Subject: Re: [Roll] Review and concerns (was: Re: Working Group Last Call: draft-ietf-roll-protocols-survey-02)

From: "David E. Culler" <[email-masked]>
Date: Tue, 09 Dec 2008 14:28:19 -0800

I would like to emphasize a few points in the thread.

Phil correctly observes that we reached consensus on the process long
ago.  After taking feedback on a early version of the draft we agreed
on (1) the definition of the universe of candidates (so the process
would terminate), (2)  that we would build a tableau of candidates
versus criteria and (3) that we would conduct a detailed analysis in
order to obtain a rough scoring of pass, fail, ?.  We discussed and
consensed on the criteria.  These are fundamentally related to the
charter - routing on (a) low-power and (b) lossy links.  We debated
small discrepancies in the analysis since the summer IETF.  We
recognized that such analysis and such criteria were imperfect, but
necessary.  We all recognized that scaling characteristics  are
essential  and yet the constants  also matter.  We recognized that even
passing all the criteria may not be sufficient for having a completely
satisfactory solution.  Thus, they are viewed as necessary, but not
sufficient.  We recognized that there would be regimes where the
constants all worked out, even if the general case did not.  But, it
would be fruitless for the whole discussion to degenerate into debates
about the exact value of innumerable tuning and scaling constants.

Some of the concerns center on the difficulty of meeting these
criteria.  Indeed, the working group was formed because there are real
problems to solve.  The application routing requirements drafts make
clear that the criteria are real, not spurious.  So, whether they hard
or not they serve well to define the goal.  At the same time, there are
several existence proofs of solutions in the market and in the research
community that meet these criteria or are very very close.  So they do
not appear to be "holy grails" but rather pragmatic guidelines for
solid design and engineering effort.

Other comments observe that the criteria do not address every possible
concern.  Indeed, they are viewed as necessary but not sufficient.  At
the same time, they go a very long way to addressing the full problem,
as substantiated by the application drafts.  So it appears that they do
serve to reasonably define a "sweet spot" goal.  Meeting the criteria
makes it extremely likely that real needs can be met with reasonable
engineering of solutions developed around this goal.

Many other concerns recognize that modifications of existing protocols
in a manner that is focused on these criteria would make them far more
suitable.  That suggests that the criteria and the analysis in the
draft serve their goal.  We are not chartered to consider such
modifications until after this ID is done.

Some concerns recognize that there are protocols outside the defined
universe that should be considered and that appear to be far better
suited to meeting the criteria than the set of IETF protocols that were
considered - since those protocols were developed without these
criteria.  Again, that suggests that the criteria are a reasonable
guide, that they do not appear to be unobtainable, and that the
analysis has provided a suitable guide.

None of the comments seem to be claiming that there is a solution
within the universe that we were chartered to consider that meets the
criteria.

These were the reasons that we reached consensus on the draft, its
criteria, and its analysis.  We could spend forever on the debate, but
if it does not change the conclusion it is only time lost.

At best it might be that if the criteria were suitably weakened there
might be an existing solution that met those relaxed criteria.  Again,
no one has proposed such a lowering of the bar and it is unclear that
such lowering would meet the application requirements.

These were the factors that led to consensus, thus enabling us to move
forward.

Re: [Roll] Working Group
LastCall:draft-ietf-roll-protocols-survey-02

To: JP Vasseur <jvasseur at cisco.com>

Subject: Re: [Roll] Working Group
LastCall:draft-ietf-roll-protocols-survey-02

From: Thomas Heide Clausen <ietf at thomasclausen.org>

Date: Tue, 9 Dec 2008 16:20:53 +0100

Cc: "Dearlove, Christopher \(UK\)" <Chris.Dearlove at
baesystems.com>, Emmanuel Baccelli <emmanuel.baccelli at
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On Dec 9, 2008, at 16:13 PM, JP Vasseur wrote:

On Dec 9, 2008, at 4:03 PM, Dearlove, Christopher (UK) wrote:

2- There is clearly a need for a solution *today*: look at all other
(deployed) non IP solutions out there

4- We are not talking about a "dream protocol": again this is very
much realistic since solutions do exist today (not IP unfortunately

:-( ....)

