Friday, May 18, 2012

BGP RIB-failure and effect on route advertisement

When examining routes advertised to BGP neighbor, notice some routes are tagged with “r”:

rtr1#sh ip bgp neighbor advertised
BGP table version is 1735468, local router ID is
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
              r RIB-failure, S Stale, m multipath, b backup-path, x best-external, f RT-Filter, a additional-path
Origin codes: i - IGP, e - EGP, ? - incomplete

   Network          Next Hop            Metric LocPrf Weight Path
r>i10.115.254.0/30            0    100      0 i
*>           21         32768 i
r>i10.115.254.4/30            0    100      0 i
r>i10.115.254.8/30            0    100      0 i

Note this is BGP “RIB-failure”, which indicates BGP fails to install the route in routing table. According to this link, the likely cause is the route is already installed by IGP which has a lower AD.