Geoff,
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.
Regards,
Jugnu
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
John-
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,
Geoff
At 02:20 PM 8/14/2006 , John DAmbrosia wrote:
All,
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)?
John