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Re: [802.3_4PPOE] Channel P2P RUNB - Ad-hoc list of attendees - UPDATE




From: Alan Flatman [mailto:a_flatman@xxxxxxxxxxxxx]
Sent: Wednesday, April 30, 2014 5:40 PM
To: Darshan, Yair
Cc: STDS-802-3-4PPOE@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_4PPOE] Channel P2P RUNB - Ad-hoc list of attendees - UPDATE




The ISO/IEC 11801 channel DC loop resistance requirements are for the temperature the cabling is designed to be used. ISO/IEC SC25 WG3 did worst case calculations some time ago to verify that this was practical.


I have copied the relevant DC loop resistance and DC resistance unbalance requirements from ISO/IEC 11801 for reference (these are attached).


Best regards,  Alan


On 29 Apr 2014, at 12:19, "Darshan, Yair" <YDarshan@xxxxxxxxxxxxx> wrote:

Thanks Alan,


I see that also here the parameters are defined at 20degC and information is supplied for shorter channels at higher temperatures than 20degC for insertion loss.


Do you have information regarding loop resistance of channel and channel components, I guess it is specified at 20degC etc. as well. How the standard addresses temperature higher or lower on this parameter?






From: Alan Flatman [mailto:a_flatman@xxxxxxxxxxxxx] 
Sent: Tuesday, April 29, 2014 10:47 AM
To: STDS-802-3-4PPOE@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_4PPOE] Channel P2P RUNB - Ad-hoc list of attendees - UPDATE




Please note that the channel length derating specified by ISO/IEC 11801 is slightly different for UTP in the temp range 40-60deg.C. Copy attached.

Best regards,

Alan Flatman


On 29 Apr 2014, at 01:14, George Zimmerman <george@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:


You may wish to see ANSI/TIA 568-C.2 Annex G  for channel length derating at elevated temperature.


George Zimmerman

CME Consulting,  Inc.

Experts in Advanced PHYsical Communications Technology



"Darshan, Yair" <YDarshan@xxxxxxxxxxxxx> wrote:



Can you point on reference showing that channel resistance at 100m specified at 50C?

You may check if you are correct by calculating the resistance at for the cable we use for Type 2 if you are near 25 ohms round loop excluding 4 connector total 0.8 ohms.




From: Jeff Heath [] 
Sent: Monday, April 28, 2014 9:37 PM
To: Darshan, Yair; STDS-802-3-4PPOE@xxxxxxxxxxxxxxxxx
Subject: RE: [802.3_4PPOE] Channel P2P RUNB - Ad-hoc list of attendees - UPDATE




I believe that this Ad-hoc should report the worst case cable imbalance at the temperature that creates the worst case condition, and is within the operating range for the ‘channel’.  In this case our analysis is including components beyond the PI because we seem collectively to feel it is prudent to do so.


I believe that there is president for worst case analysis including temperature in previous PoE Task Forces.  For instance, correct me if I am wrong here but the worst case channel resistance at 100m is specified not at 25C, but rather at a hot ‘edge’ (was it 50C ambient plus cable heating?)  In order to guarantee operability between PSEs and PDs, we needed to choose the worst case resistance of the channel.  If we want to interoperate, the same principle seems to apply here in my opinion. 


I believe that some of the pushback on this issue is perhaps because the worst case imbalance is dominated by the PD diode bridges.  These components are indeed not in the PI but we are considering them in this Ad-hoc none the less because they are material to cable imbalance.


Interoperability is a key goal for this and any dot3 standard.  I am open to other approaches in achieving this goal as long as it creates confidence in the Task Force and dot3 that component providers and OEMs will understand what they need to do and systems will interoperate.




Jeff Heath
Design Center Manager





402 East Carrillo Street, Suite D


Santa Barbara, California 93101










From: Darshan, Yair [mailto:YDarshan@xxxxxxxxxxxxx] 
Sent: Sunday, April 27, 2014 3:09 AM
To: STDS-802-3-4PPOE@xxxxxxxxxxxxxxxxx
Subject: [802.3_4PPOE] Channel P2P RUNB - Ad-hoc list of attendees - UPDATE


Hi all,


Please review if I missed your name in the list of attendees on last Thursday a-hoc meeting.




  • Yan ZHUANG
  • Ronald Tellas / Panduit
  • Larsen, Wayne /
  • Jeff Heath
  • Brian Buckmeier
  • Rick Frosch / Phihong
  • Christian BEIA / ST
  • Leonard Stencel / Bourns
  • Fred Schindler / Seen Simply
  • Koussalya Balasubramanian / Cisco

§  David Tremblay / HP



Darshan Yair


Chief R&D Engineer

Analog Mixed Signal Group

Microsemi Corporation


1 Hanagar St., P.O. Box 7220
Neve Ne'eman Industrial Zone
Hod Hasharon 45421, Israel
Tel:  +972-9-775-5100,

Cell: +972-54-4893019
Fax: +972-9-775-5111


E-mail: <mailto:ydarshan@xxxxxxxxxxxxx>.