * The label header is in network byte order.
            *  last byte is the TTL.
            *  bits 2 to 4 inclusive are the EXP bits
            */
           vnet_buffer (b0)->mpls.ttl = ((char*)h0)[3];
           vnet_buffer (b0)->mpls.exp = (((char*)h0)[2] & 0xe) >> 1;
           vnet_buffer (b0)->mpls.first = 1;

           /*
            * pop the label that was just used in the lookup
            */
           vlib_buffer_advance(b0, sizeof(*h0));

           if (PREDICT_FALSE(b0->flags & VLIB_BUFFER_IS_TRACED))
           {
               mpls_lookup_trace_t *tr = vlib_add_trace (vm, node,
                                                         b0, sizeof (*tr));
               tr->next_index = next0;
               tr->lb_index = lbi0;
               tr->lfib_index = lfib_index0;
               tr->hash = hash_c0;
               tr->label_net_byte_order = h0->label_exp_s_ttl;
           }

           vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
                                            to_next, n_left_to_next,
                                            bi0, next0);
         }

       vlib_put_next_frame (vm, node, next_index, n_left_to_next);
     }
   vlib_node_increment_counter (vm, mpls_lookup_node.index,
                                MPLS_ERROR_PKTS_DECAP, from_frame->n_vectors);
   return from_frame->n_vectors;
 }

 static char * mpls_error_strings[] = {
 #define mpls_error(n,s) s,
 #include "error.def"
 #undef mpls_error
 };

 VLIB_REGISTER_NODE (mpls_lookup_node) = {
   .function = mpls_lookup,
   .name = "mpls-lookup",
   /* Takes a vector of packets. */
   .vector_size = sizeof (u32),
   .n_errors = MPLS_N_ERROR,
   .error_strings = mpls_error_strings,

   .sibling_of = "ip4-lookup",

   .format_buffer = format_mpls_header,
   .format_trace = format_mpls_lookup_trace,
   .unformat_buffer = unformat_mpls_header,
 };

 VLIB_NODE_FUNCTION_MULTIARCH (mpls_lookup_node, mpls_lookup)

 typedef struct {
   u32 next_index;
   u32 lb_index;
   u32 hash;
 } mpls_load_balance_trace_t;

 static u8 *
 format_mpls_load_balance_trace (u8 * s, va_list * args)
 {
   CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
   CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
   mpls_load_balance_trace_t * t = va_arg (*args, mpls_load_balance_trace_t *);

   s = format (s, "MPLS: next [%d], LB index %d hash %d",
               t->next_index, t->lb_index, t->hash);
   return s;
 }

 always_inline uword
 mpls_load_balance (vlib_main_t * vm,
                   vlib_node_runtime_t * node,
                   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;
   u32 cpu_index = os_get_cpu_number();
   u32 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)
         {
           mpls_lookup_next_t next0, next1;
           const load_balance_t *lb0, *lb1;
           vlib_buffer_t * p0, *p1;
           u32 pi0, lbi0, hc0, pi1, lbi1, hc1;
           const mpls_unicast_header_t *mpls0, *mpls1;
           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);

             CLIB_PREFETCH (p2->data, sizeof (mpls0[0]), STORE);
             CLIB_PREFETCH (p3->data, sizeof (mpls0[0]), STORE);
           }

           pi0 = to_next[0] = from[0];
           pi1 = to_next[1] = from[1];

           from += 2;
           n_left_from -= 2;
           to_next += 2;
           n_left_to_next -= 2;

           p0 = vlib_get_buffer (vm, pi0);
           p1 = vlib_get_buffer (vm, pi1);

           mpls0 = vlib_buffer_get_current (p0);
           mpls1 = vlib_buffer_get_current (p1);
           lbi0 = vnet_buffer (p0)->ip.adj_index[VLIB_TX];
           lbi1 = vnet_buffer (p1)->ip.adj_index[VLIB_TX];

