[AusNOG] Small Pipe BNE/Agile issue
james at vocus.com.au
Sun Jun 15 10:37:19 EST 2008
>> In the past I've used de-aggregation to great effect to engineer
>> more traffic in dense peer meshes. It works a treat where your
>> transit provider has private peering with many of the your public
>> peers (with the peers typically local-prefing private peering
>> higher than public).
> I think this is less likely than the problem that most MLPAs
> introduce which is a longer AS-PATH. We've had this issue recently
> where we see 4 paths to one AS of equal localpref to us, but the
> other ASes two peering paths are the same or longer path so either
> not used or they bounce between the other ASes transit and peering
> as routes age etc. Not an issue for me, but for the other company
> it was. We generate enough content in Oz to kill a lot of other
> people's transit!
I think you'd be surprised, by default I would announce the aggregate
blocks and then switch to de-aggregates, it would add anywhere up to
50% more traffic. But yes MLPAs add a different set of problems.
We are about to bring up the Any2 MLPA in San Jose and they (from
first glance) don't actually send the route-server AS in the path,
which is really cool.
I'm not sure how they do it, but this is from their technical FAQ.
"no bgp enforce-first-as, This is due to the fact that a route server
doesn't send itself (its AS and IP you peer with in the next hop - it
sends you the AS and IP of the peer's next hop)."
>> As for de-aggregating past a /24, I've never seen a written rule
>> that a /24 is ok to distribute and a /25 isn't, globally nothing
>> works past a /24, that's generally accepted but peering is a bi-
>> lateral relationship (even with an MLPA).
> Hold on a tick here. How so? With an MLPA (eg PIPE/WAIX/etc) I
> have no direct relationship with the other party - only with the
> MLPA IX. If I want to mess with routing it affects all peers at
> that MLPA. For instance, I have NO idea how, except informally to
> contact almost anyone else's NOC at PIPE. Whereas for all my
> bilaterals I have a lovely list of phone numbers/email addresses/IM/
> etc if I have an issue. See recently with PowerTel's TNZ inspired
> depeering at PIPE but not WAIX - routing went all via WAIX. In
> order to get them to fix it I had to discover their NOC's details
> through AUSNOG mailing list (thanks to the people who sent me their
> details). If I had been doing bilaterals with them then I'd have
> had the details and also be able to kill routes specifically to them
> in Perth without affecting the other people on WAIX.
I was talking about routing policy, the relationship is bilateral
between you and the route-sever, they decide the "global" policy. Then
there is another bi-lateral relationship between the route-server and
the other peer, again that routing policy is between the two parties.
But yes its not great wording.
As for contact details I agree completely.
>> If using /25 or greater has a required effect there is no reason
>> not to use it but likewise no requirement to accept it.
> That's a bit out of kilter with your previous statement.
> I could ignore longer than /24s - but as you've said above at the
> MLPAs a lot of people use deaggregation to do TE. So, unless the
> MLPA IX Route Server blocks it, I'm left with little option but
> accept them or have people complain that somehow my routing skills
> are poor (something that doesn't sit well).
I'm not asking anyone to accept >/24s just saying that it actually a
very valid way to traffic engineer, some people seem to have take
offense at being sent routes >/24 and if they want to filter go ahead.
I'll keep my options open.
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