Can you point me to an existing (doesn't have to be IP) protocol
that passes all five of the ID's tests, without some major drawback
in some other area. I for one would find it interesting and useful.
(Obviously it would have to have a specification, not just a claim
made about a proprietary protocol.)

You missed my point ... I did not say that there were any of them
satisfying these criterion.
But clearly there are non IP solutions being deployed, my
point being that we need an

IP solution soon and we should make it right.

I read Chris Dearlove as asking for something concrete, justifying that
these five "criteria" that the survey I-D sets out are *attainable*
(and without some major drawbacks on the other important metrics
that the survey I-D is ignoring) and that we're not chasing a "pie
in the sky".

If one or more such protocols exist, I don't see why they aren't
discussed at this stage.

I do not think that it is in our charter to analyze *all*
possible protocols.

No, but if a good such protocol indeed existed, IP or not, having
it before us might just help quell skepticism.

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Follow-Ups:

Re:
[Roll] WorkingGroup LastCall:draft-ietf-roll-protocols-survey-02

From: Pascal Thubert (pthubert)

References:

[Roll]
Working Group Last Call: draft-ietf-roll-protocols-survey-02

From: JP Vasseur

Re:
[Roll] Working Group Last Call: draft-ietf-roll-protocols-survey-02

From: Ian Chakeres

Re:
[Roll] Working Group Last Call: draft-ietf-roll-protocols-survey-02

From: Philip Levis

Re:
[Roll] Working Group Last Call:draft-ietf-roll-protocols-survey-02

From: Dearlove, Christopher (UK)

Re:
[Roll] Working Group Last Call:draft-ietf-roll-protocols-survey-02

From: Thomas Heide Clausen

Re:
[Roll] Working Group Last Call:draft-ietf-roll-protocols-survey-02

From: Emmanuel Baccelli

Re:
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From: JP Vasseur

Re:
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From: Emmanuel Baccelli

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From: JP Vasseur

Re:
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From: Dearlove, Christopher (UK)

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---

From: "Emmanuel Baccelli" <[email-masked]>
Date: Thu, 11 Dec 2008 16:09:30 +0100

On Tue, Dec 9, 2008 at 11:28 PM, David E. Culler
<[email-masked]>wrote:
> universe that should be considered and that appear to be far better suited
> to meeting the criteria than the set of IETF protocols that were considered
> - since those protocols were developed without these criteria.  Again, that
> suggests that the criteria are a reasonable guide, that they do not appear
> to be unobtainable, and that the analysis has provided a suitable guide.
>
> None of the comments seem to be claiming that there is a solution within
> the universe that we were chartered to consider that meets the criteria.
>

Even admitting that the universe you defined is wide enough (a point which
is actually agued since the beginning), we could conclude to this only if
this universe (defined in the charter) is covered entirely. Again, I have
seen nothing said about NEMO or DTN, so reports of investigations in these
fields need to be included in the draft anyways.

Second, if we are not going into aI am still wondering what existing
protocols/algorithms, IP compatible or not, are being "hinted at" here.
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From: "Emmanuel Baccelli" <[email-masked]>
Date: Thu, 11 Dec 2008 16:14:06 +0100

Sorry, mistyped, and sent by mistake. So here's the correct, full version of
my email, see below:

On Thu, Dec 11, 2008 at 4:09 PM, Emmanuel Baccelli <
[email-masked]> wrote:

>
>
> On Tue, Dec 9, 2008 at 11:28 PM, David E. Culler <[email-masked]
> > wrote:
>>
>>

Even admitting that the universe you defined is wide enough (a point which
is actually agued since months), we could conclude to this only if this
universe (defined in the charter) is covered entirely. Again, it is not the
case: I have seen nothing said about NEMO or DTN, so reports of
investigations in these fields need to be included in the draft anyways.

