[ipv6-wg] RE: [address-policy-wg] IPv6 allocations for 6RD

Michael

key words here are 'average' and 'generous'. Perhaps you should try to
read first. Same goes for your statement of counting addresses. In cases
like these, I think orders of magnitude are more interesting than
narrowly defined numbers. 4 million is roughly 0.1% of the IPv4 pool.
Since I think the AVERAGE ISP is probably smaller than that (either in
customer count or allocated space), giving all of them 32 bits (or the
full IPv4 space) PLUS 4-8 bits of network space (not host space!) for
their 6rd plan sounds wasteful to me. 

The 6rd draft has prefix compression for a reason. Sparse number spaces
for expansion and automation are fine. Very sparse number spaces you
know from the outset will never be filled or usable for other purposes,
are not.

That is why deploying multiple instances of 6rd in order to benefit from
prefix compression to collapse that  required number space without
losing functionality sounds like the right direction for me.

Remco

(and if we decide that a /24 is a better standard to hand out to LIRs
than a /32, I can predict today that somebody will come up with a very
clever reason to say that /16s are probably even better. Repeat until
bored - or out of space.)

-----Original Message-----
From: address-policy-wg-admin at ripe.net
[mailto:address-policy-wg-admin at ripe.net] On Behalf Of
michael.dillon at bt.com
Sent: vrijdag 27 november 2009 11:04
To: address-policy-wg at ripe.net; ipv6-wg at ripe.net
Subject: RE: [address-policy-wg] IPv6 allocations for 6RD

> Fair enough, I'll bite. Given 2^32(or 4 billion) IPv4 
> addresses, and say, 4 million IP's allocated to the average 
> ISP (I'm being generous
> here) there's your 0.1%. The rest of the space will go unused 
> since we're using 32 bits to identify these sparse blocks in 
> the v4->v6 translation. Not counting customer /56s, 48s, /60s 
> or whatever.

But customers, and /56s are the essential things to count.
Again, you just throw in the number 4 million without explaining
where it comes from. IPv4 ISPs come in all sizes with 
one /24 allocation and some with many allocations of sizes
ranging from /17 to /12.

Counting IP addresses in IPv6 makes no sense. The addressing
hierarchy of IPv6 is designed to have large blocks of unused
and unusable addresses. This is both to allow for expansion
without changing the network architecture, and to allow for
automated address assignment functions which rely on large
sparse number spaces to avoid collisions.

--Michael Dillon



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