nanog mailing list archives
Re: Multi site BGP Routing design
From: Steve Bertrand <steve () ibctech ca>
Date: Fri, 05 Jun 2009 21:59:54 -0400
Michael K. Smith wrote:
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 Then you would just have to set your local route origination so that the appropriate routes were withdrawn when the backnet link goes down.
I stand corrected. I've read about this, but does anyone have operational experience with it that they can share? Even though we are a very small SP, I always feel that going against the traditional grain when doing things like this may leave a trail of undocumented, hard-to-troubleshoot issues in the future. To rephrase the OP's question, would it be BCP to acquire a second ASN, and without further de-aggregating, continue advertising each site's IP space to the DFZ, but from dissimilar ASs as opposed to the same one? Steve
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Current thread:
- Multi site BGP Routing design Justin Krejci (Jun 05)
- Re: Multi site BGP Routing design Steve Bertrand (Jun 05)
- Re: Multi site BGP Routing design Chris Adams (Jun 05)
- RE: Multi site BGP Routing design John.Herbert (Jun 05)
- Re: Multi site BGP Routing design Steve Bertrand (Jun 05)
- RE: Multi site BGP Routing design John.Herbert (Jun 05)
- Re: Multi site BGP Routing design Chris Adams (Jun 05)
- Re: Multi site BGP Routing design Steve Bertrand (Jun 05)
- Re: Multi site BGP Routing design Michael K. Smith (Jun 05)
- Re: Multi site BGP Routing design Steve Bertrand (Jun 05)
- RE: Multi site BGP Routing design Ivan Pepelnjak (Jun 06)
- Re: Multi site BGP Routing design Saqib Ilyas (Jun 06)
- Re: Multi site BGP Routing design Adam Greene (Jun 06)
- RE: Multi site BGP Routing design Justin Krejci (Jun 08)
- RE: Multi site BGP Routing design Ivan Pepelnjak (Jun 09)
- Re: Multi site BGP Routing design Steve Bertrand (Jun 05)
- RE: Multi site BGP Routing design John.Herbert (Jun 05)
- Re: Multi site BGP Routing design Chuck Anderson (Jun 05)
- Re: Multi site BGP Routing design Steve Bertrand (Jun 05)