Re: [802.3BA] XR ad hoc Phone Conference Notice
There was 75% consensus for the objectives as they are
currently written. The 100m OM3 objective has been stable for 18
months. As you're know, to change or add to the objectives, there
needs to be a motion made.
Personally, I like the 100m OM3 MMF.
Eventually someone will deploy a 40GBASE-SR4 in their data
center, and the 100m OM3 reach will permit them to have the option of
upgrading to 100GBASE-SR4 when that specification is done. If they do
a 100GBASE-SR10, then they may have the ability to upgrade to 1TBASE-SR10 in the
future.
One of the greatest aspects for 100BASE-T and
1000BASE-T was the ability to re-use an existing infrastructure of Category 5
cabling. Maybe the task force could consider 100m OM3 MMF the new UTP
copper cabling?
Cheers,
Brad
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.
<snip>
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 attractive 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
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| PKOLESAR@xxxxxxxxxxxx,
STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
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| RE: [802.3BA] XR ad hoc Phone
Conference Notice |
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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 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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| STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
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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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