Subject: Re: [nemo] WG Last Call on draft-ietf-nemo-terminology

From: Masafumi Watari <[email-masked]>
Date: Tue, 15 Nov 2005 14:09:59 +0900

Hi,

I apologize if this is a bit too late to give comments on this, but
I belive this draft was silent for some time and so with an attempt to
raise some discussion, here are the ones that concerns me.

   Issue A16: [VALIDATE B4 CLOSING 0510] NEMO-link vs mobile subnet/link
   Proposition: By Thierry 0410: Since we agreed to keep MNP instead of
   NEMO-prefix, I think it would be consistent to keep mobile subnet or
   mobile link instead of NEMO-link. Comments ?

I agree with this.  Not just keeping it consistent with MNP, the term
NEMO-link is hard to grasp.  I would suggent MNL as Mobile Network
Link, however I don't see the term "NEMO-link" used in RFC 3963
so I don't know if we really need such term in the first place.
Any comments ?

   Issue A23: [OPEN 0410] Keep nested and multihoming scenario in draft?
   Proposition: by Thierry: Nested and Multihomed Mobile Networks: is
   draft-ietf-nemo-terminology the right location to describe the two
   scenarios ?

Yes.  They are useful and are refered to by the RO drafts.

   Issue A22: [OPEN 0410] Add term for "Depth of a Nested-NEMO"
   Proposition: "Depth" may be useful to deal with Nested-NEMO
   Proposition: Please propose a clear definition

This, I don't know.  The RO drafts use "level of nesting" but I guess
this is a bit different.  It would be useful I guess when phrasing
a MR at a specific nest level, like "A MR at depth 3".

regards,
watari

On 2005/10/28 15:51, Thierry Ernst wrote:
> Dear all,
> 
> This is a WG last call for draft-ietf-nemo-terminology before submission
> to the IESG. The call ends on Nov.09th (NEMO meeting day).
> 
> I have submitted a revised version of the terminology. Changes include:
> - figure brush up 
> - updated text for the home network models
> - 2 new terms from the NEMO RO drafts
> 
> You can check the issues http://www.sfc.wide.ad.jp/~ernst/nemo/ . Issues
> addressed in the draft are these marked "Validate B4 Closing 0510".
> 
> If no one complains, I will close all issues marked "Validate B4
> Closing" and, if no one gives input on issues marked as "Open" I will
> also close them, with a "Reject" mention.
> 
> 
> Thierry.
> 
> 
> On Thu, 27 Oct 2005 10:50:02 -0400
> [email-masked] wrote:
> 
> 
>>A New Internet-Draft is available from the on-line Internet-Drafts
>>directories. This draft is a work item of the Network Mobility Working
>>Group of the IETF.
>>
>>	Title		: Network Mobility Support Terminology
>>	Author(s)	: T. Ernst, H. Lach
>>	Filename	: draft-ietf-nemo-terminology-04.txt
>>	Pages		: 27
>>	Date		: 2005-10-27
>>	
>>This document defines a terminology for discussing network mobility
>>   issues and solution requirements.
>>
>>A URL for this Internet-Draft is:
>>http://www.ietf.org/internet-drafts/draft-ietf-nemo-terminology-04.txt
>>
>>To remove yourself from the I-D Announcement list, send a message to 
>>[email-masked] with the word unsubscribe in the body of
>>the message.  You can also visit
>>https://www1.ietf.org/mailman/listinfo/I-D-announce to change your
>>subscription settings.
> 
> 
> 
>

---

From: Thierry Ernst <[email-masked]>
Date: Thu, 17 Nov 2005 19:14:48 +0900

Hi Watari,

Thanks for your feedback on this.

>    Issue A16: [VALIDATE B4 CLOSING 0510] NEMO-link vs mobile
>    subnet/link Proposition: By Thierry 0410: Since we agreed to keep
>    MNP instead of NEMO-prefix, I think it would be consistent to keep
>    mobile subnet or mobile link instead of NEMO-link. Comments ?
> 

What I didn't like in the term "MNP" is the wording "mobile network"
(many people are still confused with cellular networks for mobile
devices), but since we agreed to keep MNP, MNL would make sense, but
it's easily misstyped to MNP ... So, let's not introduce new term,
either we use NEMO-link or mobile-subnet (mobile-link should be
disqualified because a NEMO can be made of severals links).

Is anyone ever seen NEMO-link used in IETF documents ? If not, let's
remove it.

>    Issue A23: [OPEN 0410] Keep nested and multihoming scenario in
>    draft? Proposition: by Thierry: Nested and Multihomed Mobile
>    Networks: is draft-ietf-nemo-terminology the right location to
>    describe the two scenarios ?
> 

OK, conclusion is "keep".
 
> a MR at a specific nest level, like "A MR at depth 3".

