Re: [802.3BA] XR ad hoc Phone Conference Notice
All,
I think Paul's suggestion is a good one; I would like to
add some other input (in the form of questions) from my point of
view:
1. Do we have the right MMF objective (support
at least 100m on OM3 fiber)?
My data suggests that we don't; we have tried to come at
this from two different directions, trying to be as unbiased as possible in
assessing the situation. I presented Corning sales data in November 2006
(see http://www.ieee802.org/3/hssg/public/nov06/swanson_01_1106.pdf).
This data showed a need to support a link length longer than 100m and I
recommended that we support 200m at that time.
We also polled our customers, offering three options, a low
cost, single PMD at 100m on OM3, a slightly higher cost single PMD at 150-200m
on OM3, and a third option that would specify two PMDs consisting of both option
1 and option 2. The results were overwhelmingly in favor of Option 2, a single
PMD at longer length. A small number supported Option 3 (2 PMDs) but NONE
supported Option 1. While it is true that many of our customers have a
substantial portion of their link lengths that are less than 100m, they all have
link lengths longer than 100m. One customer noted that more than half of his
data center had link lengths longer than 100m.
All the data for datacenter seems to suggest that 100m is
TOO SHORT to cover a significant portion of the datacenter
application.
Pepeljugoski presented new data yesterday on HPC link
lengths that show 85% being less than 20m and 98% less than 50m. This might
suggest that 100m is TOO LONG for HPC applications.This leads to
another question of whether there is any economic or technical advantage to
a shorter MMF objective for HPC?
2. Is there consensus on supporting a longer reach
objective for MMF?
I think there is, others on the call yesterday did not. I
base my opinion on the straw poll conducted in Munich:
Straw Poll #15: Should we continue to work on a proposal
for an annex to extend the reach of a
40GBASE-SR4 and 100GBASE-SR10 in addition to the proposal(“pepeljugoski_01_0508.pdf”) as in
“jewell_01_0508.pdf”.
Yes: 55
No: 3
3. Could we achieve 75% support for adding a new MMF
objective?
I don't
know but if we could not, I would be forced to vote against adopting the current
MMF baseline proposal (which I don't want to do) and I think others may also.
This may or may not lead to an impasse similar to what we experienced in
802.3ae.
I
understand the concern that adding the objective without a clear consensus on
how to support the new objective could lead to delay but I have found this
committee to be very resourceful in driving to a solution after we have made a
decision to go forward. 40G is one recent example of a situation where no
consensus turned very quickly to consensus.
I think
adding a new objective is the right approach and in the long run will save the
task force valuable development time.
4. Can we agree on the right assumptions on the 10G
model to evaluate the various proposals?
Everyone seems to be using slightly different variations of
the model to evaluate the capability of the proposal; we need to agree on a
common approach of analysis.
5. Can we not let the discussion on OM4 cloud the
decision?
We can get extended link lengths on OM3. By achieving
longer lengths on OM3, even longer lengths will be possible on OM4 with the same
specification. What I don't want people to think is that OM4 is required to get
longer lengths.
6. Summary
John D'Ambrosia has provided advice that if we want to move
forward with a new MMF objective, July is the time to do it - if we delay the
decision, it is guaranteed to delay the overall process. Some might think if we
make the decision, it will delay the overall process but we don't know that yet.
I don't think adding an informative specification on a PMD is the right way to
go - let's get the MMF objective(s) right - we owe it to ourselves and to our
customers. To do anything less is just avoiding the issue. Let's get the
objectives set, get the assumptions correct and utilize the process set up by
Petrilla and Barbieri to drive toward the hard decisions that we are all very
capable of making.
Sincerely,
Steve Swanson
Alessandro,
I'd like to continue your thread with some observations
that have driven me to certain conclusions, and to follow that with a suggestion
about how to parse the approach and drive to a consensus position.
