I would like to suggest that we first
agree on criteria that the proposals should meet. All proposals should
include description what the test is stressing and how it would work for
a broad class of EDC chips. I strongly believe that in this process of
developing the standard, we have thoroughly investigated the channel and
used advanced models (that were made available to the standard in various
forms) to include degradations originating in the optical portion of the
link. While doing that, we argued about percentages and statistics, while
in the meantime we have heard very little about the EDC models. The performance
of the entire link depends on ALL components, and hence, there is little
benefit into going into very detailed channel models, without using models
for the rest of the link components that give the same level of accuracy
as the fiber model. At the end, the overall accuracy will be determined
by the least accurate component model.
Based on my limited experience with
EDC chips, I believe that the current EDC chip models are rudimentary (I
would compare them to a Gaussian approximation for the MMF impulse response)
and that the standard can not develop the stressor levels with confidence
without better models. I would only commend Clariphy (Norm and Tom) for
coming forward with a model that is one step forward towards our goal of
a robust and cost effective standard. However, I would like to stress that
this is only the first step, and we need more openness from the EDC vendors.
In particular, I would like to see the now unnamed implementation penalties
be assigned names and have models that address them. Those models should
also address the interdependence with the rest of the penalties that we
have so far taken into account (and that we just added). What I say is
that the total of the all implementation penalties in magnitude may
be OK, but their individual distribution may need some tweaking.
Without better knowledge what the EDC
degradations are, and what parameters affect them, we can't develop
cost effective stress tests and there will always be the danger that something
slips through the tests that should not.
So, I believe that we have to discuss
these issues first, and then it will be easy to determine the stressor
P.S. I understand the desire of the
EDC chip vendors to protect their IP. However, I think that at this point
we do not have the sufficient level of details to develop the necessary
P.O.Box 218 (mail)
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Jim McVey <jim.mcvey@FINISAR.COM> Sent by: owner-stds-802-3-10gmmf@IEEE.ORG
03/22/2005 06:34 PM
Please respond to
"IEEE P802.3aq 10GBASE-LRM"
[10GMMF] TP3: Request for
suggested stressor levels
Hello TP3 Members,
Per our teleconference today (Tuesday March 22), I am soliciting inputs
for the TP3 stressor level. This stress level should be consistent
with the goal of practical implementation at reasonable cost and power.
Please include the rational for your suggestion.
I will summarize the suggestions identifying them as "Suggestion A",
"Suggestion B", etc. with no mention of names. My goal
is to publish this summary by close of business Thursday, March 24, 2005.
As discussed in the call, this solicitation is aimed at getting full input
from the EDC manufacturers, but suggested values from any interested party
are encouraged as well.