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Hi Chris, Xuyu, my understanding was the task force technically discussed over the last three years about 400GBASE-DR4 option and included 100G single lambda PAM4 into the 802.3bs. This because it was assumed the best and feasible (in terms of technology, costs, yields and time to market) option. We trust the IEEE 802.3bs 400Gb/s Ethernet task force did it, over all interface implementation we selected. For instance 400GBASE-FR8/LR8 PAM4 technology implementation was selected against 400GBASE-FR4 PAM4, DMT, 400GBASE-FR8/LR8 (50G) NRZ. 100G single lane it’s a generic nomenclature, but
100GBASE-DR it’s not. It implies propagation over 500m single-mode fiber (3dB loss), so it’s the same technical problem. If we’re saying that 100GBASE-DR is not a straightforward derivation of 400GBASE-DR4 PAM4 which is already defined into 802.3bs standard, we’re saying that 400GBASE-DR4 wasn’t built on above bases,
so better to drop from 802.3bs if there are better solutions. But at this point better to discuss again merits for 200GBASE-SR8, 200GBASE-DR2, 200GBASE-FR4, and 200GBASE-LR4 PMDs too, so to find better technologies and implementation with respect what the
400Gb/s task force selected to be in July this year. Marco Just a feedback, daily we have customers asking for compatibility even across different standards solutions even for interface without the same suffix (ER/LR, LRM/LR etc…), as well 10GBASE-SR/100GBASE-SR10/40GBASE-SR4
compatibility for data center application became a given for them. From: Xuyu (Helen) [mailto:helen.xuyu@xxxxxxxxxx]
I agree with chris’s
point. 100G single lane is one of important solutions for future research and need solid work. Including this to bs will bring an expected debate and delay.
发件人: Chris Cole [mailto:chris.cole@xxxxxxxxxxx]
John
Further, given the broad and substantial research effort into 100G single wavelength by the optics industry, it is best for 802.3 to let those efforts play out, and not engage in more crystal balling.
802.3 is not the best place to first report and debate fundamental research results. The right place for this are refereed journals and technical conferences.
Chris From: John D'Ambrosia [mailto:jdambrosia@xxxxxxxxx]
So you are saying do something different than what is agreed upon for dr4?
From: Chris Cole [mailto:chris.cole@xxxxxxxxxxx]
John, 100GBASE-DR implies nothing about modulation format. It simply designates a single lane 500m interface. Modulation would be selected based on technical and other merit. Compatibility with a 4x standard
would be a consideration but hardly an overriding one. Chris From: John D'Ambrosia [mailto:jdambrosia@xxxxxxxxx]
Chris, Yes I am ? anything differing than what is being done in .3bs will add delay ? but your assumption was not clear from your use of 100G-DR nomenclature.
However, it seems to me that there is a hard argument to use something different for a single lane approach than what is used for a x4 lane approach.
John From: Chris Cole [mailto:chris.cole@xxxxxxxxxxx]
John,
We are once again reminded that trying to predict the future by more than one technology generation ahead is a low probability of success activity and therefore should not be done in standards bodies.
From: John D'Ambrosia [mailto:jdambrosia@xxxxxxxxx]
Chris, I am not getting your point here ? how are we introducing further delay? We already have DR4 in the 400G standard. What additional delay will there be to just have a single lane implementation? John From: Chris Cole [mailto:chris.cole@xxxxxxxxxxx]
Hi Steve One reason we may not want to do 100GBASE-DR in 802.3bs is to not add considerably delay to the 802.3b schedule while we debate the merit of supporting measurements. And given the research results
we are seeing presented in recent technical publications and conferences, we are sure to see the modulation debate re-opened, which is an even better prescription to delay 802.3bs schedule. Chris From: Trowbridge, Stephen J (Steve) [mailto:steve.trowbridge@xxxxxxxxxxxxxxxxxx]
Hi Chris and Rob, Just to play devil’s advocate here, I think it depends on the objectives agreed in the study group. If the only stuff we have objectives to do for 200G are the same things we are doing at 400G with fewer lanes, sure, it all folds right in to P802.3bs. Specifically: We would specify 8-lane CCAUI-8 and 4-lane CCAUI-4 C2C and C2M interfaces. We would specify 200GBASE-SR8, 200GBASE-DR2, 200GBASE-FR4, and 200GBASE-LR4 PMDs. But the flies in the ointment would be if we have objectives to build a 200GBASE-SR4, 200GBASE-CR4, or 200GBASE-KR4 PMD, which I think would be quite challenging on the current P802.3bs schedule. Presumably the reason you think 100G belongs with 50G is that you assume this project needs to do interfaces like 100GBASE-SR2, 100GBASE-CR2, 100GBASE-KR2. But why wouldn’t you do, for example, a
100GBASE-DR interface in the P802.3bs project? Regards, Steve From: Rob (Robert) Stone [mailto:rob.stone@xxxxxxxxxxxx]
Chris I agree with your observation, and I have been thinking the same thing with respect to the partitioning of the work. It would seem that if possible, using the KR4 FEC for 50 and 100G would have a lot of benefits with respect to compatibility with existing MAC rates and 25G based technologies. I would expect that
it is likely we will see co-existence of 25 and 50G / lane technologies within the same environment, and if so we should make an effort when defining the logic to enable straightforward low power connections between the different generations. Using end ? end
KP4 FEC would help facilitate that. Thanks Rob From: Chris Cole [mailto:chris.cole@xxxxxxxxxxx]
The idea of rolling 200G into the 400G project is compelling. In prior discussions, we had rejected this as too late for 802.3bs TF, so it’s encouraging to see we are willing to revisit. One mental
test of why this makes sense is to consider what we would have done in 400G Study Group if we knew what we know now. Given the CFI support, it could be argued that most people would have supported both 200G and 400G. If anything, 200G is more compelling.
Chris From: John D'Ambrosia [mailto:jdambrosia@xxxxxxxxx]
Dear Task Force Participants, This email is to make sure that everyone is aware of conversations happening in the 50/100/200G Study Group Phone Conference that happened yesterday ? Dec 2. There has been discussion at how the multi-lane 100G/200G
solutions might be rolled into the 802.3bs project. To that end ? I gave a presentation at the conference call that looked at potential modifications / additions to our PAR / CSD. See
http://www.ieee802.org/3/50G/public/adhoc/archive/dambrosia_120215_50GE_NGOATH_adhoc_v2.pdf I encourage everyone to review this presentation and consider the findings on the last few pages. Individuals may wish to participate in the upcoming 50/100/200G ad hoc calls that Mr. Nowell has planned. For more information
see http://www.ieee802.org/3/50G/public/adhoc/index.html. I will be working on the meeting announcement for the January interim, and anticipate that there will be a joint session of our Task Force with the Study Groups to further consider these implications. Regards, John D’Ambrosia Chair, IEEE P802.3bs 400GbE Task Force |