I have given the CFI some more thought and I am still struggling with the inclusion of 200G in the scope of the NGMMF CFI. I have developed a short deck (attached)
that highlights my concerns. As you know, I am a huge supporter of MMF solutions and believe that MMF has lots to offer the IEEE application community going forward but remain concerned with the continued “promotion” of a duplex plant for short reach applications.
• The
case for including 200G over fewer MMF pairs in the CFI is not clear
– Is
it an upgrade path for proprietary solutions on existing duplex cabling?
– Do
customers want to deploy 200G straight away?
– I
see no upgrade path past 200G on duplex cabling
– The
identified solutions cannot support breakout
• It
is for these reasons that I cannot support 200G in the scope of the NGMMF CFI
– I
don’t think anything will come to light in the SG that will change this view
– But
I remain open to counter arguments
At this point, I will not be able to support the CFI as currently worded. I could fully support the CFI if it was focused on 400G over fewer MMF pairs which is really
what I think we are really trying to address anyway (an alternative to 400GBASE-SR16).
Global Technology & Industry Standards
Corning Optical Communications
Standards are a bridge between markets and technologies; whoever controls the bridge controls the future…
Dear Dale, thanks for those useful comments.
Dear Steve, thanks for expressing your concerns in detail. I am delighted that you fully support the 400G aspect of the CFI! I encourage you to bring your concerns over 200G duplex to the Study Group that I hope will meet in January, for
a full and fair hearing.
If I followed your suggestion, then you and I would effectively be making the decision for everyone about whether 802.3 will consider 200G duplex PMDs.
If I keep 200G duplex in scope – as suggested by the Wells Fargo use-case shown in the CFI draft from Charlotte (slide 16 in link) – then I am allowing a 75% vote in the Study Group to determine what 802.3 should do.
To me the choice between those two options is clear: we should form a Study Group and hear presentations that are both for and against 200G duplex, then vote in March!
The gentleman from Wells Fargo who attended the NEA ad hoc session in Charlotte has expressed interest in contributing additional material regarding the application of 200G duplex over MMF during the Study Group. I think many people would
want to see that. You may wish to make a contribution against an objective for 200G duplex PMDs. Should we deny the community the opportunity to hear this debate?
I hope you can be persuaded that this is the right approach within our process, with a greater chance of leading to the optimal outcome for the Ethernet ecosystem. In the meantime, I have removed your name as a supporter, per your note
below.
As to your detailed points, Dale Murray has expressed well many of my specific thoughts on why we should consider 200G duplex in the Study Group.
With regard to OM5, I have reduced the references to two (2) in the draft we will review Friday (linked below); this is the minimum. MMF progressed from OM1 to OM2 to OM3 to OM4 as we moved from LEDs to VCSELs and higher speeds. This
is the progression of technology. In that same vein, it runs counter to all indications to pretend that WDM and OM5 have no role to play within the scope of this CFI. TIA completed standardization of OM5 by 2016 with no dissenting votes. All major MMF fiber
and structured cabling companies voted “yes.” OM5 MMF has also successfully progressed through the international fiber & structured-cabling standards bodies, including IEC 60793-2-10ed6 where OM5 was approved with no dissenting votes. OM5 has a natural role
to play as multiple wavelengths are used over MMF. Ethernet is not a platform for promoting any technology for its own sake, but it is a place where technology evolves and is codified. It is our responsibility to recognize and consider advancements that are
relevant to this CFI.
Robert Lingle, Jr., Ph.D.
Director, Market & Technology Strategy
<image001.png>
Your Optical Fiber Solutions Partner™
2000 Northeast Expy | Norcross, GA 30071
Office: 770-798-5015
Mobile: 404-886-3581
Steve,
I also questioned whether the CFI effort should include a 200G duplex MMF solution and a while back I spoke with Robert about it. He had at least one request for it to be included and he,
as the leader of this effort, has chosen to let the process play out rather than screen out objectives prior to becoming a study group.
I have since spoken with a vendor who sees a need for a 200G MMF duplex solution. While I am not yet clear on the market opportunity it might have, I guess it depends on whether 200GbE ever
becomes an enterprise speed. I do see the lag shrinking between cloud and enterprise so it could happen. I also note the MMF duplex solutions are mostly for brownfield applications so they need to be considered independently of SR4 solutions. Having both is
not a conflict.
You correctly note that the IEEE did not support a duplex solution at 40G and 100G, but the need was there and the need is being satisfied by both proprietary and MSA efforts. As to not having
40G and 100G MMF duplex solutions, I note that we also did not standardize PSM4 at 40G or at 100G, but we are now doing so at 400G.
The decisions made in 802.3ba were done in 2008 and much has changed since then.
You correctly note that 802.3cd rejected a duplex 100G MMF solution (SR1.2) and instead chose an SR2 solution. It was my impression that .3cd prioritized breakout opportunity over brownfield
MMF duplex. Will we see the applications that were suggested for SR2? I’m not sure. We will see deployment of both proprietary and MSA-based 100G duplex MMF solutions and we at LightCounting project a good future for this product category. So I respectfully
disagree that because duplex solutions were not standardized at 40G and 100G that sets an unchangeable precedent.
