Joel,
The channels submitted in goergen_02_0709
and goergen_02_0904 certainly do have great value and should be used by the
working group for further work. However, they should not be used to the
exclusion of other channels that represent complete channels. Both the
signaling work and the setting of the channel limit should be based on a wide
selection of data and must include data that represents real channels. I
submit the following reasons to support this conclusion.
1) A connector
agnostic test system is a worthy goal. However, this is not achieved by
omitting the connectors. Additionally, each connector is accompanied by
two via fields with their associated breakouts. This is not well
represented by a single via transition.
2) A test
system does not necessarily take into account the tradeoffs that inevitably
occur in the design of a cost-effective, high density system.
3) We can only compare
the public data and there are significant differences. It is difficult to
predict how these differences will impact the performance for any particular
line code / equalization as illustrated in sinsky_01_0904.
Again, the test board data
from goergen_02_0709 and goergen_02_090 should be considered, but must be put
into perspective. We cannot rely exclusively on incomplete test systems
or contrived models however valuable they may be.
-Bill Peters
From: owner-stds-802-3-blade@listserv.ieee.org
[mailto:owner-stds-802-3-blade@listserv.ieee.org] On Behalf Of Joel Goergen
Sent: Friday, October 01, 2004
4:27 PM
To:
STDS-802-3-BLADE@listserv.ieee.org
Subject: [BP] Data Presented in
Goergen_02_0904
Fellow collegues,
During the back plane meeting this week in Ottawa, it was pointed out on several
occasions by one colleague that the channels submitted for review and
simulation as reported in goergen_02_0709 and goergen_02_0904 are not real
channels and therefore, should not be used by the working group in any capacity.
I've studied this concern at length and defend my work in whole as follows.
1) The intent of a connector-less test card was agreed to in part by the
members of the channel ad-hoc. It's creation, though not a new concept at
all, was to prevent a common set of test cards from becoming connector
evaluation boards by the industry. My understanding of the ATCA platform
is that this MSA has agreed to 'ONE' connector. Therefore, evaluating
comparative back planes in an ATCA environment is easy. It does not
address the diverse nature of the telecom segment, which is the primary intent
of the connector-less cards.
2) I've examined all the channel data presented to the public, as well as that
submitted to me in private. All of the public data submitted to IEEE as
presentations, and all of the private data sent to me directly correlates to
the data from the connector-less back plane cards. Do the comparison
yourself ... Look at every channel and compare it to all the data submitted and
you will see the same likeness. The data speaks for itself. All the
effects form various degrees of inferior channel design are included, certainly
not excluding any of those seen in Peters_01_0904.
Therefore, if my data is not valid to consider, then what data 'IS' valid for
consideration? It's clearly acceptable to simulate a channel and then
measure the likeness to real before continuing with the remaining
simulations/approximations. These test back planes correlate perfectly
and I stand by the design, implementation, and data collected. If the
majority body feels the data is not valid, I am perfectly fine with recalling
the data and the cards. It's cheaper for me.
Joel Goergen