Chris,
thanks for your input. I am glad
that our opinions are aligned on the need to address a longer reach. As
I stated to Joel, I am favoring a second longer-reach PMD, not a change
to the existing 100m objective.
My hope is that this continued discussion
solidifies the Task Force's position that a longer reach solution is of
key importance, as we do not yet know if a sufficient number of the Task
Force membership have been convinced.
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
Chris Cole <chris.cole@xxxxxxxxxxx>
07/11/2008 11:01 AM
Please respond to
Chris Cole <chris.cole@xxxxxxxxxxx>
To
STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
cc
Subject
Re: [802.3BA] XR ad hoc Phone Conference
Notice
Paul,
Thank you for continuing to put in effort to answer the difficult question
as to what is the distribution of reaches in various types of data centers.
Because there are many applications, some of which you discuss in your
latest email, different distributions can be arrived at.
What has been clearly communicated by many suppliers and end users is that
100m OM3 reach is acceptable for many important applications and that this
set of applications must be supported at the lowest possible cost. This
includes HPC, but also includes other applications. This is a message given
to us by many of our customers, and we intend to address their requirements.
Through the diligence of yourself, Steve and others, we have been shown
that there are applications requiring reaches longer then 100m.
Given this common understanding, it is not constructive to continue to
argue to increase the lowest reach to something more then 100m, or to argue
that reaches greater then 100m do not need to be supported. We already
have a baseline proposal for supporting a 100m OM3 reach, so we need to
focus our efforts on defining an additional proposal on how to support
extended reach, and how to fold that into the 100m OM3 baseline proposal.
My preference is for an informative annex or annexes, but there are other
ways this can be done, although perhaps requiring more effort.
Chris
________________________________________
From: Paul Kolesar [mailto:PKOLESAR@xxxxxxxxxxxx]
Sent: Friday, July 11, 2008 7:33 AM
To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3BA] XR ad hoc Phone Conference Notice
Steve,
thanks for furthering the discussion. Your views make sense to me.
I'd like to examine the super computer cabling distance distribution that
Petar shared with us yesterday in a bit more detail. I've plotted
it to allow folks to see it in graphical form.
This data has several features that are remarkably similar to that of general
data center cabling.
1) The distribution is highly skewed towards the shorter end of the distribution.
2) The distribution has a very long tail relative to the position of the
mode, the most frequent length, at 20m.
3) The mode is at a distance that is one fifth of the maximum length.
The white dot on the graph represents the coordinate of equivalent coverage
relative to the 100m objective to the data center cabling distribution.
Speaking to Steve's point that questions the correctness of the 100m
objective for HPC environments, I would venture to say that a 25m objective,
which is the roughly equivalent in coverage to the 100m objective we are
attempting to apply to data centers, would not be satisfactory for the
HPC environment, as it would leave a significant portion of the channels
without a low-cost solution.
It is clear that the 100m objective is a near-perfect match to the needs
of HPC. Yet I do not believe that HPC should be the primary focus
of our development. We must be developing a solution that properly
satisfies a much larger market than this or we are wasting our time. Indeed,
given that latency is a major performance concern for HPC, the vendors
of such machines may prefer to use InfiniBand. This could mean that
one of the primary customers to which we have tuned our present objective
will actually not use Ethernet, but will benefit anyway by driving InfiniBand
to adopt the same 100m PMD specs that 802.3ba defines. This possibility
reinforces my perspective that we need to properly address a broader set
of customers - those that operate in the general data center environment.
It is clear from all of the data and surveys that remaining only
with a 100m solution misses the mark for this broader market. Continuing
under this condition will mean that the more attrac!
tive solution for links longer than 100m in the general data center will
be to deploy link aggregated 10GBASE-SR. Its cost will be on par
and it will reach the distances the customers need in their data centers.
Is this the future you want for all our efforts, or do you want to face
the facts and address the issue head on with a solution that gives data
center customers what they need?
Next week these decisions will be placed before the Task Force. I
hope we choose wisely.
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
"Swanson, Steven E" <SwansonSE@xxxxxxxxxxx>
07/11/2008 07:32 AM
To
PKOLESAR@xxxxxxxxxxxx, STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
cc
Subject
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.
Kolesar presented his company's sales data in September 2006 (see http://www.ieee802.org/3/hssg/public/sep06/kolesar_01_0906.pdf).
His data also suggested that longer link lengths were needed and he recommended
150m at that time.
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
________________________________________
From: Paul Kolesar [mailto:PKOLESAR@xxxxxxxxxxxx]
Sent: Thursday, July 10, 2008 7:19 PM
To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3BA] XR ad hoc Phone Conference Notice
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 th!
e 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
Subject
Re: [802.3BA] XR ad hoc Phone Conference Notice
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
From:
Frank Chang <ychang@xxxxxxxxxxx>
To:
STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Date:
07/09/2008 10:29 PM
Subject:
Re: [802.3BA] XR ad hoc Phone Conference Notice
________________________________________
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
----------------