Subject: [mobile-ip] Draft on Mobile IP Architecture and Reorg

From: "James Kempf" <[email-masked]>
Date: Wed, 26 Feb 2003 09:32:49 -0800

Folks,

Pekka Nikander and I wrote a draft on separating out Mobile IP along the
architectural boundaries of global v.s. local link routing changes. The draft is
draft-kempf-mobileip-arch-00.txt. This draft was primarily intended as a
recommendation on the upcoming reorg of Mobile IP, which will be discussed at
the NSIIM BOF.

The draft makes a recommendation for taking all the work currently involved in
local link routing (CARD in Seamoby, ODAD, FastRA, FRA, etc. in IPv6, and FMIPv6
in Mobile IPv6) and grouping them together into a separate working group with a
tightly focussed charter based on architectural considerations, so that any
changes to RFC 2461 and 2462 are well-designed and co-ordinated.

                jak

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From: Greg Daley <[email-masked]>
Date: Fri, 28 Feb 2003 10:41:19 +1100

Hi James,

Thanks for the draft.  Certainly it highlights an
interesting way to delimit mobility issues
(local & global).

I have a question regarding the difference between
regional mobility (aka LMM) which you've indicated
in the document.

Most of the listed LMM schema seem to attempt to solve
both regional movement control and local-route repair
functions which you mentioned.

Where these systems are combined (for example HMIPv6,
which allows some flexibility in MAP placement) do you
think this is more regional/global than a local optimization?

Greg D.

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From: "James Kempf" <[email-masked]>
Date: Thu, 27 Feb 2003 17:44:11 -0800

rechartering is supposed to take place.)

> functions which you mentioned.

They don't do local route repair. The MN must do a binding update with the MAP
(or RRAgent in MIPv4) when it moves. During the time the time the regional
registration is underway, the regional agent is sending packets to the old
access router. These packets are dropped unless other measures are taken. The
duration of the drops is reduced, of course, because the RTT to the regional
agent is less than to the home agent.

> think this is more regional/global than a local optimization?

It's the "flexibility" that I'm worried about (putting my service provider hat
on).

It certainly is possible to tune MAP placement such that the number of packets
dropped achieves some optimal value for some number, say 95%, of the MNs. But
the other, say 5%, will experience suboptimal performance because the actual
handover time is probabilistic.

Handling the problem locally at the access router by tunneling packets, like
FMIPv6 does, is easier. That's local route repair. There's no need for tuning,
no additional agent required (reducing cost and operational complexity), and all
MNs are covered up to the capacity of the two access routers to handle the
tunnels.

            jak

PS: Caveat: the draft doesn't talk about location privacy, for which regional
agents are quite useful.

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From: "Xiaoming Wang" <[email-masked]>
Date: Fri, 28 Feb 2003 13:47:00 +0900

> FMIPv6 does, is easier. That's local route repair. There's no

I don't agree.

> MNs are covered up to the capacity of the two access routers to handle the

Local route repair is not a panacea for all possible situations. For
example, two geographically adjacent access routers are separated with
several hops away and with considerable delay. In this situation, local
route will experience performance degrade, while regional mobility will
achieve better performance.

From above we can conclude that these two solutions both have their own
locks that they are good at openning. For regional mobility, it happens well
before the packet arrives the destination link and is suitable for the
situation I stated above. For local route repair, it takes effect immdiately
after the packet arrives the destination link and is suitable for the
situation that previous and next access routers are not far in topology from
each other.

Therefore, I think there is need for regional mobility. The point is how to
combine regional and local more efficiently, and with low cost and less
complexity.

xiaoming

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From: "Nick 'Sharkey' Moore" <[email-masked]>
Date: Fri, 28 Feb 2003 16:57:52 +1100

On Wed, Feb 26, 2003 at 09:32:49AM -0800, James Kempf wrote:
>
> [draft-kempf-mobileip-arch-00]
> The draft makes a recommendation for taking all the work currently
> involved in local link routing (CARD in Seamoby, ODAD, FastRA, FRA,
> etc. in IPv6, and FMIPv6 in Mobile IPv6) and grouping them together
> into a separate working group with a tightly focussed charter
> based on architectural considerations, so that any

Looks interesting.

Hmmm ... correct me if I'm misunderstanding, but we're really 
considering separating the ideas of:

	1. What happens before the "Binding"
		(movement detection, address configuration, ...)

	2. What happens after the "Binding"
		(home agents, MAPs, traffic redirection, binding cache
			entries, RR testing ...)

Where "Deciding when/who to BU" fits in I'm not sure ... although
your 4.1 suggests it's part of the latter part, I'd have to think
about it and work out if I agree ...

I'm not entirely convinced that splitting the WG along this line
is going to be a good idea, but I'll let those more experienced 
in the way of IETF think _that_ one over :-)

Hope to catch up with many of you in SF ...

-----N
-- 
Nick 'Sharkey' Moore			<[email-masked]>
Research Fellow, CTIE			Tel: +61 3 9905 3707
Monash University,  Australia		Fax: +61 3 9905 5358

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From: "Charles E. Perkins" <[email-masked]>
Date: Fri, 28 Feb 2003 11:45:42 -0800

Hello James,

> changes to RFC 2461 and 2462 are well-designed and co-ordinated.

That's a lot of work to be grouped together for a tightly focussed
charter.  Looking at the initial paragraphs the draft, I think that
there may be some confusion about what is called a "routing identifier".
It needs to be shown how routing changes character when
it's done on a small scale, as opposed to a large scale.

Are you promoting RFCs 2461/2462 to tablets engraved in stone?
Can you enunciate the "architectural considerations" embodied
by those engravings?  I would like to suggest, that "architecture"
is an _enabling_ concept, not necessarily meant to make good designs
ineligible.

Regards,
Charlie P.

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From: "James Kempf" <[email-masked]>
Date: Fri, 28 Feb 2003 13:25:59 -0800

Charlie,

Let's take this to the [email-masked] list. That's where the
reorg discussion is supposed to happen.

            jak