From: Doan Dung Chi (dungchid@gmail.com)
Date: Mon Jul 21 2008 - 00:37:59 ART
Hex Number behind message "%BGP-3-NOTIFICATION: received from neighbor
X.X.X.X (peer in wrong AS) 2 bytes" is local AS. It's not AS that Remote
Router need to peer.The Question is " How do I find AS to assign to command
"neighbor X.X.X.X local-as {AS}?".
----- Original Message -----
From: "Lars Christensen" <perseusdk@gmail.com>
To: "'Marko Milivojevic'" <markom@markom.info>; "'GS CCIE-Lab'"
<ccielab@groupstudy.com>
Sent: 21 July, 2008 03:04
Subject: RE: Peer in wrong AS at BB2 router | Will proctor tell us the right
AS or will provide the access to BB router?
>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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