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I am glad we are on the same page on these important issues. From my perspective, the objective of this adhoc in a study group phase can be met by Dave’s table.
May I suggest another adhoc to exhaustively go over the case studies of what Dave’s table means/implies in the Task Force as this in my mind is a considerable amount of work. For instance I think it deserves some added perspective of what the overall likelihood of some of the corner cases actually are. I think there are a lot of premeditations and combinations here to cosider. Just creating a list of PSEs, ‘Y’ cables, Mid-Spans on the PSE side, and PD types in combination with ‘Y’ cables on the PD side would seems to generate a fairly large set to consider. For that matter, we should consider the likelihood of running into ‘Y’ cables at all. It something I would like to see open for the entire group to see and ponder.
Also I would guess we would want to establish some sort of baseline error (false detection) rate, what could loosely be compared to the acceptable BER of a PHY system. (this is only a loose comparison!) This could for instance be based on existing false detections that cause undesirable results in real systems today.
I guess what I am saying is that some corner cases and their effect on the ultimate specification for PoE++ are not just black and white and I would want the larger group to have time to consider there likelihood and therefore risk in some sort of agreed upon context.
I am by no means an expert in what work goes in a Study Group and what work goes in a Task Force but I would prefer to get to the Task Force sooner and solve these issues where we can actually make material decisions based on technical merit, cost, and risk which we are (mostly?) prevented from doing in a Study Group.
BTW, given all of this this I totally see why you cannot quickly evaluate the cases for Dave’s table, or really any table at this stage of a Study Group. This amount of work could delay out ability to get to the Task Force if it were fully explored in the Study Group.
I fully agree that we need to keep it simple and also per Jeff comment not to imply or suggest solution.
During the meeting on Thursday we will review first the initial material that I have send you and getting your specific inputs and comments and discuss it.
I appreciate if you can send specific inputs today, e.g. the text that you believe is implying or suggesting solutions (per Jeff comment) so I can send you updated presentation that is addressing your comment.
I will not have time to address or modify the presentation per Dave inputs so we can address it during the meeting or afterwards over mails to verify it covers all devices.
I like the terseness of your table.
I have attached a presentation to this email with some thoughts on the compatibility matrix. I think we need to keep it as simple as possible, while still conveying the information needed. I wanted to get this suggestion in front of everyone before the conference call.
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Thanks for the comments.
Regarding comment #1: I have addressed the foot notes at the relevant places and it affected the requirements. Please see attached updated slide 10 in the cases were PD power >PSE power.
Regarding comment #2: Please see slide 4 where you can find part of the answers to your question and I hope the missing data will be captured by the ad-hoc members prior the ad-hoc call. We need the information from the group as well. No doubt about it and yes, it may take some time unless everybody agrees that what is in the presentation covers our scope of interests.
Recommended Slide Changes:
· Update table on slide 9 to include footnotes 2 & 3 after the text “work” for all pertinent cells.
· I suspect it will take a considerable amount of time to put together the various device lists outlined on slide 3. Will this data be captured prior to the Ad-Hoc call?
Please see attached Compatibility Matrix Ad-Hoc material for our Compatibility Matrix Ad-Hoc conference call.
Meanwhile, until the formal ad-hoc conference call meeting, I'll appreciate if you review it and send your inputs over the reflector to start the discussion so we can better prepared for this meeting.
I am planning to have at least one ad-hoc conference call until the IEEE802.3 Geneva Interim which its details I'll send to you within a day or two.
4P-PoE Compatibility Matrix Ad-Hoc Chair.