Subject: RE: [Diffserv] Yesterday's EF discussion

From: "Manfredi, Albert E" <[email-masked]>
Date: Mon, 18 Dec 2000 16:31:18 -0500

Brian E Carpenter:

> Bruce, the reason I chose to put the naming question to the list is
> that the naming issue was very far from explicit in the discussion
> on Tuesday, and there wasn't time to make it explicit.
> 
> My intention is to close off the naming discussion tomorrow 
> December 19,
> and state what I see as the rough consensus.

Sorry I didn't commit to memory all of the suggestions, but did anyone
recomment something like, say, Guaranteed Frame Rate (GFR)? :))

Dunno, I just pulled that one out of the air.

Bert

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From: Brian E Carpenter <[email-masked]>
Date: Mon, 18 Dec 2000 16:22:23 -0600

The current question is whether the charny-et-al-compromise specification
is going to be called EF. [If not, let the games commence :-]

  Brian

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From: demir <[email-masked]>
Date: Wed, 20 Dec 2000 14:26:02 -0800 (PST)

Brian,
Obviously, there is a WG consensus on keeping the EF name. I am completely
disagree with this consensus (I have the feeling that you will tell me to
deal with it. I am :) Now, charny-et-al-compromise specification is on the
way to replace EF. However, to me, it is not "righ way". I am
"VERY" unable to see what it is that RFC-2598 is missing as a PHB. I have
made that statement before. Oh I see. "low loss", "low latency", "low
jitter" is very "relative" and not "precise". How far a PHB can go 
other than saying "low". RFC-2598 has an obvious reasoning for
this: "loss, latency and jitter are all due to the traffic experiences
while transiting network". I thought a PHB should have a  
"consistent-reasoning" about expected "aggregate bahaviors". RFC-2598 has 
a very "consistent-reasoning: "we show the generality of this PHB by
noting that it can be produced by more than one mechanism and give an
example of its use to produce at least one service, a virtual leased
line". I am "VERY" unable to see a "consistent-reasoning" on
charny-et-al-compromise (I have the sense that you will tell me to wait
for the draft or try harder to see it. I disagree cause the "general
idea" is clear to me). Is the problem that to make RFC-2598 more
"precise" by giving an "approximate" formula on "delay bound" and a
"specific" algorithm on "well-defined rate"? This might create a big
"misunderstanding" and wrong "consistent-reasoning". "loss", "delay" and
"jitter" are all related to mechanisms underneath and how network traffic
control is achieved ("traffic conditioners"). With support of network
traffic control and "appropriate" scheduling mechanisms, delay depends on
"burstiness" allowed. So does "loss" and "jitter". In addition to this,
"loss" depends on "queue management" and "jitter" requires individual flow
"state". Providing "bound" on one of these will affect the others (loss,
delay, jitter). It doesn't seem reasonable to me that a PHB is having a
"risk" of all these problems. What is the next step will be if "current
EF" fails to achieve the "goal"? I guess, "jitter' didn't work,
"delay" failed, let's deal with "loss" :) I assume if we put alot of
"burden" on a PHB it will be a very "smart PHB". We know that doesn't
scale. RFC-2598 has a way of dealing with it: "well-defined rate" where a
PHB can be "smart" about. Diffserv has a way of being smart about
"diffserv domain" related "issues": PDB. May be, what EF is missing is to
elaborate on this. It seems it is okay for a PHB to "approximate" to
"worst-case delay bound" by Diffserv WG (previously "delay variance
bound". I am sorry to say that the behavior of the hop (EF) has
changed. Now, it is approximating to bound "delay" with a
"specific" algorithm where it is not related to "worst-case delay
bound" which requires "state" for individual flows or some assumptions. I
don't see any problem with RFC-2598 other than, may be, some
elaboration. There are 8 (eight) choices to bound "something" (loss,
delay, jitter) if a PHB is willing to take some "risks" on
"consistent-reasoning"; each having a different behavior and the most
general way to express this is that something is *always* less than
something. How things are done is details and it is wrong to specify a
detail unless it is universally accepted. 

My 2 cents,

Alper K. Demir

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From: Brian E Carpenter <[email-masked]>
Date: Wed, 20 Dec 2000 17:23:32 -0600

Demir,

You are in the dissenting minority. As I said yesterday, let's
wait for the new PHB draft to see if we still have a rough consensus.

  Brian

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From: demir <[email-masked]>
Date: Wed, 20 Dec 2000 16:54:05 -0800 (PST)

Brian,
I don't see myself in the dissenting minority. I don't have any problem
with "accepting!" consensus. I am in the "accepting!" minority :) I only
"speculated" on a "end-to-end argument" related to current PHB discussion. 

Alper K. Demir