Subject: Re: [MOBILE-IP] handover

From: Patrice Calhoun <[email-masked]>
Date: Wed, 26 Apr 2000 05:36:57 -0700

O.K., so here is my 2 cents.

I strongly believe that this WG should look into how Mobile IP can be used to
provide fast hand-off. Unfortunately, doing so means that we need to make
some assumptions about the underlying link layer. If the link layer doesn't
provide signal strength measurement, then there is only so much we CAN do
with it.

I am against trying to come up with an approach that will be generic for ALL
wireless link layers. I believe that we should make some assumptions, and try
to solve the problem given that set of assumptions. If we run across another
link layer that has a completely different set of capabilities, then we address
it as need be.

BTW, I see this as being NO different than IP over different link/physical
layers. There isn't a generic solution, and we shouldn't make that assumption
here either.

PatC

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From: "Andrew T. Campbell" <[email-masked]>
Date: Wed, 26 Apr 2000 09:48:01 -0700

Pat:

I agree.

> link layer that has a completely different set of capabilities, then we address

That is were the open API works.

You can define the API, e.g., with various attribites: SNR and
quality indicators, etc. If some wireless links
support these attributes then fine if others don't also
fine.

MIP/CIP/others can chose to use or not use the API attributes (switching
functions on or off).

The API exposes measured "state" but can also be used (in more advance
cases)
to programming the device - but that is a side issue.

The separation of concerns is, however, fundamental and the API is the
vehicle.

My message is that we should not define protocol but an API.

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From: Phil Neumiller <[email-masked]>
Date: Wed, 26 Apr 2000 08:19:35 -0500

> link layer that has a completely different set of capabilities, then we address

Why not make it generic but flexible enough to adapt to a variety of link layers.
Wireless link layers experience high variance of QoS and to make MIP work better
over these environments it should be made "self-aware" of the highly varying QoS
classes fluctuating below it.

> layers. There isn't a generic solution, and we shouldn't make that assumption

Ok so folks are supposed to write drafts for IP over X, for X = wireless link layer
1 to infinity?  This could get quite messy over the next few years as more and more
competing wireless link layers emerge.

Thanks,

Phil

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From: "Tom K. Weckström" <[email-masked]>
Date: Wed, 26 Apr 2000 19:57:14 +0300

Hi,

I would be "bull" in this issue.

I agree with Charlie that regional registrations do bring clear
advantages to MIP. I have seen the improvements 'live', and this even
fits well together with RFC2002. In addition to reducing the signaling
traffic load, the regionalization of the handoffs makes the handoffs
faster. This is what is most likely needed in the almost chaotic
wireless network environment of the future.

I agree with Pat that we have to make some sort of assumptions about
the link layer below. These can be quite general. E.g. the signal
strength measurement ability. We could even make a list of assumtions/
minimal requirements for a L3 handoff to succeed in the first place.

> competing wireless link layers emerge.

What about making the interface generic enough for the current link
layers to interface with L3/MIP and telling the future L2 implementors
to look at the defined interface to make their new L2 work with MIP?

--
        Tom Weckström           Dynamics group
                                Helsinki University of Technology
                                [email-masked]

http://www.cs.hut.fi/Research/Dynamics/

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From: Behcet Sarikaya <[email-masked]>
Date: Thu, 27 Apr 2000 09:35:58 +0900

Hello Pat,
  Nice to see that you are on the bulls' side as well.
>layers. There isn't a generic solution, and we shouldn't make that
assumption
I did not know there was a different IP defined for each link/physical
layer.

--Behcet

--
Behcet Sarikaya
Computer Communications Lab.
The University of Aizu
Tsuruga, Ikki-machi, Aizu-wakamatsu City
Fukushima, 965-8580 Japan
Tel. +81-242-37-2559 Fax. +81-242-37-2742
Home page:  http://www.u-aizu.ac.jp/~sarikaya/
email: [email-masked]