Subject: RE: [Monami6] Accept draft-wakikawa-mobileip-multiplecoa-04.txt asMonami6 WG Document

From: "Soliman, Hesham" <[email-masked]>
Date: Fri, 28 Oct 2005 11:50:01 -0400

3. I dont understand the need for a BID. the draft
says

>          The BID is an identification number used to distinguish 
>          multiple bindings registered by the mobile node.  Assignment of
>          distinct BID allows a mobile node to register multiple binding
>          cache entries for a given home address.

  doesnt the HoA/CoA pair uniquely identify a binding?
  do you want a unique identifier for a particular
  binding even when the CoA changes? in that case why
  not associate the interface with a particular binding? 
  maybe I am missing something.

 >In general, I think the BID is useful. At any given time, the HoA/CoA pair is unique - however, when you   
 >want to update a particular binding (i.e, replace CoA1a with CoA1b, say), the BID will help locate the 
 >binding. Without it, you would have to include CoA1a in the BU so that the HA/CN can identify the 
 >correct CoA to replace with CoA1b. 

=> I agree with Vijay. In fact, the binding is uniquely identified by the 
HoA. If you want to add another CoA then the HA would search by the 
HoA and *add* another CoA to the binding, instead of the current behaviour,
which is to replace the CoA. So, I don't see a need to have another 
identifier to the binding entry. And you don't need to include the 
old CoA in the BU.

Hesham

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From: Vidya Narayanan <[email-masked]>
Date: Fri, 28 Oct 2005 11:29:11 -0500

> identifier to the binding entry. And you don't need to include the

  I don't understand. Say you have registered CoA1a for your
802.11binterface. You roam to a new AP/AR and get a new CoA, CoA1b.
When you
register CoA1b with the HA/CN, how does the HA/CN know that it is meant to
update CoA1a, as opposed to any other CoA it has for the same HoA or as
opposed to additionally creating a binding for CoA1b?
 Vidya
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From: Henrik Levkowetz <[email-masked]>
Date: Fri, 28 Oct 2005 21:36:51 +0200

on 2005-10-28 17:50 Soliman, Hesham said the following:
> 
> 
> 3. I dont understand the need for a BID. the draft says
> 
>> The BID is an identification number used to distinguish multiple
>> bindings registered by the mobile node.  Assignment of distinct BID
>> allows a mobile node to register multiple binding cache entries for
>> a given home address.
> 
> doesnt the HoA/CoA pair uniquely identify a binding? do you want a
> unique identifier for a particular binding even when the CoA changes?
> in that case why not associate the interface with a particular
> binding? maybe I am missing something.
> 
> 
>> In general, I think the BID is useful. At any given time, the
>> HoA/CoA pair is unique - however, when you want to update a
>> particular binding (i.e, replace CoA1a with CoA1b, say), the BID
>> will help locate the binding. Without it, you would have to include
>> CoA1a in the BU so that the HA/CN can identify the correct CoA to
>> replace with CoA1b.
> 
> => I agree with Vijay. In fact, the binding is uniquely identified by
> the HoA. If you want to add another CoA then the HA would search by
> the HoA and *add* another CoA to the binding, instead of the current
> behaviour, which is to replace the CoA. So, I don't see a need to
> have another identifier to the binding entry. And you don't need to
> include the old CoA in the BU.

I believe the following is a correct statement:  You can make everything
work just fine without a BID; by looking up bindings by HoA/CoA, and
referring  to bindings in the same way.  You could always say 'move
flow so-and-so to HoA/CoA pair thus-and-thus.

Viewed like this, the introduction of a BID is an extra indirection,
which may (or may not) be warranted by conceptual ease of handling
flow movement, or by protocol efficiency.

Protocol efficiency is best addressed after it is functionally complete
and one can analyze or measure where (if at all) it is deficient in
efficiency.  I'd suggest that as long as a BID is not functionally
necessary, it should be left out out, and only introduced if
measurements or stringent analysis show a clear performance benefit,
or alternatively a conceptual elegance which can sway the masses ;-)

	Henrik

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From: Ryuji Wakikawa <[email-masked]>
Date: Sun, 30 Oct 2005 20:05:22 +0900

Hi Hesham

At Fri, 28 Oct 2005 11:50:01 -0400,
> identifier to the binding entry. And you don't need to include the 

In that case, HA may keep invalid CoAs in BC.  

ryuji

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From: Ryuji Wakikawa <[email-masked]>
Date: Sun, 30 Oct 2005 20:13:57 +0900

Hello Henrik

At Fri, 28 Oct 2005 21:36:51 +0200,
> flow so-and-so to HoA/CoA pair thus-and-thus.

If HoA/CoA pair is never changed, your statement works.  
However, CoA can be changed by MN's movement.  At least, an identifier
(say BID or old CoA) is necessary to manage multiple CoAs bound to
single HoA.

We do not discuss flow move in the spec. I wish you read the draft:-)
We need to fundamental solution which allow MN to register multiple
CoAs to HA/CN.  On top of such solution, MN can direct flow, or
bicast, or keep several CoAs as backup. These policy management will
be separately discussed in Monami WG. See WG milestone.

Jun 05	Submit Multiple CoA Registration to IESG
Dec 06	Submit Flow/binding policies exchange to IESG

ryuji

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From: Henrik Levkowetz <[email-masked]>
Date: Sun, 30 Oct 2005 14:09:21 +0100

> Hello Henrik

[...]

> (say BID or old CoA) is necessary to manage multiple CoAs bound to

Agreed; using the old CoA is what I was trying to say above.

> We do not discuss flow move in the spec. I wish you read the draft:-)

I will, once I finish the pre-meeting sprint I'm currently on... ;-)

> be separately discussed in Monami WG. See WG milestone.

That's fine.

Regards,

	Henrik