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Joel, Thank you for taking a leadership role in this important area. You pioneered 20/25G electrical interfaces, which contributed to the establishment of 25G as today’s fastest industry mainstream per lane rate. This new effort and related efforts will contribute to establishing 50G as the next industry mainstream per lane rate. While focus on the details of the electrical interface is important to making progress, it will be beneficial to have continued participation by the full 802.3bs project. High-volume, low-cost 10G and 40G have tightly coupled electrical and optical interfaces, specifically SFI and XLPPI (un-retimed) for SFP+ and QSFP+, respectively. The excellent work in 802.3bm has now established a tightly coupled electrical and optical interface (CAUI-4 with .bj KR4 FEC) as the basis of high-volume low-cost 100G. All future 100G slots will use the .bm defined electrical interface, as will 25G single lane slots. A lesson from the success at 10G, 40G and 100G is to recognize that high-volume low-cost 400G, as well as 40/50G single lane and next gen 100G, will have tightly coupled electrical and optical interfaces. One way to do this is to follow the lead of 802.3bj and 802.3bm and consider defining several FECs that can support a range of copper, MMF and SMF 50G per lane applications. One possible discussion starting point is the set of KR4, KP4 and BCH FECs, which would provide a range of coding gains and operating BERs. In .bm we already established the precedent of selecting different FEC port configurations for different PMDs; CAUI-4 with no FEC supporting LR4, and CAUI-4 with KR4 FEC supporting SR4. Tight coupling requires careful allocation of FEC gain and operating BER for the electrical and optical portions of the link, which is an effort that requires participation by all 802.3bs contributors.
Chris From: Joel Goergen (jgoergen) [mailto:jgoergen@xxxxxxxxx] All Please let Vasu and myself know if you would be interested in participating in consensus building around the following topics
Please reach out to Vasu and myself RATHER then a "reply all" to this reflector. This is a consensus building meeting only towards developing 400GbE electrical interfaces proposals that Vasu and I have been trying to converge on. The straw polls that we did in San Diego indicate we need to drive hard on electrical consensus. Thanks Joel / Vasu |