           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 = vnet_buffer (p0)->ip.flow_hash = 0;
           hc1 = vnet_buffer (p1)->ip.flow_hash = 0;

           if (PREDICT_FALSE (lb0->lb_n_buckets > 1))
           {
               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 = mpls_compute_flow_hash(mpls0, hc0);
               }
           }
           if (PREDICT_FALSE (lb1->lb_n_buckets > 1))
           {
               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 = mpls_compute_flow_hash(mpls1, hc1);
               }
           }

           dpo0 = load_balance_get_bucket_i(lb0, hc0 & (lb0->lb_n_buckets_minus_1));
           dpo1 = load_balance_get_bucket_i(lb1, hc1 & (lb1->lb_n_buckets_minus_1));

           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, cpu_index, lbi0, 1,
                vlib_buffer_length_in_chain (vm, p0));
           vlib_increment_combined_counter
               (cm, cpu_index, lbi1, 1,
                vlib_buffer_length_in_chain (vm, p1));

           if (PREDICT_FALSE(p0->flags & VLIB_BUFFER_IS_TRACED))
           {
               mpls_load_balance_trace_t *tr = vlib_add_trace (vm, node,
                                                               p0, sizeof (*tr));
               tr->next_index = next0;
               tr->lb_index = lbi0;
               tr->hash = hc0;
           }

           vlib_validate_buffer_enqueue_x2 (vm, node, next,
                                            to_next, n_left_to_next,
                                            pi0, pi1, next0, next1);
        }

       while (n_left_from > 0 && n_left_to_next > 0)
         {
           mpls_lookup_next_t next0;
           const load_balance_t *lb0;
           vlib_buffer_t * p0;
           u32 pi0, lbi0, hc0;
           const mpls_unicast_header_t *mpls0;
           const dpo_id_t *dpo0;

           pi0 = from[0];
           to_next[0] = pi0;
           from += 1;
           to_next += 1;
           n_left_to_next -= 1;
           n_left_from -= 1;

           p0 = vlib_get_buffer (vm, pi0);

           mpls0 = vlib_buffer_get_current (p0);
           lbi0 = vnet_buffer (p0)->ip.adj_index[VLIB_TX];

           lb0 = load_balance_get(lbi0);

           hc0 = vnet_buffer (p0)->ip.flow_hash = 0;
           if (PREDICT_FALSE (lb0->lb_n_buckets > 1))
           {
               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 = mpls_compute_flow_hash(mpls0, hc0);
               }
           }

           dpo0 = load_balance_get_bucket_i(lb0, hc0 & (lb0->lb_n_buckets_minus_1));

           next0 = dpo0->dpoi_next_node;
           vnet_buffer (p0)->ip.adj_index[VLIB_TX] = dpo0->dpoi_index;

           vlib_increment_combined_counter
               (cm, cpu_index, lbi0, 1,
                vlib_buffer_length_in_chain (vm, p0));

           vlib_validate_buffer_enqueue_x1 (vm, node, next,
                                            to_next, n_left_to_next,
                                            pi0, next0);
         }

       vlib_put_next_frame (vm, node, next, n_left_to_next);
     }

   return frame->n_vectors;
 }

 VLIB_REGISTER_NODE (mpls_load_balance_node) = {
   .function = mpls_load_balance,
   .name = "mpls-load-balance",
   .vector_size = sizeof (u32),
   .sibling_of = "mpls-lookup",

   .format_trace = format_mpls_load_balance_trace,
 };

 VLIB_NODE_FUNCTION_MULTIARCH (mpls_load_balance_node, mpls_load_balance)
	/*
	* mpls_lookup.c: MPLS lookup
	*
	* Copyright (c) 2012-2014 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.
	*/

