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This is what OIF tried to do, and I think history shows how difficult it was to get concensous and a method. Very few people even know how to design a system with this concept. I disagree with it for a standard body in the current form. You can not select a method, mathematical or mask, without first deciding the level of design practice a system cost will tolerate. Once the basic outline of an SDD21 is defined, the rest falls into place. When established, one now understands the degree mask sets have, or mathematicl modeling has to cover, or signaling understands it's limitations. Without understanding this relationship to SDD21, picking any channel to simulate, good or bad, gets you nowhere. What are you going to test it to, for example? What criteria are you going to state the mathematical model works under? And worse yet, you can't assume positive outcome until after you build it and measure it. I repeat again ... -develop an SDD21 that includes the desired level of design practice. -develop an attenuation accrual to compensate for the design practise as it applies to our individual design cost structures. -develop channels that meet this, fall below it and above it. -simulate and pick the signaling -develop a mathematical model if need be as normative. simple, fast, and easy for ANYONE to do once the accrual method is established. IEEE should learn from the mistakes in OIF and move forward. -joel Mike-Lerer wrote: 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 |