[138640] in North American Network Operators' Group
Re: Internet Edge Router replacement - IPv6 route
daemon@ATHENA.MIT.EDU (Leo Bicknell)
Fri Mar 11 13:59:11 2011
Date: Fri, 11 Mar 2011 10:58:09 -0800
From: Leo Bicknell <bicknell@ufp.org>
To: nanog@nanog.org
Mail-Followup-To: nanog@nanog.org
In-Reply-To: <49506.1299866835@localhost>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
--wac7ysb48OaltWcw
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable
In a message written on Fri, Mar 11, 2011 at 01:07:15PM -0500, Valdis.Kletn=
ieks@vt.edu wrote:
> On Fri, 11 Mar 2011 09:38:12 EST, Joe Maimon said:
> > rfc3927 does not require 64 bits and works sufficiently well wherever i=
t=20
> > is employed. SLAAC should be redesigned to be configurable to work with=
=20
> > however many bits are available to it and it should be a standard=20
> > feature to turn that knob all the way from on - off with 128 bit stops=
=20
> > in between.
>=20
> Feel free to explain how SLAAC should work on a /96 with 32 bits of host =
address
> (or any amount smaller than the 48 bits most MAC addresses provide). Rem=
ember
> in your answer to deal with collisions.
Well, I at least think an option should be a /80, using the 48 bits
of MAC directly. This generates exactly the same collision potential
as today we have with a /64 and an EUI-64 constructed from an EUI-48
ethernet address. The router is already sending RA's for SLAAC to
work, sending along one of a well-known set of masks would be a
relatively minor modification.
That said, ND has built into it DAD - Duplicate Address Detection.
There is already an expectation that there will be collisions, and
the protocols to detect them are already in place. I see little
to no reason you couldn't use a different length subnet (like the
/96 in your example), randomly select an address and do DAD to see
if it is in use. Indeed, this is pretty much how AppleTalk back
in the day worked (with a 16 bit number space).
The probability of collision is pretty low, and the penalty/recovery
(picking a new address and trying again) is rather quick and cheap.
If a service provider is going to end up giving me a /64 at home (I
know, a whole different argument) I'd vastly prefer to use /80 or /96
subnets with either of these methods, and still be able to subnet the
space. I suspect if /64's are given out one or both will come to be
"standard".
--=20
Leo Bicknell - bicknell@ufp.org - CCIE 3440
PGP keys at http://www.ufp.org/~bicknell/
--wac7ysb48OaltWcw
Content-Type: application/pgp-signature
Content-Disposition: inline
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2.0.13 (FreeBSD)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=6Ey6
-----END PGP SIGNATURE-----
--wac7ysb48OaltWcw--
