Do ATM-based Exchange Points make sense anymore?

Mikael Abrahamsson swmike at swm.pp.se
Sat Aug 10 11:24:28 UTC 2002


On 10 Aug 2002, Paul Vixie wrote:

> why on god's earth would subsecond anything matter in a nonmilitary situation?

It does when you start doing streaming anything, say TV or telephony. I
agree that this wont be solved using any current L3 or above protocol
since BGP takes quite a while to recalculate anyway. Any redundancy has to
be pre-calculated or on a lower level, this is where for instance SRP/DPT
claims excellence, guess same claims come from the MPLS crowd.

I guess you have to pay a 50% tax on capacity to handle this whatever you 
do.

Personally I agree with you, the KISS principle is golden here. Peering 
should be cheap, that is the only reason to do it, and therefore one does 
not want a lot of complexity that brings up the cost. Tweaking eBGP dead 
timers to 5-10 seconds works well in most cases.

I have some idea about bringing together some of the signalling from
DPT/SRP into a switching ethernet environment (for instance, have some
kind of signalling between switches (propagated to hosts) that a certain
port has gone down and notify that certain mac addresses are no longer
reachable). I have not looked into it more carefully and it would take
several years to get any standard implemented (even though I feel that it
wouldn't be that hard to do). Just state what mac addresses was removed 
from your forwarding table due to link down, signalling this to everybody 
connected to you. Probably won't scale to very large L2 domains, but would 
perhaps be ok for 50-100 nodes connected to an IX.

-- 
Mikael Abrahamsson    email: swmike at swm.pp.se




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