bgpd: prevent type-5 route creation if bgp_vrf->l3_vni is 0

After a router reboot the L3 network via it converges before the L2
network. This is because MLAG intentionally holds down bridge-access
and vxlan-network ports for some time (MLAG init-delay) to prevent traffic
from switching to a router that is not fully ready. This also means that
routes (from vrf-peering sessions) that qualify for evpn type-5
advertisments are available long before the L3-VNI is available for that
tenant VRF. In these windows bgpd was adding these evpn-type-5 routes with
a L3-VNI of 0 (which was not fixed up after the L3-VNI became available) -

BGP routing table entry for 100.0.0.1:2:[5]:[0]:[0]:[32]:[200.1.1.1]
Paths: (1 available, best #1)
  Advertised to non peer-group peers:
  MSP1(uplink-1) MSP2(uplink-2)
  Route [5]:[0]:[0]:[32]:[200.1.1.1] VNI 0 >>>>>>>>
  65001 65535
    36.0.0.9 from 0.0.0.0 (27.0.0.9)
      Origin incomplete, metric 0, valid, sourced, local, bestpath-from-AS 65001, best
      Extended Community: ET:8 RT:5544:4001 Rmac:44:38:39:ff:ff:01
      AddPath ID: RX 0, TX 327
      Last update: Wed Feb 27 18:37:10 2019

Fix is to defer creating type-5 routes till the L3-VNI is available for
that tenant VRF (this was already being done for most cases; fixup takes
care of some that missed the check).

Ticket: CM-24022

Signed-off-by: Anuradha Karuppiah <[email protected]>

bgpd/bgp_evpn_vty.c

@@ -3358,7 +3358,8 @@ DEFUN (bgp_evpn_advertise_type5,
 	}
 
 	/* advertise type-5 routes */
-	bgp_evpn_advertise_type5_routes(bgp_vrf, afi, safi);
+	if (advertise_type5_routes(bgp_vrf, afi))
+		bgp_evpn_advertise_type5_routes(bgp_vrf, afi, safi);
 	return CMD_SUCCESS;
 }
 

bgpd/bgp_routemap.c

@@ -3399,7 +3399,7 @@ static void bgp_route_map_process_update(struct bgp *bgp, const char *rmap_name,
 				"Processing route_map %s update on advertise type5 route command",
 				rmap_name);
 
-		if (route_update) {
+		if (route_update && advertise_type5_routes(bgp, afi)) {
 			bgp_evpn_withdraw_type5_routes(bgp, afi, safi);
 			bgp_evpn_advertise_type5_routes(bgp, afi, safi);
 		}