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Re: [HSSG] MAC Data Rate of Operation Objective



I agree with most of what you have said.  If it doesn’t make the implementation too complicated, though, I would advocate a granularity of one 10G channel, rather than groups of 4 (why hem ourselves in?).  There will have to be some fiddling in the PHY (could this be made into a musical someday??), but I think the PMDs should remain unchanged from what has already been defined.  Really, what is needed is an extra sub-layer that can do the de-skewing.  


On the issue of lane failure, I don’t see why we shouldn’t make it graceful – i.e., continue to operate over the remaining lanes.  





From: Geoff Thompson [mailto:gthompso@xxxxxxxxxx]
Sent: Monday, August 14, 2006 3:53 PM
To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re: [HSSG] MAC Data Rate of Operation Objective



I count myself as an advocate of Proposal B.
I do not agree that "Proposal B" is unbounded, rather that we are still very early in the process (we have not even met as a Study Group yet) and we have not yet had the "Study" of the issue of precisely what we would would be appropriate to  propose in this area. That is Study Group work!

My prejudices and suspicions going into the process lie something along the following lines:

  • I am guessing a "PHY that binds" (PTB) similar in philosophy to the copper PHYs in EFM
  • I expect configurable but fixed speeds aligned to the number of lanes
  • Initial market relevance (and therefore initial projects) would be based on 10G lanes
  • I have a gut feel that we should talk in lane groups of 4 (for 10G lanes)
  • I would guess that 12 or 16 would be our max.
  • We will draw heavily on work that has been done for 10G optical PHYs but we will end up having to fiddle a bit.
  • I expect ribbon fiber for data centers
  • I expect WDM for metro and carrier

Other topics will bounce in and out of our discussions.
One of the most difficult will be whether or not we will depart from a strict model of [n lanes in a single point-to-point link]. There are certainly a number of places to go, e.g.

  • Is "n" set in the standard or configurable?
  • What happens when you lose a lane?

        (i.e. slow down by 1/n or stop)

  • Do we need to take on dual homing?

        (My personal opinion is that is out of scope for this project)

That ought to be enough to get things kicked off.

Best regards,


At 02:20 PM 8/14/2006 , John DAmbrosia wrote:


In regards to proposed MAC data rates, I have seen two basic proposals

        Proposal A) 100 Gb/s

        Proposal B) Scalable Solution

Proposal A supports the traditional 10x increase in speed. 

Proposal B, as presently discussed, is unbounded.  (The following are only my observations of statements made on the reflector by others)  The lowest limit proposed was a 4x10 approach for 40 Gb/s.  No upper limits have been proposed.  It has been suggested that this approach should use existing PMDs, but there have been also been comments regarding use of 10G, 25G, and 40G lambdas, but that carriers would want to leverage their existing DWDM layer, which mean baudrate in the 9.95-12.5 Gig.  Consuming wavelengths has been brought up as a possible concern.  It was also suggested that the greatest bandwidth demands are on VSR links < 50m and that the longer reach (>10km) may be able to live with 4x10G.  (Data in support of these observations that could be used to guide the creation of objectives would be welcome.)


An objective for Proposal A could be similar to what was done for 10 GbE Support a speed of 100.000 Gb/s at the MAC/PLS service interface.


For Proposal B, given its current unbounded nature and multiple discussion points, I am not sure what would be proposed.  I am looking to the advocates of this proposal to provide some verbiage to the reflector for discussion.  Using the objective above as a basis: Support a speed greater than 10.000 Gb/s at the MAC/PLS service interface, would create too broad an objective.


Also for both proposals what are people s thoughts on an objective that would specify an optional Media Independent Interface (MII)?