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Re: [8023-POEP] Solved another problem with DS



Steve and all,

 

Regardless of the discussion now it is clear from last IEEE meeting presentations the following:

 

  1. All 2P PDs with power < 12.95W are SS according to 802.3af.
  2. All 2P PDs with power  >12.95W  and up to MP=XX wats (e.g. 30W) are also SS similar in configuration to 802.3af.
  3. All 4P Pds with power  > 12.95W and up to MP=XX wats (e.g. 30W)  may have SS or DS. We didn’t decide yet.
  4. All 4P PDs with power > MP and lower than HP=2xMP best to have DS.

 

Yair

 

 


From: owner-stds-802-3-poep@xxxxxxxx [mailto:owner-stds-802-3-poep@xxxxxxxx] On Behalf Of Steve Robbins
Sent: Thursday, June 01, 2006 12:07 AM
To: STDS-802-3-POEP@xxxxxxxxxxxxxxxxx
Subject: Re: [8023-POEP] Solved another problem with DS

 

Mike,

 

As I wrote to Yair this morning, the Task Force already agreed (almost unanimously if I recall correctly) that the new standard would definitely allow “medium” power (up to 30W) on 2P.  A 2P PD would still need to work with either endspan or midspan, therefore 2P=SS (and SS will never go away completely for reasons of backward compatibility with 802.3af).

 

However, nobody (that I’m aware of) is still talking about using SS for high power.  That debate seems to be over, and DS won.  So 4P=DS.

 

But DS would be required only for high-power (>30W) PDs.

 

Let’s recap:

  • Low power (0 to 13W) must be SS for backward compatibility.
  • Medium power (13 to 30W) may be either SS or DS:  The designer gets to choose.  (FYI, this “grey zone” was my recent idea and hasn’t been voted on yet.)
  • High power (>30W) must be DS to avoid overheating the wires.

 

These bullets reflect my best understanding of the general consensus of the group at present.  (If anyone thinks this doesn’t reflect the general consensus, please let me know.)

 

BTW, I use 30W for this example, but of course that is still tentative on the decision about the max allowable current on 2P.  So this number will probably change.  And “13W” is how much an Af-PSE can supply, at the PD-end of the cable.

 

Steve

 


From: owner-stds-802-3-poep@xxxxxxxx [mailto:owner-stds-802-3-poep@xxxxxxxx] On Behalf Of Michael Altmann
Sent: Wednesday, May 31, 2006 1:19 PM
To: STDS-802-3-POEP@xxxxxxxxxxxxxxxxx
Subject: Re: [8023-POEP] Solved another problem with DS

 

Steve,

 

This seems like (yet another) another problem with SS, not DS.  The problem with identification as you diagramed on your slide#5 is that the PD has a SS input.

 

If the PD has separate signature control over each pair, then it would take power from whichever PSE could supply it, as determined in the classification stage.

…/Mike

Michael Altmann
Principal Engineer
Akros Silicon Inc.
(916) 351-8100 x-239
mike@xxxxxxxxxxxxxxxx
http://www.akrossilicon.com


From: owner-stds-802-3-poep@xxxxxxxx [mailto:owner-stds-802-3-poep@xxxxxxxx] On Behalf Of Steve Robbins
Sent: Wednesday, May 31, 2006 7:59 AM
To: STDS-802-3-POEP@xxxxxxxxxxxxxxxxx
Subject: Re: [8023-POEP] Solved another problem with DS

 

Yair,

 

I think you missed the point.

 

The solution is NOT to “…mandate separate signatures for each 2P…” because we also want “medium power” on 2P.  The Task Force already agreed to this.

 

So there will be some PDs in the 15W to 30W(?) range that have an input structure like an Af-PD (SS with diode bridges).

 

The obvious upgrade path for a user would be to add a medium-power At-midspan in-line with his existing Af-endspan.  These two PSEs can’t share the load since the PD is SS.  So the At-midspan has to supplant (take the place of) the Af-endspan.

 

I showed a method to assure the midspan will power the MP PD every time.  I think this will be essential to the 802.3at standard.

 

Steve

 


From: Yair Darshan [mailto:YairD@xxxxxxxxxxxxxx]
Sent: Wednesday, May 31, 2006 4:11 AM
To: Steve Robbins; STDS-802-3-POEP@xxxxxxxxxxxxxxxxx
Subject: RE: [8023-POEP] Solved another problem with DS

 

Steve and all,

 

The problem shown in this presentation can be easily solved by mandating detection and classification signature for every 2P in the PD.

Specifically separate signatures for each 2P and not a common one as measured at the RJ45.

See attached presentation in page 13 for the proposed scope of work.

This is the idea of how standard can be simplified.

Doing the above is not requiring any special specifications from the PSE.

The Endspan PSE will detect and classify pair A.

The Midspan PSE will detect and classify pair B.

Both channels will turned on within the current 802.3af timings or similar to it.

Since each channel A and B are not tied together at the diode bridge output, the PD can be operated easily by using the PD circuitry which is TBD (implementation independent).

 

Yair

 

 

 


From: owner-stds-802-3-poep@xxxxxxxx [mailto:owner-stds-802-3-poep@xxxxxxxx] On Behalf Of Steve Robbins
Sent: Wednesday, May 31, 2006 12:14 AM
To: STDS-802-3-POEP@xxxxxxxxxxxxxxxxx
Subject: [8023-POEP] Solved another problem with DS

 

Guys,

 

I think I’ve solved another problem that’s inherent with DS.  See the attached pdf.  (Only about 10 more tough problems to go!) 

 

I’d sure appreciate some comments.

 

Steve