Subject: [RAM] Geographic addressing

From: Iljitsch van Beijnum <[email-masked]>
Date: Mon, 19 Mar 2007 15:57:57 +0100

[directed to the RAM list with CCs to the draft authors, please trim  
on followups as necessary]

I just read draft-wang-ietf-efit-00.txt, which mentions:

6.2.  Location-Based Addressing

    Another way to allocate addresses in an aggregatable manner is to
    base the allocation on locations, which was proposed by Deering in
    early 90's [MetroAddr].  This approach can avoid user renumbering
    when they change providers, as long as they stay in the same
    location.

    More recently a similar proposal, Geo-based addressing [GeoAddr] has
    been made.  Although this proposal has certain differences from
    [MetroAddr], for example encoding latitude and longitude information
    into the address instead of metro-area ID, the two proposals bear
    fundamental similarities.  They are both proposed as one of the  
ways,
    but not necessarily the only way, to allocate IPv6 addresses, both
    envisioned coexistence of location-based and provider-based
    addresses, and which type to use would be based on the need of
    individual parties.

    However location-based addressing imposes two infeasible conditions
    to the routing system.  First, routing over location-based addresses
    requires that ISPs interconnect at each location.  Second, location-
    based addresses do not reflect interconnectivity among providers to
    enable routing policies.

Although the specifics of the proposals that are cited may impose new  
requirements on on the topology of ISP networks, this doesn't  
necessarily follow from geographic addressing in general. A few years  
ago I wrote this draft:

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

The idea here is that each AS holds a full view of the entire default- 
free zone, but rather than giving each individual BGP router within  
the AS a full copy of the DFZ, each router only handles part of the  
DFZ. This means packets must first be forwarded to the place where  
the routing information for the destination address is known, and  
then they are forwarded to their destination. This is the basic idea  
of increased stretch routing. However, if we can locate the routers  
that hold the routing information for a certain part of the address  
space close to the place where that address space is used, there may  
not be any detours to speak of in practice, avoiding the down side of  
increased stretch routing.

In the event that there is no interconnection in the area where the  
addresses are used, aggregation breaks or detours happen, but as long  
as this is for a relatively small fraction of prefixes/packets, that  
shouldn't be a problem.

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