[115083] in North American Network Operators' Group
Re: Multi site BGP Routing design
daemon@ATHENA.MIT.EDU (Michael K. Smith)
Fri Jun 5 21:37:51 2009
Date: Fri, 05 Jun 2009 18:37:02 -0700
From: "Michael K. Smith" <mksmith@adhost.com>
To: Steve Bertrand <steve@ibctech.ca>, Justin Krejci <jkrejci@usinternet.com>
In-Reply-To: <4A29AD73.1040503@ibctech.ca>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
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were withdrawn when the backnet link goes down.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
