From: Antonio Soares (amsoares@netcabo.pt)
Date: Tue Mar 20 2007 - 21:24:53 ART
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Yes, see this example:
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
R1(config)#router bgp 100
R1(config-router)#
R1(config-router)#neighbor 183.1.28.2 remote 300
AS100(config-router)#
3d02h: %BGP-3-NOTIFICATION: received from neighbor 183.1.28.2 2/2 (peer in
wrong AS) 2 bytes 0064
R1(config-router)#
3d03h: %BGP-3-NOTIFICATION: received from neighbor 183.1.28.2 2/2 (peer in
wrong AS) 2 bytes 0064
R1(config-router)#
R2(config)#router bgp 200
R2(config-router)#neighbor 183.1.28.8 remote 400
.Mar 28 08:33:09.251: %BGP-3-NOTIFICATION: sent to neighbor 183.1.28.8 2/2
(peer in wrong AS) 2 bytes 0064
R2(config-router)# FFFF FFFF FFFF FFFF FFFF FFFF FFFF FFFF 002D 0104 0064
00B4 9601 0808 1002 0601 0400 0100 0102 0280 0002 0202 00
R2(config-router)#
.Mar 28 08:33:48.163: %BGP-3-NOTIFICATION: sent to neighbor 183.1.28.8 2/2
(peer in wrong AS) 2 bytes 0064
R2(config-router)# FFFF FFFF FFFF FFFF FFFF FFFF FFFF FFFF 002D 0104 0064
00B4 9601 0808 1002 0601 0400 0100 0102 0280 0002 0202 00
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Router R2 informs R1 that R1 is in the wrong AS (0x0064=100). Now we know
that R1 is in AS100 so let's correct this:
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
R2(config-router)#no neighbor 183.1.28.8 remote 400
R2(config-router)#
R2(config-router)# neighbor 183.1.28.8 remote 100
R2(config-router)#
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Now R1 says that R2 is in the wrong AS (0x00C8=200):
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
3d03h: %BGP-3-NOTIFICATION: sent to neighbor 183.1.28.2 2/2 (peer in wrong
AS) 2 bytes 00C8
R1(config-router)# FFFF FFFF FFFF FFFF FFFF FFFF FFFF FFFF 002D 0104 00C8
00B4 9601 0202 1002 0601 0400 0100 0102 0280 0002 0202 00
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
So let's correct in R1:
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
R1(config-router)#no neighbor 183.1.28.2 remote 300
R1(config-router)# neighbor 183.1.28.2 remote 200
R1(config-router)#
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
And we have it:
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
R1(config-router)#
3d03h: %BGP-5-ADJCHANGE: neighbor 183.1.28.2 Up
R1(config-router)#
Rack1R2(config-router)#
.Mar 28 08:42:29.011: %BGP-5-ADJCHANGE: neighbor 183.1.28.8 Up
Rack1R2(config-router)#
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-----Original Message-----
From: Cecil Wilson [mailto:Cecil.Wilson@flextronics.com]
Sent: terga-feira, 20 de Margo de 2007 19:23
To: Antonio Soares; iyux2000@gmail.com; ccielab@groupstudy.com
Subject: RE: Debug BGP Question
Hello
are you saying this is one way to find the remote AS?
(peer in wrong AS) 2 bytes 0036 hex for AS54?
Cecil G. Wilson
IT Network Services
Office: (901) 215-2710
Cell: (901) 601-6201
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Antonio Soares
Sent: Tuesday, March 20, 2007 8:43 AM
To: iyux2000@gmail.com; ccielab@groupstudy.com
Subject: RE: Debug BGP Question
Whenever you have a misconfiguration, your local router will send a BGP
notification to the other peer like this:
%BGP-3-NOTIFICATION: sent to neighbor 54.1.1.254 2/2 (peer in wrong AS)
2 bytes 0036 FFFF FFFF FFFF FFFF FFFF FFFF FFFF FFFF 002D 0104 0036 00B4
D412
0301 1002 0601 0400 0100 0102 0280 0002 0202 00
Here 0x0036 means BGP AS54. So the local router is saying to its peer
that it's in the wrong AS=54. This way is know the remote AS.
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Sent: segunda-feira, 19 de Margo de 2007 23:17
Subject: Debug BGP Question
Good morning, GS
I have a question regarding to the real lab exam, i'am sure that it
awlays ask you configure "local-as" command due to the neighbor
configured with the wrong as. But if the question didn't tell you the
wrong AS number that is configured on the other side (e.g. on BB1). Is
there possible a way to find the wrong-AS-number from the BGP debug
command? I tried serveral debug commands, but i can not figure it out.
Thank you for your reply.
This archive was generated by hypermail 2.1.4 : Sun Apr 01 2007 - 06:35:52 ART