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Re: [802.3_4PPOE] Unbalance margin (yseboodt3)

Lennart –

I’m afraid I may not be understanding what you are trying to say (or else you changed wording without actually meaning to) –


You make a distinction in your wording, which is either unintentional, or the meaning is obscure:

Icon-2P-unb max for the PSE and PD, item 5 in the table is: “Pairset current for PSE and PD due to unbalance”, and

Iunbalance-2P min that the PSE must support, in item 5a is:  “pairset current including unbalance effect”.


Then, in, you specify the other language for Iunbalance: “is the current a PSE is able to source on a pairset due to unbalance as defined in Table 145–16”


You changed the Icon-2P-unb max language FROM “pairset current including unbalance effect” TO “due to unbalance”, which would ordinarily mean “the component of the current due to unbalance (excluding the nominal current)” to me (and I expect most readers). If you are trying to communicate something with this change of language, I don’t know what it is, and I suggest we need another try at it.  Otherwise I think that:

“Pairset current for PSE and PD due to unbalance including the unbalance effect per the assigned Class (for single-signature PDs)” is the right thing to say for item 5.


I would also suggest the same language in


On a different note, you’ve gone to this trouble of defining a new, separate parameter Iunbalance to be the current supported, only so you can compute Icon2P.  why not just put Icon2P in the table appropriately?

It might look a little messier in the table, because it will have a min (Icon - IPort-2P-other; (whatever the value of Iunbalance-2P is for that class )) in it, but for the reader, it would all be in one place then, and be simpler to follow.

And, you wouldn’t have to define new values…



From: Lennart Yseboodt [mailto:lennartyseboodt@xxxxxxxxx]
Sent: Friday, August 25, 2017 8:56 AM
To: STDS-802-3-4PPOE@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_4PPOE] Unbalance margin (yseboodt3)


Hi all,

I copy-pasted the table and forgot to update the name in the second table. Sorry about the confusion.

Attached a new version with correct naming.

Yair - the intention is twofold

a) make appropriate parameters for the 3 requirements

b) create margin between maximum allowed unbalance and what the PSE needs to support

This goes beyond adding a few mA. I've rounded off to the nearest 100mA multiple, but we can also pick something else.

Kind regards,



On Fri, Aug 25, 2017 at 5:46 PM, Yair Darshan <YDarshan@xxxxxxxxxxxxx> wrote:

Hi Lennart


Thanks for this work.

I saw some issues please see detailed review inside the file attached. The main issues are:

  1. In Table 145-16 you have duplicate names. It is not clear which is IUnbalance-2P.
  2. It will be better to propose numbers for the additional item 5a based on technical consideration. It looks that the end result of this work is to get effective higher Icon-2P_unb margins which, I guess is not the objective of this presentation/baseline. The purpose of this base line is to decouple between the maximum current unbalance current on a pair in PSE and PD that meets current unbalance requirements and the current that the PSE has to be capable to supply over 2-pairs which need to be a minimum value. For this purpose, you need just to specify that:

Icon_pse_capable_2P (or whatever the name is) = Icon-2P_unb+0.002 (I used this concept for ILIM-2P). This will create the gray area required between the two-definition of “max current” and “current capability “ and will resolve the confusion you have raised.

    1. As for the need (or not ) for margins in Icon-2P_unb value, please see darshan_03_0917.pdf that will update these numbers due to other reasons based on analysis and you will get a bit more margins (You saw this during our discussions and we can talk more about it if needed.







From: Lennart Yseboodt [mailto:lennartyseboodt@xxxxxxxxx]
Sent: Friday, August 25, 2017 3:57 PM
To: STDS-802-3-4PPOE@xxxxxxxxxxxxxxxxx
Subject: [802.3_4PPOE] Unbalance margin (yseboodt3)



Hi all,

Please see the attached baseline for review.

Kind regards,