Mike,
For further discussion on distinct identity please see slide #9 of https://www.ieee802.org/3/dj/public/adhoc/optics/0223_OPTX/nowell_3dj_optx_adhoc_01a_230222.pdf.
This slide addressed what Distinct Identity means per the IEEE 802 LMSC Operations Manual.
As I noted on this slide
Project Scopes or Objectives in a single project have been distinct by:
- Different media
- Different reaches
- Different number of either fibers or differential pairs of the same media
- Different number of optical wavelengths
Take for example the original IEEE P802.3df
You can see all of the various examples I am noting, where the media, number of fibers, or lambdas were sufficient to meet distinct identity.
Hope this helps.
John
From: Chris Cole <chris.cole@xxxxxxxxxxxx>
Sent: Tuesday, February 21, 2023 2:08 PM
To: STDS-802-3-B400G@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_B400G] 10km over duplex SMF objective
Hi Mike
Not one reason, but multiple reasons have been given by TF participants as to why they see distinct identity between the two objectives. One of them is support of higher reach, as for example discussed by Tom in his presentation, and identified by you.
However, a higher loss budget can be used in other ways than extending the reach, for example as I mentioned in my email in support of high loss elements like optical switches over intra-datacenter reaches, which are less than 2km.
Cedric pointed out that's what's critical is low latency which is contrary to supporting longer reaches with their commensurate higher penalties which have to be dealt with. Changing 10km to 15km would not be welcomed for this example.
DSP alignment with DR4 and FR4 is critical to LR4 cost. To some, coherent alignment with ZR and ZR+ is important, while to others it's not.
This suggests we should avoid listing all the distinctions in the objectives. One wavelength and four wavelengths are sufficient, and result in many distinctions, some of which are discussed above.
Chris
From: Mike Dudek <mdudek@xxxxxxxxxxx>
Sent: Monday, February 20, 2023 10:30 PM
To: Chris Cole <chris.cole@xxxxxxxxxxxx>; STDS-802-3-B400G@xxxxxxxxxxxxxxxxx <STDS-802-3-B400G@xxxxxxxxxxxxxxxxx>
Subject: [EXTERNAL]: RE: [802.3_B400G] 10km over duplex SMF objective
I have some concerns about this discussion and “distinct identity
“To me the question about “distinct identity” is whether there are significant differences in the objectives that would cause a customer to choose one solution over the other even if the cost of the chosen solution is higher. i.e. there is something distinctly different that out-weighs the cost factor. I’ve listed a few differences that have justified the distinct identity in my mind in the past. I’m wondering whether any of these apply in this case.
- One does not work on existing installed media, the other doesn’t
- One lends itself easily to break-out but needs more fiber.
- Different lengths of fiber are supported.
- One can inter-operate relatively easily with a different spec, the other can’t. (i.e. multi-spec modules can be created).
The only item I’ve noticed in this discussion is that the Coherent proposal can support a longer reach fiber/higher loss budget. If that is the major reason that people think there is a difference in the application then I think the objective should state that. i.e. make the additional objective. “Define a physical layer specification that supports 800 Gb/s operation over a single SMF in each direction with lengths up to at least 15 km.
From: Chris Cole <chris.cole@xxxxxxxxxxxx>
Sent: Tuesday, February 14, 2023 9:23 AM
To: STDS-802-3-B400G@xxxxxxxxxxxxxxxxx
Subject: [EXT] Re: [802.3_B400G] 10km over duplex SMF objective
External Email
Hi Tom
Thank you for your support and for your presentation which clearly illustrated the different applications at play.
Chris
From: Tom Williams (tjwill) <00001db419eaf3e1-dmarc-request@xxxxxxxxxxxxxxxxx>
Sent: Tuesday, February 14, 2023 8:52 AM
To: STDS-802-3-B400G@xxxxxxxxxxxxxxxxx <STDS-802-3-B400G@xxxxxxxxxxxxxxxxx>
Subject: [EXTERNAL]: Re: [802.3_B400G] 10km over duplex SMF objective
Hi Chris,
Thanks for initiating this discussion. I agree that this approach is good for the industry and allows each technology to focus on the benefits that bring the most value. I support this proposal.
Tom
From: Chris Cole <chris@xxxxxxxxxxxxxxx>
Date: Monday, February 13, 2023 at 7:41 PM
To: STDS-802-3-B400G@xxxxxxxxxxxxxxxxx <STDS-802-3-B400G@xxxxxxxxxxxxxxxxx>
Subject: [802.3_B400G] 10km over duplex SMF objective
Dear 802.3dj Colleagues,
During last week's meeting, there were a number of excellent presentations which gave us a clearer picture of the 10km over duplex SMF objective.
Williams showed that the IMDD LR4 solution can result in the lowest cost if it leverages high volume DR4 and FR4 [ieee802.org]. (Spoiler alert: DR4 and FR4 PHYs will support LR4.) He further showed that the Coherent LR1 solution can have an unallocated link budget which can be used to support greater reach [ieee802.org]. We know that LR1 can easily have an even greater unallocated link budget which can be used for high-loss short-reach intra-datacenter applications like optical switching. This suggests that in the Task Force there are multiple important constituencies which will not be well served by one solution.
Other presentations showed that there is important technical work that needs to be done and decisions that need to be made. An IMDD example is the FWM penalty. A Coherent example is O-band vs. C-band. The IMDD and Coherent technical issues and decisions are distinct, and their investigations are decoupled. After discussing this and process issues with our distinguished Chair, John D’Ambrosia, we would like to propose to the Task Force that we replace the following objective:
Define a physical layer specification that supports 800 Gb/s operation:
· over a single SMF in each direction with lengths up to at least 10 km,
with the following:
Define a physical layer specification that supports 800 Gb/s operation:
· over 1 wavelength over a single SMF in each direction with lengths up to at least 10 km,
· over 4 wavelengths over a single SMF in each direction with lengths up to at least 10 km.
These two objectives are distinctly different, and examples can be found in prior projects, as well in 802.3dj itself, which has objectives targeting 800 GbE 2km operation over either 4 parallel fibers or 4 wavelengths.
We would like to get your feedback on this approach, and incorporate received comments into a proposal to be made during the March Plenary meeting.
Thank you
Chris
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