Subject: [Diffserv] Yesterday's EF discussion

From: Brian E Carpenter <[email-masked]>
Date: Wed, 13 Dec 2000 12:25:44 -0600

Summary of conclusions from EF discussion on 12/12/2000
-------------------------------------------------------

1. After discussion, the 5 possible directions for the EF PHB were
reduced to 4:

0/ Do nothing. The WG agrees that we are not yet ready to replace RFC 2598 
due to lack of consensus. Publish the Charny et al and EFRESOLVE drafts as 
Informational RFCs, and revisit the question in late 2001.

This option was rapidly eliminated by straw poll.

1/ The WG agrees that the work of the EFRESOLVE design team is the basis of the 
revised EF RFC, and that Charny et al should be progressed for the record as an
Informational RFC.

2/  The WG agrees that the  work of Anna Charny's group, modified as in the 
"possible compromise" message sent to the WG by Bruce Davie on Decemebr 7 
is the basis of the revised EF RFC and that the EFRESOLVE draft should be 
published for the record as an Informational RFC.

3/ The WG agrees that the two groups are talking about two different PHBs 
and that they both should be worked on independentlly, as two separate 
standards track documents.

A first straw poll showed that a small majority of those voting would be
prepared to accept two PHBs (option 3).

A second straw poll showed that if only one PHB was to be standardised
to update RFC 2598, a large majority would prefer option 2.

A third straw poll showed that a large majority would prefer only one
PHB (this is not inconsistent with the first straw poll, but it
eliminates option 3).

It was however observed that anyone can submit a PHB to the WG, although
the WG charter currently excludes defining more standard PHBs.

There was insufficient time to discuss the issues of naming and
code points.

----------------------

Proposed expression of WG consensus:
  
   A replacement for RFC 2598 should be drafted, in the strict format
   of a PHB definition as specified in RFC 2474, based on the 
   "possible compromise" revision to the model described in
   draft-charny-ef-definition-01.txt. This is to be progressed as 
   a WG draft intended to be submitted as a Proposed Standard.

Open issues:

   Authorship of the new document.
     Chair's proposal: all contributors to RFC 2598, 
     to draft-charny-ef-definition-01.txt, and to 
     draft-ietf-diffserv-efresolve-00.txt should be recognized as authors.

   Should the recommended code point be 101110?
     Chair's proposal: yes

   What should the name of the PHB be?
     Chair's proposal: Defined Rate (DR). I believe that after this long
     and confusing discussion, it would be wise to retire the previous name.

       Brian Carpenter
       diffserv co-chair

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From: Juha Heinanen <[email-masked]>
Date: Wed, 13 Dec 2000 21:48:17 +0200 (EET)

>      and confusing discussion, it would be wise to retire the previous name.

if i implement an af class by assigning it to a wfq of a certain weight,
it defines a rate for that class.  does this mean that by proper
admission control to that class, i can in fact implement using an af
class a service that is equivalent to a service that would result if i
would be using the dr phb instead?  if so, do we really need (for other
than political reasons) ef or this new thing?

this brings me back to a point that i have made before, i.e., i feel
that the whole phb concept is not that useful.  what is useful is the
description of the actual (queuing, droping, policing, etc.) mechanisms
that the routers may implement and a way to validate them.  a well
documented list of such mechanisms including their parametrization would
be to the buyer of a router a much more useful thing than a claim that
the router implements a certain list of phbs.

-- juha

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From: demir <[email-masked]>
Date: Wed, 13 Dec 2000 12:31:39 -0800 (PST)

Very nice points. That's how I feel, too.

Alper K. Demir

---

From: Brian E Carpenter <[email-masked]>
Date: Wed, 13 Dec 2000 15:25:33 -0600

Juha, Demir,

This may be what you feel, but the WG and the whole diffserv model
are based on the concept of PHB. So this discussion is really out of scope
within the WG.

As has been observed recently, the concrete realisation of a PHB may well
be a specific configuration of the lower level mechanisms that you mention.
That's not news.

  Brian

---

From: Grenville Armitage <[email-masked]>
Date: Wed, 13 Dec 2000 13:55:55 -0800

Juha Heinanen wrote:
	[..]
> it defines a rate for that class.

you have established a wfq with certain rate, which might be *used*
to support an AF class.

>  does this mean that by proper
> class

but you're not implementing it with "an af class". you're implementing
a particular "..wfq of a certain weight..." - not the same thing.

> a service that is equivalent to a service that would result if i
> would be using the dr phb instead?

quite possibly.

>  if so, do we really need (for other

EF implies requirements on how you configure your schedulers.
you could map some AF class onto a queue served by a scheduler
configure to give EF/DR-type behavior, but that hardly removes
the value of documenting what exactly *is* EF/DR behavior.

> that the routers may implement and a way to validate them.

ultimately once you generalize the proprietary and/or
algorithm-specific terminology from such descriptions you will
end up with a PHB.

cheers,
gja
________________________________________________________________________
Grenville Armitage                    http://members.home.net/garmitage/
Bell Labs Research Silicon Valley

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From: demir <[email-masked]>
Date: Wed, 13 Dec 2000 14:41:47 -0800 (PST)

Grenville,

> you have established a wfq with certain rate, which might be *used*

"Admission control" might change alot more than "a wfq with certain rate".

Alper K. Demir

---

From: Grenville Armitage <[email-masked]>
Date: Wed, 13 Dec 2000 14:53:20 -0800

> "Admission control" might change alot more than "a wfq with certain rate".

Your point completely eludes me.

gja

---

From: "Bill Courtney" <[email-masked]>
Date: Wed, 13 Dec 2000 18:59:22 -0800

Hi Brian,

Among other things, you solicited opinion on the following

>      and confusing discussion, it would be wise to retire the previous
name.

