Rib-failure BGP

On November 20, 2009, in CCIE, by Darren

Sometimes when configuring BGP you’ll come accross routes that show rib-failure. What exactly does this mean?

Have a look at this output:

R3#sh ip bgp
   Network          Next Hop            Metric LocPrf Weight Path
r> 172.16.220.0/24  172.16.220.1        0             0 3 i
*> 192.68.0.0/16    172.16.220.1        0             0 3 {2,1} i
*> 192.68.10.0      172.16.220.1                      0 3 2 i

172.16.220.0/24 is showing up as r> – but what exactly is going on? There is a command you can use to see what’s happened: show ip bgp rib-failure

R3#sh ip bgp rib-failure
Network            Next Hop                      RIB-failure   RIB-NH Matches
172.16.220.0/24    172.16.220.1        Higher admin distance              n/a

Here it’s telling me that the BGP could not be injected into the routing table as there is already a route with a higher administrative distance there. This is proved with the ip routing table:

R3#sh ip route 172.16.220.0
Routing entry for 172.16.220.0/24
  Known via "connected", distance 0, metric 0 (connected, via interface)
  Routing Descriptor Blocks:
  * directly connected, via FastEthernet0/1
      Route metric is 0, traffic share count is 1

Essentially a RIB-failure is a note letting you know that the route is in BGP, but it has not been injected into the IP routing table even though it is a valid and best route

(25 April 2012) – Note that rib failure prefixes are still advertised to BGP neighbours. This is not like EIGRP and RIP who will not. You can however prevent BGP from advertising rib-failure routes by configuring bgp suppress-inactive under the BGP process.

Tagged with:  

© 2009-2014 Darren O'Connor All Rights Reserved