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Mike, Wild ideas are good at this time. Our 500 meter reach objective would be best if a common form factor could be used to also meet our 100 meter objective. Copper cabling and our 20 meter objective could be in
yet a different form factor, but a common one for all would certainly be better, at least not precluded. If CAUI-4 departs from CEI-28G-VSR for supporting 100GBASE-LR4 such as requiring FEC as a chip to module electrical interface (encode and decode locally, not over the whole link), then I think the market will
opt to stick with CEI-28G-VSR as the electrical interface, since the choice of electrical interface is optional for 802.3 PMDs. We need to assume many will use 802.3bm optics and never implement 802.3bj backplane. In this case, the market may demand very much that 802.3bm links not employ FEC to avoid additional latency. It may all
just be a matter of perception, which we will need to try to manage. Jeff From: Mike Dudek [mailto:mike.dudek@xxxxxxxxxx]
Sorry I wasn’t able to attend the meeting. Here are a few thoughts. Some rather wild!!! I think that the question of what happens without FEC may be of interest (is that perhaps the 20m option? With reduced power (in the host IC) and reduced latency.
Also although 802.3bj is defining the backplane and copper interfaces with FEC always on in the Tx it doesn’t mean that it is always on in the Rx. I think that this could also affect the definition of CAUI-4. I think there is a question as to whether FEC is mandatory in CAUI-4 (host to module (so far it’s been assumed CAUI-4 needs to meet its BER objective
without FEC). If it is then when connecting to a 100GBASE-LR4 with a 4 lane interface we would require the FEC decoder/encoder in the module to drive the non-FEC 100GBASE-LR4.
One other really wild suggestion is whether our “low cost single-mode objective” might be based on the 100GBASE-LR4, still meeting 10km but with FEC. Mike Dudek QLogic Corporation Senior Manager Signal Integrity 26650 Aliso Viejo Parkway Aliso Viejo CA 92656 949 389 6269 - office. From: Jonathan King [mailto:jonathan.king@xxxxxxxxxxx]
Dear all Here are draft minutes of the 25th October MMF Ad Hoc meeting. The presentation will be posted shortly on the MMF Ad Hoc web page. Please let me have any suggested amendments – thank you !
In particular, please check that I have your listed name and affiliation correctly (there were a few single names without affiliation I couldn’t work out ). As provisionally agreed on the call, the next MMF Ad Hoc meeting will be on Thursday 8th November at 8:00 am Pacific. Best wishes jonathan |