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Dear TF members,
I recently participated in a channel model ad hoc call where there was discussion about creating a "current design practices" channel model and an "enhanced design practices" channel model. I believe that the general interpretation of "current" was ATCA-like and "enhanced" was the improved material/design. There was a straw poll taken on the call, and it was pretty unanimous that 1000BASE-KX and 10GBASE-KX4 should operate over the "current" channel. The poll for 10GBASE-KR was pretty much split between "current" and "enhanced".
If 10GBASE-KR supports the "current" channel model, then it would support both channels compliant with the "current" model and the "enhanced" model. This would result in only one channel model in the specification. If 10GBASE-KR supports the "enhanced" channel model, then it would only support channels compliant with the "enhanced" model. This would result in two channel models in the specification. This would mean that a 1000BASE-KX backplane that is using a channel compliant with the "current" model and not compliant with the "enhanced" model would not be able to use 10GBASE-KR over that backplane; therefore, unless the backplane has been designed with extra channels, there would be no way for the end user to upgrade that system to be a 10G backplane. The same could be said for 10GBASE-KX4 not being able to go from 4-lane to a single lane.
I know the typical response would be "duh!" I'm asking this because I'm looking at the Objectives for this project. In the Objectives, I see references to "over a single lane" with a subset of defining two PHYs for that lane and to "over the 802.3ap channel model." These strike me as implying only one channel model in the specification. If that model is "enhanced", then the results of the straw poll related to 1000BASE-KX and 10GBASE-KX4 are invalidated. Therefore, if the TF feels very strongly about supporting the "current" channel model for 1000BASE-KX and 10GBASE-KX4, then the TF has selected a channel model and that is the one that should be used for 10GBASE-KR.
This is only my personal opinion. I'm sure that others will have opinions on this. :-)
Thanks,
Brad