a radical proposal (Re: protocols that don't meet the need...)

Edward B. DREGER eddy+public+spam at noc.everquick.net
Wed Feb 15 20:56:01 UTC 2006

AO> Date: Wed, 15 Feb 2006 21:41:53 +0100
AO> From: Andre Oppermann

AO> Err, the problem is not the number of AS numbers (other than having to
AO> move to 32bit ones).  The 'problem' is the number of prefixes in the

It's both.

AO> routing system.  The control plane scales rather well and directly
AO> benefits from Moore's law.  With todays CPU's there is no problem
AO> handling 2 million routes and AS numbers.  Absolutely not.

For some equipment.  However, I encounter a number of 7200s still in 

AO> Things get a bit more hairy with the forwarding plane though.  The
AO> faster the link speed the less time it has per lookup and the larger
AO> the routing table the more routes it has to search in that ever shrinking
AO> amount of time.


AO> You see, saving on AS numbers is not really going to help much where it
AO> matters.

It's also saving on route count.  In my example, Cox and SBC partner up 
and share an ASN and a netblock.  That's _one_ global route for a ton of 
dual-homed leaves.

AO> IMHO, and I have stated this before, the best way to handle the route
AO> issue is to hand out IPv6 /32 for multihoming and make it the routeable


AO> entity.  Perfect matches in hardware are pretty easy to do for large
AO> numbers of them compared to longest match.  On the plus side perfect
AO> match scales much better too and can be done in parallel or distributed
AO> within a routing chip.  Doing the same for longest-match requires a lot
AO> more effort.  With perfect-match having 2 million routes is not much of
AO> a problem too.

All true.  But can we wait for all the forklifts?

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