RE: [dhcwg] Dual-stack hosts using DHCP (was Re: [dhcwg] draft-ietf-dhc-dhcpv6-opt-nisconfig-05.txt)

Ralph, et al:

I fully agree with your "wg_member" comments. I too believe this is a
host issue and not a DHCP protocol issue.

- Bernie

-----Original Message-----
From: dhcwg-admin@ietf.org [mailto:dhcwg-admin@ietf.org] On Behalf Of
Ralph Droms
Sent: Monday, March 15, 2004 6:06 PM
To: dhcwg@ietf.org
Subject: [dhcwg] Dual-stack hosts using DHCP (was Re: [dhcwg]
draft-ietf-dhc-dhcpv6-opt-nisconfig-05.txt)

<wg_chair>
In the interest of forward movement, I would like the WG to pick up the
conversation about dual-stack issues around the two specific drafts
draft-ietf-dhc-dhcpv6-opt-sntp-00 and
draft-ietf-dhc-dhcpv6-opt-nisconfig-05.
</wg_chair>

<wg_member>
After re-reading draft-ietf-dhc-dual-stack-00 and considering the
discussion of dual-stack issues at the WG meeting in Seoul, I find
myself in agreement with kre's analysis (included below).

Fundamentally, there is a problem here that rightfully belongs in the
administrative or management policy in the host itself.  A host may
receive configuration information from a variety of sources: PPP, RAs
(IPv6), well-known addresses for services, SLP, DNS SRV RRS, DHCP,
manual configuration, etc.  The host itself may be connected to multiple
physical interfaces or multiple logical interfaces (e.g., VPN).

I can imagine constructing multiple plausible scenarios in which the
host would use configuration information from multiple sources in
different ways.  And, looking at the problem from the DHCP point of
view, there is no way for the DHCP server to determine how the host is
configured, and, therefore no way for the DHCP server to determine the
right way to deliver the configuration information to the host.

Therefore, it seems to me the right thing to do is for the various
sources of configuration information to operate independently, allowing
the host to make any decisions about integrating the information from
the various sources.

In the case of DHCP, I think the right thing to do is to
keep DHCPv4 and DHCPv6 separate, so the host treats information from
DHCPv4 and DHCPv6 as arriving from different sources, and makes its own
decisions about how to integrate the information.

In the case of draft-ietf-dhc-dhcpv6-opt-sntp-00 and
draft-ietf-dhc-dhcpv6-opt-nisconfig-05, the right thing to do would be
to carry only IPv6 address in these options, leaving the decision about
how to use those addresses up to the receiving host. </wg_member>

- Ralph

At 06:11 PM 2/11/2004 +0700, Robert Elz wrote:
>     Date:        Tue, 10 Feb 2004 08:10:23 -0800
>     From:        Harald Tveit Alvestrand <harald@alvestrand.no>
>     Message-ID:  <2015037.1076400623@localhost>
>
>   | Apologies - just because I think you're wrong is no excuse for
> snapping at
>   | you.
>
>No apologies needed, at least not for me - the message I replied to
>wasn't directed (specifically) at me.   In any case, I didn't view your
>comment as in any way objectionable, just farcical...
>
>   | I still think you're wrong.
>
>I fully understand your point of view.   And I certainly agree,
>getting different config info from different sources is a problem, and 
>one that it would be nice to have a clean solution to.
>
>But I don't think you can really expect DHCP to suddenly provide it, or

>not in the context of the DHCPv6 NIS configuration option in any case.
>
>The problem is much broader than that - there are many more sources of 
>config info than just N interfaces each providing host config 
>information via DHCP.
>
>Config info is also available via well known addresses (ie: SNTP could 
>be using the well known multicast address, instead of a particular 
>server) or via SLP, or perhaps even DNS SRV records, or ...
>
>Any and all of that might conflict with any other of it.   What a host
>should do in circumstances like those isn't easy to specify.
>
>DHCP on the other hand has been as it is now since day 1 - it gets 
>config info about an interface, and throws in all kinds of host 
>configuration at the same time - naturally leading to (potentially)
multiple different
>configs being received.   DHCPv4 is like that, DHCPv6 isn't any
different.
>Altering that would be a major project, and NIS configuration just 
>isn't important enough to embark upon that!
>
>kre
>
>ps: I haven't read today's list traffic yet (the last message I saw was

>my own - the one full of typos).

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