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 Then you would just have to set your local route origination so that the appropriate routes were withdrawn when the backnet link goes down.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