[j-nsp] AS-PAth Prepend and Loop Command

[Umar Ahmed]

Hi Reza - I did some testing in the lab to see what would happen if you
tried to prepend someone elses AS to an announcement - and this is what
I got. The peer would not come up, the traceoptions show :

The peer will not come up stating :

Jan  7 23:25:55.072684 BGP RECV Notification code 3 (Update Message
Error) subcode 11 (AS path attribute problem)

This is running Junos 8.5 R1.4

So to help your understanding remember you only prepend your own AS to
others and AFAIK you cant prepend AS's that don't belong to you onto an
announcement. I cant speak for other vendors, however I'm sure the
implementation will be in accrodance to the RFC and they will get the
same result.
I encourage you to do some testing in the lab to understand this concept
better.. Any questions gimme a shout !


regards,

 

Umar Ahmed

JNCIE-M # 281, FNCNE
-----Original Message-----
From: juniper-nsp-bounces at puck.nether.net
[mailto:juniper-nsp-bounces at puck.nether.net] On Behalf Of Reza Sharifi
Sent: 06 January 2008 22:12
To: juniper-nsp at puck.nether.net
Subject: [j-nsp] AS-PAth Prepend and Loop Command

Hi All,
 
If I have an external BGP connection to my neighbor, and if the neighbor
is Prepending my own AS to the routes that is sending to me, do I need
to implement the command " set routing-options autonomous-system loop to
all of my internal routers inside my AS in order to get those routes?
So far, the only way I have been able to get the routes to all my
internal routers is by applying the loop command, and do a clear BGP
neighbor soft-inbound I am running JUNOS 7.3R3.6, Is there any other way
of implementing this?
 
Thanks,
Reza
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