	#include <vlib/vlib.h>
	#include <vnet/pg/pg.h>
	#include <vnet/mpls/mpls.h>
	#include <vnet/fib/mpls_fib.h>
	#include <vnet/dpo/load_balance.h>

	vlib_node_registration_t mpls_lookup_node;

	typedef struct {
	u32 next_index;
	u32 lb_index;
	u32 lfib_index;
	u32 label_net_byte_order;
	u32 hash;
	} mpls_lookup_trace_t;

	static u8 *
	format_mpls_lookup_trace (u8 * s, va_list * args)
	{
	CLIB_UNUSED (vlib_main_t * vm) = va_arg (args, vlib_main_t );
	CLIB_UNUSED (vlib_node_t * node) = va_arg (args, vlib_node_t );
	mpls_lookup_trace_t * t = va_arg (args, mpls_lookup_trace_t );

	s = format (s, "MPLS: next [%d], lookup fib index %d, LB index %d hash %d"
	"label %d eos %d",
	t->next_index, t->lfib_index, t->lb_index, t->hash,
	vnet_mpls_uc_get_label(
	clib_net_to_host_u32(t->label_net_byte_order)),
	vnet_mpls_uc_get_s(t->label_net_byte_order));
	return s;
	}

	/*
	* Compute flow hash.
	* We'll use it to select which adjacency to use for this flow. And other things.
	*/
	always_inline u32
	mpls_compute_flow_hash (const mpls_unicast_header_t * hdr,
	flow_hash_config_t flow_hash_config)
	{
	// FIXME
	return (vnet_mpls_uc_get_label(hdr->label_exp_s_ttl));
	}

	static inline uword
	mpls_lookup (vlib_main_t * vm,
	vlib_node_runtime_t * node,
	vlib_frame_t * from_frame)
	{
	vlib_combined_counter_main_t * cm = &load_balance_main.lbm_to_counters;
	u32 n_left_from, next_index, * from, * to_next;
	mpls_main_t * mm = &mpls_main;
	u32 cpu_index = os_get_cpu_number();

	from = vlib_frame_vector_args (from_frame);
	n_left_from = from_frame->n_vectors;
	next_index = node->cached_next_index;

	while (n_left_from > 0)
	{
	u32 n_left_to_next;

	vlib_get_next_frame (vm, node, next_index,
	to_next, n_left_to_next);

	while (n_left_from >= 4 && n_left_to_next >= 2)
	{
	u32 lbi0, next0, lfib_index0, bi0, hash_c0;
	const mpls_unicast_header_t * h0;
	const load_balance_t *lb0;
	const dpo_id_t *dpo0;
	vlib_buffer_t * b0;
	u32 lbi1, next1, lfib_index1, bi1, hash_c1;
	const mpls_unicast_header_t * h1;
	const load_balance_t *lb1;
	const dpo_id_t *dpo1;
	vlib_buffer_t * b1;

	/* 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);

	CLIB_PREFETCH (p2->data, sizeof (h0[0]), STORE);
	CLIB_PREFETCH (p3->data, sizeof (h0[0]), STORE);
	}

	bi0 = to_next[0] = from[0];
	bi1 = to_next[1] = from[1];

	from += 2;
	n_left_from -= 2;
	to_next += 2;
	n_left_to_next -= 2;

	b0 = vlib_get_buffer (vm, bi0);
	b1 = vlib_get_buffer (vm, bi1);
	h0 = vlib_buffer_get_current (b0);
	h1 = vlib_buffer_get_current (b1);

	lfib_index0 = vec_elt(mm->fib_index_by_sw_if_index,
	vnet_buffer(b0)->sw_if_index[VLIB_RX]);
	lfib_index1 = vec_elt(mm->fib_index_by_sw_if_index,
	vnet_buffer(b1)->sw_if_index[VLIB_RX]);

	lbi0 = mpls_fib_table_forwarding_lookup (lfib_index0, h0);
	lbi1 = mpls_fib_table_forwarding_lookup (lfib_index1, h1);
	lb0 = load_balance_get(lbi0);
	lb1 = load_balance_get(lbi1);

	hash_c0 = vnet_buffer(b0)->ip.flow_hash = 0;
	hash_c1 = vnet_buffer(b1)->ip.flow_hash = 0;

	if (PREDICT_FALSE(lb0->lb_n_buckets > 1))
	{
	hash_c0 = vnet_buffer (b0)->ip.flow_hash =
	mpls_compute_flow_hash(h0, lb0->lb_hash_config);
	}
	if (PREDICT_FALSE(lb1->lb_n_buckets > 1))
	{
	hash_c1 = vnet_buffer (b1)->ip.flow_hash =
	mpls_compute_flow_hash(h1, lb1->lb_hash_config);
	}

