Greetings,
I am configuring BGP on an IOS XR 4.2.1 system and I have noticed that even
though the router immediately determines that a next hop is unreachable it
keeps the routes installed until BGP times out.
Under normal circumstances 'show bgp nexthop ip.add.re.ss' looks like this:
RIB Related Information
Gateway: reachable, non-Connected route, prefix length 32
When there is a connectivity failure between the two systems it almost
immediately changes to this:
RIB Related Information
Gateway: unreachable, non-Connected route, prefix length 4
Why then, given that it knows it's no longer a valid nexthop would it continue
to route prefixes to it?
Routing entry for 192.168.116.0/24
Known via "bgp xxxxx", distance 200, metric 0, type internal
Installed Aug 7 22:08:15.809 for 00:12:09
It also continues to announce this route to upstream peers; again even though
it knows it can't reach the next hop.
It does eventually stop doing this; but only after the normal BGP timeout
period (which I believe is 300 seconds).
Is there a setting you need to enable so that if there is a RIB failure it will
immediately stop doing this?
Thanks,
-Drew
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