Subject: Re: [MOBILE-IP] Pro-active Handoff and FA Location

From: "Andrew T. Campbell" <[email-masked]>
Date: Fri, 1 Dec 2000 00:21:46 -0800

Ajoy Singh wrote:

> I hate to talk about CDMA or any other link layer in Mobile/IP list,

Reality check:

IP isn't designed for Ethernet and Mobile IP not for CDMA.
But Ethernet is THE link layer and CDMA (W or 2000) will
likely be THE wireless link for 2.5G, 3G, 4G (whatever that
is), WLAN (802.Xs), etc.

Should we get real - or not?

It would be nice to see MIP get deployed.....some day ..

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From: Ajoy Singh <[email-masked]>
Date: Thu, 30 Nov 2000 23:31:02 -0600

Hello Andrew,
Just one clarification. By fast handoff, I was referring to Hesham's
proposal. I know, the name is confusing as proactive and other solution
also addresses fast handoff problem. But I  would prefer a solution that
does not impose hard real time constraint as imposed by  Hesham's (fast
handoff)
proposal. BTW, I am very much interested to see mobile/IP deployed. Please
dont get me wrong.
regards,
ajoy

-----Original Message-----
From: Andrew T. Campbell [mailto:[email-masked]]
Sent: Friday, December 01, 2000 2:22 AM
To: Ajoy Singh
Cc: [email-masked]; [email-masked]
Subject: Re: [MOBILE-IP] Pro-active Handoff and FA Location

Reality check:

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From: Pat Calhoun <[email-masked]>
Date: Fri, 1 Dec 2000 07:18:44 -0800

> Should we get real - or not?

Yes we should, and perhaps you misread Ajoy's e-mail. Hesham has been very
consistent in pushing any of our arguments regarding the limitations of
CDMA2000, and how the "fast handoff" proposal would not work in such
environments. If Pete McCann or Tom Hiller is reading this, I would ask that
he points to the same CDMA2000 spec that we discussed on the design team
conference calls that make it clear that there is no time for mobiles to
perform Mobile IP registration when a handoff occurs.

> It would be nice to see MIP get deployed.....some day ..
Same here!

PatC

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From: "M. Scott Corson" <[email-masked]>
Date: Sat, 2 Dec 2000 10:22:09 -0500

>Should we get real - or not?

Reality?  You can predict reality?  For how long?  Do you give stock advice
as well? ;-)

Seriously, probably not a good idea to assume/predict anything regarding
air interface technology going forwards...let's leave the IP stuff wide
open for all types of link layers in accordance with its basic
architectural philosophy.

In that spirit it's generally not a good idea to put a lot of bits over the
old link during handoff, because it may be getting lousy which is why you
are then handing off.  Whether you can predict handoff in advance with high
probability also depends on the technology.

IP standards should remain wide open, flexible and designed to work well
for the worst-case (poor old links, no prediction).  The other cases are
generally only easier and can be handled with appropriate implementations.

Layer 3 messaging over the old link, to the extent that it is even useful
in IPv4 (debatable), should at most be an option, but not a required part
of fast handoff.

On that basis I largely favor the pro-active draft.

-Scott

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From: Eunsoo Shim <[email-masked]>
Date: Sat, 2 Dec 2000 19:21:33 -0500

> architectural philosophy.

Following this philosophy, I think soft handoff in link layers also should
be considered as a special case even though it is available in the upcoming
3G wireless networks (WCDMA, CDMA2000) and the current 802.11 WLAN. Thus I
am not sure it is a good assumption that the mobile node or the old FA can
figure out the new FA's IP address exactly from the link layer information
while the mobile node is attached to the old BS(or FA). I think the
assumption is in both of the drafts (Proactive Handoff, Fast Handoff) on the
table.

Eunsoo

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From: Pete McCann <[email-masked]>
Date: Wed, 6 Dec 2000 16:34:59 -0600

Hi, Eunsoo,

>> architectural philosophy.

ES> Following this philosophy, I think soft handoff in link layers also should
ES> be considered as a special case even though it is available in the upcoming
ES> 3G wireless networks (WCDMA, CDMA2000) and the current 802.11 WLAN. Thus I
ES> am not sure it is a good assumption that the mobile node or the old FA can
ES> figure out the new FA's IP address exactly from the link layer information
ES> while the mobile node is attached to the old BS(or FA). I think the
ES> assumption is in both of the drafts (Proactive Handoff, Fast Handoff) on the
ES> table.

ES> Eunsoo

You are right that predicting the next FA is made much more difficult
when there are multiple technologies involved, which is why I
personally think that fast handoff (whether Proactive or Fast) is
going to be confined (at least at first) to single-technology networks.
(Mike Dolan and I have a difference of opinion on this, as you might
be able to tell from his previous e-mail).  However, given a single
technology like cdma2000, I think it is perfectly reasonable for
neighboring FAs (preferably co-located with BSCs, in my opinion)
to get each other's IP addresses from link-layer triggers.  This would
be a very small addition to the provisioned information that must be
in place to make hard handoff work (think about all the power measurements
that are being made and signaled).

Also, please don't get confused and think that we are addressing soft
handoff: we most certainly are not trying to tackle that problem with
either of these drafts.  Soft handoff is a much more complicated ball
of wax with all kinds of real-time requirements and logically runs
well below the IP layer of the MN's IP stack.  Both of these drafts
address hard handoff between BSCs containing separate frame selectors,
i.e., the frame selector after the handoff is not the same one as
before the handoff.  Even if Hesham disagrees with this he would argue
that even more is being handed off: i.e., the FAs may contain multiple
BSCs (or whatever the equivalent of a BSC in your technology of
choice).  However in this case the set of neighbors could grow to be
quite large and the provisioning of neighbor IP addresses might begin
to become problematic.

-Pete