Is the export policy selective under valley-free?

William Waites ww at styx.org
Wed Sep 3 17:42:34 UTC 2008


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Le 08-09-03 à 19:26, Valdis.Kletnieks at vt.edu a écrit :
>
> OK, I'm looking at this, and having a *little* trouble buying that  
> there's
> exactly zero or one p2p links - consider the case where the last  
> 'c2p' link
> is to provider A, who peers with B but not C, and B peers with both  
> A and C,
> and the first p2c link lands at C.  Don't you end up with "cp2 p2p  
> p2p p2c" in
> that case?  Or is there a convention saying we compress the A-B and  
> B-C
> links into a notational A-C link?  Or are we defining A-B or B-C  
> links as
> being a c2p type instead, even though they're peering and not transit?

If B passes along C's routes to A then that is not (in the model) a  
peering
relationship. Only your own and your customers' routes get sent to  
peers not
routes learned from other peers.

So in this case B-C looks like p2c and A-B could be either p2p or c2p.

Cases of partial transit, where B might repeat C's routes to peers but  
not
to upstrem providers are not, AFAIK treated in the model.

Cheers,
- -w

- --
William Waites                       <ww at styx.org>
http://www.irl.styx.org/          +49 30 8894 9942
CD70 0498 8AE4 36EA 1CD7  281C 427A 3F36 2130 E9F5

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