Subject: [dhcwg] WG last call on draft-ietf-dhc-mipadvert-opt-01.txt (SECOND REQUEST)

From: Ralph Droms <[email-masked]>
Date: Wed, 22 Oct 2003 09:58:00 -0400

SECOND REQUEST - To date, the only response to this WG last call has been
the chair's review of the document.  If enough responses are not received to
support the acceptance of this document, it *will not* be submitted to the
IESG for publication.  Please respond to this WG last call.  If you support
acceptance of the document without change, respond with a simple
acknowledgment, so that support for the document can be assessed.

-----
This message announces a WG last call on "DHCP Option for Mobile IP Mobility
Agents" <draft-ietf-dhc-mipadvert-opt-01.txt>.  The last call will conclude
at 5PM ET on Friday, 10/24/2003.

Please respond to this WG last call.  If you support acceptance of the
document without change, respond with a simple acknowledgment, so that
support for the document can be assessed.

draft-ietf-dhc-mipadvert-opt-01.txt defines a new DHCP Option called the
Mobility Agent Option, and two sub-options of the Mobility Agent Option: the
Network Access Identifier Sub-Option, which provides
identifying information about a DHCP client to the DHCP server and the
Mobility Agent Announcement sub-option, which announces the address of one
or more mobility agents available to a host. This draft is available as
http://www.ietf.org/internet-drafts/draft-ietf-dhc-mipadvert-opt-01.txt

- Ralph Droms 

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dhcwg mailing list
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---

From: Kim Kinnear <[email-masked]>
Date: Wed, 22 Oct 2003 10:17:21 -0400

Ralph,

I support this document moving forward, with one small
reservation.

I don't see the value in having zero length suboptions.  I don't
think we generally allow them (though someone will doubtless
correct me if I'm wrong).  If there is some valid, semantically
interesting reason for allowing zero length suboptions, then I
think the meaning should be spelled out, otherwise I think they
should be disallowed.

Kim

---

From: "Bernie Volz" <[email-masked]>
Date: Wed, 22 Oct 2003 10:32:32 -0400

Kim, et al:

1. I too support this document moving forward.

2. I do believe that zero length suboptions should be allowed. For example,
we're using a zero length option to request Rapid Reply (see new draft) and
if a similar request was to be used for mobile agents, why prohibit it or
require a meaningless value to be passed (such as a flag). If a new
suboption is defined in the future that requests an alternative behavior if
the option is present, why require it to carry an extra meaningless "flag"
byte.

In some cases having a flag byte is important since there are really three
implied settings:
- Disable feature
- Enable feature
- Use your configured default (no option/suboption)

But in others, just having the option/sub-option present is sufficient (such
as in the DHCPv6 Rapid Commit case).

So, I'm in favor of leaving this in the draft.

- Bernie

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of Kim
Kinnear
Sent: Wednesday, October 22, 2003 10:17 AM
To: Ralph Droms; [email-masked]
Subject: Re: [dhcwg] WG last call on draft-ietf-dhc-mipadvert-opt-01.txt
(SECOND REQUEST)

Ralph,

Kim

---

From: Henrik Levkowetz <[email-masked]>
Date: Wed, 22 Oct 2003 16:54:14 +0200

Hi,

	I don't know how much weight it carries (as I'm the author) but
I do support this document moving forward.

	Henrik

> http://www.ietf.org/internet-drafts/draft-ietf-dhc-mipadvert-opt-01.txt

	Henrik

-- 
  What a wonderful world it is that has girls in it!

---

From: Kim Kinnear <[email-masked]>
Date: Wed, 22 Oct 2003 11:06:41 -0400

>So, I'm in favor of leaving this in the draft.

        Well ... I didn't say that I think zero length options (or
        in this case, suboptions) are terrible.  Just a little
        confusing.

        My more thoughtful position (which I don't believe
        conflicts with Bernie's, but he may have a different
        response) is as follows:

        --------------

        If there is some semantic content to a zero length (in
        this case sub-option), then I believe that it should be
        spelled out in the draft as specifically allowed, and the
        semantic content of the zero length suboption should be
        explicitly defined.

        Otherwise, I believe that zero length suboptions should
        not be allowed.

        To put this another way -- if you want to allow a zero
        length suboption (or option, in another draft), I think
        that you should be required to explicitly state that it
        *is* allowed, and you should be required to state what it
        means if it shows up with zero length.

        -------------------

        The rapid response draft follows these guidelines, since
        it explicitly says what to do with a zero length option.

        My (small) quarrel with the mipadvert draft is that it
        says:

   The Mobility Agent Information field shall NOT be terminated with a
   255 sub-option.  The length N of the DHCP Mobility Agent Information
   Option shall include all bytes of the sub-option code/length/value
   tuples.  Since at least one sub-option must be defined, the minimum
   Mobility Agent Information length is two (2).  The length N of the
   sub-options shall be the number of octets in only that sub-option's
   value field.  A sub-option length may be zero.  The sub-options need
   not appear in sub-option code order.

        I think that the sentence: "A sub-option length may be
        zero." should be replaced with the following:

        "A sub-option length may not be zero unless the
        specification of the sub-option explicitly allows a zero
        length sub-option, and in this case the meaning of the
        zero length sub-option MUST be made explicit."

        That's all -- still kind of a nit.

        Cheers -- Kim

---

From: "Bernie Volz" <[email-masked]>
Date: Wed, 22 Oct 2003 11:18:03 -0400

Sorry for the misunderstanding. I have no issue with clarifying the
language.

- Bernie

-----Original Message-----
From: Kim Kinnear [mailto:[email-masked]] 
Sent: Wednesday, October 22, 2003 11:07 AM
To: Bernie Volz; 'Kim Kinnear'; 'Ralph Droms'; [email-masked]
Subject: RE: [dhcwg] WG last call on draft-ietf-dhc-mipadvert-opt-01.txt
(SECOND REQUEST)

        --------------

        -------------------

        Cheers -- Kim

---

From: Henrik Levkowetz <[email-masked]>
Date: Wed, 22 Oct 2003 17:27:02 +0200

>         zero length sub-option MUST be made explicit."

This makes sense to me, and (supposing it is deemed that the draft can
go forward) I'll update it accordingly.

	Henrik

---

From: Ted Lemon <[email-masked]>
Date: Wed, 22 Oct 2003 13:02:11 -0500

> think the meaning should be spelled out, otherwise I think they

I agree with this.   There is a precedent, but it's a big hassle to 
support this - it's better for the suboption to just have a boolean 
value.