[143360] in North American Network Operators' Group
Re: IPv6 end user addressing
daemon@ATHENA.MIT.EDU (David Conrad)
Sun Aug 7 18:44:55 2011
From: David Conrad <drc@virtualized.org>
In-Reply-To: <3E3FDD2AC2CEF442A9D2B00CF5F6D0409A733475@winexmp02>
Date: Sun, 7 Aug 2011 12:44:00 -1000
To: Jonathon Exley <Jonathon.Exley@kordia.co.nz>
Cc: "nanog@nanog.org" <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
Jonathon,
On Aug 7, 2011, at 12:09 PM, Jonathon Exley wrote:
> This has probably been said before,
Once or twice :-)
> but it makes me uncomfortable to think of everybody in the world being =
given /48 subnets by default.
This isn't where the worry should be. Do the math. Right now, we're =
allocating something like 300,000,000 IPv4 addresses per year with a =
reasonable (handwave) percentage being used as NAT endpoints. If you =
cross your eyes sufficiently, that can look a bit like 300,000,000 =
networks being added per year. Translate that to IPv6 and /48s:
There are 35,184,372,088,832 /48s in the format specifier currently =
defined for "global unicast". For the sake of argument, let's increase =
the the 'network addition' rate by 3 orders of magnitude to =
300,000,000,000 per year. At that rate, which is equivalent to =
allocating 42 /48s per person on the planet per year, the current format =
specifier will last about 100 years. And there are 7 more format =
specifiers.
> but wouldn't it be wise to apply some conservatism now to allow the =
IPv6 address space to last for many more years?=20
The area to be more conservative is, perhaps unsurprisingly, in the =
network bureaucratic layer. I believe current allocation policy states =
an ISP gets a minimum of a /32 (allowing them to assign 65536 /48s), but =
"if justified" an ISP can get more. There have been allocations of all =
sorts of shorter prefixes, e.g., /19s, /18s, and even (much) shorter. =
An ISP that has received a /19 has the ability to allocate half a =
billion /48s. And of course, there are the same number of /19s, /18s, =
and even (much) shorter prefixes in IPv6 as there are in IPv4...
> After all, there are only 4 bits of IP version field so the basic =
packet format won't last forever.
True. There is no finite resource poor policy making can't make scarce.
Regards,
-drc
