Re: [BP] Number of channel models
So, let me ask the obvious. What is the additional adder (as a percentage)
from a financial and power perspective, performance hit (if any) and time to
market hit doing a dual use (meaning supporting both channel models) part? I
presume that there is no free lunch.
jonathan
-----Original Message-----
From: owner-stds-802-3-blade@listserv.ieee.org
[mailto:owner-stds-802-3-blade@listserv.ieee.org]On Behalf Of Booth, Bradley
Sent: Tuesday, November 02, 2004 11:41 AM
To: STDS-802-3-BLADE@listserv.ieee.org
Subject: [BP] Number of channel models
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