Subject: [Monami6] Fw: I-D ACTION:draft-montavont-mobileip-multihoming-pb-statement-04.txt

From: Thierry Ernst <[email-masked]>
Date: Thu, 9 Jun 2005 14:15:56 +0900

Dear all,

Here is the official announcement of the Problem Statement draft, please
comment on the document (structure, scenarios, spelling, issues). If you
have a comment on a specific scenario or issue, please add the scenario
(x,x,x) or issue number in the subject line.

Thierry

Subject: I-D ACTION:draft-montavont-mobileip-multihoming-pb-statement-04.txt
From: [email-masked]
To: [email-masked]
Date: Wed, 08 Jun 2005 15:51:53 -0400
List-Id: i-d-announce.ietf.org

A New Internet-Draft is available from the on-line Internet-Drafts directories.

	Title		: Analysis of Multihoming in Mobile IPv6
	Author(s)	: N. Montavont, et al.
	Filename	: draft-montavont-mobileip-multihoming-pb-statement-04.txt
	Pages		: 33
	Date		: 2005-6-8
	
The use of multiple interfaces is foreseen to provide ubiquitous,
   permanent and fault-tolerant access to the Internet, particularly on
   mobile nodes which are more prone to failure or sudden lack of
   connectivity.  However, Mobile IPv6 currently lacks support for such
   multihomed nodes.  Individual solutions have been proposed to extend
   Mobile IPv6 but all issues have not been addressed in a single
   document.  The purpose of the present document is thus to fill up
   this gap and to raise the discussion in order to make sure that
   forthcoming solutions will address all the issues.  In this document,
   we propose a taxonomy to classify the situations where a mobile node
   could be multihomed.  This taxonomy is then used to highlight the
   issues preventing mobile nodes operating Mobile IPv6 to be
   multihomed.

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---

From: Romain KUNTZ <[email-masked]>
Date: Mon, 20 Jun 2005 16:29:54 +0900

Dear authors,

Thank you for your work.
I have few comments about this draft.

In section 4 (Taxonomy), I have a concern with Figure 1.

     Link1      Link2      -->     IPv6 Link (n/a *)
      |          |
      +-----+----+
            |              -->   Physical layer  (x)
           IF1

For me it sounds like IF1 is connected to 2 links at the same time,
whereas I think you mean that IF1 is connected on a link where 2 IPv6
prefixes are advertised. I think the drawing is quite confusing.

> 5.5  (n,1,1): n ifaces, 1 HoA, 1 CoA
> [...]
> o  Fault Recovery and Ubiquitous Access
> 
>       These goals are achievable, but in a limited manner.  The MN can
>       build a temporary IPv6 address on its other interface but it
>       cannot register the temporary address with its HA because the node
>       is using its HoA.  If the node needs to update its location
>       following a movement, it will not be able to use its HoA on the
>       interface connected to its home link.  This issue is detailed in
>       Section 6.2.3.
> 
>       As MIPv6 cannot be used on these addresses, the MN will not be
>       able to redirect any flow to another address.  For instance, if
>       the MN looses its connection to its home link, all flows must be
>       initiated again with the CoA address valid on the other interface
>       of the MN.  Fault recovery is then only possible without
>       transparency and none of the MIPv6 features can help in case of a
>       failure.

In that case, I would say that if the MN looses its connection to its
home link, then the HoA becomes available and MIPv6 can be used to bind
the CoA of the other interface to this HoA, and register it on the HA.
Then all flows that used the HoA can seamlessly go on on the other
interface. Am I wrong?

> [13]  Montavont, N., Noel, T., and M. Kassi-Lahlou, "MIPv6 for
>          Multiple Interfaces", draft-montavont-mobileip-mmi-00 (work in
>          progress), July 2002.
> 

I have seen a 01 version on the author webpage, so maybe the 00 is not
the latest one.

Regards,

-- 
Romain KUNTZ
[email-masked]

---

From: Nicolas Montavont <[email-masked]>
Date: Mon, 20 Jun 2005 09:16:45 -0400

Hello Romain

Thank you for your comments :)
See my replies inline

>     Link1      Link2      -->     IPv6 Link (n/a *)
As you said, it represents two IPv6 prefixes advertised on the link
where the interface is connected, but it doesn't prevent the case where
the interface is connected to different links.
Given that, I don't know how to draw it differently to be less confusing...

>Then all flows that used the HoA can seamlessly go on on the other
No you're perfectly right, the MN can use the HA once it disconnects
from its home link.
It's the other way around which may raise an issue: if the MN is still
connected to its home link and its CoA changes. I'll re-word for the
next revision.

