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Re: Resolving geo discussions

On dinsdag, apr 15, 2003, at 17:45 Europe/Amsterdam, Brian E Carpenter wrote:

or if it only presents
a single point of view



I think you mean "a clear conclusion" :-)



Do I?




it must get into the nitty gritty and not
suffice with "I know someone in Jakarta who connects to Reykjavik so
geo aggregation can't work".





Yes, but there is the pesky interaction with economic forces to 
consider.

That makes it hard to avoid the final conclusion being a judgement.



Economy is much like routing: if you get to assign the costs, you can 
pretty much make it do anything.



[...]


If we accept some constraints, we can do much better.



[...]




I don't think that allows for the economic constraints that
mean that certain traffic is only allowed to travel on links
paid for by certain parties.




I'm only concerned with routing inside individual provider networks, so 
this shouldn't be a problem.




In other words you can theorize
about some ideal mathematical model, but how do you mix in
the economic constraints? One of today's constraints, for example,
is "get rid of the packet as quick as you can, unless it's going
to my own customer" and that has major impact on the BGP4 topology.




Yes, this is an important issue. Please read section 10 in my draft, 
but here is my conclusion:



	Since networks can control the level of late exit routing by

	(selectively) de-aggregating and many interconnection (peering)

	agreements call for equal traffic volumes in both directions, the

	potential for changes in the flow of traffic should not adversely 
affect

	existing networks.




I think this quickly gets into Research Group territory.




Hm, can we afford to wait for results there?



The way I see it, if we start giving out GAPI addresses now, we have a 
few years to come up with good aggregation before we really need it. If 
it turns out that geo aggregation is unworkable a solution like MHAP 
that can use PI addresses without the need to have them in the routing 
tables can still save us without renumbering. Only if that doesn't work 
either the GAPI users need to renumber.



On the other hand, if the IRTF comes up with something good in 3 years, 
everyone who is multihoming using some kind of ad-hoc method such as 
shooting holes in PA will need to renumber at that point for it to 
work. That probably means that very few people will use it as 
renumbering is a huge pain.




In a routed network, the gains aren't as big as all intermediate nodes

need to know the more specifics for packets that may need to be routed

through them, but some quick guestimates land around the 50% mark.

That's 18 months according to Moore, which doesn't sound like much but

1.5 years interest on the "aluminum factory" as one former boss used 
to

call it (our new network cost the same as an aluminum factory (and

probably used as much electricity too)) adds up to a substantial pile

of change.




But it isn't just Moore's law. It's convergence time. And this is 
exactly

where we are still waiting for useable output from the Routing

Research Group.


Aggregation helps with convergence too.