The table is from the July 2022 meeting, we have a better understanding what is feasible now in regard to package and PCB losses based on Rich Mellitz and my contribution from October session.
The 1.65 dB/in or Rich 1.6 dB/in are feasible in the next 2-4 years.
In 802.3ck I proposed 16 dB with 11.9 dB allocated to the host PCB that allow up to ~10” of PCB trace length and generally this has supported high radix switch implementations.
Where people have resorted to BiPass cables and retimers generally has been to support 2 m of Cu cable, and this problem be acute at 200G!
As suggested by John and Chris, a contributions from you would provide the task force the data needed to better define and categorize different classes of AUIs.
Ghiasi Quantum LLC
Begin forwarded message:
Subject: Re: [802.3_B400G] Oct 2022 Series Webpage Update
Date: September 24, 2022 at 8:50:49 AM PDT
The last row of your table ( lengths for various media) are not sufficient for high radix applications due to high density of connections) in addition to (what you already mentioned) package loss which are >5 dB
Loss budgets should be based on reasonable optimization of the lengths and losses/in of segment of the channel(s) available in immediate future ( 2-4 years)
Dear IEEE 802.3df Participants,
Just to add what Chris said with the loss of conventional PCB based AUI gets more like CR/KR, the need for lower loss/power that can operated with end-end FEC it will require segmenting the AUIs.
The segmentation could be, see page 5
- CPC (co-packaged Cu) AUI-Type3
- NPO may work with AUI Type-3 or may need AUI Type-4.
The bigger challenge with AUI classic as the bump-bump losses >25 dB may require operating at 1E-4 that would require termination of KP4 FEC, then the total latency become 2xKP4 FEC + KP4/concatenated BCH FEC.
Just a note of cautions the assumed package loss of 5.0 dB used in the table below with further investigation is optimistic even for next Gen substrate material at least on the high radix switches.
Dear IEEE 802.3df Participants,
I trust everyone rushed to review next week's material as soon as John announced its availability, and discovered the excellent exposition by Mr. Lusted. For those with limited time and trying to decide which presentation to read, may I kindly call your attention to:
As always, Kent is gently steering us towards wisdom, which for some of us who prefer the more direct approach, is a bit too old school.
What's clear is that a single large loss AUI C2M is no longer sufficient and we should write multiple specifications to adequately meet the need of mushrooming applications, specifically:
- Traditional large loss for LR backplane, CR passive DAC, and VSR front pluggable
- New XSR for NPO, twinax-over-PCB, active copper, and XSR front pluggable
Obviously the exact loss is TBD, however a good start for the XSR value are the shorter reach examples in last year's presentation by Sam and Nathan.
In off-line discussions, there has been a lot of interest in XSR's potential to save power, which we will direct into a proposal for the next meeting. For those that would like to join us in contributing or reviewing, please send me an email so that we can put you on copy as we iterate a draft.
The proposed PAR modification to IEEE P802.3df and the proposed IEEE P02.3dj PAR have been uploaded.
For the proposed PAR modification to P802.3df, the date for Item 4.2 could not be entered as presented to the Task Force. The date proposed to the Task Force was Nov. 2023, however, the MyProject system will not permit entry of a date earlier than Jan 2024. Mr. Law has contacted IEEE SA Solutions Support regarding this issue. At this time the date of Jan 2024 has been entered for Item 4.2 with the following noted entered for 8.1 –
Item 4.2: The earliest date that Myproject would allow to be entered is Jan 2024. This prevented the entry of the desired date of Nov 2023. (A bug report has been submitted to IEEE SA Solutions Support. This item of the PAR will be updated to the desired date of Nov 2023 and this note deleted immediately upon a solution being provided.)
For the consideration of the Task Force - the motion to adopt this proposed PAR will be modified to allow modification of the PAR in accordance with the note above.
Chair, IEEE P802.3df Task Force
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