How do I find out the AS number my eBGP neighbour is using to peer with me?

Unanswered Question
Aug 29th, 2008

Hi - is there a way of finding out what AS number an EBGP peer is using to peer with my router? Obviously do a debug and reset the BGP peers, but I wondered if there's any 'show' command which can show me the same thing?

Note - I don't mean the neighbour's AS number but my own router's!

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rajib_das Fri, 08/29/2008 - 02:35

Hi lucy,

you can see the AS number of neighbor with "show ip bgp Summary" command


lucy.west@uk.ea... Fri, 08/29/2008 - 06:39

Hi - I'm actually after finding out my own AS number that they're peering with: my router's part of a subconfederation.

I know i'd see this in a debug of the OPEN message when establishing neighbours - I just wondered if there's another way of seeing it without resetting the neighbour?


cisco_lad2004 Fri, 08/29/2008 - 05:15

in addition to previous reply....u will get error message if u trying configure a differnet AS, I dont recommend it in case cisco removed this safety pin and allows the reconfig on a new AS :-)

TST-POP1-NPE01(config)#router bgp 65001

BGP is already running; AS is 64512


lucy.west@uk.ea... Fri, 08/29/2008 - 06:41

Hi - thanks but I'm trying to find out the AS number of my own router that they're peering with. I have subconfederation configured: if I did a debug on BGP and reset the peers then I think we'd see it with the OPEN BGP message, is there another way to see if without resetting peers/debug?


Giuseppe Larosa Fri, 08/29/2008 - 08:51

Hello Lucy,

to see the AS number as seen by others do

sh run | beg router bgp

and look at the line that say

bgp confederation identifier that is the public AS number you are looking for

Hope to help



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