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Fred & all
– I believe this straw poll is about what we think the standard needs to say, to build consensus, not a survey
of customers. I too would not want specific temperatures and environmental parameters in the standard.
This would be contrary to existing 802.3 practice.
I would generally not support an informative section on effects of temperature, as it will end up being implementation
specific, confusing, and won’t add to interoperability. I think we should treat these issues as Yair stated on slide 6 of his presentation with the standard text from
clause 33: 33.7.7 Temperature and humidity The PD and PSE powered cabling link segment is expected to operate over a reasonable range of environmental conditions related to temperature, humidity, and physical handling. Specific requirements and values for these parameters are beyond the scope of this standard. I disagree that this means to “focus on results at room temperature”, but rather, that individuals looking at
the specifications we make (for example, for imbalance in the PSE PI)
will have to consider what temperature range they can reasonably meet those specs over, and whether that is sufficient for their product needs.
These are individual determinations, but can be driven by technical presentations.
Remember though, we don’t spec the component parts (e.g., magnetics) or their temperature range, we spec the PI as a port and its electrical parameters. This same (or very similar) language is repeated again and again in IEEE Std. 802.3, and is also the way PHYs
are tested. In my opinion and experience, it is up to manufacturers (of both components and boxes) to specify their temperature range and compliance points.
For example, if a product says it is compliant with 802.3at, and is designed for a temperature range of
0°C to 70°C, then it should meet its specifications (including compliance) over that temperature range.
I have been involved in thermal chamber tests where (PHY and box) products are tested at their temperature corners.
While all compliance tests aren’t performed, if a functional or interoperability problem is found at temperature, those are followed up on.
IEEE 802.3 specifies the range (independent of temperature) of electrical parameters that are needed for interoperability,
and should do the same for PoE. PHY products have, for example, frequency accuracy specs that need to be met across the design temperature range.
Manufacturers make choices of what temperature they will design to (some do 0 to 70, some do
-40 to 85, etc.), and need a compliance spec they can test to. George Zimmerman Principal, CME Consulting Experts in Advanced
PHYsical Communications Technology george@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx 310-920-3860 (PLEASE NOTE NEW EMAIL ADDRESS.
THE OTHER WILL STILL WORK, BUT PLEASE USE THIS FOR CME BUSINESS) From: Fred
Schindler [mailto:grog06@xxxxxxxxx] Hi Chad, I misspoke. Yair is doing a straw poll with three choices. I felt a choice was missing and started this email chain. In my email, I used the word survey as equivalent to straw poll although I now realize they are not equivalent.
Thanks, Fred From: Chad Jones (cmjones) [mailto:cmjones@xxxxxxxxx]
What is this: “I do not think this is a choice in the P2P ad hoc survey but it should be”? Is there
a plan to do some sort of survey? Can you provide details? Chad Jones MGR, HW ENG, Cisco Systems Chair, IEEE P802.3bt 4PPoE Task Force From:
<Darshan>, Yair Darshan <YDarshan@xxxxxxxxxxxxx> Hi Fred, Thanks for your inputs. So you prefer? a)
Single worst case number at room temperature? b)
Single worst case number at TBD low temperature were this low temperature represents wide market applications? (and no further text/inputs/requirements/guidelines for lower than that minimum temperature
point?) c)
Else? I understand from your response that you prefer option (b)? Yair From: Fred Schindler [mailto:grog06@xxxxxxxxx]
Hello Pair-to-Pair Ad Hoc, I think adding temperature details to the IEEE .3BT specification will result in problems. Stating values at temperature is not standard for IEEE specifications.
Not all vendors will operate in the same temperature range. Requirements should be provided for interoperable operation. Some of this may be arrived at by considering temperature for the broader market. Vendors
with wider operational needs will need to use cable made for the application and tested with .3BT requirements. Guidance for cable parameters should reference cable standards. The .3BT standard should provide guidance on how to use cable standard values for
the .3BT standard. ð
I do not want parameters for specific temperatures in the requirements of the .3BT specification.
I do not think this is a choice in the P2P ad hoc survey but it should be. That is, I do not want this information in the appendix either as this will require .3BT to wait for cable standards to provide the values. Values
in the appendix are not tested. Thanks for your consideration, Fred Schindler From: Darshan, Yair [mailto:YDarshan@xxxxxxxxxxxxx]
Hi all, Please review if I missed your name in the list of attendees on last Thursday a-hoc meeting. Thanks Yair ----
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David Tremblay / HP ------ Darshan Yair Chief R&D Engineer Analog Mixed Signal Group Microsemi Corporation 1 Hanagar St., P.O. Box 7220 Cell: +972-54-4893019 E-mail: <mailto:ydarshan@xxxxxxxxxxxxx>. |