I disagree with your proposal and believe that the EF name should be
retained.

My reasons are that

1) As I read the options and the WG consensus, the WG wanted to *fix EF*,
not
to provide a new PHB that has no relationship to EF. (I apologize to the WG
if I have misread its intention.) I think that the consensus should be
respected.

2) There is a great deal of interest in the industry (vendors and service
providers) and in the academic and user community for having a final version
of EF. We in the WG have continued to whet this interest by a) arriving at
a consensus in Pittsburgh that *EF* should be made implementable and
b)arriving
at a consensus in San Diego that the preferred *EF fix* would take the
approach
laid out in the draft-charny compromise. There seems to be no reason for a
sudden change in the name of the PHB. If a change were warranted, the time
to
have made it would have been the instant that the WG agreed that EF needed
fixing. Yet, no one spoke out that such a change should be made. (Although
it was the case that some felt that no fix was necessary, and that any
so-called
"fix" should instead be captured in some new PHB. As we know, this feeling
was not embraced by the WG consensus.) A change seems unnecessary, and
would,
I believe create at least as much confusion in the community as it would
alleviate.

3) As I have expressed in mailings back around the time just before the
Pittsburgh meeting, the behavior defined in draft-charny-00 (and, as Bruce
expressed at the meeting in San Diego, the behavior defined in the
draft-charny
compromise) is a minimal departure from the *words* written in RFC 2598.
Since
the WG agreed to fix EF via the compromise, it is not too much of a stretch,
to conclude that the WG felt that the draft-charny-compromise behavior is
close to the behavior that RFC 2598 sought to define. (Again, I apologise if
I am reading the consensus incorrectly. If I am, other responses to your
suggestion will certainly make that clear to me.) Since the behaviors are
close, no change to the name is required, so none should be made.

Bill

---

From: Grenville Armitage <[email-masked]>
Date: Wed, 13 Dec 2000 22:50:34 -0800

Brian E Carpenter wrote:
	[..]
>      and confusing discussion, it would be wise to retire the previous name.

Brian, I think this suggestion is a good one. Clearly there are differing
opinions over what RFC2598 intended. I watched from the rear of the room
yesterday. I too saw a crowd sentiment broadly in favor of
draft-charny(modified) as the WG PHB to support VW and similar services.
But given the fact that "EF" has been differently interpreted by a number
of relatively intelligent people, I cannot see the value in anyone being
'damn right' about owning the EF name from this point onwards. The WG needs
a standards track PHB believed to support VW, etc, services....the name
"Defined Rate" captures the rough consensus towards the rate-based
interpretation of RFC2598.

cheers,
gja (not, it must be noted, speaking of behalf of EFRESOLVE)

---

From: demir <[email-masked]>
Date: Thu, 14 Dec 2000 07:43:37 -0800 (PST)

> >      and confusing discussion, it would be wise to retire the previous name.

Brian,
It sounds a good idea. However, I think, "Defined Rate" name is kind of
misleading. How about "Destined Forwarding" PHB? (AF/DF, AC/DC :)

Alper K. Demir

---

From: Bora Akyol <[email-masked]>
Date: Thu, 14 Dec 2000 14:49:49 -0800

Having a second name effectively allows two PHBs. This was NOT the 
consensus in the meeting.

Bora

At 10:50 PM 12/13/2000, Grenville Armitage wrote:

>Archive: 
>http://www2.ietf.org/mail-archive/working-groups/diffserv/current/maillist.html 
>

Bora Akyol
Pluris
[email-masked]

---

From: Grenville Armitage <[email-masked]>
Date: Thu, 14 Dec 2000 15:00:16 -0800

nobody's asking for a second name. it is a new name. 'EF' gets
retired along with RFC2598. only one PHB is the standards track
successor to RFC2598, and it will be built on charny-compromise.
no problem.

cheers,
gja

---

From: Dan Grossman <[email-masked]>
Date: Fri, 15 Dec 2000 01:19:37 -0500

Brian E Carpenter wrote:

> Summary of conclusions from EF discussion on 12/12/2000   A replacement for RFC 2598
> should be drafted, in the strict format

Um... I know this is a delicate issue, but it would look rather odd to have the co-authors
list longer than the substance of the text.  We do have an Acknowledgements section.
Suggest that co-authorship be left to the good will of the contributors, with the
understanding that it be reserved for those who contriubted significant text or major
concepts.

>    Should the recommended code point be 101110?

Yes

>      and confusing discussion, it would be wise to retire the previous name.

The name should not be changed, for reasons already discussed, and in particular because we
have caused enough  confusion to the industry,  and to do so would make matters worse.

---

From: John Schnizlein <[email-masked]>
Date: Mon, 18 Dec 2000 17:11:59 -0500

When the RFC that replaces RFC 2598 is ready for progress 
to standard based on multiple interoperable implementations
should the name be one of mostly historical interest 
(Expedited Forwarding) or something that reflects the
essential nature of the per-hop behavior it defines?

Is there anything besides expediting packet forwarding
involved in the proposed definition? In a word or two,
what is it?

John

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From: Jean-Yves Le Boudec <[email-masked]>
Date: Tue, 19 Dec 2000 09:05:44 +0100

I vote for keeping the old name EF. The industry has started working with
that name, and we shoudl keep it.

JY

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From: Tiziana Ferrari <[email-masked]>
Date: Wed, 20 Dec 2000 16:47:17 +0100 (MET)

I didn't make it for the 19th - I was away for a business trip - but I
would like to vote for keeping the name "EF".

Tiziana

> >http://www2.ietf.org/mail-archive/working-groups/diffserv/current/maillist.

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             Tiziana Ferrari      http://www.cnaf.infn.it/~ferrari
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