[arin-ppml] V6 address allocation policy

michael.dillon at bt.com michael.dillon at bt.com
Thu Jan 21 03:55:06 EST 2010

> Why not /44, /52, or /56? Why in your master plan must this 
> size be /48?

Not my master plan. Read the RFCs. /48 is the assignment for an
end site unless they can justify needing more space. /44 is
reasonable if they need two or three times the number of /64
subnets at a site, maybe a sprawling auto factory. If you are
a big ISP and you have a huge number of private residences
connected, you may wish to assign a /56 to private residence sites
because it simplifies your overall address accounting.

/52 is just plain wierd and should never happen outside the lab.

> More generally I'll point out that when organizations merge, 
> divide, consolidate and reorganize they tend to do so by a 
> relatively arbitrary combination of business function and 
> customer scope, not by physical location.

Physical locations do change hands during mergers. If you want
to consolidate your ISP supplier contracts and move the new
locations to favored ISP supplier X, just swap the /48 prefix
and do the usual IPv6 renumber dance. Job done. No need to 
rearchitect their local area network. Simples!

--Michael Dillon

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