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Re: [8023-CMSG] Problem statement

Title: Problem statement
Manoj,
 
Just trying to understand, with a few questions.
 
1) 802.17 has a classC, which allocated bandwidth in a weighted fashion
among the applicants, so that (after feedback settles) applicantions
with near-constant rate inputs will eventually be provided with their
weighted fair shared of the available bandwidth.
 
From you email response, I assume this is what CMSG desires.
 
2) 802.17 also has classA (real time) and classB (preferential), which
may be similar to differentiation and priorities. To make them work,
access controls are also required, which (I believe) is not currently
included in 802.3.  I think, however, that you think this handles the transient
issues, but I am highly skeptical. However, no point is arguing,
since its not the scope of the CMSG project.
 
3) Another problem, that often occurs in clusters, is the transient overload
problem. With computer backplanes, this is the classical every processor
reads from one memory.  Doesn't happen all that happen, cannot be
characterized by an average load, and isn't helped by priority
(all processors tend to have the same priority).
 
Problem (3) is being addresses by RBR, extensions to RPR, with
appropriate extensions of computer-backplane like flow destination-asserted
flow control, where the "destination" can also be an intermediate
bridge. This can be found at:
  http://grouper.ieee.org/groups/msc/MSC_RBR/info.html
 
I was hoping the RBR Working Group could leverage some of the CMSG
advances. However, given the differences between (3) and (1), with the
apparent CMSG leaning towards (1), I guess not.
 
I think (1) is an even harder problem, so I admire your initiative.
Best of luck!
 
DVJ
 
David V. James
3180 South Ct
Palo Alto, CA 94306
Home: +1.650.494.0926
      +1.650.856.9801
Cell: +1.650.954.6906
Fax:  +1.360.242.5508
Base: dvj@alum.mit.edu 
-----Original Message-----
From: owner-stds-802-3-cm@listserv.ieee.org [mailto:owner-stds-802-3-cm@listserv.ieee.org]On Behalf Of Wadekar, Manoj K
Sent: Monday, September 13, 2004 4:56 PM
To: STDS-802-3-CM@listserv.ieee.org
Subject: Re: [8023-CMSG] Problem statement

No, CMSG focused primarily on "oversubscription" issue.
["Transient" being addressed by "differentiation" or "priorities"].
 
 
Thanks,
- Manoj

From: owner-stds-802-3-cm@listserv.ieee.org [mailto:owner-stds-802-3-cm@listserv.ieee.org] On Behalf Of David V James
Sent: Monday, September 13, 2004 2:41 PM
To: STDS-802-3-CM@listserv.ieee.org
Subject: Re: [8023-CMSG] Problem statement

Hmm,...
 
1) I had thought the primary reason for congestion management was to avoid
the short-term problem of loss of traffic during coincidental peaks in traffic.
 
The term "oversubscription" seems to imply a long-term flow control solution.
I suppose that's OK if the original intent of (1) was misperceived or has changed.
 
DVJ
 

David V. James
3180 South Ct
Palo Alto, CA 94306
Home: +1.650.494.0926
      +1.650.856.9801
Cell: +1.650.954.6906
Fax:  +1.360.242.5508
Base: dvj@alum.mit.edu 

-----Original Message-----
From: owner-stds-802-3-cm@listserv.ieee.org [mailto:owner-stds-802-3-cm@listserv.ieee.org]On Behalf Of Booth, Bradley
Sent: Monday, September 13, 2004 1:59 PM
To: STDS-802-3-CM@listserv.ieee.org
Subject: [8023-CMSG] Problem statement

Greetings,

I wasn't able to attend the CMSG meeting in July, due to being a little busy in 802.3an, but I was looking at the problem statement that I believe was adopted by the SG.  I was a little concerned that the statement only mentioned 802.3 MAC Clients and nothing about the 802.3 MAC itself.  I was wondering if the following problem statement would still be palatable to everyone:

"802.3 MAC Clients need the ability to communicate, via 802.3 MACs, congestion information to avoid oversubscription."

Thoughts?  Feedback?

Thanks,
Brad