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

From: Pat Calhoun <[email-masked]>
Date: Fri, 1 Dec 2000 07:37:39 -0800

> > In these wireless networks, there is no additional time for
> > Mobile IP registration.
> >
>         => Which wireless links ? CDMA for example ?
>         As we mentioned during the meetings, we looked at these
>         handoff sequences and found that there is time and it is
>         certainly possible to support FH. CDMA is much more
>         flexible in terms of handoff times than other wireless
>         systems.

No. During the last call, which you may have not attended, Pete McCann
discussed one of the IS-95 specs, and how the mobile would NOt have time to
perform Mobile IP registration.

>
> > However, you failed to address my comment where I stated that this
> > co-location
> > issue is NOT a pro-active problem, since the fast handoff proposal uses
> > similar triggers. Both proposals require colocated AP/FAs.
> >
>         => The FH model allows for both MN initiation and FA initiation.
> Therefore
>         I don't see why it would need this colocation.

MN initiation is RFC 2002, as I understand it. Therefore, there is nothing
"fast" in RFC 2002. I listed both methods that the "fast handoff" proposal
supports, one which allows for inter-fa communication, which is subject to the
same limitations as pro-active in 802.11 environments, and the second being
modification of link layers. For the latter, if link layers need to change,
then A foreign Agent's IP address CAN easily be provided in the link layer as
well. Or, rather, just get IAPP to be sent to Foreign Agents, as well, as a
trigger mechanism.

CDMA2000 is similar to the IAPP approach since the PDSN does not actually
receive a trigger from the link layer, but rather receives a messages from the
PCF indicating that a handoff is occuring.

>         You also didn't answer my comments on IAPP :)

I thought I did. Could you please restate your question?

PatC

---

From: Pete McCann <[email-masked]>
Date: Fri, 1 Dec 2000 11:31:02 -0600

Hi,

Two points:

1) Handoff Timing.

For cdma2000, there is at most a couple of hundred milliseconds between
the time that the BSC recognizes the need for a handoff and the time the
handoff must take place.  The reason for this deadline is that the radio
channel to the current MN is fading quickly, but the final "handoff order"
telling the MN to connect to the new BSC must be sent over the air before
connectivity is lost.

Putting over-the-air Mobile IP signaling on the critical path will almost
certainly cause us to miss this deadline in some cases, resulting in lost
calls.  Remember it's not just the new messages but also operating system
scheduling that we have to worry about.

We are working to gather some more specific delay numbers/lost call
probabilities and we can discuss in San Diego.

2) IAPP

I don't know much about 802.11, but it occurred to me in Pittsburgh
that you could probably deploy some kind of "smart bridge" between the
two networks that would watch IAPP traffic on both of them, and by
collating the results you would be able to figure out where a MN came
from.  This would enable you to send a pro-active trigger or even to
start bridging the MN's traffic to/from the old network, obviating the
need for any MIP messaging.  The extra box might sound like a
heavyweight solution but it would really be no more onerous than the
handoff mechanisms currently in place between cellular coverage areas.
FA addresses would of course need to be provisioned during the
coverage planning stage and when forming handoff agreements with
neighboring carriers.

-Pete

>> flexible in terms of handoff times than other wireless

PC> No. During the last call, which you may have not attended, Pete McCann
PC> discussed one of the IS-95 specs, and how the mobile would NOt have time to
PC> perform Mobile IP registration.

>> I don't see why it would need this colocation.

PC> MN initiation is RFC 2002, as I understand it. Therefore, there is
PC> nothing "fast" in RFC 2002. I listed both methods that the "fast
PC> handoff" proposal supports, one which allows for inter-fa
PC> communication, which is subject to the same limitations as
PC> pro-active in 802.11 environments, and the second being
PC> modification of link layers. For the latter, if link layers need
PC> to change, then A foreign Agent's IP address CAN easily be
PC> provided in the link layer as well. Or, rather, just get IAPP to
PC> be sent to Foreign Agents, as well, as a trigger mechanism.

PC> CDMA2000 is similar to the IAPP approach since the PDSN does not
PC> actually receive a trigger from the link layer, but rather
PC> receives a messages from the PCF indicating that a handoff is
PC> occuring.

>> You also didn't answer my comments on IAPP :)

PC> I thought I did. Could you please restate your question?

PC> PatC