I think "level of nesting" and "depth" are the same. I think "depth" may
be better. We could say:

  Depth: indicates the number of sub-MRs a packet as to cross between a
            MNN and the root-MR. 

But, this is tricky: a NEMO multihomed behind several root-MRs may be a
different depths according to the exit root-MR used by the packet.  

On the overall, I'm quite in favor of adding it if the word is used in
some documents like the RO drafts. Will you use "depth" with the above
definition ?

One thing you didn't mention Watari:

In draft-ietf-nemo-ro-space-analysis-01 section 1.0 it is written:

   "the term "Route Optimization" is accepted in a
   broader sense than already defined for IPv6 Host Mobility in [3], to
   loosely refer to any approach that optimizes the transmission of
   packets between a Mobile Network Node and a Correspondent Node."

If everyone agree, I would like to add in draft-terminology the
following term (it was discussed in slide 7 of my presentation in
Vancouver):

  Routing Optimization:

    Refers to any approach that optimizes the transmission of packets
between a MNN and a CN

Thierry.

---

From: Thierry Ernst <[email-masked]>
Date: Thu, 17 Nov 2005 19:27:50 +0900

Dear all,

Thanks to all who have commented on the terminology.

Following the discussion at 64th IETF Vancouver  
(see slides NEMO WG "Terminology and Requirements" 
https://datatracker.ietf.org/public/meeting_materials.cgi?meeting_num=64)
and on the ML, I've definitely closed issues:
- A13 (improved figures)
- A14 (normative references)
- A15 (removed abbreviation i-face and e-face)
- A17 (more text in definition of mobile network)
- A18 (former definition of NEMO-link)
- A19 (RO: keep definition of CR)
- A23 (keep nested and multihoming SCENARIOS)
- A20 (remove miscellaneous section)
- A27 (clarify definitions of the Home Network Model terms)

Still open are:
- A16+A24 (NEMO-link)
- A22 (depth)
- A25 (split NEMO)
- A26 (RO term "Routing Optimization")

New one is:
- A28 (RO term for sub-optimal routing)

Issue List: 
http://www.sfc.wide.ad.jp/~ernst/nemo/

Current draft -05pre:
http://www.sfc.wide.ad.jp/~ernst/nemo/draft-ietf-nemo-terminology-05pre.html
http://www.sfc.wide.ad.jp/~ernst/nemo/draft-ietf-nemo-terminology-05pre.txt
Changes include:
- removed i-face and e-face
- added a referenre to PhD dissertation in the ACK section

The document will be sent to the IESG as soon as all issues are closed.
Thierry.

On Fri, 28 Oct 2005 15:51:54 +0900
Thierry Ernst <[email-masked]> wrote:

> 
> Dear all,
> 
> This is a WG last call for draft-ietf-nemo-terminology before
> submission to the IESG. The call ends on Nov.09th (NEMO meeting day).
> 
> I have submitted a revised version of the terminology. Changes
> include:- figure brush up 
> You can check the issues http://www.sfc.wide.ad.jp/~ernst/nemo/ .
> Issues addressed in the draft are these marked "Validate B4 Closing
> 0510".
> 
> > directories. This draft is a work item of the Network Mobility
> > Working Group of the IETF.
> > 
> > [email-masked] with the word unsubscribe in the body
> > of the message.  You can also visit

---

From: Romain KUNTZ <[email-masked]>
Date: Fri, 18 Nov 2005 10:51:27 +0900

Hello,

> - A25 (split NEMO)

I propose the following draft definition:

A split NEMO occurs when a single mobile subnet connected to multiple 
Mobile Routers, or multiple mobile subnets interconnected with routers, 
become two or more independant mobile subnets.

     |    |             |      |
    MR1  MR2           MR1    MR2
     |    |      ->     |      |
   ----------         -----  -----

     |             |          |       |
    MR1  Router   MR2        MR1     MR2
     |    |  |     |    ->    |       |
   --------  -------        -----   -----

Regards,

-- 
Romain KUNTZ
[email-masked]

---

From: Chan-Wah Ng <[email-masked]>
Date: Fri, 18 Nov 2005 10:26:47 +0800

> become two or more independant mobile subnets.

"independent".

Anyway, "multiple mobile subnets interconnected with routers" is not
very accurate and leads to controversy.  Consider

    MR1            MR1
     |              |
  ---+-+---  =>   --+---   MR2
       |                    |
      MR2                 --+--
       |
    ---+----

It fits your definition but does not falls into the normal sense of
split NEMO.

>     MR1  MR2           MR1    MR2

The above I agree, the one below needs a bit of further exploration.

>     MR1  Router   MR2        MR1     MR2

With a router, presumably a LFR, in between, the two links are separate
subnets.   So, MR1 and MR2 are handling different prefixes.  When the
two links goes separate way, what would happens is that the LFR would no
longer function as a router, since it loses its at least one of its link
for forwarding.

