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

There is a way to find out the correct AS..

Copy the bytes value (0004) and put in calc in binary and click decimal ..
the the value comes is the correct AS...

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
>

Please correct me if I am wrong.

Thanks in advance,
Mohan

Marko Milivojevic <markom_at_markom.info>
Sent by: nobody_at_groupstudy.com
08/10/2009 05:52 AM
Please respond to
Marko Milivojevic <markom_at_markom.info>

To
Joe Astorino <jastorino_at_ipexpert.com>
cc
Pradeep Malik <pradeepmlk_at_gmail.com>, Cisco certification
<ccielab_at_groupstudy.com>
Subject
Re: BGP Debug question (How to know what AS, neighbor is using to peer
with my IP ???????)

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
>>>
>>>
>>> Blogs and organic groups at http://www.ccie.net
>>>
>>>