Re: [802.3BA] XR ad hoc Phone Conference Notice
I will throw out my two cents worth.
There has been a lot of discussion on this thread about how
to extend the reach through various techniques. However everyone seems to be
missing (or avoiding) what appears to be the obvious question.. Doesn't the fact
that we are even discussing extended reach mean that the initial objective is
inadequate (and needs to be changed ?).
I don't see anyone asking for (or discussing) extended
reach for the 10km/40km PMDs.
I am still puzzled by the comment "very few who need
I think we have misinterpreted the data; my belief is that
100m does in fact cover a significant percentage of the overall links (there is
still some debate over the definition of "significant") but that most
datacenters have link lengths that exceed 100m. In our survey of customers, not
one said that 100m is adequate. Customers want a solution that covers all their
needs - it doesn't help them to have a solution that only covers a percentage of
their links even if the number exceeding 100m is less than the number of
How do we reconcile that with our
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