Subject: Re: [MOBILE-IP] Differences between the two MIPv4 handoff approac hes

From: "Hesham Soliman (EPA)" <[email-masked]>
Date: Tue, 28 Nov 2000 07:34:36 +1100

Ajoy,

>  To be fair we should also say that in 802.11 the FA wouldn't
>  know either since it is not colocated with the AP. Or at least
>  that is the case in all WLAN configurations I've seen.
>
> -> Even in case of CDMA network, FA is not collocated with radio quipment.
> We all agree that some changes are required at network side to
> get trigger at source/target Foreign agent. For example, in case of CDMA
> 2000, we might
> have to make slight modification to R-P interface to send foreign agent
> address
> from PCF to PDSN. Similarly, we have to make some changes where FA is not
> collocated
> with radio equipment. The exact nature of changes will be dependent upon
> the
> specific technology and should be decided by respective SDOs. But I think,
> we should
> not be assuming some thing which will change the handoff model of wireless
> link layer.
> For example, in case of some 802.11 based network, source AP does not know
> about the handoff
> untill link layer handoff is complete. So I think, we can not assume to
> receive
> link layer trigger at source AP and use that to initiate Mobile/IP
> registration
> through old AP.
>
        => You certainly addressed lots of issues. My point was concise
        and straight forward. The proactive approach assumes a certain
        architecture that allows the FA to know that the MN is about to
        move. The handoff control is done completely by the network.
        In some (or many) cases that is not the case. On the other hand
        Fast Handoffs does not assume that, and it allows MN initiation
        or Network initiation. This is simply due to the fact that it
follows RFC2002,
        which was designed in a very generic way, for a good reason.

        I gave WLAN as an example. There are more.
        But there is no need to get into these system specific details.
        As I'm sure you're aware, this is the MIP WG and not MIP for
        cdma2000 or WLAN or something else. So let's try to be generic
        and not confuse people with system specific issues that change
        from one year to another.

        Hesham

---

From: Ajoy Singh <[email-masked]>
Date: Mon, 27 Nov 2000 15:14:58 -0600

Hello Hesham,
I think, you misunderstood my point. Perhaps I was not clear enough. Please
see my reply.
regards,
ajoy

<AS>  The proactive FA approach assumes source and target trigger which
should cover
      most type of network. Because It is possible to receive link layer
either
        at source or target. Whereas I think, the fast handoff assumes that
        it is possible to register mobile node through old access point
        which is not possible in most of the current networks. For example,
        in case of 802.11 network, it is not possible to register through the
        old access point as only target AP knows about the handoff before
        link layer handoff is complete. So we can not assume something which is not
        doable in present network.  <AS>

   <AS> Just to be generic, we have allowed source and target trigger
        approach. We should not make unrealistic assumption such as registering
        through old access point.  <AS>

-----Original Message-----
From: Hesham Soliman (EPA) [mailto:[email-masked]]
Sent: Monday, November 27, 2000 2:35 PM
To: 'Ajoy Singh'; [email-masked]
Subject: RE: [MOBILE-IP] Differences between the two MIPv4 handoff
approac hes

        Ajoy,

        Hesham

---

From: Pat Calhoun <[email-masked]>
Date: Mon, 27 Nov 2000 13:26:14 -0800

[I somehow missed this thread.... trying to catch up]

>         move. The handoff control is done completely by the network.
correct.

>         which was designed in a very generic way, for a good reason.

Well, RFC 2002 is *the* way for mobile initiated handoff. If there is NO
network assistance, which is an assumption I'm making since you are stating
that the network does not know when the mobile is doing to handoff, then I see
no advantage in adding more to the protocol.

>         from one year to another.

hmmm..... how about you provide us with a concrete example? I know that Mobile
IP *will* be used for CDMA and WLAN. Now, if you have another link layer that
we should consider (because it will use Mobile IP), and we can provide that a
particular scheme does not work, then please let us know. However, I think
that we should be careful with your statement regarding system specific
issues. I think that we should solve problems that will be used. I am not sure
that solving problems that do not need to be solved is worth our while.

PatC