[96059] in North American Network Operators' Group
Re: DHCPv6, was: Re: IPv6 Finally gets off the ground
daemon@ATHENA.MIT.EDU (Iljitsch van Beijnum)
Sun Apr 15 17:43:31 2007
In-Reply-To: <FB0392E6-AF56-45F9-A4E2-E246CFBD088D@ca.afilias.info>
Cc: "David W. Hankins" <David_Hankins@isc.org>, nanog@merit.edu
From: Iljitsch van Beijnum <iljitsch@muada.com>
Date: Sun, 15 Apr 2007 23:42:23 +0200
To: Joe Abley <jabley@ca.afilias.info>
Errors-To: owner-nanog@merit.edu
On 15-apr-2007, at 21:35, Joe Abley wrote:
>> With IPv6, there's of course still manual configuration, but PPP
>> is out because it can't negotiate IPv6 addresses.
> I've heard you say this a few times now, but I am also told by
> various people in various places that they have succeeded in
> getting IPv6 addresses assigned using PPPoE. Colour me confused.
> Does RFC 2472 have some practical limitations in the real world
> that I haven't noticed? Or is the problem a simple matter of
> implementation?
With IPv4, PPP IPCP will negotiate a whole bunch of stuff, including
the addresses of both sides of the link. PPP IP6CP only negotiates a
32-bit unique token for each side which can then be used to create
link local addresses.
Two years ago, when I was writing my IPv6 book, I did some testing
between an Cisco 2500 and a MacOS 10.4 system to see how IPv6 over
PPP behaves, and the result was that it did work, but there was no
address assignment from the router to the Mac, not through PPP,
because it doesn't support it, and not through router advertisements,
for reasons unknown. Probably someone decided that stateless
autoconfig on a point to point link didn't make sense.
(Note that the pppd in question is common to both the BSD family and
Linux.)
I have no idea what's different in the PPP over ethernet setup, but
it could be many things, such as that the PPP implementations do
support stateless autoconfig there, or that it's not actual IPv6 over
PPP but rather IPv6 over IPv4 or over bridged ethernet.
