Subject: RE: [mobile-ip] New I-D in L3 trigger based MIPv4

From: James Kempf <[email-masked]>
Date: Fri, 9 Mar 2001 09:46:13 -0800 (PST)

Hesham,

>
>> > Please give us comments and critiques.
>> 
>> I think it would actually make alot of sense to define a standard L3
>> signalling method to do this, but wonder whether this really belongs in 
*this*
>> WG, as opposed to, say, Seamoby.
>> 
>	=> There is one already, it is called the router/agent advertisement.
>

IMHO, router/agent adverts aren't handoff co-ordinating signalling, they
are signalling to alert the mobile node that a new route option is
available for routing their traffic. There is no specific handoff
co-ordinating signalling in base MIPv4/v6. The low latency handoff
drafts add such signalling. 

Furthermore, if you look at this draft, you will see that there is
a proposal for an "L3 beacon". Now, as far as I can tell, RFC 2002
and the MIPv6 draft *already* make provision for an L3 beacon, which,
as you point out, is a router/agent advert. The only real new contribution
in this draft that I can detect is Section 6.1, which describes ways
of doing movement prediction based on measurments at L3 as opposed to L2.

		jak

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From: Youngjune Lee Gwon <[email-masked]>
Date: Fri, 9 Mar 2001 10:48:42 -0800 (PST)

James,

I thought the router advt may be too heavy for this predictive L3 link
evaluation capability discussd in the draft. Minimizing the L3 control
signaling (if we can), seems quite significant in the operator's
point of view. 

----------------------------------------------
Youngjune Gwon          [email-masked]
Research Engineer
Mobile Internet Laboratory 
DoCoMo Communications Laboratories USA, Inc.

And, the Truth will set you free.  - John 8:32
----------------------------------------------

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From: "Ajoy Singh" <[email-masked]>
Date: Mon, 12 Mar 2001 11:26:51 -0600

Hello Gwon:
I read through your proposed handoff scheme. Although It sounds interesting
to me
but I have following question:

I am not clear how the network layer and link layer handoff scheme will
coexist. If you allow control at both network and link layer then
how do you guarantee that both will make the same decision. If you think
that
network layer is controlling the wireless handover then that some trigger
mechanism
is required from network layer to link layer.

Please correct me if I missing something.

regards,
ajoy

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From: Youngjune Lee Gwon <[email-masked]>
Date: Mon, 12 Mar 2001 16:40:38 -0800 (PST)

Ajoy,

First of all, we'd like to mention that our main target is toward the
all-IP network mobility issues, perhaps targeting the beyond 3G network. 
Also, as mentioned in the draft, inter-access technology handovers that
are difficult to achieve under L2 diversity. L3 control is essential when
L2 trigger is not available for this case.  

Our method can also be combined with L2-trigger based approach, but the
principle philosophy stays the same: treating L3 essential and L2 as side
info. In case of L2 and L3 discrepancy (e.g. where L3 prediction error 
occurs), we may have to develop a sort of fault preventing mechanism that
could be implemented based upon the side information. Honestly, this is
one of the difficult problems we are facing currently, thus, part of the
future work.