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Re: My comments to the press about RFC 2474

2010-09-03 17:09:28
On 2010-09-04 08:13, Richard Bennett wrote:
 Thank you for replying Brian. I've not only read the requisite RFCs,
I've also implemented DiffServ over 802.11e. My implementations, like
those of everyone else who has done this, invoked the prioritization
mechanisms in 802.11e. This is a very common case. Another common case
implements DiffServ using 802.1d priorities.

Diffserv is about layer 3 queuing mechanisms. It isn't about mapping
to primitive layer 2 prioritisation.

We did keep backwards compatibility with IP Precedence in diffserv,
and I suppose one could implement those particular PHBs by mapping them
to layer 2 prioritisation. But the more subtle PHBs like EF and AF
simply cannot be mapped to preemptive priority queues without
destroying their defined semantics.

If you want to say that DiffServ is not itself a priority scheme but
rather a system for selecting the use of priority schemes at the Data
Link (or comparable facilities,) you're making a distinction that's too
fine for the press. 

No, I am not saying that. That is IMHO a faulty interpretation
of the intent of diffserv. In particular, I don't see how one can
read RFC 2597 and RFC 3246 and imagine that they can be mapped to
layer 2 priority.

As Russ is now invoking your message to support his
view that payment for premium service is contrary to the wishes of IETF,
that's a problem.

He's not saying that. He's effectively saying what I'm saying: payment
models are outside the scope of the standards, which don't require any
particular payment model in order to perform their job.

   Brian


RB

On 9/3/2010 1:06 PM, Brian E Carpenter wrote:
Richard,

Diffserv deals with multiple different queuing disiplines, which may
or may not be priority based. Please read RFC 2475 and if
you like, B.E. Carpenter and K. Nichols, Differentiated Services in
the Internet, Proc. IEEE, 90 (9) (2002) 1479-1494.

     Brian

On 2010-09-04 07:57, Richard Bennett wrote:
  DiffServ is a prioritization scheme, Brian, how can you say it's not?
IntServ is a reservation scheme, and DiffServ attempts to provide
desired PHBs in practice by sorting packets into priority queues and
invoking appropriate Link Layer  facilities, which are in most cases
priority-based, such as 802.11e traffic classes.

What on earth could the value of DSCPs be if they didn't map to traffic
classes in the data link?

RB

  Brian E Carpenter<brian(_dot_)e(_dot_)carpenter(_at_)gmail(_dot_)com>   
wrote:
Russ,
It has been consistently hard to explain that diffserv is not a
prioritisation scheme, even within the technical community, let
alone to the regulators and the media. I think your comments as
quoted are as good as we can expect from journalists.
It should be a matter of concern to all of us here that the US FCC
isn't confused into regulating the technology. It would set a bad
precedent for regulators in other countries. I am making no comment
as to whether they should regulate carrier's charging practices; that's
entirely a national matter that shouldn't concern the IETF in any way.
Regards
Brian Carpenter
On 2010-09-03 05:47, Russ Housley wrote:
I want the whole community to be aware of the comments that I made to
the press yesterday. Clearly, these comments do not represent IETF
consensus in any way. They are my opinion, and the reporter was
told to
express them as my opinion.

One thing that I said was not captured quite right. The article says:
"With services that require certain speeds to operate smoothly,
such as
Internet telephony, calls are given precedence over TV, Housley said."
I actually said that DiffServ can be used to make sure that traffic
associated with applications that require timely delivery, like voice
and video, to give preference over traffic associated with
applications
without those demands, like email.

The whole article is copied below, and it is online here:
http://www.nationaljournal.com/njonline/tc_20100902_7144.php

Russ

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