As far as NEMO-BS is concerned, this situation also does not fall into
the normal sense of split-NEMO problem, because MR1 and MR2 are handling
different prefixes, even when they split, there is no ambiguity in the
HA(s) on who to forward a packet destined for one of the MNPs to.

Unless the router in the figure is not a router but a bridge/switch/...,
a layer 2 device.  Which should not reflected, and thus reducing this
case to be equivalent to the first diagram you draw, from a layer 3
perspective.

It all depends on what is the motivation for the inclusion of the
split-NEMO definition.  I thought the motivation was to assist in
illustrating the problem of split NEMO as documented in
draft-ietf-nemo-multihoming-issues.  If this is indeed the case, then
the definition of split-NEMO should define cases only when the problem
of split NEMO occurs.

/rgds
/cwng

---

From: Masafumi Watari <[email-masked]>
Date: Fri, 18 Nov 2005 16:33:24 +0900

Hi Thierry,

> disqualified because a NEMO can be made of severals links).

You're saying that you don't like MNL because people would miss-type
as MNP?  I don't buy that...  NEMO-link is alreay a new term anyway,
and I've seen *very few* documents that uses such term.

> Is anyone ever seen NEMO-link used in IETF documents ? If not, let's

I haven't seen it in any documents other than yours :)  So when is it
really useful?

> some documents like the RO drafts. Will you use "depth" with the above

s/as/has/

Maybe it could be rephrased a little.  I will try and think of another
one.

>     Refers to any approach that optimizes the transmission of packets

I would agree.  Actually, I like it as is.

   Route Optimization:

regards,
watari

---

From: Alexandru Petrescu <[email-masked]>
Date: Fri, 18 Nov 2005 16:07:33 +0100

Thierry Ernst wrote:
>>  I belive this draft was silent for some time and so with an
>> attempt to raise some discussion, here are the ones that concerns
>> me.
>> 
>> I agree with this.  Not just keeping it consistent with MNP, the
>> term NEMO-link is hard to grasp.  I would suggent MNL as Mobile
>> Network Link, however I don't see the term "NEMO-link" used in RFC
>> 3963 so I don't know if we really need such term in the first
>> place. Any comments ?
> 
> 
> devices),

Probably use "moving network" instead of "mobile network"?

MNP: moving network prefix?

> VMN: assigned to a home link that doesn't belong to the mobile network

VMN: its HA is different than MR's and is not on any link of that MR.

draft nit:
> Its address is located within an MNP.

"Derived from the MNP"?

Alex

---

From: Romain KUNTZ <[email-masked]>
Date: Mon, 21 Nov 2005 11:47:33 +0900

Hello Chan-Wah,

> It fits your definition but does not falls into the normal sense of

That's right.

> HA(s) on who to forward a packet destined for one of the MNPs to.

Correct. I do not know what I had in mind when drawing this :-)
I was thinking about MR2 registering some of MR1 prefixes for redundancy 
purposes, but this has no relations with current NEMO-BS.

> the definition of split-NEMO should define cases only when the problem

I agree. So do you see other case than (n,1,1) with the following topology:

     |    |             |      |
    MR1  MR2           MR1    MR2
     |    |      ->     |      |
   ----------         -----  -----

(ie multiple MRs attached to the same mobile subnet on their ingress 
interface, registering the same prefix to the same HA)

where split NEMO is a problem?

Romain

---

From: Thierry Ernst <[email-masked]>
Date: Mon, 21 Nov 2005 11:47:32 +0900

Hi Alex,

> MNP: moving network prefix?

This term cannot be changed. (see RFC 3753)

> VMN: its HA is different than MR's and is not on any link of that MR.

Not necessarily.  The VMN and the MR can be on the same home link, and
in this case the VMN doesn't belong to the MR-administered area. In any
case, as long as the MNN does need to obtain a CoA, it is considered a
VMN.

> > Its address is located within an MNP.

Do you propose a new definition ? If yes, can you state is fully, and
can we get people to agree / disagree ? Before you do this, is this
needed, I mean please think to yourself how much it does improve the
definition (if it does).

Thierry

-- 
Thierry ERNST, PhD
WIDE, Jun Murai Lab., Keio University, Japan
Nautilus6 Chair: http://www.nautilus6.org
Web: http://www.sfc.wide.ad.jp/~ernst/
T:+81-44-580-1600 F:+81-44-580-1437
--

---

From: Chan-Wah Ng <[email-masked]>
Date: Mon, 21 Nov 2005 11:16:31 +0800

> I agree. So do you see other case than (n,1,1) with the following topology:

No, I do not at this moment.  Although strictly speaking , all
(n,>=1,>=1) networks will face the same problem, but these can always be
decomposed to multiple (n,1,1)s.

