[c-nsp] Ignoring BGP routes whose origin is own AS

[Roy]

Oliver Boehmer (oboehmer) wrote:
> Rick Kunkel <> wrote on Tuesday, March 07, 2006 7:48 AM:
>
>  I just wanted to check one thing for now: 
>   
>> I was reading today, and ran across something I'd read before but
>> forgotten.  It said that BGP speakers ignore routes they hear if that
>> route originates in their own AS, which is a step taken to avoid
>> routing loops.  What I'm wondering here is if that is applicable
>> here.  If NOC1 is announcing routes and NOC2 hears them through the
>> Internet, will it ignore them?  
>>     
>
> Yes, if NOC1 and NOC2 use the same ASN, either will drop the updates
> from the other. You can use "neighbor ... allowas-in <n>" to allow
> updates with at most <n> of your own ASN in the path.
>
> 	oli
>
>   
While this will probably work fine, I would have an alternate 
suggestion.  I had this configuration until very recently.  What I did 
was to build a GRE tunnel between NOC1 and NOC2 via the Internet and 
used that as a backup for the direct link.  A big advantage to this is 
that you can leave your spoof filters in place.   You don't have to 
accept NOC2's IP addresses via the Internet at NOC1 and vice versa.  You 
can run whatever routing protocol you want across the tunnel.

Roy