Single AS multiple Dirverse Providers

Mon Jun 10 16:54:02 UTC 2013

On Mon, Jun 10, 2013 at 11:36:44AM -0500, Dennis Burgess wrote:
> I have a network that has three peers, two are at one site and the third
> is geographically diverse, and there is NO connection between the two
> separate networks.

So, you have two islands? Technically, that would be separate 
ASNs as they are separatre routing policies, but the modern 
world has adapted. 

> Currently we are announcing several /24s out one network and other /24s
> out the second network, they do not overlap.  To the internet this works
> fine, however, providers a/b at site1 do not send us the two /24s from
> site b..   We have requested them to, but have not seen them come in,
> nor do we have any filters that would prohibit them from coming in. 
>
> Is this normal?  Can we receive those routes even though they are from
> our own AS?  What is the "best practice" in this case?  

To prevent loops in the global Internet the BGP specification
dictates this behavior, and has in all versions. Depending on 
your platform and theirs, you will all need to turn several 
knobs before you are allowed to break these rules. I would 
recommend that you gain more than passing familiarity with 
why the protocol is built this way, how it affects your use
case, and what concerns you might have WRT your providers
before you change the behavior for your case.

Cheers,

Joe

-- 
         RSUC / GweepNet / Spunk / FnB / Usenix / SAGE / NANOG