Hence, I would modify the definition of split-NEMO to:

        Split-NEMO refers to case where a mobile network that has
        multiple mobile routers handling the same MNP (or MNPs) becoming
        two or more independent mobile networks.

One can go on to be more specific, such as adding "where the
aforementioned group of mobile routers handling the same MNP(s) are no
longer all residing in the same mobile network".  That may seems messy,
but is more accurate.

The above definition avoids the use of mobile subnet, in case someone in
the future, against all odds, come up with a split-NEMO configuration
that has a LFR in between, the definition still fits :).

/rgds
/cwng

---

From: Alexandru Petrescu <[email-masked]>
Date: Mon, 21 Nov 2005 11:48:30 +0100

Hi Thierry,

> This term cannot be changed. (see RFC 3753)

Ok.

> case, as long as the MNN does need to obtain a CoA, it is considered a

Ok.

> needed, I mean please think to yourself how much it does improve the

It's not a new definition, it's a draft nit.  Within the draft the
phrase "Its address is located within an MNP" appears.  It could be
re-phrased into "Its address is derived from the...".

Alex

---

From: Romain KUNTZ <[email-masked]>
Date: Tue, 22 Nov 2005 13:02:08 +0900

> longer all residing in the same mobile network".  That may seems messy,

IMHO it is good to be accurate, in order to identify when the problem 
occurs. So what about this one:

   Split-NEMO refers to the case where a mobile network that has
   multiple mobile routers handling the same MNP (or MNPs) becomes
   two or more independent mobile networks, where the same MNP(s)
   are no longer advertised in the same mobile network.

Regards,

-- 
Romain KUNTZ
[email-masked]

---

From: Chan-Wah Ng <[email-masked]>
Date: Tue, 22 Nov 2005 14:28:33 +0800

>    are no longer advertised in the same mobile network.

Hmm, I am doubtful about the last sentence, especially the last few
words "same mobile networks".  The problem with split-NEMO is that the
MRs cannot announce the same MNP to different NEMO.

May I offer an entirely different definition:

   Split-NEMO refers to the case where a mobile network becomes
   two or more independent mobile networks due to the separation
   of Mobile Routers which are handling the same MNP (or MNPs)
   in the original mobile network before separation.

/rgds
/cwng

---

From: Romain KUNTZ <[email-masked]>
Date: Fri, 25 Nov 2005 16:50:25 +0900

Hello Chan-Wah,

Sorry for the delay !

>    in the original mobile network before separation.

Actually, I wonder if Split-NEMO should only refer to the case where
split is a problem, or to any kind of split. draft-ietf-nemo-terminology
is a terminology document and thus should be silent on the problems or
specific scenario. Other documents such as
draft-ietf-nemo-multihoming-issues-02 can then refer to Split-NEMO and
describe the problems that may occur when a split occurs (and actually
it already has a section about that).

What is your opinion?

Regards,

-- 
Romain KUNTZ
[email-masked]

---

From: Chan-Wah Ng <[email-masked]>
Date: Fri, 25 Nov 2005 16:46:01 +0800

Hello, Romain,

> Sorry for the delay !

I have no problem at all with that ... but I don't know about Thierry.
He may be anxious to get this resolved. :)

> it already has a section about that).
Ah, which was why I first asked what is the purpose of having the
split-NEMO terminology.  IMHO, its only useful for the case where there
is problem.  Where else would such a terminology be useful?  I mean when
two mobile routers previously on the same link go separate way, you
simply say "they go separate way" or "they got separated" or "they
separated".  There is no need to create a special term for that.

To me split-NEMO means that a logically single entity got separated.  It
warrants some configurations changes.  Like MNP needs to be broken into
two parts etc, etc, which is what my latest proposal is trying to
convey.  

I agree with you that the terminology (and definition) itself should not
contains hints of a problem.  That is the job of a problem statement.
But the terminology is created so that we can refer to the scenario
where the problem occurs.

"Split-NEMO" as a term is pretty much like "pinball route" to me in
nature.  It is created to help describe a problem.

/rgds
/cwng

---

From: Romain KUNTZ <[email-masked]>
Date: Fri, 25 Nov 2005 19:37:02 +0900

> separated".  There is no need to create a special term for that.

Thinking about that, a split-NEMO is basically a problem because MNNs 
may also suffer from that, even if 2 different MNPs are advertised by 
the 2 different MR that have splitted. So defining split-NEMO to any 
kind of split might be useful for people who want to use a generic term 
in their documents.

> nature.  It is created to help describe a problem.

Not necessarily. IMHO if we define a term, then it's better than 
everyone (people who wants to describe a problem, or people who just 
want to refer to a separation) use the same term.

Regards,

Romain