IEEE802.3af Ad Hoc on Mid Span Powering Issues

["RDLove" <rdlove@xxxxxxxxx>]

All, at the July plenary we established an Ad Hoc on Mid-Span powering issues.  As of the close of the July plenary, the members of the Ad Hoc were:

Michel Bohbot, , Chris DiMinico, Dan Dove, Robert Love, Mike McCormick, Larry Miller, Sterling Vaden.  In my presentation, Mid-Span Insertion and Generic Cabling Standards, I presented a "pregnant snake" configuration that had noise from the dc-power coupled onto the signal pairs as the only signal impairment.  That presentation discussed the wiring assumptions to be considered for any powering configuration. 

 

I invite all who are interested in this issue to join the AdHoc and help us determine the following:

 

What is the noise budget allocated to coupling from the dc powering circuitry and what is the rationale for that allocation? 

What other configurations do you wish to consider?  For each, develop a model that shows the relevant signal imairments.  We will then need to develop a budget for the impairments germain to that configuration.

 

Since the list of attendees with email addresses is not yet posted, I ask of both the listed members and new volunteers to the Ad Hoc to send me an e-mail note stating you will be participating.  I will send a note to all that respond in a few days with an email list of all members to date, so that we can each create a Mid-Span Powering Ad Hoc email list to use in sending emails to each other.

 

We should be able to establish a signal impairment budget along with the rationale, for each configuration we propose.  Hopefully that work will be complete in advance of the September interim 802.3af meeting, and we can generate a short presentation of our results for that interim.

 

Best regards,

 

Robert D. Love
President, LAN Connect Consultants
7105 Leveret Circle
Raleigh, NC 27615
Phone: 919 848-6773
Fax: 720 222-0900
email: rdlove@xxxxxxxx