Subject: RE: [mobile-ip] IPv4 Fast Handover Support for 802.11

From: George Tsirtsis <[email-masked]>
Date: Thu, 28 Mar 2002 14:11:49 -0500

James,

Maybe the larger question is why WE (the IETF) is concerned with how a link
layer mobility management protocol works and indeed why are we discussing
how it should be changed to become better or worst. Otherwise we should also
get the specs from GSMA, 3GPP, 3GPP2, and a hundred other organizations and
start analyzing them and trying to make them do this and that.

I think this does not make any sense at all...and I wonder...is it only me?

George

-----Original Message-----
From: James Kempf [mailto:[email-masked]]
Sent: Thursday, March 28, 2002 6:46 PM
To: [email-masked]
Subject: Re: [mobile-ip] IPv4 Fast Handover Support for 802.11

Hesham,

> => Which is exactly my point. IAPP is not relevant here.
> The only way to do it in WLAN (at least so far) is to
> make sure that the MN initiates the handover
> based on internal triggers.
>

If the vendors build IAPP into their APs and 802.11 handover is designed
to require a secure IAPP transaction to complete before the new AP lets
the MN send packets onto the new link, then this will lengthen 802.11
handover out considerably beyond the rather poor performance of the
current round of AP products. Regardless of what the MN does prior to
handover. So I think it is very relevent indeed.

> => I don't understand why PREREG is not considered
> a solution here? We always assumed that IAPP is
> not relevant.
>

It doesn't matter which fast handover algorithm is used, if the IAPP
transaction takes, say, 200 ms to complete and the L2 handover takes 200
ms to complete before the MN is allowed to get new packets through the
new AP, then any optimization at Layer 3 will  be in the noise. I wasn't
making a point about PREREG v.s. POSTREG, I was making a point about how
the assumptions being made by the 802.11 committee are causing both
algorithms to be not useful.

> => James I don't understand why or how you can do that.
> Unless you have connection oriented l2s with the MN
> reporting measurements to the APs, you can't
> do it. Is IEEE going to design a cellular network
> now?
> Even if this happens, are we going to run IAPP
> between subnets?? Even if we do that, wouldn't
> there still be some interruption from the time
> IAPP does its thing, till the MN actually moves?
>
> The level of complication is astounding and frankly
> I don't understand why you would want to do that.
>
> If people within the WG keep ignoring the work that this
> WG is doing, then I agree, nothing produced
> by the WG will ever be used!
>

Please stay calm, Hesham.

"We" are not going to run IAPP, that is what the 802.11 committee wants
to do. The problem IAPP is supposed to solve is to tell the old access
point to unallocate buffers and clean up other data structures
associated with providing the MN with IP connectivity. Onto that, there
has been additional stuff loaded, like context transfer. Also, I believe
they are thinking of using it for flushing the ARP cache.

I'd suggest that if you have some interest in seeing the right thing
done, you contact Bernard Abboba who has been  monitoring them closely,
and have him brief you on the details. Also, take a look at the 802.11f
IAPP spec, http://grouper.ieee.org/groups/802/11/ and browse from there.
If you see something that he and I have missed, then  please let us
know. We are just trying to convince them that their protocol needs some
work if it will properly support fast IP handover.

                jak

---

From: "James Kempf" <[email-masked]>
Date: Thu, 28 Mar 2002 11:54:05 -0800

George,

Good point.

The 802.11 committee drafted a liason letter which is on the IETF liason
page regarding EAP after a period of informal contacts between the
committee and an IETF member, namely Bernard. The letter requested some
joint action regarding EAP, the BOF held in Minneapolis is a result, and
if the IESG approves, a WG will form.

The work I've been discussing is currently in the current informal
stage, which Bernard and I are pursuing because we'd like to see 802.11
do the right thing for supporting IP handover. At some point, it may
become desirable to formalize the association through a liason letter
similar to what was drafted for EAP.

So, IETF is doing nothing formally with respect to 802.11f right now,
Bernard and I are. IETF is doing something formally with 802.11i
regarding EAP, and that is described in the aformentioned liason letter.

            jak

---

From: Rajeev Koodli <[email-masked]>
Date: Thu, 28 Mar 2002 11:59:46 -0800

Sorry to interrupt..

I think if IAPP is improved in IEEE, that's good; another crucial step
towards supporting real-time applications during WLAN mobility..
For us, we should constrain ourselves with IP mobility aspects. If it
turns out that certain link-specific issues are of interest, they should
be handled separately in an appropriate "link-specific extensions"
document.

In general, I have reservations to including L2-specific optimizations
in the base specification.

My 2 cents..

-Rajeev