	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));

	dpo0 = load_balance_get_bucket_i(lb0,
	(hash_c0 &
	(lb0->lb_n_buckets_minus_1)));
	dpo1 = load_balance_get_bucket_i(lb1,
	(hash_c1 &
	(lb1->lb_n_buckets_minus_1)));

	next0 = dpo0->dpoi_next_node;
	next1 = dpo1->dpoi_next_node;

	vnet_buffer (b0)->ip.adj_index[VLIB_TX] = dpo0->dpoi_index;
	vnet_buffer (b1)->ip.adj_index[VLIB_TX] = dpo1->dpoi_index;

	vlib_increment_combined_counter
	(cm, cpu_index, lbi0, 1,
	vlib_buffer_length_in_chain (vm, b0));
	vlib_increment_combined_counter
	(cm, cpu_index, lbi1, 1,
	vlib_buffer_length_in_chain (vm, b1));

	/*
	* before we pop the label copy th values we need to maintain.
	* The label header is in network byte order.
	* last byte is the TTL.
	* bits 2 to 4 inclusive are the EXP bits
	*/
	vnet_buffer (b0)->mpls.ttl = ((char*)h0)[3];
	vnet_buffer (b0)->mpls.exp = (((char*)h0)[2] & 0xe) >> 1;
	vnet_buffer (b0)->mpls.first = 1;
	vnet_buffer (b1)->mpls.ttl = ((char*)h1)[3];
	vnet_buffer (b1)->mpls.exp = (((char*)h1)[2] & 0xe) >> 1;
	vnet_buffer (b1)->mpls.first = 1;

	/*
	* pop the label that was just used in the lookup
	*/
	vlib_buffer_advance(b0, sizeof(*h0));
	vlib_buffer_advance(b1, sizeof(*h1));

	if (PREDICT_FALSE(b0->flags & VLIB_BUFFER_IS_TRACED))
	{
	mpls_lookup_trace_t *tr = vlib_add_trace (vm, node,
	b0, sizeof (*tr));
	tr->next_index = next0;
	tr->lb_index = lbi0;
	tr->lfib_index = lfib_index0;
	tr->hash = hash_c0;
	tr->label_net_byte_order = h0->label_exp_s_ttl;
	}

	if (PREDICT_FALSE(b1->flags & VLIB_BUFFER_IS_TRACED))
	{
	mpls_lookup_trace_t *tr = vlib_add_trace (vm, node,
	b1, sizeof (*tr));
	tr->next_index = next1;
	tr->lb_index = lbi1;
	tr->lfib_index = lfib_index1;
	tr->hash = hash_c1;
	tr->label_net_byte_order = h1->label_exp_s_ttl;
	}

	vlib_validate_buffer_enqueue_x2 (vm, node, next_index,
	to_next, n_left_to_next,
	bi0, bi1, next0, next1);
	}

	while (n_left_from > 0 && n_left_to_next > 0)
	{
	u32 lbi0, next0, lfib_index0, bi0, hash_c0;
	const mpls_unicast_header_t * h0;
	const load_balance_t *lb0;
	const dpo_id_t *dpo0;
	vlib_buffer_t * b0;

	bi0 = from[0];
	to_next[0] = bi0;
	from += 1;
	to_next += 1;
	n_left_from -= 1;
	n_left_to_next -= 1;

	b0 = vlib_get_buffer (vm, bi0);
	h0 = vlib_buffer_get_current (b0);

	lfib_index0 = vec_elt(mm->fib_index_by_sw_if_index,
	vnet_buffer(b0)->sw_if_index[VLIB_RX]);

	lbi0 = mpls_fib_table_forwarding_lookup(lfib_index0, h0);
	lb0 = load_balance_get(lbi0);

	hash_c0 = vnet_buffer(b0)->ip.flow_hash = 0;
	if (PREDICT_FALSE(lb0->lb_n_buckets > 1))
	{
	hash_c0 = vnet_buffer (b0)->ip.flow_hash =
	mpls_compute_flow_hash(h0, lb0->lb_hash_config);
	}

