Re: [802.3BA] XR ad hoc Phone Conference Notice
I agree that the objective states "at least 100m
on OM3 MMF", but the question is what is the cost point for exceeding the
100m? Can you provide data that shows the relative cost between 10
parallel MMFs vs. 1 SMF running 2-400m?
There was also another reason that 100m was seen as a
good reach. At these data rates, it may take a long time for a UTP or any
twisted-pair solution to satisfy the typical 100m data center reach.
Failure to provide a cost effective solution for that market has a direct impact
to the broad market potential.
Just to be crystal clear, the objective
"at least 100m on OM3 MMF"
agree that 100m meets that objective, Kolesar and I presented data in November
2006 noting that 100m was not adequate. We were assured that longer link lengths
could be accommodated because of the words "at least." This was my beef in
survey of our customers 0/20 said that 100m was adequate and that MMF was
preferred over SMF where possible.
don't understand why it is OK to have two link length objectives for SMF (and we
considered a third (2-4km)) but we can't have two link length objectives for
MMF. Better yet from my point of view is to have one PMD that satisfies both -
the premium that we are talking about at the module level (estimated at ~20%) is
in the noise for 40/100.
a compromise here of some sorts.
That's an excellent point. I'm glad that Jeff
brought this up.
The objectives state 100m on OM3. That is the
requirement of the project and one by which the draft standard will be
judged. There is no requirement to satisfy a
Sr. Principal Engineer, AMCC
If I interpret correctly, you are saying that all users
should amortize the cost of very few who need extended reach.
We need to be careful how we proceed here - we should not
repeat the mistakes of the past if we want successful standard.
P.O.Box 218 (mail)
1101 Kitchawan Road, Rte.
Yorktown Heights, NY 10598
||07/09/2008 10:29 PM
||Re: [802.3BA] XR ad hoc Phone Conference
Thanks for your
comment. You missed one critical point that there is cost increase from OM3 to
OM4. If you take ribbon cable cost in perspective, OM4 option is possibly the
largest of the 4 options.
Besides, the use of OM4 requires to tighten TX
specs which impact TX yield, so you are actually compromising the primary goal.
From: Jeff Maki [mailto:jmaki@xxxxxxxxxxx]
Sent: Wednesday, July 09, 2008 7:02 PM
Subject: Re: [802.3BA] XR ad hoc
Phone Conference Notice
Dear MMF XR Ad Hoc Committee Members,
I believe our current objective
of “at least 100 meters on OM3 MMF” should remain as a primary goal, the
baseline. Support for any form of extended reach should be considered only
if it does not compromise this primary goal. A single PMD for all reach
objectives is indeed a good starting premise; however, it should not be
paramount. In the following lists are factors, enhancements, or approaches
I would like to put forward as acceptable and not acceptable for obtaining
increase for the baseline PMD (optic) in order to obtain greater than 100-meter
2. EDC on the system/host board in any
3. CDR on the system/host board as part
of the baseline solution
4. EDC in the
baseline PMD (optic)
5. CDR in the baseline
1. Use of OM4
2. Process maturity that yields longer
reach with no cost increase
In summary, we should not burden the baseline
solution with cost increases to meet the needs of an extended-reach
Jeffery J. Maki,
Principal Optical Engineer
Juniper Networks, Inc.
1194 North Mathilda Avenue