nanog mailing list archives

Re: Multi site BGP Routing design


From: "Michael K. Smith" <mksmith () adhost com>
Date: Fri, 05 Jun 2009 18:37:02 -0700

On 6/5/09 4:42 PM, "Steve Bertrand" <steve () ibctech ca> wrote:

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?

No, because your router at site 2 will not accept any prefix with its
own AS in the AS_PATH (which site 1 would be advertising from).


If you're running Cisco with the right IOS it looks like you could use the
'neighbor x.x.x.x allowas-in' command to accept your own AS.  Then you would
just have to set your local route origination so that the appropriate routes
were withdrawn when the backnet link goes down.

Mike



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