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

	dpo0 = load_balance_get_bucket_i(lb0,
	(hash_c0 &
	(lb0->lb_n_buckets_minus_1)));

	next0 = dpo0->dpoi_next_node;
	vnet_buffer (b0)->ip.adj_index[VLIB_TX] = dpo0->dpoi_index;

	vlib_increment_combined_counter
	(cm, cpu_index, lbi0, 1,
	vlib_buffer_length_in_chain (vm, b0));

	/*
	* before we pop the label copy th values we need to maintain.
	* The label header is in network byte order.
	* last byte is the TTL.
	* bits 2 to 4 inclusive are the EXP bits
	*/
	vnet_buffer (b0)->mpls.ttl = ((char*)h0)[3];
	vnet_buffer (b0)->mpls.exp = (((char*)h0)[2] & 0xe) >> 1;
	vnet_buffer (b0)->mpls.first = 1;

	/*
	* pop the label that was just used in the lookup
	*/
	vlib_buffer_advance(b0, sizeof(*h0));

	if (PREDICT_FALSE(b0->flags & VLIB_BUFFER_IS_TRACED))
	{
	mpls_lookup_trace_t *tr = vlib_add_trace (vm, node,
	b0, sizeof (*tr));
	tr->next_index = next0;
	tr->lb_index = lbi0;
	tr->lfib_index = lfib_index0;
	tr->hash = hash_c0;
	tr->label_net_byte_order = h0->label_exp_s_ttl;
	}

	vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
	to_next, n_left_to_next,
	bi0, next0);
	}

	vlib_put_next_frame (vm, node, next_index, n_left_to_next);
	}
	vlib_node_increment_counter (vm, mpls_lookup_node.index,
	MPLS_ERROR_PKTS_DECAP, from_frame->n_vectors);
	return from_frame->n_vectors;
	}

	static char * mpls_error_strings[] = {
	#define mpls_error(n,s) s,
	#include "error.def"
	#undef mpls_error
	};

	VLIB_REGISTER_NODE (mpls_lookup_node) = {
	.function = mpls_lookup,
	.name = "mpls-lookup",
	/* Takes a vector of packets. */
	.vector_size = sizeof (u32),
	.n_errors = MPLS_N_ERROR,
	.error_strings = mpls_error_strings,

	.sibling_of = "ip4-lookup",

	.format_buffer = format_mpls_header,
	.format_trace = format_mpls_lookup_trace,
	.unformat_buffer = unformat_mpls_header,
	};

	VLIB_NODE_FUNCTION_MULTIARCH (mpls_lookup_node, mpls_lookup)

	typedef struct {
	u32 next_index;
	u32 lb_index;
	u32 hash;
	} mpls_load_balance_trace_t;

	static u8 *
	format_mpls_load_balance_trace (u8 * s, va_list * args)
	{
	CLIB_UNUSED (vlib_main_t * vm) = va_arg (args, vlib_main_t );
	CLIB_UNUSED (vlib_node_t * node) = va_arg (args, vlib_node_t );
	mpls_load_balance_trace_t * t = va_arg (args, mpls_load_balance_trace_t );

	s = format (s, "MPLS: next [%d], LB index %d hash %d",
	t->next_index, t->lb_index, t->hash);
	return s;
	}

	always_inline uword
	mpls_load_balance (vlib_main_t * vm,
	vlib_node_runtime_t * node,
	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;
	u32 cpu_index = os_get_cpu_number();
	u32 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)
	{
	mpls_lookup_next_t next0, next1;
	const load_balance_t lb0, lb1;
	vlib_buffer_t * p0, *p1;
	u32 pi0, lbi0, hc0, pi1, lbi1, hc1;
	const mpls_unicast_header_t mpls0, mpls1;
	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);

