I made one tweak relative to this change as previously agreed: the very
last paragraph of the original section was not marked to be deleted but had
been pulled up earlier in the section. I deleted the duplicate text.
I also changed one word in the abstract, per another LC suggestion and
discussion with Bob.
Thanks,
--MM--
The best way to predict the future is to create it. - Alan Kay
Privacy matters! We know from recent events that people are using our
services to speak in defiance of unjust governments. We treat privacy and
security as matters of life and death, because for some users, they are.
On Tue, Aug 12, 2014 at 1:29 PM, Robert Sparks
<rjsparks(_at_)nostrum(_dot_)com> wrote:
This text would work for me.
The chairs and AD should verify it reflects consensus.
Thanks!
RjS
On 8/8/14, 8:17 AM, Bob Briscoe wrote:
Robert,
We're glad you found it accessible. Thank you for pointing out the
inconsistency between this, 7141 & 6789 - I (Bob) am impressed given I was
a co-author of all of them and I hadn't noticed. We have suggested edits
below to remove the inconsistency, moving up the last para and adding some
explanatory text (unlike the original text, it is not indented).
Ideally, RFC6789 should have said that its definition of congestion-volume
is applicable to today's Internet and may change. Given most RFCs only
apply to today's Internet, we don't think we need to go to the trouble of
updating 6789. So, instead, we have qualified the applicability of 6789 in
this document.
=======================================================================
CURRENT:
Whether to use bytes or packets is not obvious. For instance, the
most expensive links in the Internet, in terms of cost per bit, are
all at lower data rates, where transmission times are large and
packet sizes are important. In order for a policy to consider wire
time, it needs to know the number of congested bytes. However, high
speed networking equipment and the transport protocols themselves
sometimes gauge resource consumption and congestion in terms of
packets.
This document does not take a strong position on this issue.
However, a ConEx encoding will need to explicitly specify whether it
assumes units of bytes or packets consistently for both congestion
indications and ConEx markings (see network layer requirement E in
Section 3.3). It may help to refer to the guidance in [RFC7141].
[RFC7141] advises that congestion indications should be interpreted
in units of bytes when responding to congestion, at least on today's
Internet. In any TCP implementation this is simple to achieve for
varying size packets, given TCP SACK tracks losses in bytes. If an
encoding is specified in units of bytes, the encoding should also
specify which headers to include in the size of a packet (see network
layer requirement F in Section 3.3).
SUGGESTED:
Whether to use bytes or packets is not obvious. For instance, the
most expensive links in the Internet, in terms of cost per bit, are
all at lower data rates, where transmission times are large and
packet sizes are important. In order for a policy to consider wire
time, it needs to know the number of congested bytes. However, high
speed networking equipment and the transport protocols themselves
sometimes gauge resource consumption and congestion in terms of
packets.
[RFC7141] advises that congestion indications should be interpreted
in units of bytes when responding to congestion, at least on today's
Internet. [RFC6789] takes the same view in its definition of
congestion-volume, again for today's Internet.
In any TCP implementation this is simple to achieve for
varying size packets, given TCP SACK tracks losses in bytes. If an
encoding is specified in units of bytes, the encoding should also
specify which headers to include in the size of a packet (see network
layer requirement F in Section 3.3).
RFC 7141 constructs an argument for why equipment tends to be built so
that the bottleneck will be the bit-carrying capacity of its interfaces not
its packet processing capacity. However, RFC 7141 acknowledges that the
position may change in future, and notes that new techniques will need to
be developed to distinguish packet- and bit-congestion.
Given this document describes an abstract ConEx mechanism, it is intended
to be timeless. Therefore it does not take a strong position on this issue.
However, a ConEx encoding will need to explicitly specify whether it
assumes units of bytes or packets consistently for both congestion
indications and ConEx markings (see network layer requirement E in
Section 3.3). It may help to refer to the guidance in [RFC7141].
=======================================================================
Regards
Bob Briscoe & Matt Mathis
On Wed, Aug 6, 2014 at 1:28 AM, Robert Sparks
<rjsparks(_at_)nostrum(_dot_)com>
wrote:
I am the assigned Gen-ART reviewer for this draft. For background on Gen-ART,
please see the FAQ at
< http://wiki.tools.ietf.org/area/gen/trac/wiki/GenArtfaq>.
Please resolve these comments along with any other Last Call comments you
may receive.
Document: draft-ietf-conex-abstract-mech-12 Reviewer: Robert Sparks Review
Date: 5-Aug-2014 IETF LC End Date: 8-Aug-2014 IESG Telechat date: Not on
an upcoming telechat agenda
Summary: Ready for publication as Informational
This document handles a complex description problem in a very accessible
way. Thank you for the effort that has gone into creating it.
One minor point to double-check:
This document goes out of its way to push decisions about measuring in
packets, bytes, or other units to the concrete  encoding proposals.
RFC6789 was explicit about conex exposing a metric of congestion-volume
measured in bytes.
RFC6789 was published a couple of years ago - has that part of it become
stale? If so, it would be good for this document to explicitly call that
out.
If not, (most of section 4.6 goes back to -04 which predates RFC6789), does
this document need to retain the this flexibility in its description?
________________________________________________________________
Bob Briscoe, BT