[AusNOG] Small Pipe BNE/Agile issue

[James Spenceley]

>
>> 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.

--
James