[121679] in North American Network Operators' Group
Re: Using /126 for IPv6 router links
daemon@ATHENA.MIT.EDU (Steven Bellovin)
Sun Jan 24 17:01:39 2010
From: Steven Bellovin <smb@cs.columbia.edu>
In-Reply-To: <20100125081519.7be21cda@opy.nosense.org>
Date: Sun, 24 Jan 2010 17:01:21 -0500
To: Mark Smith <nanog@85d5b20a518b8f6864949bd940457dc124746ddc.nosense.org>
Cc: "nanog@nanog.org" <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Jan 24, 2010, at 4:45 PM, Mark Smith wrote:
>=20
> Actually, from what Christian Huitema says in his "IPv6: The New
> Internet Protocol" book, the original IPv6 address size was 64 bits,
> derived from Steve Deering's Simple Internet Protocol proposal.
> IIRC, they doubled it to 128 bits to specifically have 64 bits as the
> host portion, to allow for autoconfiguration.
Actually, Scott Bradner and I share most of the credit (or blame) for =
the change from 64 bits to 128.
During the days of the IPng directorate, quite a number of different =
alternatives were considered. At one point, there was a compromise =
proposal known as the "Big 10" design, because it was propounded at the =
Big Ten Conference Center near O'Hare. One feature of it was addresses =
of length 64, 128, 192, or 256 bits, determined by the high-order two =
bits. That deal fell apart for reasons I no longer remember; SIPP was =
the heir apparent at that point. Scott and I pushed back, saying that =
64 bits was too few to allow for both growth and for innovative uses of =
the address. We offered 128 bits as a compromise; it was accepted, =
albeit grudgingly. The stateless autoconfig design came later.
--Steve Bellovin, http://www.cs.columbia.edu/~smb