First let's consider what various customers
are telling us. The Corning survey of their customers, which has been
presented to the Ethernet Alliance, the XR ad-hoc, and will be presented next
week to 802.3ba, shows that the large majority of customers want a single PMD
solution that can provide 150m on OM3 and 250m on OM4. A minority were
willing to accept a two PMD solution set that delivers the lowest cost PMD to
serve up to 100 m and a second PMD to serve the extended distances as above.
Not a single response indicated a preference for a solution limited to
100m. We also hear strongly expressed opinions from various system vendors
that a longer distance solution is not acceptable if it raises cost or power
consumption of the currently adopted 100m PMD. Under these conditions, and
given the options presented and debated within the XR ad-hoc, I believe you are
justified in concluding that a single PMD cannot satisfy all these constraints.
Yet it is clear to me that the market will demand a low-cost PMD that can
support more than 100m to fulfill the distance needs of data centers.
Therefore I conclude that the correct compromise position is to develop a
two-PMD solution. If the committee does not undertake this development, it
is likely that several different proprietary solutions will be brought to the
market, with the net result of higher overall cost structures.
So let's
consider how to choose from among the various proposals for an extended reach
PMD and let the determination of how to document it within the standard be
addressed after that.
I would
propose a series of polls at next week's meeting designed to gauge the
preferences of the Task Force. I do not think that any XR proposal will
garner >75% at the outset, so I would propose the use of Chicago rules
wherein members may vote for all the proposals they find acceptable. From
this we can see which of the solutions is least acceptable. Then through a
process of elimination from the bottom, and repeated application of Chicago
rules for the remainder, finally determine the most acceptable solution.
Depending on the degree of
maturity of the specifications or other considerations for the chosen solution,
the Task Force will be better able to determine how it should be handled within
the standard. For example, a proposal with a maturity on par with the
adopted baseline could be put forth under a new objective without undue concern
of becoming a drag on the timeline, while a proposal of lesser maturity could be
placed in an annex without an additional objective.
Regards,
Paul Kolesar
CommScope
Inc.
Enterprise Solutions
1300 East Lookout Drive
Richardson, TX 75082
Phone: 972.792.3155
Fax: 972.792.3111
eMail:
pkolesar@xxxxxxxxxxxxx
| "Alessandro Barbieri
(abarbier)" <abarbier@xxxxxxxxx>
07/10/2008 04:43 PM
|
Please respond
to
"Alessandro Barbieri (abarbier)"
<abarbier@xxxxxxxxx> |
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To
| STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
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cc
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Subject
| Re: [802.3BA] XR ad hoc Phone
Conference Notice |
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Matt,
here is my
*personal* read of the situation in the XR ad hoc:
a) I think there
could be consensus on supporting XR, as long as we pick a solution that does not
impact the cost structure of the 100m PMD. Because of that I also don't feel a
single PMD is realistic at this point.
a) The trouble however is that there is
no consensus (>75%) on any of the technical proposals. No one proposal has a
clear lead over the others.
Of the three options you list below, I think adding
an objective for a ribbon XR PMD could have a major impact on the project
schedule, because it seems we are nowhere near technical consensus. We could
drag the discussion for several TF meetings...I am not sure delaying the project
over this specific topic is worth it.
We can always resort to non-standard solutions to fulfill
market requirements we can't address within IEEE, or come back in the future
with another CFI.
At the end of the conference call earlier today I requested
that we get together after hours next week to see if we can accelerate consensus
building.
All the data is on the
table now, so if we don't show any material progress, I am not sure we should
extend this ad hoc.
Alessandro
From: Matt Traverso
[mailto:matt.traverso@xxxxxxxxx]
Sent: Thursday, July 10, 2008 10:07
AM
To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re:
[802.3BA] XR ad hoc Phone Conference Notice
Colleagues,
I
feel that we are coming to a situation similar to the impasse at 40G vs. 100G
where different participants call different segments of the networking industry
their customer.
