Multi site BGP Routing design

John.Herbert at ins.com John.Herbert at ins.com
Fri Jun 5 19:40:15 CDT 2009


This is a good concept but if the ISP route is a Juniper then as I recall by default it looks ahead, sees the as-path routing loop if it were to send it to the other router, and doesn't send it. So while you might be able to configure it on the receiving router, if the sending router won't send it, you're SOL.

j.

________________________________
From: Chuck Anderson [cra at WPI.EDU]
Sent: Friday, June 05, 2009 20:33
To: nanog at nanog.org
Subject: Re: Multi site BGP Routing design

On Fri, Jun 05, 2009 at 05:50:28PM -0500, Justin Krejci wrote:
> If the private link between the two sites fails, will BGP allow for us to
> access the IP subnets at site 2 from site 1 via the internet given that both
> sites are advertising under the same ASN?

Maybe.  Especially if both sites are connected to the same ISP, you
can tweak some BGP knobs to allow your own ASN to appear in the AS
PATH N times where N > 1, and accept the routes anyway.




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