bgp rib-failure

I was working a lab and the task has me injecting a prefix into bgp with the network command.  The route is relflected to internal bgp peers via a router who has that same segment directly connected.  Since it is directly connected on the route-reflector server, there will be a RIB-failure on that router (it prefers the directly connected route to the BGP learned route).  The route-reflector will not install the BGP route into its routing table.  Despite the RIB-failure, the BGP peers are getting and forwarding NLRI about this prefix.  I was expecting them to do so... which is good... otherwise you would never be able to advertise networks into BGP that you were connected to... which would be a very bad thing!

So, here's the question.  I was researching the "RIb-failure" and found this document on Cisco's site that explains it.  But it says that that the peers will not advertise the prefix if there is a RIB failure.  Can someone clarify for me when a RIB failure will cause the NLRI to be blocked from advertisement and when it will not cause the NLRI to be blocked?




Per the following link:

Q. What does r RIB-Failure mean in the show ip bgp command output?
R1> show ip bgp
BGP table version is 5, local router ID is
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure
Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path
r> 0 130 0 30 i
*> 0 125 0 30 i

When BGP tries to install the bestpath prefix into Routing Information Base (RIB) (for example, the IP Routing table), RIB might reject the BGP route due to any of these reasons:

  • Route with better administrative distance already present in IGP. For example, if a static route already exists in IP Routing table.

  • Memory failure.

  • The number of routes in VPN routing/forwarding (VRF) exceeds the route-limit configured under the VRF instance.

In such cases, the prefixes that are rejected for these reasons are identified by r RIB Failure in the show ip bgp command output and are not advertised to the peers. This feature was first made available in Cisco IOS Software Release 12.2(08.05)T.


Sign In or Register to comment.