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Re: A use for site local addresses?


> Not if we are assigning 200 addresses to each user (never to be 
> reclaimed in
> many cases) They touted IPv6 as 1 address per person in the world for 
> years
> to come.

I don't think you are grasping the scale of the IPv6 address space.

A little simple math (that I'm sure I'll get wrong :-)):

According to the US Census bureau:
- Estimated world population as of 3/26/03, 17:40:10 GMT+5: 
- Estimated world population in 2050: ~9,000,000,000

Taking Brian's number (35,184,372,088,832 or 2^45) for the number of 
/48s currently available for assignment according to the RFCs today, 
you get:
- 5600 /48s per person today
- 3909 /48s per person in 2050

Note that those are /48s (each capable of addressing 64K /64s or, if 
you want ignore the autoconfiguration goop that eats the lower 64, 
1,208,925,819,614,629,174,706,176 /128s).

A bit more than 1 address per person in the world.  And that's just one 
format specifier.

(Not that this matters,  we can't even route 0.001% of Brian's number, 
but that's a rant for another time)

Arguing for site locals on the basis of conservation of address space 
is a waste of time, regardless of the validity of those arguments -- 
IPv6 address quantities are just too big.  Where private addressing 
(including site locals) could conceivably have value is:
- removing the need to deal with the address allocation 
- removing concerns about provider lock-in due to costs of renumbering.

One of the downsides of site locals is the same downside you get with 
1918 space -- merge two companies using private address space and 
you'll probably have to deal with address space collisions, forcing one 
of the two to renumber.  Much easier and simpler to simply allocate 
(potentially non-routed) globally unique /48s to everybody that asks.  
Note that last sentence well.


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