bgpd, doc: Allow route-map policy modifications to also affect route …

…reflectors.

By default, attribute modification via route-map policy out is ignored on
reflected routes. This patch provides an option to allow this modification
to occur. Once enabled, it affects all reflected routes.

Signed-off-by: Dinesh G Dutt <ddutt@cumulusnetworks.com>

bgpd/bgp_route.c

@@ -1078,9 +1078,9 @@ bgp_announce_check (struct bgp_info *ri, struct peer *peer, struct prefix *p,
       info.attr = attr;
 
       /* The route reflector is not allowed to modify the attributes
-	 of the reflected IBGP routes. */
-      if (from->sort == BGP_PEER_IBGP
-	  && peer->sort == BGP_PEER_IBGP)
+	 of the reflected IBGP routes, unless configured to allow it */
+      if ((from->sort == BGP_PEER_IBGP && peer->sort == BGP_PEER_IBGP) &&
+	  !bgp_flag_check(bgp, BGP_FLAG_RR_ALLOW_OUTBOUND_POLICY))
 	{
 	  bgp_attr_dup (&dummy_attr, attr);
 	  info.attr = &dummy_attr;

bgpd/bgp_vty.c

@@ -1527,6 +1527,80 @@ ALIAS (no_bgp_default_local_preference,
        "local preference (higher=more preferred)\n"
        "Configure default local preference value\n")
 
+static void
+peer_announce_routes_if_rmap_out (struct bgp *bgp)
+{
+  struct peer *peer;
+  struct listnode *node, *nnode;
+  struct bgp_filter *filter;
+  afi_t afi;
+  safi_t safi;
+
+  /* Reannounce all routes to appropriate neighbors */
+  for (ALL_LIST_ELEMENTS (bgp->peer, node, nnode, peer))
+    {
+      for (afi = AFI_IP; afi < AFI_MAX; afi++)
+	for (safi = SAFI_UNICAST; safi < SAFI_MAX; safi++)
+	  {
+	    if (CHECK_FLAG(peer->af_flags[afi][safi], PEER_FLAG_REFLECTOR_CLIENT))
+	      {
+		/* check if there's an out route-map on this client */
+		filter = &peer->filter[afi][safi];
+		if (ROUTE_MAP_OUT_NAME(filter))
+		  {
+		    if (BGP_DEBUG(update, UPDATE_OUT))
+		      zlog_debug("%s: Announcing routes again for peer %s"
+				 "(afi=%d, safi=%d", __func__, peer->host, afi,
+				 safi);
+
+		    bgp_announce_route_all(peer);
+		  }
+	      }
+	}
+    }
+}
+
+DEFUN (bgp_rr_allow_outbound_policy,
+       bgp_rr_allow_outbound_policy_cmd,
+       "bgp route-reflector allow-outbound-policy",
+       "BGP specific commands\n"
+       "Allow modifications made by out route-map\n"
+       "on ibgp neighbors\n")
+{
+  struct bgp *bgp;
+
+  bgp = vty->index;
+
+  if (!bgp_flag_check(bgp, BGP_FLAG_RR_ALLOW_OUTBOUND_POLICY))
+    {
+      bgp_flag_set(bgp, BGP_FLAG_RR_ALLOW_OUTBOUND_POLICY);
+      peer_announce_routes_if_rmap_out(bgp);
+    }
+
+  return CMD_SUCCESS;
+}
+
+DEFUN (no_bgp_rr_allow_outbound_policy,
+       no_bgp_rr_allow_outbound_policy_cmd,
+       "no bgp route-reflector allow-outbound-policy",
+       NO_STR
+       "BGP specific commands\n"
+       "Allow modifications made by out route-map\n"
+       "on ibgp neighbors\n")
+{
+  struct bgp *bgp;
+
+  bgp = vty->index;
+
+  if (bgp_flag_check(bgp, BGP_FLAG_RR_ALLOW_OUTBOUND_POLICY))
+    {
+      bgp_flag_unset(bgp, BGP_FLAG_RR_ALLOW_OUTBOUND_POLICY);
+      peer_announce_routes_if_rmap_out(bgp);
+    }
+
+  return CMD_SUCCESS;
+}
+
 static int
 peer_remote_as_vty (struct vty *vty, const char *peer_str, 
                     const char *as_str, afi_t afi, safi_t safi)
@@ -10006,6 +10080,10 @@ bgp_vty_init (void)
   install_element (BGP_NODE, &no_bgp_default_local_preference_cmd);
   install_element (BGP_NODE, &no_bgp_default_local_preference_val_cmd);
 
+  /* bgp ibgp-allow-policy-mods command */
+  install_element (BGP_NODE, &bgp_rr_allow_outbound_policy_cmd);
+  install_element (BGP_NODE, &no_bgp_rr_allow_outbound_policy_cmd);
+
   /* "neighbor remote-as" commands. */
   install_element (BGP_NODE, &neighbor_remote_as_cmd);
   install_element (BGP_NODE, &no_neighbor_cmd);

bgpd/bgpd.c

@@ -5528,6 +5528,10 @@ bgp_config_write (struct vty *vty)
       if (bgp_flag_check (bgp, BGP_FLAG_ASPATH_MULTIPATH_RELAX)) {
 	vty_out (vty, " bgp bestpath as-path multipath-relax%s", VTY_NEWLINE);
       }
+      if (bgp_flag_check (bgp, BGP_FLAG_RR_ALLOW_OUTBOUND_POLICY)) {
+	vty_out (vty, " bgp route-reflector allow-outbound-policy%s",
+		 VTY_NEWLINE);
+      }
       if (bgp_flag_check (bgp, BGP_FLAG_COMPARE_ROUTER_ID))
 	vty_out (vty, " bgp bestpath compare-routerid%s", VTY_NEWLINE);
       if (bgp_flag_check (bgp, BGP_FLAG_MED_CONFED)

bgpd/bgpd.h

@@ -107,7 +107,7 @@ struct bgp
   struct thread *t_startup;
 
   /* BGP flags. */
-  u_int16_t flags;
+  u_int32_t flags;
 #define BGP_FLAG_ALWAYS_COMPARE_MED       (1 << 0)
 #define BGP_FLAG_DETERMINISTIC_MED        (1 << 1)
 #define BGP_FLAG_MED_MISSING_AS_WORST     (1 << 2)
@@ -124,6 +124,7 @@ struct bgp
 #define BGP_FLAG_ASPATH_CONFED            (1 << 13)
 #define BGP_FLAG_ASPATH_MULTIPATH_RELAX   (1 << 14)
 #define BGP_FLAG_DELETING                 (1 << 15)
+#define BGP_FLAG_RR_ALLOW_OUTBOUND_POLICY (1 << 16)
 
   /* BGP Per AF flags */
   u_int16_t af_flags[AFI_MAX][SAFI_MAX];

doc/bgpd.texi

@@ -753,6 +753,12 @@ Apply a route-map on the neighbor.  @var{direct} must be @code{in} or
 @code{out}.
 @end deffn
 
+@deffn {BGP} {bgp route-reflector allow-outbound-policy} {}
+By default, attribute modification via route-map policy out is not reflected
+on reflected routes. This option allows the modifications to be reflected as
+well. Once enabled, it affects all reflected routes.
+@end deffn
+
 @c -----------------------------------------------------------------------
 @node BGP Peer Group
 @section BGP Peer Group