Re: BGP Debug question (How to know what AS, neighbor is using

Sometime ago I wrote a troubleshooting article on this subject that
you may find useful. Get it here:

http://cisco.markom.info/2008/10/peering-with-unknown-autonomous-system.html

--
Marko
CCIE #18427 (SP)
My network blog: http://cisco.markom.info/
On Mon, Aug 10, 2009 at 07:31, Joe Astorino<jastorino_at_ipexpert.com> wrote:
> I wanted to follow up on this with the group. B I think I misunderstood the
> original question. So I think you are asking is there a way to know what the
> incorrectly configured AS number is? B There is no way I know of.
>
> R2(config-router)#do sh run | s bgp
> router bgp 2
> B no synchronization
> B bgp log-neighbor-changes
> B neighbor 100.100.24.4 remote-as 99
> B no auto-summary
>
> router bgp 4
> B no synchronization
> B bgp log-neighbor-changes
> B neighbor 100.100.24.2 remote-as 2
> B no auto-summary
>
> R2(config-router)#
> *Jul 11 00:18:42.815: %BGP-3-NOTIFICATION: sent to neighbor 100.100.24.4 2/2
> (peer in wrong AS) 2 bytes 0004 FFFF FFFF FFFF FFFF FFFF FFFF FFFF FFFF 002D
> 0104 0004 00B4 6464 1804 1002 0601 0400 0100 0102 0280 0002 0202 00
>
> R4(config-router)#
> *Aug 10 09:31:46.319: %BGP-3-NOTIFICATION: received from neighbor
> 100.100.24.2 2/2 (peer in wrong AS) 2 bytes 0004
>
> On Mon, Aug 10, 2009 at 2:57 AM, Joe Astorino <jastorino_at_ipexpert.com>wrote:
>
>> It actually tells you exactly what you need there. B 0x0021 is the AS
>> number. B Convert that to decimal and you are all set. So in this case,
>> 0x0021 = AS 33
>>
>>
>>
>> On Mon, Aug 10, 2009 at 2:16 AM, Pradeep Malik <pradeepmlk_at_gmail.com>wrote:
>>
>>> Hi All,
>>>
>>> My question is; what debug cmds could we use to find out AS that neighbor
>>> has configured for my peering B i.e B If I am X.X.X.X and this statement is
>>> at B neighbor B " B bgp X.X.X.X remote-as Y" B  B How to know AS Y ? B If I
>>> troubleshoot on my router, it only gives below notification and it shows
>>> hexa decimal value of AS configred at my side but not on neighbor side..
>>>
>>> *Dec B 9 14:25:00.010: %BGP-3-NOTIFICATION: received from neighbor
>>> 150.2.3.254 2/2 (peer in wrong AS) 2 bytes 0021
>>>
>>> any suggestions ???
>>>
>>> Cheerz,
>>> PM
>>>
>>>
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>>
>>
>> --
>> Regards,
>>
>> Joe Astorino - CCIE #24347 R&S
>> Technical Instructor - IPexpert, Inc.
>> Cell: +1.586.212.6107
>> Fax: +1.810.454.0130
>> Mailto: B jastorino_at_ipexpert.com
>>
>
>
>
> --
> Regards,
>
> Joe Astorino - CCIE #24347 R&S
> Technical Instructor - IPexpert, Inc.
> Cell: +1.586.212.6107
> Fax: +1.810.454.0130
> Mailto: B jastorino_at_ipexpert.com
>
>
> Blogs and organic groups at http://www.ccie.net
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
Blogs and organic groups at http://www.ccie.net