For MMF, I'd like to see an optimized solution at
100m per all of the work that has been done.
I'd like to
understand if folks feel that a different status for the extended reach
a)
Informative
b) Normative
c) New objective
would significantly alter
the technically proposed solution from the Ad Hoc. Opinions?
Chris,
The case of slow market/industry transition from LX4
to LRM is one of the reasons why I would like to see the industry adopt 40G
serial from the launch. The slow adoption of LRM has primarily been
limited by end customer knowledge of the solution. 40G serial technology is
available.
thanks
--matt
Hi Gourgen,
Some numbers might help clarify what
close to 0 means.
For 2008, Lightcounting gives a
shipment number of approximately 30,000 for 10GE-LRM (and for 10GE-LX4 it's
about 60,000.) So close to 0 would apply if we were rounding to the nearest
100K. As an aside, 10GE-LRM supports 220m of MMF, not 300m.
300m of OM3 is supported by 10GE-SR,
which Lightcounting gives as approximately 400,000 in 2008, so that would be
close to 0 if we rounding to the nearest 1M.
Another interesting sideline in looking
at these numbers is that 2 years after the 10GE-LRM standard was adopted in
2006, despite the huge investment being made in 10GE-LRM development, and
despite very little new investment being made in 10GE-LX4, the 10GE CWDM
equivalent (i.e. 10GE-LX4, 4x3G) is chugging along at 2x the volume of the 10GE
Serial solution that was adopted to replace it.
This should put some dim on hopes that
very low cost 40GE Serial technology can be developed from scratch in two years
and ship in volume when the 40GE standard is adopted in 2010.
Chris
From: Gourgen Oganessyan [mailto:gourgen@xxxxxxxxxxx]
Sent: Wednesday, July 09, 2008 8:02
PM
To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3BA] XR ad hoc Phone Conference
Notice
Petar,
Well, sadly that's what has been
happening in the 10G world, people are forced to amortize the cost of 300m reach
(LRM), while in reality the number of people who need 300m is close to 0.
That's why I am strongly in support of
your approach of keeping the 100m objective as primary goal.
Frank, OM4 can add as much cost as it
wants to, the beauty is the added cost goes directly where it's needed, which is
the longer links. Alternatives force higher cost/higher power consumption on all
ports regardless of whether it's needed there or not.
Gourgen Oganessyan
Quellan Inc.
Phone: (630)-802-0574 (cell)
Fax:
(630)-364-5724
e-mail: gourgen@xxxxxxxxxxx
From: Petar Pepeljugoski [mailto:petarp@xxxxxxxxxx]
Sent: Wednesday, July 09, 2008 7:51 PM
To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3BA] XR ad hoc Phone Conference
Notice
Frank,
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.
Regards,
Peter
Petar Pepeljugoski
IBM Research
P.O.Box 218 (mail)
1101
Kitchawan Road, Rte. 134 (shipping)
Yorktown Heights, NY 10598
e-mail:
petarp@xxxxxxxxxx
phone: (914)-945-3761
fax:
(914)-945-4134
Hi Jeff;
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.
Frank
From: Jeff Maki [mailto:jmaki@xxxxxxxxxxx]
Sent: Wednesday, July 09, 2008 7:02 PM
To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
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 extended reach.
Not Acceptable:
1. Cost increase for the baseline PMD (optic) in order to obtain
greater than 100-meter reach
2. EDC on the system/host board in any case
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 PMD (optic)
Acceptable:
1. Use of OM4 fiber
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 solution.
Sincerely,
Jeffery
Maki
————————————————
Jeffery J. Maki, Ph.D.
Principal Optical
Engineer
Juniper
Networks, Inc.
1194 North
Mathilda Avenue
Sunnyvale, CA 94089-1206
Voice +1-408-936-8575
FAX +1-408-936-3025
www.juniper.net
jmaki@xxxxxxxxxxx
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