From: Lars Christensen (perseusdk@gmail.com)
Date: Sun Jul 20 2008 - 17:04:14 ART
I might add to Marko's post, that you probably could configure your side of
the peering as the "always slave" end of the peering using the "neighbor
x.x.x.x transport connection-mode passive" statement. This way you should be
able to only listen for the connection and thereby get the intended AS as
described below. However, I can't remember if this requires you to configure
the opposite end as the master actively, but you might want to try it.
Regards,
Lars Christensen
CCIE #20292
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Marko Milivojevic
Sent: 20. juli 2008 21:47
To: GS CCIE-Lab
Subject: Re: Peer in wrong AS at BB2 router | Will proctor tell us the right
AS or will provide the access to BB router?
Yes -- read my previous post :-)
When you configure neighbor with any AS, you will receive the message
informing you of the remotely configured ASN.
In your example:
> BGP: 172.16.255.5 received NOTIFICATION 2/2 (peer in wrong AS) 2 bytes
000A
Look at the end. Hex number "000A" is remotely configured ASN. You
just change your configuration to peer with AS 10 and you're done.
Of course, in order for all this to happen, you need to configure BGP
first. As you correctly noticed, there is no way to know in advance,
so you need to think creatively if faced with this sort of question.
You know the sure way to find out the information you need -- active
BGP. Configure it using any remote as number you can think of. You
will receive information you need for proper configuration within
seconds.
In CCIE lab, this sort of question is used to test troubleshooting skills.
-- Marko CCIE #18427
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