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

[Tim Chown <[e-mail]>]

I think that's probably fair comment, but have not yet read all the mail
thread and IETF WG minutes.

I think there is an open question here for the dual-stack case.  In other
WGs, esp. v6ops, where such questions arise a discussion is held and then
documented (e.g. for dual-stack SMTP best practice).  If the result is that 
we decide it is a host issue, I think there is still value in documenting 
the issues and explaining why we came to a certain conclusion.

The problem of manual configurations "clashing" with DHCP is mentioned in
the draft.   That exists for v4 now of course, without dual-stack.  

This would also allow us to document what the issues are for the host in
handling the information it receives from DHCPv4 and DHCPv6 servers, 
if we assume best practice is to not carry IPv4 options in DHCPv6.

Consistency of information seems to be a pillar in the argument; and that
is a local administrative issue.   There are some cases where this may not
be possible, e.g. where the v4 and v6 provider is different, but these
may be fringe cases. 

Tim

On Tue, Mar 16, 2004 at 08:29:47AM -0500, Bernie Volz wrote:
> 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: [e-mail] [mailto:[e-mail]] On Behalf Of
> Ralph Droms
> Sent: Monday, March 15, 2004 6:06 PM
> To: [e-mail]
> 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 <[e-mail]>
> >     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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