FIB path preference

Paths are given a preference, lowest value is 'best'. Only paths that are up are up contribute to fprwarding - that's unchanged. What's new is that of the path's that re up only those that have the best preference contribute. A poor man's primary and backup. It's not true primary/backup function because the FIB must converge before the lower preference paths are used.

Change-Id: Ie4453c4a7b1094c6c2b51fe1594b8302103bb68e
Signed-off-by: Neale Ranns <nranns@cisco.com>

3 files changed, 20 insertions, 22 deletions

diff --git a/src/vnet/ip/ip.api b/src/vnet/ip/ip.api
index 7097a13014d..fa363370c56 100644
--- a/src/vnet/ip/ip.api
+++ b/src/vnet/ip/ip.api
@@ -31,6 +31,7 @@ define ip_fib_dump
 /** \brief FIB path
     @param sw_if_index - index of the interface
     @param weight - The weight, for UCMP
+    @param preference - The preference of the path. lowest preference is prefered
     @param is_local - local if non-zero, else remote
     @param is_drop - Drop the packet
     @param is_unreach - Drop the packet and rate limit send ICMP unreachable
@@ -43,7 +44,8 @@ define ip_fib_dump
 typeonly manual_print manual_endian define fib_path
 {
   u32 sw_if_index;
-  u32 weight;
+  u8 weight;
+  u8 preference;
   u8 is_local;
   u8 is_drop;
   u8 is_unreach;
@@ -374,6 +376,7 @@ autoreply define ip_add_del_route
   /* Is last/not-last message in group of multiple add/del messages. */
   u8 not_last;
   u8 next_hop_weight;
+  u8 next_hop_preference;
   u8 dst_address_length;
   u8 dst_address[16];
   u8 next_hop_address[16];
diff --git a/src/vnet/ip/ip_api.c b/src/vnet/ip/ip_api.c
index 2680d6010dc..d00ae76cfe8 100644
--- a/src/vnet/ip/ip_api.c
+++ b/src/vnet/ip/ip_api.c
@@ -716,7 +716,8 @@ add_del_route_t_handler (u8 is_multipath,
 			 const ip46_address_t * next_hop,
 			 u32 next_hop_sw_if_index,
 			 u8 next_hop_fib_index,
-			 u32 next_hop_weight,
+			 u16 next_hop_weight,
+			 u16 next_hop_preference,
 			 mpls_label_t next_hop_via_label,
 			 mpls_label_t * next_hop_out_label_stack)
 {
@@ -729,6 +730,7 @@ add_del_route_t_handler (u8 is_multipath,
     .frp_sw_if_index = next_hop_sw_if_index,
     .frp_fib_index = next_hop_fib_index,
     .frp_weight = next_hop_weight,
+    .frp_preference = next_hop_preference,
     .frp_label_stack = next_hop_out_label_stack,
   };
   fib_route_path_t *paths = NULL;
@@ -971,6 +973,7 @@ ip4_add_del_route_t_handler (vl_api_ip_add_del_route_t * mp)
 				   ntohl (mp->next_hop_sw_if_index),
 				   next_hop_fib_index,
 				   mp->next_hop_weight,
+				   mp->next_hop_preference,
 				   ntohl (mp->next_hop_via_label),
 				   label_stack));
 }
@@ -1029,6 +1032,7 @@ ip6_add_del_route_t_handler (vl_api_ip_add_del_route_t * mp)
 				   &nh, ntohl (mp->next_hop_sw_if_index),
 				   next_hop_fib_index,
 				   mp->next_hop_weight,
+				   mp->next_hop_preference,
 				   ntohl (mp->next_hop_via_label),
 				   label_stack));
 }
diff --git a/src/vnet/ip/lookup.c b/src/vnet/ip/lookup.c
index 6547cad51b1..533d010a738 100755
--- a/src/vnet/ip/lookup.c
+++ b/src/vnet/ip/lookup.c
@@ -360,6 +360,7 @@ vnet_ip_route_cmd (vlib_main_t * vm,
   fib_prefix_t *prefixs = NULL, pfx;
   mpls_label_t out_label, via_label;
   clib_error_t *error = NULL;
+  u32 weight, preference;
   u32 table_id, is_del;
   vnet_main_t *vnm;
   u32 fib_index;
@@ -441,26 +442,6 @@ vnet_ip_route_cmd (vlib_main_t * vm,
 	  pfx.fp_proto = FIB_PROTOCOL_IP6;
 	  vec_add1 (prefixs, pfx);
 	}
-      else if (unformat (line_input, "via %U %U weight %u",
-			 unformat_ip4_address,
-			 &rpath.frp_addr.ip4,
-			 unformat_vnet_sw_interface, vnm,
-			 &rpath.frp_sw_if_index, &rpath.frp_weight))
-	{
-	  rpath.frp_proto = FIB_PROTOCOL_IP4;
-	  vec_add1 (rpaths, rpath);
-	}
-
-      else if (unformat (line_input, "via %U %U weight %u",
-			 unformat_ip6_address,
-			 &rpath.frp_addr.ip6,
-			 unformat_vnet_sw_interface, vnm,
-			 &rpath.frp_sw_if_index, &rpath.frp_weight))
-	{
-	  rpath.frp_proto = FIB_PROTOCOL_IP6;
-	  vec_add1 (rpaths, rpath);
-	}
-
       else if (unformat (line_input, "via %U %U",
 			 unformat_ip4_address,
 			 &rpath.frp_addr.ip4,
@@ -482,6 +463,16 @@ vnet_ip_route_cmd (vlib_main_t * vm,
 	  rpath.frp_proto = FIB_PROTOCOL_IP6;
 	  vec_add1 (rpaths, rpath);
 	}
+      else if (unformat (line_input, "weight %u", &weight))
+	{
+	  ASSERT (vec_len (rpaths));
+	  rpaths[vec_len (rpaths) - 1].frp_weight = weight;
+	}
+      else if (unformat (line_input, "preference %u", &preference))
+	{
+	  ASSERT (vec_len (rpaths));
+	  rpaths[vec_len (rpaths) - 1].frp_preference = preference;
+	}
       else if (unformat (line_input, "via %U next-hop-table %d",
 			 unformat_ip4_address,
 			 &rpath.frp_addr.ip4, &rpath.frp_fib_index))