From: Brian Dennis (bdennis@internetworkexpert.com)
Date: Mon Mar 06 2006 - 21:18:52 GMT-3
If you do a "debug ip bgp" it will tell you that the AS is incorrect and
what the AS should be. See below.
Rack1R1#
*Mar 1 00:29:04.067: BGP: 145.1.125.5 bad OPEN, remote AS is 50,
expected 500
Rack1R1#
Also even if you do not enable debugging you will receive a message like
the ones below:
Rack1R1#
*Mar 1 00:31:12.131: %BGP-3-NOTIFICATION: sent to neighbor 145.1.125.5
2/2 (peer in wrong AS) 2 bytes 0032
Rack1R1#
Rack1R5#
*Mar 7 22:23:46.439: %BGP-3-NOTIFICATION: received from neighbor
145.1.125.1 2/2 (peer in wrong AS) 2 bytes 0032
Rack1R5#
By converting 0032 from hex to decimal we can see that R5 is running as
AS 50 and not 500.
Lastly here are the configurations used to generate the messages above:
R1:
router bgp 1
neighbor 145.1.125.5 remote-as 500
R5:
router bgp 50
neighbor 145.1.125.1 remote-as 1
HTH,
Brian Dennis, CCIE #2210 (R&S/ISP-Dial/Security)
bdennis@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-224-8987
Direct: 775-745-6404 (Outside the US and Canada)
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
jnkmail4eva@yahoo.com
Sent: Monday, March 06, 2006 3:51 PM
To: ccielab@groupstudy.com
Subject: BGP session
Let's say there are two routers, A and B, trying to form a peer
relationship.
I have no control over B's router.
Is there a way to identify on A what B is using as remote AS in it's bgp
configuration.
To re-phrase, when I turn debugging on routerr A I am not able to
identify what router B is using for AS # to form a peer relationship.
I do get a message on router A, the remote peer is using incorrect AS
followed by hex numbers.
Is there a way to identify from debug or some sort of tcpdump as to what
router B is using as remote-as to form a relationship.
This has to do with the local-as command.
This archive was generated by hypermail 2.1.4 : Sat Apr 01 2006 - 10:07:38 GMT-3