Received-only Paths in the BGP RIB

Look at the example output for the show ip bgp command below.

 7606 9837 9837 9837 18250, (Received from a RR-client), (received & used)
   198.32.212.61 (metric 20) from 203.17.96.105 (203.17.101.40)
     Origin IGP, metric 0, localpref 90, valid, internal, best
     Community: 4854:6002
     Originator: 203.17.101.24, Cluster list: 203.17.101.40, 203.17.101.22

 1221 2764 9837 18250, (received-only)
   203.62.252.39 from 203.62.252.39 (203.62.252.39)
     Origin IGP, localpref 100, valid, external

Why has a path with a lower localpref of 90 been installed in the FIB, rather than another path that has a higher localpref of 100. Also, why is the path with a higher localpref marked as “received-only”?

Referring to this, the path in question has been denied by routing policy, but still remains in the RIB due to the enabling of soft-reconfiguration inbound on the router. Due to this setting, routes that have been denied by routing policy will still be stored on the router so as to minimize the impact of disruptions that may occur when the BGP session is cleared or reset. And tada, that’s all there is to this question.

Related posts:

  1. backscatter mail
  2. slash 31
  3. AS 47868 Goes Wild with AS-Prepending
  4. BGP Man in the Middle Attacks

This entry was posted on Wednesday, March 11th, 2009 at 12:43 pm and is filed under technology. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

Leave a Reply