Subject: Re: [mobile-ip] RE: Potential issues with Registration Revocation draft

From: "Steven M. Glass" <[email-masked]>
Date: Thu, 01 May 2003 14:32:32 -0400

On Wednesday, April 30, 2003, at 11:14  AM, Kuntal Chowdhury wrote:

>
>
> Parviz Yegani wrote:
>> At 05:53 PM 4/28/2003 -0500, [email-masked] wrote:
>>> The IETF process for WG last call and IETF last call produced
>>> comments that have been addressed by the authors. We cannot
>>> keep on revisiting the draft at every turn or at the convenience
>>> of folks who may have missed the opportunity to comment. That
>>> said I agree with Steve that the draft is now at a stage wherein
>>> we really do not want to make changes other than the ones that
>>> have been agreed to as a result of WG and IETF last call and
>>> feedback from AD review and IESG comments. So while the offer
>>> to help make the changes is welcome, it is way too late in the
>>> process.
>>>
>>> -Basavaraj

>> Agreed. It's way too late for the authors to take any new comments.
>> As far as 3GPP2 is concerned we don't see any problem with the
>> draft.
>
> Parviz, with all due respect, I don't think your statement reflects 
> the most recent status of the discussion in 3GPP2. There are indeed 
> quite a few open issues in 3GPP2 (V&V comments) on this subject.

     You're saying these are issues we can do something about in the 
scope of registration revocation?

>   Some of the issues are: how to prevent the race condition with 
> revocation by previous FA during inter PDSN/FA handoff,

     How can our draft address this?  You're talking about 2 separate 
messages for which there is simply no coordination over.  Moreover any 
message going from the 'previous' FA to the HA saying the binding is 
gone (and arriving first) is going to have this effect; the HA doesn't 
have a crystal ball to know there's another registration for this MN on 
the way, so I don't see how you're going to solve this problem by 
focusing on revocation.  My recommendation is to let the binding go 
away, but to NOT release the address being used by the MN; there should 
be a lifetime associated with it which is the same (or greater) than 
whatever the remaining mobile ip lifetime was - actually, my "Home 
Agents as DHCP Proxies" draft recommended it be a multiple of MIP 
binding lifetimes (say 1x or 2x) and whenever the MN reregisters, the 
HA refreshes the DHCP lease.  This way if the MN doesn't reregister, 
the lease expires naturally.  Anyway, this is outside the scope of 
registration revocation.

>  how to utilize the I-bit from HA etc,

     How is this something that's unresolved in our draft?  If you can 
provide me with some details or whatever the confusion is, I'm willing 
to try to help.

>  IPsec/FA-HA etc.

     We recommend strong protection, e.g. IPsec between FA and HA.  I'm 
not sure we can do anything about defining how this should be done in a 
draft whose scope is limited to registration revocation.

>  Some of these issues are linked to what has been communicated to the 
> authors in previous email on this thread.

     As far as I know we've responded to every single email we received.

> OTOH, I personally think, there was ample time for the authors to make 
> necessary changes to address the potential issues here.

     Are you saying there was something we said we'd do, but didn't?  We 
disagreed about some 'features' but never did the Mobile IP WG reach 
consensus, or was given convincing motivation for adding the 
complexities proposed by the other features.  The comments from the 
IESG stated the draft was seemingly overly complicated for a simple 
idea, and I actually somewhat agree, but how much more complicated 
would it have been e.g. if revocations were negotiated [requiring a lot 
more state than the state 3G isn't willing to commit for batch 
revocations], or if we defined error codes [so the sender of a 
revocation had to keep enough state to assist the other end in 
recovering from the error], etc.  As the 3G list is a 'closed' list, 
I'm not at all up on what's being said about this draft on 3G, but 
based on the list you gave of open "issues" above I'd say Parviz's 
statement that "3G has no problem with [the specifics] of _this_ draft" 
is fair as the issues you mentioned are beyond the scope of the draft.

                               Cheers,
                                   Steve