From: Jeff Maki [mailto:jmaki@xxxxxxxxxxx]
Sent: Friday, July 11, 2008 11:41 AM
To: STDS-802-3-HSSG@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3BA] XR ad hoc Phone Conference Notice
Paul,
I am not sure if you
meant this, but I will say that the current objective of 100 meters should NOT
be shortened.
Jeff
————————————————
Jeffery
J. Maki, Ph.D.
Principal
Optical Engineer
Juniper
Networks, Inc.
Voice
+1-408-936-8575
FAX
+1-408-936-3025
www.juniper.net
————————————————
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 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.
Phone:
972.792.3155
Fax: 972.792.3111
eMail:
pkolesar@xxxxxxxxxxxxx
|
" 07/11/2008 07:32
AM |
|
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
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
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
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
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.
Phone:
972.792.3155
Fax: 972.792.3111
eMail:
pkolesar@xxxxxxxxxxxxx
|
"Alessandro
Barbieri (abarbier)" <abarbier@xxxxxxxxx>
07/10/2008 04:43
PM
|
|
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
e-mail: petarp@xxxxxxxxxx
phone:
(914)-945-3761
fax: (914)-945-4134
|
From:
|
Frank Chang
<ychang@xxxxxxxxxxx>
|
|
To:
|
|
|
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.
Voice
+1-408-936-8575
FAX
+1-408-936-3025
www.juniper.net
jmaki@xxxxxxxxxxx
————————————————