Re: [8023-CMSG] Purpose
Jonathan,
Congratulations! Without making any changes to 802.3 you may claim that all
the CMSG objectives were already met.
Indeed, current 802.3 (with upcoming additions) already supports copper and
optical media, 100 Mb/s, 1 Gb/s, and 10 Gb/s rates, consistent with 802
architecture, provides predictable operation, and supports OAM. Anything
else we should do?
Seriously, I think your list of objectives is really just a set of
constraints that should be observed. But what this study group wants to
achieve? What is missing?
I am not certain that QoS should not be an objective. The very reasons to
use congestion management are to get better performance than afforded by the
best-effort operation. I agree that the term QoS is overloaded. So, let's
talk about specific parameters: delay, jitter, frame loss, and may be
bandwidth utilization as well. An attention should be given to decoupling of
bandwidth and delay. Many time-division systems suffer from this.
This group may do some interesting things that would improve performance. I
will just list some general ideas and let the group decide if these are the
worthy of studying further:
1. PAUSE frame provides ON/OFF control. It is known that such control
methods do not easily achieve steady state behavior, especially is control
loop delay is high. On the opposite, they tend to amplify traffic
oscillation throughout the network, as a result increasing jitter and packet
loss. One way to improve the performance is to change the rate control from
ON/OFF paradigm to "adjust by delta" paradigm. (Add a new MAC Control
message?)
2. 802.3ah P2MP STF introduced Multi-Point Control Protocol that performed
explicit rate control for multiple devices. It can be extended (actually
simplified) to be used on P2P links.
One question that is not completely clear to me is why 802.3 and not 802.1?
Cheers,
Glen
> -----Original Message-----
> From: owner-stds-802-3-cm@listserv.ieee.org [mailto:owner-stds-802-3-
> cm@listserv.ieee.org] On Behalf Of Jonathan Thatcher
> Sent: Thursday, April 29, 2004 3:35 PM
> To: STDS-802-3-CM@listserv.ieee.org
> Subject: Re: [8023-CMSG] Purpose
>
> Okay, I'll take a shot at the objectives:
>
> First, my list of anti-objectives:
> -- No support for half-duplex
> -- No changes to PCSs / PMAs / PMDs
> -- No simultaneous support for PAUSE and CM
> -- Not end-to-end flow control (no transaction layer)
> -- No traffic classification (e.g. looking at L3/L4/L5...)***
> -- No reordering within class (e.g. by priority within class)
> -- Not QoS****
>
> Objectives:
> -- Shall support up to 100 m of media (copper or optical)*****
> -- Shall support 100 Mb/s, 1 Gb/s, and 10 Gb/s
> -- Shall be consistent with IEEE 802.3 and IEEE 802.1 layer architecture
> -- Shall provide predictable, consistent network-wide operation
> -- Shall be consistent with slow protocols (e.g. OAM)
>
> Questions:
> -- Maximum supported latency across link (MAC to MAC)?
> -- Support of FEC?
>
> *** this does not mean that there isn't some traffic class identifier
> provided by L2 and used within L2. It means that L2 does not classify the
> flow and associate it with the identifier.
> **** QoS is an ambiguous, overloaded term. In most cases, it is associated
> with a contract with a user rather than a feature or function provided to
> a
> higher layer. Frequently it includes policies, shaping, rate limits, etc.
> Congestion management has little to nothing to do with this.
> ***** not necessarily all media!
>
> > -----Original Message-----
> > From: owner-stds-802-3-cm@listserv.ieee.org
> > [mailto:owner-stds-802-3-cm@listserv.ieee.org]On Behalf Of Benjamin
> > Brown
> > Sent: Thursday, April 22, 2004 8:09 AM
> > To: STDS-802-3-CM@listserv.ieee.org
> > Subject: [8023-CMSG] Purpose
> >
> >
> > Hi,
> >
> > I thought I'd try to kick start some discussions around the
> > Congestion Management Study Group's purpose for existence.
> > We have 3 tasks to accomplish between now and the May
> > interim. We need to develop a PAR, 5 Criteria and a list of
> > objectives. Ideally we can accomplish this in May in order to
> > pre-circulate the PAR and 5 Criteria so that we can formally
> > request Standards Board approval in the July meeting. During
> > the July meeting, we'll refine the objectives and hopefully not
> > change the PAR and 5 Criteria so the Standards Board is
> > approving the same thing we pre-circulated. If we miss this
> > May deadline, things get ugly. I'd rather not go into those
> > details, mostly because I don't know them well enough to
> > talk to but also because it sidetracks the discussion.
> >
> > The bottom line is that we need to work on those 3 items.
> > The PAR and 5 Criteria are used to get support from the
> > Standards Board. The objectives are used by WG 802.3
> > in order to validate the 5 Criteria. I intend to begin working
> > on the 5 Criteria and posting them to this reflector, probably
> > using individual threads. I would really appreciate some
> > discussion around them now since we've only got about a
> > day and a half at the May meeting. If we wait until then to
> > even see them, we may not be able to make the progress
> > we'd like to make.
> >
> > The implication of the above is that now is not the time to
> > propose solutions. That is the work for the task force. If
> > we can't get the above 3 items completed in order to become
> > a task force, the best solution in the world doesn't help us.
> > There will be time for solution proposals.
> >
> > If anyone has ideas or suggestions for objectives or any of
> > the 5 Criteria, please don't hesitate to start a thread on them.
> > Remember, I'm just the moderator of this process. I need
> > all of you participants to show that you're sufficiently interested
> > to actually participate. In fact, this is one of the Criteria - Broad
> > Market Potential - Multiple vendors, multiple users!
> >
> > Regards,
> > Ben
> >
> > --
> > -----------------------------------------
> > Benjamin Brown
> > 178 Bear Hill Road
> > Chichester, NH 03258
> > 603-491-0296 - Cell
> > 603-798-4115 - Office
> > benjamin-dot-brown-at-ieee-dot-org
> > (Will this cut down on my spam???)
> > -----------------------------------------
> >