Subject: [ippm] Path Capacity

From: Dana Blair <[email-masked]>
Date: Thu, 23 Mar 2006 12:51:32 -0500

I have ready the draft called "Defining Network Capacity".
The draft nicely defines path capacity.

Is there any work in progress on standard technique to measure IP Layer
Available Path Capacity ?

thanks,
Dana

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From: "Philip F. Chimento Jr." <[email-masked]>
Date: Thu, 23 Mar 2006 14:25:08 -0500

Hi Dana:
We decided in the WG to put that on the back burner and get the  
initial definitions done. Your question brings up the obvious  
question to the WG (appropriate for the mailing list) of "What do we  
do with this now? Do we stop with the definitions, or do we analyze  
what has been implemented/proposed so far and pick or propose  
something that the WG thinks captures the essential measurement?"

So, are there any mailing list reactions to this?

Philip F. Chimento Jr.
Johns Hopkins University
Applied Physics Laboratory

On Mar 23, 2006, at 12:51, Dana Blair wrote:

> [email-masked] https://www1.ietf.org/mailman/listinfo/ippm

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From: Henk Uijterwaal <[email-masked]>
Date: Fri, 24 Mar 2006 22:29:02 +0100

Hi Dana, Phil,

>So, are there any mailing list reactions to this?

I think that there are two issues:

1. Is this document ready?
    a. Does the document define everything that we need to define?
    b. Are the definitions correct/acceptable?

2. What next?

To answer (1), I like to hear from more people than the few mentioned
in the draft who read it.  So, everybody please read and comment, even
a simple "yeah, I read it, it looks fine" is very helpful.  I don't want
to finish this document as an RFC only to find out that we forgot something
later (or that there is still discussion on some quantities).

After (1) is done, we should look at what has been done.  There are a lot
of tools out there, do they measure what we want to measure?  What is
their accuracy?  What techniques do they use?  Is one technique clearly
better than another (and in which circumstances), etc.  This probably
requires another draft.

Henk

>>Available Path Capacity ?

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1160438400. Watch this space...

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From: Dana Blair <[email-masked]>
Date: Mon, 27 Mar 2006 08:20:25 -0500

>    b. Are the definitions correct/acceptable?

I think we need to define the solution space.  I'm not sure which  
document
should contain it.

Solutions could be categorized into the following:
1.  1 hop, 2 hops, multi-hop
		Does the solution work over a single hop, 2 hops, or multiple hops ?
2.  Endpoint Cooperation
		Does the endpoint of the path need to cooperate in the measurement ?
3.  Intermediate hops cooperative or not
		Do any of the intermediate hops need to cooperate in the measurement ?
4.  Should there be some consideration of queue depth for one, some, or
		all links in the path ?

I suspect depending on the answer to these questions, various solutions  
will have
range of accuracy, scalability, and overhead.

thanks,
Dana

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From: "Philip F. Chimento Jr." <[email-masked]>
Date: Mon, 27 Mar 2006 12:39:51 -0500

Dana:
Let me go back in history a little bit so that it clearer what the  
intent of this draft was and how it (sort of) evolved.

Mark Allman was the original driver of this draft and I think (Mark,  
are you lurking? If so, correct any mistaken impressions that I have)  
that as a result of a workshop held by CAIDA on this subject (i.e.  
measuring capacity), Mark came to Henk and Matt Z. with the  
suggestion that IPPM try to standardize it. Joe Ishac and I  
volunteered to work on the draft. As you probably know, there was a  
plethora of tools discussed at the workshop (and since, more have  
been added) that all purport to measure capacity along a path, and of  
course, each is slightly different. We discussed a couple of times in  
the workgroup how we should approach the problem: whether we should  
propose a set of definitions of the quantity itself (to try to get  
clarity); whether we should survey the many tools and try to extract  
what they in fact DID measure; whether we should propose metrics of  
our own; etc. The consensus of the work group seemed to be that we  
should strive for clarity and focus only on the definition of what  
the (ideal) quantities were (or should be). So, Joe and I started  
marching down that path. We think that we are there (or almost)  
modulo additional advice from the work group on the mailing list.
With this in mind, Henk (and Joe and I) are requesting that people  
read the draft and comment as to whether it has fulfilled its intent  
as defined by the workgroup. Beyond that, there are a number of very  
interesting questions relating to the tools that are currently in  
use, and how close they come to capturing the quantities that are  
defined in the draft. (I would like to emphasize at this point, that  
the draft does not define METRICs, on purpose, only the quantities  
themselves.) Further there is the question of whether the work group  
should choose as a metric one of the measures already in use, or  
whether we should define another metric that takes the best from all  
the many that are out there. These are all questions for subsequent  
drafts.

Philip Chimento
Johns Hopkins University

On Mar 27, 2006, at 08:20, Dana Blair wrote:

> I suspect depending on the answer to these questions, various  
> solutions will have

---

From: Dana Blair <[email-masked]>
Date: Mon, 27 Mar 2006 14:06:06 -0500

> intent of this draft was and how it (sort of) evolved.

I know that I'm late to this discussion so existing players should  
decide on moving existing draft to
RFC or not.  I don't have a strong opinion.

