[address-policy-wg] Re: Geographical routing, was: Policy proposal: #alpha: TLD Anycast Allocation Policy

On 31-mrt-05, at 16:20, Michael.Dillon at radianz.com wrote:

>> If I've understood correctly, geographical addressing will lead
>> to forced interconnection of providers in the geographical area

This is a common misconception. Unfortunately, many people have 
assumptions about geography in routing based on mailing list 
discussions.

> We have enough knowledge of intercontinental cable routes
> today in order to design a geographical aggregation topology.
> There are unlikely to be any significantly new intercontinental
> or overland paths that could not be predicted based on today's
> knowledge. It would make an interesting university research
> project to design such an addressing topology and I hope that
> someone will take up the challenge. Until we have this kind of
> work on the table to discuss, it is hard to prove that geographic
> addressing will work or that it won't work.

I put a lot of effort into geographic addressing. Some of you may even 
remember that I talked about this at RIPE 44 and RIPE 46: once for the 
IPv6 wg, which was slightly perplexed, and then for the routing wg 
where I don't think anyone got it. It's a significant departure from 
business as usual, I'm afraid... Have a look at:

http://www.bgpexpert.com/presentations/
http://www.muada.com/drafts/draft-van-beijnum-multi6-isp-int-aggr-01.txt

The interesting part here is that each AS gets to implement 
geographical aggregation completely independent from every other AS. 
This includes NOT aggregating, which means that there is absolutely NO 
difference between simply doing PI and following my proposal for anyone 
who chooses to carry all routes everywhere (except that the address 
space for multihomers must be allocated according to geography). There 
are no changes to BGP.

The idea is that everyone announces their geographical customer routes 
everywhere, but people filter out the geographically undesirable 
routing information _within_ _their_ _own_ _AS_. So there is no 
dependency on free transit, and only a limited dependency on 
interconnection. When there is lack of interconnection in an area, this 
doesn't lead to lack of reachability, just to lack of aggregation. In 
the common case where a multihomer connects to two ISPs in the same 
area and both ISPs are well-connected in the area, there is potential 
for aggregation.

In places where there are so many multihomers that the amount of 
routing information becomes problematic, there is bound to be 
reasonable interconnection, especially when looking at the continent or 
part-of-a-continent scale.