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Re: [8023-POEP] List of questions regarding cabling and connector s



Martin-

I do not believe that we have the ability to rule this case out.
It is a legitimate configuration under ISO/IEC 11801.

geoff

At 01:10 PM 9/14/2005 , Patoka, Martin wrote:

The case that might have driven the statement is locals that put two ethernet channels per 4 pair cable ... 
This would be 2, 2 pair implementations.  It was unclear to me if we have chosen to rule this cae out totally.

 
Martin
 
Martin Patoka
Systems Engineer
Texas Instruments

214-567-5487
mpatoka@xxxxxx
 
-----Original Message-----
From: owner-stds-802-3-poep@xxxxxxxx [mailto:owner-stds-802-3-poep@xxxxxxxx] On Behalf Of Yair Darshan
Sent: Wednesday, September 14, 2005 3:56 PM
To: STDS-802-3-POEP@xxxxxxxxxxxxxxxxx
Subject: Re: [8023-POEP] List of questions regarding cabling and connector s

Hi Steve,

 

The meeting right now is addressing the questions we have to the ISO/IEC committee.

Regarding the validity of Jo's work I have also noticed this point and as I mentioned earlier his work requires further review since few

things there obviously not reflecting our system behavior. I'll review it in details and we will discuss more on it.

 

Yair

 

 

 

 

 

 

 

From: owner-stds-802-3-poep@xxxxxxxx [mailto:owner-stds-802-3-poep@xxxxxxxx] On Behalf Of Steve Robbins
Sent: Wednesday, September 14, 2005 10:31 PM
To: STDS-802-3-POEP@xxxxxxxxxxxxxxxxx
Subject: Re: [8023-POEP] List of questions regarding cabling and connector s

 

Regarding the issue of cable heating, I have a concern about Jo Wallings analysis.  In his supporting document, "walling_2_0905.pdf" the last sentence in the second paragraph states "...under the assumption that all pairs in all cables are energized with the same current."

 

This is a valid assumption for PoE Plus, since it appears very likely that we'll use a 4-pair system.  But Jo's assumption is invalid for 802.3af since only half of the pairs are carrying current.

 

So I think Jo overestimated the heat dissipation in the cables (for 802.3af) by a factor of 2.