Subject: Re: [MOBILE-IP] Architectural v.s. Incremental Lession for Fast H andoff Discussion

From: George Tsirtsis <[email-masked]>
Date: Wed, 20 Dec 2000 16:33:18 -0500

-----Original Message-----
From: Bernard Aboba
To: [email-masked]
Sent: 12/20/00 3:19 PM
Subject: Re: [MOBILE-IP] Architectural v.s. Incremental Lession for Fast
Handoff Discussion

>If we merge the proposals, I wonder if, two years from now, one of our
working group chairs won't be
>up on stage at the plenium giving exactly the same presentation as
Randy
did but for
>mobile IP.

>I'd therefore like to ask the working group to reconsider its hum for
merging.

If there's anything I've learned over the last few years in the IETF, it
is that merging two proposals for the sake of "consensus" is often a very
bad idea.
Too frequently we end up with the worst aspects of both proposals, an
outcome which is often worse than choosing one or the other. It is often
better to choose one architecturally clean proposal, even if all of the
"features" that are desired can't be shoehorned into it.

GT> True! but not if the proposals in question happen to cover different
scenarios...in which case non of the two is architecturaly 'clean'. Instead
a superset framework may do the trick...Even if this is not possible maybe
slight extensions to one proposal may be enough to gain the main (not
necessarely all) features of the other... I think this can be done in this
case.

George

---

From: "Karim El-Malki (ERA)" <[email-masked]>
Date: Thu, 21 Dec 2000 13:08:27 +0100

> From: George Tsirtsis [mailto:[email-masked]]
> Sent: den 20 december 2000 22:33
> H andoff Discussion

I don't believe such extensions are possible. There are differences
between the two approaches presented at the last mtg. which prevent
them from being used together (i.e. at the same time). However, I also
think that the two approaches cover a wide range of scenarios. This is
confirmed by the v6 handoffs work which is involving solutions equivalent
to the proactive and fast h'off drafts. So a merger which involves mixing
functionality from the proactive and fast drafts does not make technical
sense to me. After all it seems to be clear that one approach cannot do
for all situations, so the two methods of improving L3 handoffs should be
maintained. Slight extensions to one of the two won't do the same.

Rgds,
/Karim

---

From: "Hesham Soliman (EPA)" <[email-masked]>
Date: Fri, 22 Dec 2000 02:10:56 +1100

Hello Phil and all,

        Generally speaking I do think that merging two solutions to simply
        achieve consensus is not the best way to go. In addition, the two
drafts
        in question are based on different assumptions. However, as you said
below
        it was expressed during the meeting that there maybe scenarios where

        one approach may work better than the other. Therefore, eliminating
one
        draft completely may not be a good idea. Unless we know which
assumptions
        will prevail in the long term we can't eliminate one of the
approaches. I recall
        a comment about using a clairvoyant !

        So I feel that we're in no position to eliminate one approach or
simply mix them
        together. However it would be good to have both approaches in the
same
        document and detailing the assumptions behind each one
        (that is if we can -I hope- agree on the assumptions). This work
        must be done by the authors as they know the approaches best.

        As to using the IPv6 outcome, I'm not sure that will be useful, I
believe
        the IPv6 draft includes both approaches already with modifications
        to accomodate MIPv6. The V4 drafts are much more stable and
        will be required by systems sooner. The IPv6 draft will need a bit
more
        time to get stable and will be used (on a large scale) at a later
time.

        Regards,
        Hesham

> I agree with your sentiment here.  I'd like to hear more discussion from
> the working group on a particular course of action.  The design team went
> round on this a couple of times also.
>
> I expect to get some guidance from our AD soon and will share that with
> the list.
>
> In the meantime perhaps we could get some feedback on the following
> possibilities:
> 1) we've heard a few sentiments on not combining for a couple of different
> reasons
> 2) combining the two drafts seemed to have significant support within the
> room at San Diego
> 3) a third possibility that has been suggested is trying to reuse the work
> of the v6 design team to come up with a v4 proposal
>
> This is a good time to hear the thoughts of the working group.
>
> Phil

---

From: George Tsirtsis <[email-masked]>
Date: Thu, 21 Dec 2000 10:44:01 -0500

Phil,

I think another approach would be to take one of the proposals and see if it
can be extended...rather than trying to fully combine the two.

In particular, I think that the FA assisted proposal can be made more widely
applicable if you allow the source and destination triggers to be IP layer
messages when the Link Layer does not provide this functionality. This BTW
would give this proposal one of the main features of the other one...i.e.:
indepedence from link layers....

