BGP not to include loopback ip addresses

KSVY_KSVY_2 · ‎12-01-2009

I have a 7206 router configured with ingress sub-interfaces. I need only one of the two networks, including loopback that associated with it, to be included in BGP routing process. In other words, I want to exclude one loopback ip address ( loopback 0) and one /27 LAN from BGP routing on router.

Current BGP router configured process:

router bgp 65xxx
no synchronization
bgp router-id 14x.x.x.240
bgp log-neighbor-changes
network 14x.x.x.240 mask 255.255.255.255
neighbor GCP peer-group
neighbor GCP remote-as 65321
neighbor 14x.x.x.245 peer-group GCP
neighbor 14x.x.x.245 description ** BGP chvpkre1 **
neighbor 14x.x.x.245 ebgp-multihop 255
neighbor 14x.x.x.245 update-source Loopback1

need to block/filter out from BGP routing process:

Loopback 0

ip address 13x.x.x.240 255.255.255.255

14x.x.138.0 255.255.255.224

allow into BGP routing process:

Loopback 1

ip address 14x.x.x.240 255.255.255.255

14x.x.137.0 255.255.255.224

any suggestions?

thanks, Kevin

Laurent Aubert · ‎12-01-2009

Hi Kevin,

I don't understand this configuration:

Loopback 1

ip address 14x.x.x.240 255.255.255.255

14x.x.137.0 255.255.255.224

Do you mean secondary address ?

Also you are using loopback 1 as your source address for your eBGP peering. In this case, this loopback should not be announced into BGP as it could create a recursive loop during the lookup (BGP next-hop learned inside BGP -> very bad)

HTH

Laurent.