BGP problem

Unanswered Question
Jul 3rd, 2007

Hi

I have three router connected into serially R1-R2-R3, I have establist IBGP relationship between R1-R2, but when i establish EBGP relation using loopback, i getting strange error.

% Cannot configure the local system as neighbor

or

% Specify remote-as or peer-group commands first

anybody tell me how i can resolve.

I have this problem too.
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dasmith Tue, 07/03/2007 - 05:29

In the case of the first error message, it appears that you may be using the routers own local loopback IP address in a BGP neighbor statement, resulting in the condition that a router will net set up a BGP neighbor with itself. When using loopbacks as the router ID in BGP, it is important that an IGP can find those loopbacks, or in some cases, use static routes to ensure that the router can get to the neighbors loopback IP.

sundar.palaniappan Tue, 07/03/2007 - 05:30

From the error message it appears your neighbor statement is pointing to the router's own loopback IP address itself instead of the nieghbor's IP address. Can you make sure the neighbor command is pointing is to the peer's loopback IP address. Also, since you are configuring neighbor relationship with a loopback you need to configure ebg-miltihop, syntax is "neighbor ebgp-multihop".

HTH

Sundar

Pavel Bykov Tue, 07/03/2007 - 05:43

Ok, if you have R2 and R3, and you want to establish session between them using loopback then:

on R2:

router bgp XXX

neighbor R3-loopback-addr remote-as YYY

neighbor R3-loopback-addr update-source loopback0

neighbor R3-loopback-addr ebgp-multihop

on R3:

router bgp YYY

neighbor R2-loopback-addr remote-as XXX

neighbor R2-loopback-addr update-source loopback0

neighbor R2-loopback-addr ebgp-multihop

sdoremus33 Tue, 07/03/2007 - 16:57

Pavlo is exactly right when using loopbacks to adv prefixes(to peers),you should the following config in the network

Ex:

router bgp "as#"

neighbor "next-hop address" "as#"

neighbor "next-hop address" update-source loopback

ebgp neighbor "next-hop address" "ebgp multihop"

sdoremus33 Tue, 07/03/2007 - 17:00

Pavlo is exactly right when using loopbacks to adv prefixes(to peers),you should the following config in the network

Ex:

router bgp "as#"

neighbor "loopback address" "as#"

neighbor "loopback address" update-source loopback

ebgp neighbor "loopback address" "ebgp multihop"

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