Customer AS

> This is mainly due to the fact that Sprint does not listen to any
> announcements from its peers for anything within its "non-portable"
> blocks.

What?!? I.e. if a Sprint customer C is multi-homed and their Sprint line
goes down, traffic to C from other Sprint customers will not be able to
reach C?

Yes. Sean encourage(s/ed) other providers to do the same sort of filtering.
He doesn't like the fact that he's still carrying stuff inside his network
that he would filter from a peer, but apparently he's hoping that someone
else (some other provider) will force the issue for him (inside of Sprintlink).

> BTW, Sprint also does not listen to any of its peers ASes through
> other peers so peering with Sprint and still paying someone for
> transit services do not help you get more redundancy with Sprint's
> network.

And this is considered good networking architecture? Jeezus!

It's a reasonable way to make sure that your peers won't f*ck you by
redistributing routes for everyone else into you through their session.

If that's your goal, you either have to limit the as-paths you'll hear
from a peer or not hear routes with any peer's AS through any other peer.

And it has the side-benefit of making people realize that they'd better
run a *real* network with good connectivity between their interior and
all of the exchange points they're at. (Meaning if you peer with someone
with this policy, you're on your own as far as connectivity to that someone).