Re: [BP] Question regarding Channels
My proposal is the following.
Assuming the 802.3ap Task Group agree's that for 10 Gigabit Serial Signaling
we are not concerned with optimizing operation over legacy backplanes.
1) Utilize the Channel's developed by the Channel Ad Hoc to evaluate 10
Gigabit Serial Signaling Solutions. Based on that evaluation choose a
signaling solution.
2) Given a signaling solution develop a normative mathematical tool to
evaluate the potential Bit Error Rate performance of a channel given a
complaint transmitter and receiver. As I envision it this would be a tool
similar to the OIF's Stat-Eye which would take as input measured Channel S
parameters and evaluate the potential Bit Error Rate of the Channel relative
to 802.3ap objectives.
The Channel Ad Hoc's Mask sets and evaluation channels would be an
informative part of the specification.
One benefit of the mathematical approach is that it is able to
quantitatively take into account anomalies in the channel parameters,
ripple, notches, .... much better than mask sets are able to.
The mathematical approach also allows various trade-offs. Low loss channels
will have better signal to noise at the receiver and can therefore tolerate
more cross talk. High loss channels will have smaller signals at the
receiver and be more sensitive to crosstalk.
The Channel Compliance Tool would allow system designers to evaluate
backplanes of interest based on their S parameters to determine whether they
are 10 Gigabit Serial Signaling Capable.
Mike Lerer
Box 636
Londonderry, NH 03053
Home: 603-434-4205
Cell: 603-548-3704
-----Original Message-----
From: owner-stds-802-3-blade@listserv.ieee.org
[mailto:owner-stds-802-3-blade@listserv.ieee.org] On Behalf Of Reuven Segev
Sent: Friday, October 08, 2004 1:21 PM
To: STDS-802-3-BLADE@listserv.ieee.org
Subject: Re: [BP] Question regarding Channels
Mike,
I am just trying to make sure I understand your proposal for the
802.3ap.
A. Develop a signaling solution for the 1G and XAUI. The purpose is to
target 'legacy' backplanes.
B. Develop an analytical tool for the 10G solution in order to assist
designers evaluate the compatibility of backplanes (legacy and new) with
this solution.
My take on the discussion was that the group will create a 'channel
model' that will serve as a 'golden channel'. This 'golden channel' will
serve for the evaluation of 10G solutions and eventually will help
backplane designers design backplanes that will guarantee (is there such
a thing?) with a high degree of confidence that the 10G solution will
operate to the spec.
I would therefore add a third goal:
C. Develop a 'golden channel model' for a 10G signal.
Reuven Segev
Director of Marketing
TeraChip, Inc.
Tel: (650)320-8148 ext 204
Cell: (415)307-7683
-----Original Message-----
From: Mike-Lerer [mailto:mike@MIKE-LERER.COM]
Sent: Friday, October 08, 2004 6:27 AM
To: STDS-802-3-BLADE@listserv.ieee.org
Subject: Re: [BP] Question regarding Channels
As a System Architect and Designer, I think before we spend overly much
time debating the characteristics of particular channels, we should
first see if we can agree on the problem we are trying to solve.
The group needs to be clear on the problem.
The ATCA market is projected to develop into a large and important
market and as such is of interest to 802.3ap members.
However, today and for the short to medium term future, ATCA is only a
small fraction of the Total Available Market.
The ATCA market will include both Existing (Legacy) and New (Greenfield)
products. Products of potential interest to 802.3ap include:
Line Cards
Switch Cards
Passive backplanes
Do we want 802.3ap to include auto-negotiation to allow support for
existing Gigabit Ethernet and XAUI Line Cards.
My Answer is YES.
Do we want 802.3ap to auto-negotiate to allow a future switch fabric
card to be built that supports existing Gigabit Ethernet Line Cards,
XAUI Line Cards and new 10 Gigabit Serial Line Cards
My Answer is YES.
Do we want to support 10 Gigabit Serial Links on Existing ATCA
Backplanes designed for 1 Gigabit or XAUI speeds.
My Answer is NO.
As a System Designer, I know that there are some parameters that I have
under my control and some I do not.
I have no control over the Mechanical outline, the Thermal Budget, or
the Power Budget for an ATCA card.
I have control over the Line Card and Backplane:
materials and construction
design and manufacturing practices
I desire an optimal solution for the constraints which I am unable to
change:
Space (must integrate between 10 & 100 links on a single ASIC)
Power (because thermal issues are my most severe constraint)
Could the 802.3ap Task Group spend its time seeking a 10 Gigabit Serial
signaling solution that will operate over existing Gigabit and XAUI
backplanes?
My Answer is Yes
Should the 802.3ap Task Group spend its time seeking a signaling
solution that will operate over existing Gigabit and XAUI backplanes?
My Answer is Absolutely NOT.
What should the Task Group be concerned with? In my opinion two things.
1) Developing an optimal signaling solution for those channels
which
meet the criteria developed by the Channel Ad Hoc. These represent
realistic best practices for backplane construction. These channels do
not unnecessarily burden the potential solution with the power, cost and
complexity of legacy support.
2) Developing an Analytical Tool driven by S parameters, along the
lines of Stat-Eye which will allow the quantitative characterization of
a particular backplane as Complaint with 802.3ap 10 Gigabit Serial
Signaling.
To aid the development of the market for 802.3ap 10 Gigabit Serial
Signaling, the most important thing is not burdening the standard with
legacy requirements. The most important thing is to provide a tool that
will allow systems designers to unequivocally know if an existing (or
planned) backplane will operate reliably at 10 gigabit serial rates.
Mike Lerer
Chief Architect Rapid Prototypes Inc.
Chairman Physical Link Layer Working Group of the Optical
Internetworking Forum Chairman Hardware Working Group of the Network
Processing Forum Box 636 Londonderry, NH 03053
Cell: 603-548-3704