George
-----Original Message-----
From: Roberts Philip-qa3445
To: [email-masked]
Sent: 12/21/00 9:43 AM
Subject: Re: [MOBILE-IP] Architectural v.s. Incremental Lession for Fast
Handoff Discussion
...

In the meantime perhaps we could get some feedback on the following
possibilities:
1) we've heard a few sentiments on not combining for a couple of
different reasons
2) combining the two drafts seemed to have significant support within
the room at San Diego
3) a third possibility that has been suggested is trying to reuse the
work of the v6 design team to come up with a v4 proposal

Phil

---

From: "Karim El-Malki (ERA)" <[email-masked]>
Date: Thu, 21 Dec 2000 17:30:51 +0100

Hi George

> indepedence from link layers....

The two solutions can't work together as you are saying. You can
either use the Mobile IP Registration from the MN in Fast Handoffs
or the inter-FA messaging in Proactive Handoffs so I can't see a
reason for having both at the same time. However a document describing
the two alternatives would be a good solution. In any case I think
we decided that the authors of the two proposals would get
together and talk about this again following the feedback from the WG.

Rgds,
/Karim

---

From: Basavaraj Patil <[email-masked]>
Date: Thu, 21 Dec 2000 10:32:03 -0600

>1) we've heard a few sentiments on not combining for a couple of

Just combining the I-Ds may not provide the desired solution for
handoffs. What really needs to be done is to evaluate the scenarios
(current and possible future) and apply the handoff solutions
currently being proposed to these and determine if there are gaps and
shortcomings.

>2) combining the two drafts seemed to have significant support within

The idea here was to combine the two proposals by the design team as a
start. Revision 0 would then be made available to the WG as a whole
and hopefully have WG members evaluate, critic and contribute to the
I-D to make it applicable to other scenarios. Subsequent revisions of
the I-D should produce a WG document that has consensus and includes a
complete solution. However I am still not sure if this approach will
get the results we hope for in the short term.

>work of the v6 design team to come up with a v4 proposal

Rather than just reusing the v6 design team proposal, the intent
should be for the v4 and v6 design teams to ensure that both proposals
are tackling all handoff cases and scenarios and are working from the
same set of requirements and assumptions.

-Basavaraj

---

From: James Kempf <[email-masked]>
Date: Thu, 21 Dec 2000 08:41:39 -0800

>maintained. Slight extensions to one of the two won't do the same.

I agree with Karim here, but rather advocate that the working group should
decide, not split the difference.

The fundamental difference between the two proposals are that the proactive
draft makes no assumptions about packet delivery after L2 at the old FA
has decided to do handoff and before L2 at the new FA has completed handoff,
whereas the Hesham/Karim draft does. In realistic deployment, I don't think
such assumptions can be made. One could, I suppose, argue that the Hesham/Karim
draft could be used when there is no L2 support for informing the FA that
a handoff is about to take place, but, in such situations, I think that
standard mobile IP is the best one can do.

                jak

---

From: James Kempf <[email-masked]>
Date: Thu, 21 Dec 2000 08:50:49 -0800

George,

>indepedence from link layers....

In fact, the discussion about using the 802.11 IPP prior to the San Diego meeting
would do precisely that. However, IPP may need some extensions (if these
are not already in the protocol, the spec I have is 2 years old).

                jak

---

From: "Hesham Soliman (EPA)" <[email-masked]>
Date: Fri, 22 Dec 2000 03:53:08 +1100

> decide, not split the difference.
        => Agreed. I also think we should state the assumptions and possible

        use scenarios in one document that mentions both solutions.

> such assumptions can be made.
>
        => I'm actually a bit tired of saying the same think all over again,

        so excuse me if I don't answer that. But let me just say that
        the Fast Handoffs draft makes no assumptions about how MIP
        signalling can be mapped onto radio channells in a partcular
cellular
        system. If you read that statement carefully you'll se how
        specific and short lived an assumption like that is.
        There are ways of mapping MIP signlling in an efficient manner
        on these channells.

> One could, I suppose, argue that the Hesham/Karim
        => True, the Fast Handoffs draft can be used in this case also.

> standard mobile IP is the best one can do.
        => The Fast Handoffs draft _IS_ standard MIP with some
        behavioural optimisations and without changing the protocol.
        The anticipation combined with simultaneuos bindings is
        just a behavioural optimisation of RFC2002.

        Hesham