Second, if we are not going into a long research phase, I am still wondering
what existing protocols/algorithms, IP compatible or not, are being "hinted
at" here, which could meet the "dream" criterii that are evoked in the
draft. Chris Dearlove and other people have asked this question many times,
and it is yet to be answered.

Emmanuel

---

From: Geoff Mulligan <[email-masked]>
Date: Thu, 11 Dec 2008 11:21:36 -0700

I asked in Menneapolis, but didn't get a good answer.

Why was IS-IS not included in the survey?  Is it considered too similar
to OSPF - there are some differences.

	geoff

On Thu, 2008-12-11 at 16:14 +0100, Emmanuel Baccelli wrote:
> Sorry, mistyped, and sent by mistake. So here's the correct, full
> version of my email, see below:
> 
> On Thu, Dec 11, 2008 at 4:09 PM, Emmanuel Baccelli
> <[email-masked]> wrote:
>         
>         
>         <[email-masked]> wrote:
>                 
>                 Some concerns recognize that there are protocols
>                 outside the defined universe that should be considered
>                 and that appear to be far better suited to meeting the
>                 criteria than the set of IETF protocols that were
>                 considered - since those protocols were developed
>                 without these criteria.  Again, that suggests that the
>                 criteria are a reasonable guide, that they do not
>                 appear to be unobtainable, and that the analysis has
>                 provided a suitable guide.
>                 
>                 None of the comments seem to be claiming that there is
>                 a solution within the universe that we were chartered
>                 to consider that meets the criteria.
>         
> 
> 
>  
> Even admitting that the universe you defined is wide enough (a point
> which is actually agued since months), we could conclude to this only
> if this universe (defined in the charter) is covered entirely. Again,
> it is not the case: I have seen nothing said about NEMO or DTN, so
> reports of investigations in these fields need to be included in the
> draft anyways.
> 
> 
> Second, if we are not going into a long research phase, I am still
> wondering what existing protocols/algorithms, IP compatible or not,
> are being "hinted at" here, which could meet the "dream" criterii that
> are evoked in the draft. Chris Dearlove and other people have asked
> this question many times, and it is yet to be answered.
> 
> 
> Emmanuel

---

From: JP Vasseur <[email-masked]>
Date: Sun, 14 Dec 2008 18:39:17 +0100

Hi Geoff,

> to OSPF - there are some differences.

There are differences of course, as far as the set of criterion is  
concerned, the results will be identical to OSPF.

JP.

---

From: "David E. Culler" <[email-masked]>
Date: Sun, 14 Dec 2008 15:18:13 -0800

Precisely. 

The relationship and rationale are addressed in the text of the 
document.  So it is covered whiling keeping the table compact.  
(Actually, the discussion was in there from the first draft.)

---

From: Geoff Mulligan <[email-masked]>
Date: Mon, 15 Dec 2008 07:38:14 -0700

David,
  I guess I didn't find any discussion of IS-IS.  I see that IS-IS is
described as a link state protocol (like OSPF) but thats all I found.  I
don't know the nuances of the differences between IS-IS and OSPF to be
able to know that they are so similar that IS-IS didn't need to examined
separately rather than group with all link state protocols.

	geoff

---

From: JP Vasseur <[email-masked]>
Date: Mon, 15 Dec 2008 16:36:16 +0100

Hi Geoff,

> separately rather than group with all link state protocols.

Thanks for your feed-backs but yes indeed, looking at the criterion  
we're interested in, the conclusions
equally apply to both routing protocols.

Thanks.

JP.

---

From: Philip Levis <[email-masked]>
Date: Tue, 16 Dec 2008 09:09:50 -0800

> equally apply to both routing protocols.

JP is correct. We will add a sentence stating this.

Phil