RIB-Failure. Not as bad as I immediately thought

Whilst labbing out a BGP scenario I came across the following in a sh ip bgp output.

I noticed in the output that I had a RIB-failure. Failure. I immediately started to wonder what exactly did this mean. I could still ping the hosts at the end of the route and the route was marked as best.

A little investigative work yielded these results

Firstly, a RIB-Failure isn’t a bad thing. It is a fetautre that was introduced in IOS 12.2T. It essentially means that a BGP route cannot be placed into the routing table. The reason being is that a route with a lower AD is in the routing table.

In the scenario I was working out, I had placed a static route for traffic to go to my ISP. This was on the 192.168.1.4/30 network. Due to static routes having an AD of 1, this beat my eBGP route.

Previously, routes that now days would be marked with an r for RIB-Failure, would have silently slipped into the nether with no reason as to why they didn’t make the routing table. This feature at a glance allows Network Engineers/Admins to note a route has a better path injected into the routing table that isn’t by the BGP process.

The more you know. 🙂

2 thoughts on “RIB-Failure. Not as bad as I immediately thought

  1. Anthony says:

    Yes! It is a very handy command. I used it when doing a BGP and found it will state the reason why the route was not injected into the RIB.

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