	CLIB_PREFETCH (p2->data, sizeof (mpls0[0]), STORE);
	CLIB_PREFETCH (p3->data, sizeof (mpls0[0]), STORE);
	}

	pi0 = to_next[0] = from[0];
	pi1 = to_next[1] = from[1];

	from += 2;
	n_left_from -= 2;
	to_next += 2;
	n_left_to_next -= 2;

	p0 = vlib_get_buffer (vm, pi0);
	p1 = vlib_get_buffer (vm, pi1);

	mpls0 = vlib_buffer_get_current (p0);
	mpls1 = vlib_buffer_get_current (p1);
	lbi0 = vnet_buffer (p0)->ip.adj_index[VLIB_TX];
	lbi1 = vnet_buffer (p1)->ip.adj_index[VLIB_TX];

	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 = vnet_buffer (p0)->ip.flow_hash = 0;
	hc1 = vnet_buffer (p1)->ip.flow_hash = 0;

	if (PREDICT_FALSE (lb0->lb_n_buckets > 1))
	{
	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 = mpls_compute_flow_hash(mpls0, hc0);
	}
	}
	if (PREDICT_FALSE (lb1->lb_n_buckets > 1))
	{
	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 = mpls_compute_flow_hash(mpls1, hc1);
	}
	}

	dpo0 = load_balance_get_bucket_i(lb0, hc0 & (lb0->lb_n_buckets_minus_1));
	dpo1 = load_balance_get_bucket_i(lb1, hc1 & (lb1->lb_n_buckets_minus_1));

	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, cpu_index, lbi0, 1,
	vlib_buffer_length_in_chain (vm, p0));
	vlib_increment_combined_counter
	(cm, cpu_index, lbi1, 1,
	vlib_buffer_length_in_chain (vm, p1));

	if (PREDICT_FALSE(p0->flags & VLIB_BUFFER_IS_TRACED))
	{
	mpls_load_balance_trace_t *tr = vlib_add_trace (vm, node,
	p0, sizeof (*tr));
	tr->next_index = next0;
	tr->lb_index = lbi0;
	tr->hash = hc0;
	}

	vlib_validate_buffer_enqueue_x2 (vm, node, next,
	to_next, n_left_to_next,
	pi0, pi1, next0, next1);
	}

	while (n_left_from > 0 && n_left_to_next > 0)
	{
	mpls_lookup_next_t next0;
	const load_balance_t *lb0;
	vlib_buffer_t * p0;
	u32 pi0, lbi0, hc0;
	const mpls_unicast_header_t *mpls0;
	const dpo_id_t *dpo0;

	pi0 = from[0];
	to_next[0] = pi0;
	from += 1;
	to_next += 1;
	n_left_to_next -= 1;
	n_left_from -= 1;

	p0 = vlib_get_buffer (vm, pi0);

	mpls0 = vlib_buffer_get_current (p0);
	lbi0 = vnet_buffer (p0)->ip.adj_index[VLIB_TX];

	lb0 = load_balance_get(lbi0);

	hc0 = vnet_buffer (p0)->ip.flow_hash = 0;
	if (PREDICT_FALSE (lb0->lb_n_buckets > 1))
	{
	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 = mpls_compute_flow_hash(mpls0, hc0);
	}
	}

	dpo0 = load_balance_get_bucket_i(lb0, hc0 & (lb0->lb_n_buckets_minus_1));

	next0 = dpo0->dpoi_next_node;
	vnet_buffer (p0)->ip.adj_index[VLIB_TX] = dpo0->dpoi_index;

	vlib_increment_combined_counter
	(cm, cpu_index, lbi0, 1,
	vlib_buffer_length_in_chain (vm, p0));

	vlib_validate_buffer_enqueue_x1 (vm, node, next,
	to_next, n_left_to_next,
	pi0, next0);
	}

	vlib_put_next_frame (vm, node, next, n_left_to_next);
	}

	return frame->n_vectors;
	}

	VLIB_REGISTER_NODE (mpls_load_balance_node) = {
	.function = mpls_load_balance,
	.name = "mpls-load-balance",
	.vector_size = sizeof (u32),
	.sibling_of = "mpls-lookup",

	.format_trace = format_mpls_load_balance_trace,
	};

	VLIB_NODE_FUNCTION_MULTIARCH (mpls_load_balance_node, mpls_load_balance)