As to OM5 reflected in the CFI deck, it’s has been reduced considerably to mostly “FYI” material. Reach is important, especially in multimode so it’s not wrong to suggest there is a new technology
that could extend reach. The poll on reach you cite from 802.3ba was many years ago when data centers were much smaller. Since then, extended short reach (eSR) modules have been popular at 40G and this will repeat at 25G and 100G.
At this stage of the process, we need to get a study group formed to consider next-gen MMF objectives. If an objective is proposed in a study group for 200G MMF duplex, it will need to be
defended and achieve the necessary vote threshold. The process will play itself out.
Dale Murray
In advance of the CFI meeting in Orlando, I would like to comment on the CFI wording. I fully support the work on NG MMF but cannot support the proposed wording of
the motion. I am asking the group to consider modifying the wording to focus on 400 Gb/s PHYs over Fewer MMF Pairs than Existing Ethernet Projects and removing 200 Gb/s.
My rationale is as follows:
There is motivation to support a 400G solution over fewer pairs as an alternative to 400GBASE-SR16.
We are standardizing 200GBASE-SR4 in 802.3cd and there is no precedent for supporting a duplex solution at 200G – at least it was not supported at 40G or 100G – so
why are we now thinking that it will be supported at 200G?
In IEEE 802.3ba, we defined 40GBASE-SR4; a proposal for a duplex solution was rejected by 802.3ba
· It
was noted that a 4 lane parallel short wavelength based PMD is the highest density, lowest power consumption and lowest cost 100m solution and I don’t think that has changed.
· A
straw poll to consider a duplex option yielded the result to develop a duplex based standard outside of 802.3ba by more than a 2 to 1 margin; several voted for the case that no duplex MMF solution was needed.
· 40GBASE-SR4
was adopted 85-0
In IEEE 802.3bm, we defined 100GBASE-SR4; a proposal for a duplex solution was not proposed in 802.3bm
· To
my recollection, no 100G MMF duplex option was proposed
In IEEE 802.3cd, we are defining 100GBASE-SR2 and 200GBASE-SR4; a proposal for a duplex solution (100GBASE-SR1.2) was rejected by 802.3cd
· Both
a parallel and a duplex solution were considered in the 100G work
· A
straw poll showed support for the parallel solution over the duplex solution by a 3 to 1 margin
· A
subsequent motion to standardized the parallel solution passed by a 6 to 1 margin
There seems to be no reason to now support a duplex 200G solution when we have not standardized a duplex solution at 40G duplex nor a duplex solution at 100G.
Regarding the inclusion of OM5 in the CFI, I think it is a distraction that takes away from the main point of the CFI. It is clear that all perceived solutions can
be supported on OM3 and OM4 and while some are purporting support for a 150m link length on OM5, this does not seem to be a requirement based on a poll in 802.3ba:
The goal for extending the reach on MMF should be:
F. there should be no goal for extended reach
It is for this reason that I would remove the slides on OM5; the inclusion of a 200G solution seems like an attempt to legitimize a certain transceiver/fiber combination
(4 wavelength SWDM over OM5) when it is not really needed.
So, to summarize, I will fully support the CFI if it is worded as follows:
Motion at Closing Plenary:
Move that the IEEE 802.3 Ethernet Working Group authorizes the formation of a study group to develop a Project Authorization Request (PAR) and Criteria for Standards
Development (CSD) responses for "Next-generation 400 Gb/s PHYs over Fewer MMF Pairs than Existing Ethernet Projects"
I will withdraw my support of the CFI if it is worded as follows:
Motion at Closing Plenary:
Move that the IEEE 802.3 Ethernet Working Group authorizes the formation of a study group to develop a Project Authorization Request (PAR) and Criteria for Standards
Development (CSD) responses for "Next-generation 200 Gb/s and 400 Gb/s PHYs over Fewer MMF Pairs than Existing Ethernet Projects"
Global Technology & Industry Standards
Corning Optical Communications
Standards are a bridge between markets and technologies; whoever controls the bridge controls the future…
We will hold two telecons related to Next-Gen MMF PMDs from Noon to 1pm Eastern US time on Friday October 13th and Friday October 27th.
The agenda for the first call will be to discuss the wording of a motion to authorize a Study Group to be made at the closing Plenary in Orlando.
We will also discuss any final tweaks to the CFI deck.
The second call will only be held if there is any business not finished on the first call.
Call-in and web information below
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Robert Lingle, Jr., Ph.D.
Director, Market & Technology Strategy
<image001.png>
Your Optical Fiber Solutions Partner™
2000 Northeast Expy | Norcross, GA 30071
Office: 770-798-5015
Mobile: 404-886-3581
<Roadmap comparison.pptx>