If/When we get to evaluating various proposals, I'll be  
commenting/suggesting/evaluating in the context
of the solution spaces that I suggested.

thanks,
Dana

> measuring capacity), Mark came to Henk and Matt Z. with the suggestion  
> that IPPM try to standardize it. Joe Ishac and I volunteered to work  
> on the draft. As you probably know, there was a plethora of tools  
> discussed at the workshop (and since, more have been added) that all  
> purport to measure capacity along a path, and of course, each is  
> slightly different. We discussed a couple of times in the workgroup  
> how we should approach the problem: whether we should propose a set of  
> definitions of the quantity itself (to try to get clarity); whether we  
> should survey the many tools and try to extract what they in fact DID  
> measure; whether we should propose metrics of our own; etc. The  
> consensus of the work group seemed to be that we should strive for  
> clarity and focus only on the definition of what the (ideal)  
> quantities were (or should be). So, Joe and I started marching down  
> that path. We think that we are there (or almost) modulo additional  
> advice from the work group on the mailing list.
> interesting questions relating to the tools that are currently in use,  
> and how close they come to capturing the quantities that are defined  
> in the draft. (I would like to emphasize at this point, that the draft  
> does not define METRICs, on purpose, only the quantities themselves.)  
> Further there is the question of whether the work group should choose  
> as a metric one of the measures already in use, or whether we should  
> define another metric that takes the best from all the many that are  
> out there. These are all questions for subsequent drafts.
>
>
>
>
> Philip Chimento
> Johns Hopkins University

---

From: Mark Allman <[email-masked]>
Date: Tue, 28 Mar 2006 19:09:10 -0500

> are you lurking? 

Yeah...

> If so, correct any mistaken impressions that I have) that as a result
> of a workshop held by CAIDA on this subject (i.e.  measuring
> capacity), Mark came to Henk and Matt Z. with the suggestion that IPPM
> try to standardize it.

This is all pretty accurate.  I am not sure the idea was mine and I am
not sure it came from the CAIDA/IMRG bandwidth estimation workshop, per
se.  But, I think that ended up being the driver of the current effort.
So, yeah, your high order bits are right, I think.

Henk said I don't count because I have already said the draft looks OK.
That's fine, I can move on to the next steps then... :-)

I wonder if the community has actually converged on particular
techniques for capacity characterization.  I have not really been
tracking this to a great extent and so I am not sure.  Maybe it's time
to get the IMRG to host another workshop to try for some more concrete
goals of actually kicking something to the IETF?  Just a thought... I'd
certainly love to hear input (if Henk and Matt wouldn't consider it too
off topic).

Thanks for kicking this along guys!

allman

_______________________________________________
ippm mailing listFrom [email-masked] Wed Mar 29 01:02:51 2006
To: "Philip F. Chimento Jr." <[email-masked]>
From: Mark Allman <[email-masked]>
Subject: Re: [ippm] Path Capacity 
Organization: ICSI Center for Internet Research (ICIR)
Song-of-the-Day: Sweet Home Alabama
Date: Tue, 28 Mar 2006 19:09:10 -0500
Cc: Henk Uijterwaal <[email-masked]>, [email-masked]
Reply-To: [email-masked]

> are you lurking? 

Yeah...

> If so, correct any mistaken impressions that I have) that as a result
> of a workshop held by CAIDA on this subject (i.e.  measuring
> capacity), Mark came to Henk and Matt Z. with the suggestion that IPPM
> try to standardize it.

This is all pretty accurate.  I am not sure the idea was mine and I am
not sure it came from the CAIDA/IMRG bandwidth estimation workshop, per
se.  But, I think that ended up being the driver of the current effort.
So, yeah, your high order bits are right, I think.

Henk said I don't count because I have already said the draft looks OK.
That's fine, I can move on to the next steps then... :-)

I wonder if the community has actually converged on particular
techniques for capacity characterization.  I have not really been
tracking this to a great extent and so I am not sure.  Maybe it's time
to get the IMRG to host another workshop to try for some more concrete
goals of actually kicking something to the IETF?  Just a thought... I'd
certainly love to hear input (if Henk and Matt wouldn't consider it too
off topic).

Thanks for kicking this along guys!

allman

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From: "Philip F. Chimento Jr." <[email-masked]>
Date: Wed, 29 Mar 2006 04:09:10 -0500

Thanks for chiming in. I don't know the answer to your question, but  
it is a really good question. I think that answering it is part of an  
analysis effort I was hinting at before. I don't know whether such an  
effort would be better placed in IMRG or IPPM (maybe you, Henk and  
Matt Z should discuss).

Phil Chimento
Johns Hopkins University

---

From: Henk Uijterwaal <[email-masked]>
Date: Thu, 30 Mar 2006 16:30:21 +0200

Hi alk,

>That's fine, I can move on to the next steps then... :-)

You do count as one of the people who said that this was a good draft ;-)

>certainly love to hear input (if Henk and Matt wouldn't consider it too

I think there are two questions:

  * What techniques have been developped recently to measure capacity.
    This is IMRG.

  * For the techniques that are mature, standardize whatever has to
    be standardized.  Give some hints for parameters and related
    to that: expected accuracies.  Sort-of an applicability statement.
    This is IETF.

I'd certainly be interested in a workshop on either topic.

Henk