Re: [8023-POEP] System Architecture
Hi Yair,
I've updated item [1] below based on the discussion we had on the
classification call today.
Regards,
David
[1] A single PI can support either [a] a PD powered through either pairs
AB or pairs CD, or [b] two independent PDs, one power through pair AB and
one powered through pair CD.
For option [1a] the same discovery (and classification if supported)
resistance is presented on pairs AB and CD. After power is presented on
either pair these are removed. For option [1b] the same or different
discovery (and classification if supported) resistance is presented on
pairs AB and CD. Once power is presented on pair AB this is removed from
pair AB. Once power is presented on pair CD this is removed from pair CD.
I believe this matches what Hugh proposed earlier this week [
http://www.ieee802.org/3/poep_study/email/msg00283.html ].
David Law/GB/3Com wrote on 14/06/2006 14:10:17:
> Hi Yair,
>
> Here are some thoughts on what you have suggested.
>
> Regards,
> David
>
> 1. A single PD in a PoE system can get power from each 2P
simultaneously.
>
> I'm not sure I would look at things from the point of view of the PD
> as I thought we were going to treat the 2 PDs that can be behind a
> single RJ45 as two separate PDs. I would therefore suggest we look
> at things from the point of the RJ45, or using the correct Clause 33
> terminology, the PI. Based on this, and including support for legacy
> Clause 33 as well, I would suggest:
>
> [1] A single PI can support either [a] a single Low Power PD powered
> through either pairs AB or pairs CD, [b] a single Medium Power PD
> powered through pair AB or [c] two independent Medium Power PDs, one
> power through pair AB and one powered through pair CD.
>
> 2. It is possible that a PD system will get power from N x
> Ports=RJ45 by utilizing a PD system that is constructed fron N PDs.
> 3. item 2 is out of scope of the standard due to the fact that the
> standard define what happen in a single port.
>
> I'm not sure I would call this a 'PD system'. I would certainly
> agree that a 'system' could get power through N x RJ45 connectors,
> each of which would be a PI, with either 1 or 2 PDs 'behind' each of
> these PIs. I would therefore suggest:
>
> [2] It is possible for a 'system' to be powered through N x PIs with
> each PI supporting either one or two PDs (see item [1] above).
>
> [3] Specification for Item 2 is out of scope as the standards
> defines what happens at a PI which is the conformance test point.
>
> "Yair Darshan" <YairD@xxxxxxxxxxxxxx> wrote on 14/06/2006 13:11:34:
>
> > Hi David,
> > I agree with your observation from the RJ45 connector point of view.
> > It is actually a basic rule that we are using in the standard i.e. to
> > define a port not a system.
> > In short you are saying that:
> > 1. A single PD in a PoE system can get power from each 2P
> > simultaneously.
> > 2. It is possible that a PD system will get power from N x Ports=RJ45
by
> > utilizing a PD system that is constructed fron N PDs.
> > 3. item 2 is out of scope of the standard due to the fact that the
> > standard define what happen in a single port.
> > I'll revise the presentation accordingly.
> > Thanks
> > Yair
> >
> > -----Original Message-----
> > From: owner-stds-802-3-poep@xxxxxxxx
> > [mailto:owner-stds-802-3-poep@xxxxxxxx] On Behalf Of David Law
> > Sent: Wednesday, June 14, 2006 2:17 PM
> > To: STDS-802-3-POEP@xxxxxxxxxxxxxxxxx
> > Subject: Re: [8023-POEP] System Architecture
> > Hi Yair,
> > I'm not sure about this idea of N x 2P. The case of 2 x 2P PDs behind
a
> > single RJ45 (or 8 pin connector to use the term used in your slides)
is
> > certainly a special case we need to look at. But since the RJ45 has
only
> > 8-pins you cannot provide any more than 2 x 2P PDs behind a single
RJ45.
> > Anything from 3 x 2P upwards requires multiple RJ45s.
> > However I would not classify the case of a system with multiple RJ45s
> > that
> > chooses to implement PDs behind N of these connectors as a case of N x
> > 2P.
> > This is simply a case of multiple PDs that happen to be located within
> > the
> > same system. The fact that these multiple PDs happen to be located in
> > the
> > same system should have no impact on the specification. I would go as
> > far
> > as to suggest that such system (however system can be defined - within
> > same box/chassis/packaging) specifications, certainly in respect to
> > Detection and Classification, are beyond the scope of the project.
> > There are products that ship today that provide two RJ45 and implement
> > two
> > PDs behind them to provide redundancy. I believe these are compliant
> > with
> > Clause 33 of IEEE Std 802.3-2005 and certainly would not agree with
> > retrospectively imposing requirements on these.
> > Regards,
> > David
> >
> > owner-stds-802-3-poep@xxxxxxxx wrote on 14/06/2006 00:14:40:
> > > Hi all,
> > > Please find my action item for tomorrow's meeting.
> > > It is revised presentation from May meeting that focus on the
concept
> > > 4P=2x2P and the more general case of N Pairs = Nx2P..
> > > Please feel free to comment.
> > > Thanks
> > > <<Flexible PD implementation driven Architecture 002.pdf>>
> > > Yair
> > > Darshan Yair
> > > Chief Engineer
> > > PowerDsine Ltd. - The Power over Ethernet Pioneers
> > > 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:yaird@xxxxxxxxxxxxxx
> > > <BLOCKED::blocked::BLOCKED::mailto:yaird@xxxxxxxxxxxxxx> >.
> > > <http://www.powerdsine.com
> > > <BLOCKED::blocked::BLOCKED::http://www.powerdsine.com/> >
> > >
> > > [attachment "C.htm" deleted by David Law/GB/3Com]
> > > [attachment "Flexible PD implementation driven Architecture 002.pdf"
> > > deleted by David Law/GB/3Com]