>I have seen a 01 version on the author webpage, so maybe the 00 is not
You're right, I'll change that for the next revision.

Nicolas

---

From: Nicolas Montavont <[email-masked]>
Date: Mon, 20 Jun 2005 09:16:45 -0400

Hello Romain

Nicolas

---

From: "Eun Kyoung PAIK" <[email-masked]>
Date: Tue, 21 Jun 2005 09:03:01 +0900

Hi authors,

Thank you for your good work.
I have few comments and questions as follows:

In order to meet some of the goals (particularly load balancing and
   load sharing), multiple paths must be maintained simultaneously
   between the mobile node and the home network(s).

==> When the RO is executed, multiple paths must be maintained
simultaneously between the mobile node and the network(s) in which CN(s)
located. So, how about re-word "home network(s)" into "Internet" ?

Basically, this can translate into the following enumeration of
requirements:

==> [TYPO] Basically, this can "be" translate"d" into the following
enumeration of requirements:

4.  Taxonomy

==> It describes the meaning of "1" and "n", but not "0". Since you have
distinct (n,n,0) configuration, it's better to add the explanation about "0"
explicitly even though all of us know what "0" is. :-)

* because number of IPv6 links is equal to the number of CoAs, z
                  Figure 1: Illustration of the Taxonomy

==> I think it is not always true. If we have multiple interfaces, single
link, and multiple CoA, the number of interfaces is equal to the number of
CoAs.

Regards,
Eun

---

From: "Eun Kyoung PAIK" <[email-masked]>
Date: Tue, 21 Jun 2005 09:03:01 +0900

Hi authors,

4.  Taxonomy

Regards,
Eun

---

From: Chan-Wah Ng <[email-masked]>
Date: Tue, 21 Jun 2005 10:20:04 +0800

Hello Eun-Kyoung,

> located. So, how about re-word "home network(s)" into "Internet" ?

Hmm... that would sounds like the links between MN and its access
network.  I would rather change it to "between the mobile node and the
home network(s) or its correspondent node(s)".

> explicitly even though all of us know what "0" is. :-)

True. ;)

> link, and multiple CoA, the number of interfaces is equal to the number of

I think you mis-understand the term "IPv6 link".  We are not talking
about a physical link, but a conceptual link in which IPv6 views its
lower layers.  So your example would indeed translate into multiple
links.

/rgds
/cwng

---

From: Chan-Wah Ng <[email-masked]>
Date: Tue, 21 Jun 2005 10:20:04 +0800

Hello Eun-Kyoung,

True. ;)

/rgds
/cwng

---

From: Nicolas Montavont <[email-masked]>
Date: Tue, 21 Jun 2005 08:58:24 -0400

Eun-Kyoung, Chan-Wah,

Thank you for your review. Comments inline.

>home network(s) or its correspondent node(s)".
Yes, I'd prefer home network + CN, rather than Internet. I'll change 
this for the next revision if it's ok for everybody.

>>explicitly even though all of us know what "0" is. :-)
I'll add this as well

Nicolas

---

From: Nicolas Montavont <[email-masked]>
Date: Tue, 21 Jun 2005 08:58:24 -0400

Eun-Kyoung, Chan-Wah,

I'll add this as well

Nicolas

---

From: Romain KUNTZ <[email-masked]>
Date: Wed, 22 Jun 2005 19:33:00 +0200

Hello Nicolas,

> the interface is connected to different links.

but, how do you connect an interface to 2 different links at the same time?

> Given that, I don't know how to draw it differently to be less confusing...

Maybe by replacing Link with Prefix?

Regards,

-- 
Romain KUNTZ
[email-masked]

---

From: Thierry Ernst <[email-masked]>
Date: Fri, 1 Jul 2005 02:06:39 +0900

Sorry for delay in answering, I lacked time and Internet access.

I comment below.

On Wed, 22 Jun 2005 19:33:00 +0200
Romain KUNTZ <[email-masked]> wrote:

> >>whereas I think you mean that IF1 is connected on a link where 2
> >IPv6>prefixes are advertised. I think the drawing is quite confusing.
> >> 
> > 
> > where the interface is connected, but it doesn't prevent the case
> > where the interface is connected to different links.
> 

I vote for it. What matters from a mobility perspective is not the
number of links, but the number of prefixes. On the figure, it can be
drawn as in draft-ietf-nemo-multihoming-issues.

Thierry.