Subject: [MOBILE-IP] [Fwd: draft-ietf-mobileip-3gwireless-ext-04.txt]

From: "Charles E. Perkins" <[email-masked]>
Date: Fri, 18 Aug 2000 13:27:09 -0700

Hello folks,

I have sent the following message earlier this afternoon, in an
attempt to reopen discussion about the abovementioned Internet
Draft which is currently under consideration for Experimental status.

Yingchun has informed me that the 3gwireless approach has been
implemented as part of the IOS 4.1 standard within CDMA2000.
I do not know whether that should affect the discussion at this
point in time.

Regards,
Charlie P.

-------- Original Message --------
Subject: draft-ietf-mobileip-3gwireless-ext-04.txt
Date: Fri, 18 Aug 2000 13:08:28 -0700
From: "Charles E. Perkins" <[email-masked]>
Organization: Nokia Research Center
To: [email-masked], [email-masked],[email-masked],
[email-masked],[email-masked],Gopal Dommety
<[email-masked]>, [email-masked],[email-masked],
[email-masked],[email-masked],
[email-masked],[email-masked], [email-masked],
[email-masked],[email-masked], [email-masked],
[email-masked],[email-masked],
[email-masked],[email-masked],
[email-masked],[email-masked],
[email-masked],[email-masked],
[email-masked],"Lipford, Mark"
<[email-masked]>,[email-masked], [email-masked]
CC: Tom Hiller <[email-masked]>,Phil Roberts
<[email-masked]>,"Basavaraj Patil (NTC/Dallas)"
<[email-masked]>,David Oran <[email-masked]>, Rob Coltun
<[email-masked]>
BCC: Pat Calhoun <[email-masked]>,James Kempf <[email-masked]>

Hello draft co-authors,

>From the discussion below, and after a careful re-reading of the draft,
I hope to show that this protocol specification does not at all fit
well within the mainstream of work within the mobile-ip working group.
I believe that it is actively harmful, because any core network
implementing their protocol would find it correspondingly much more
difficult to implement "actual" Mobile IP specifications.  I say
"actual" in quotes because the specifications in question are not
yet Proposed Standard, and also because I do not think that the
3gwireless specification fits well in its current formulation nor
has it received sufficient working-group review.

The first basic problem with the 3G wireless draft is the specification
of the Registration Update and the Registration Acknowledgement
message types.  Neither of them is clearly specified, and to the
extent that I understand their purpose, neither one is necessary.
The intended results of those messages are done better by use of
the Binding Update and Binding Acknowledgement messages which are
already specified in the Route Optimization draft.

The respecification of the Registration Request draft is also
faulty, and exhibits the well-known fallacy of doing the same
thing in two different ways.  In this particular instance, we
see that the alt-Registration Request message has failed to keep
up with recent developments regarding the 'V' bit.  We can expect
this to continue, especially given the strong likelihood that
some new Mobile IP developments will involve interactions between
the Registration Request message and AAA services.

Figuring out when to send an alt-Registration Request will be
additionally complicated by the standardization of the upcoming
Regional Registration protocol specification, which is currently
in Last Call.

Another element of confusion is represented by the lack of
IP addressability for mobile nodes subordinate to the protocol
operations described in the 3gwireless draft.  In fact, nowhere
in the draft is there any indication that mobile nodes in their
system will have IP addresses.  Furthermore, mobile nodes in
this draft are basically identified by a MN ID field, which is
expected to be the same as the mobile node's IMSI.  Recent work
within the mobile-ip working group has gone in the direction of
using the NAI for analogous purposes of allowing a Registration
Request to emanate from a mobile node that does not yet have
a home address assigned.  I would suggest that the 3gwireless
draft use the NAI extension instead of their current MN ID.
The IMSI is widely expected to show up as data within NAI
extensions to Mobile IP registration requests, so this should
not cause any problems to the 3gwireless authors.

As an example to support my contention that this draft is actively
harmful to current work items within the mobile-ip working group,
say that a PDSN implements Regional Registrations.  This is very
likely, given recent discussion.  How then would such a PDSN manage
its route tables if it ever received a message on port 697?
It might be very difficult to figure this out.  It would be
possible to get messages that required incompatible operations.

Similarly, if a mobile node implements smooth handover messages
using IPv4 Binding Updates, then there would be a conflict between
actions required by the Binding Update message and the port 697
messages.

I have numerous other syntactic and editorial comments that I
think would need attention before the draft should be considered
at all.  If need be, I will supply these additional comments.
However, before going to that trouble, I think that it is more
important to consider the viability of the draft.  I hope that the
authors of the draft will follow through on their previous agreement
to find a better integration strategy with other existing mobile-ip
working group drafts, specifically including Route Optimization and
Regional Registration.  If it is the contention of the 3gwireless
authors that the previous drafts are too complicated for their
implementation purposes, then we should have the discussion.
I have offered to do so, more than once.  One possible outcome
would be to get simpler drafts for specific protocol features
needed by the 3gwireless authors.

I note that Nortel Networks had brought some similar concerns to
light a couple of years ago, and we reached a beneficial improvement
to the Route Optimization draft which allowed the inclusion of
multiple correspondent node addresses in the Binding Warning
message.  I fully expect that we can make similar improvements
as needed to the IPv4 Binding Update message for use in the
role needed by the authors of the 3gwireless draft.

I also note that the name of the draft is misleading.  As far as
I know, there is no consensus behind this protocol specification
within 3GPP or within MWIF.  I also do not think there is any
consensus behind this protocol within 3GPP2, but I note that
several of the listed authors are indeed active within 3GPP2.
My guess is that this draft has limited support even there.  But
either way, it seems very clear to me that the draft should NOT
be named in any way to imply that it represents _the_ 3G solution
for wireless mobility management.  Far from it.

Lastly, I note that this draft has attracted almost no discussion
within the mobile-ip working group.  When I asked several others
about it, they said it was because most people generally don't care.
But I care.  I care because I think it is damaging to the progress of
other longstanding mobile-ip working group items.  In order to best
meet the needs of all parties, I offer my best effort to work with
the authors of the 3gwireless draft to make the other drafts meet
their needs.  I hope this will be sufficient to resolve what could
otherwise be a situation causing problems for the future.

Sincerely,
Charles E. Perkins

PS. I regret that I have only now been able to make time for this
    set of comments.  It would have been much better to raise the
    discussion during working-group last call, but that slipped
    right by me and was over before I knew it.