[ppml] geo addressing

[Michael.Dillon at btradianz.com]

> Based on past events, same city homing doesn't strike me as scaleable 
> anymore, in even moderate availablity environments.  Geographic 
> diversification of the infrastructure seems more the trend, so one event 

> (nature, man, etc) doesn't effect all.  So, say I'm homed in Boston and 
NYC. 
> Which address space do I announce, the Boston space in NYC or the NYC 
space 
> in Boston, or my direct assignments which are neither?

In the absence of any research studies on the needs of 
mid-sized companies, I would say that if you have determined
that you need diverse connections to two cities you would
be foolish to acquire geotopological IP addresses. Instead you
should get a classic IPv6 allocation and announce it in both 
cities.

However, one thing that researchers could find out is how
common it is to build such diversity between city pairs
and what city pairs people are likely to use. In that case
a 3 tier geotopological addressing system that aggregates
at the regional level as well as the city and continent
levels, could allocate small virtual cities within a regional
aggregate that represent these city pairs. Then you would 
get addresses from the virtual city. But this only makes 
sense if it simplifies something and it is only likely to
be simpler in a few cases where there is a LOT of 
multi-city diversity being demanded.

If, for whatever reason, you decided to use geotopological
addresses anyway and announce the foreign addresses in
Boston and NY, then this would only have local impact in
the routing tables. Montreal would send traffic for your NY 
addresses to New York. If your New York circuit was down,
presumably you would be redirecting that traffic to Boston.

> I'm not sold on why is this needed, and question if it represents 
> something that will move IPv6 implementation forward.

It is not intended to move IPv6 implementation forward. The
assumption is that IPv6 will be implemented and that pressure
on the routing table will increase as more and more small and
mid-size companies demand BGP multihoming as part of their
network diversity. Geotopological addressing can reduce this 
routing table pressure without any new protocols or any new
technology. Geotopological addressing is an administrative 
solution to the problem that gives competing businesses more
options and fewer constraints in how they operate IP networks.

--Michael Dillon