Re: [v6ops] DHCPv6/SLAAC Make Hosts Confusing-//RE: new draft: draft-liu-bonica-v6ops-dhcpv6-slaac-problem

Lorenzo Colitti <lorenzo@google.com> Sun, 27 October 2013 14:58 UTC

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From: Lorenzo Colitti <lorenzo@google.com>
Date: Sun, 27 Oct 2013 23:58:33 +0900
Message-ID: <CAKD1Yr13YGiRfHm0RoOoGe+02SCXcPFE7rgBG=RiT1-dTfEnrg@mail.gmail.com>
To: Gert Doering <gert@space.net>
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Cc: "v6ops@ietf.org" <v6ops@ietf.org>, Ted Lemon <mellon@fugue.com>, "Ole Troan \(otroan\)" <otroan@cisco.com>, Dave Thaler <dthaler@microsoft.com>, "draft-liu-bonica-v6ops-dhcpv6-slaac-problem@tools.ietf.org" <draft-liu-bonica-v6ops-dhcpv6-slaac-problem@tools.ietf.org>
Subject: Re: [v6ops] DHCPv6/SLAAC Make Hosts Confusing-//RE: new draft: draft-liu-bonica-v6ops-dhcpv6-slaac-problem
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On Sun, Oct 27, 2013 at 11:52 PM, Gert Doering <gert@space.net> wrote:

> > > I do not think that I made an actual proposal here.
> > I mean "Stateful RA could actually be piggybacked onto DHCP, so that the
> > router just creates a DHCP message and forwards it upstream, or answers
> > it locally, depending on the circumstances." xing
>
> This is called "DHCP relay or DHCP server on the router".  I can't see
> what this has to do with RA ("periodically multicasted to everyone who
> wants to receive it").
>
> This idea is... completely lacking the understanding of the difference
> between solicited and unsolicited information, and also of the existing
> possibilities of just having a DHCPv6 server (or relay) on the router
> itself.
>

The way I read that was:

1. Host sends RS.
2. Router gets RS, encapsulates it in DHCPv6 option to DHCPv6 server.
3. Server replies with RA parameters.
4. Router sends unicast RA to host.

The unicast RA would have more information than the multicast RA (e.g.,
more specific routes). The idea being that you if you do this you can send
different clients different information (which is one of the things that
DHCPv6 offers but RAs typically do not).

So it's basically a RA-to-DHCPv6 translator in the router.

If you want to do it this way, I don't see why you would use DHCPv6 and not
something like radius, but I suppose you might want to do that if you need
to keep state on the server (radius is stateless).