[153441] in North American Network Operators' Group
IPv6 /64 links (was Re: ipv6 book recommendations?)
daemon@ATHENA.MIT.EDU (Jean-Francois.TremblayING@videotro)
Wed Jun 6 10:37:20 2012
In-Reply-To: <CAHHzyzAO=-oqcKfrd4fOnzcaxr-HuUydajjNr_=DEgP0OD12bg@mail.gmail.com>
To: anton@huge.geek.nz
From: Jean-Francois.TremblayING@videotron.com
Date: Wed, 6 Jun 2012 10:35:48 -0400
Cc: NANOG list <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
Anton Smith <anton@huge.geek.nz> a =E9crit sur 06/06/2012 09:53:02 AM :
> Potentially silly question but, as Bill points out a LAN always=20
> occupies a /64.
>=20
> Does this imply that we would have large L2 segments with a large
> number of hosts on them? What about the age old discussion about
> keeping broadcast segments small?
The /64 only removes the limitation on the number of *addresses* on=20
the L2 domain. Limitations still apply for the amount of ARP and=20
ND noise. A maximum number of hosts is reached when that noise
floor represents a significant portion of the link bandwidth. If
ARP/ND proxying is used, the limiting factor may instead be the=20
CPU on the gateway.=20
The ND noise generated is arguably higher than ARP because of DAD,=20
but I don't remember seeing actual numbers on this (anybody?).=20
I've seen links with up to 15k devices where ARP represented=20
a significant part of the link usage, but most weren't (yet) IPv6.=20
/JF
