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Re: [802.3_4PPOE] Summary of the missing requirements for Transients for <=30uS



Hi Chad,

Please see below.

Yair

 

From: Chad Jones (cmjones) [mailto:cmjones@xxxxxxxxx]
Sent: Thursday, June 14, 2018 2:13 AM
To: Yair Darshan <YDarshan@xxxxxxxxxxxxx>
Cc: STDS-802-3-4PPOE@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_4PPOE] Summary of the missing requirements for Transients for <=30uS

 

EXTERNAL EMAIL

I’m fine deleting this purely informative text. But it was voted in there for a reason and it will take 75% to get it out.

Yair:

  1. I am fine with deleting too. There reason we add it was to indicate that is such short durations, Vpse can go below Vtran-2P also because of inductance and not because PSE deliberately lower its output voltage. I believe that this informative text is useful as long as you give it the correct weight i.e. you say that there is no requirements behind it which currently it is not clear that this is the case. You see, the meaning of it must be as in clause 33. By adding this text we opened the door to question such: OKwhat is the requirement here?
  2. Why we need 75% if a comment on this to delete will be accepted. I guess you mean in case that there is no concensus to accept to delete?

I will be doing roll call votes on the call next week, and if necessary, 802.3 voters only votes if I perceive block voting. You will have to work the TF to get the 75% majority on your side. If this thread is any indication, you have a lot of work to do.

Yair: What are the problems you see with keeping this text and adding that “requirements for transients below 30usec are not define” which give you the same end result as deleting the text as in clause 33?

 

Yair

 

Chad Jones

Tech Lead, Cisco Systems

Chair, IEEE P802.3bt 4PPoE Task Force

Principal, NFPA 70 CMP3

From: Yair Darshan <YDarshan@xxxxxxxxxxxxx>
Date: Wednesday, June 13, 2018 at 6:31 AM
To: Chad Jones <cmjones@xxxxxxxxx>
Cc: 4PPOE Reflector <STDS-802-3-4PPOE@xxxxxxxxxxxxxxxxx>
Subject: RE: [802.3_4PPOE] Summary of the missing requirements for Transients for <=30uS

 

OK, so what if we delete this text Transients less than 30 μs in duration may cause the voltage at the PI to fall below VTran-2P.” and make clause 145 identical to clause 33? In this regard?

Yair

 

From: Chad Jones (cmjones) [mailto:cmjones@xxxxxxxxx]
Sent: Tuesday, June 12, 2018 10:01 PM
To: Yair Darshan <YDarshan@xxxxxxxxxxxxx>
Cc: STDS-802-3-4PPOE@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_4PPOE] Summary of the missing requirements for Transients for <=30uS

 

EXTERNAL EMAIL

You are asking to state something is not specified. End of sentence. Not a different case and no place for this in our standard. 

-Chad

Sent from my phone

Please excuse tiping errors 😃


On Jun 12, 2018, at 11:07 AM, Yair Darshan <YDarshan@xxxxxxxxxxxxx> wrote:

Hi Chad,

 

This is totally different case.

 

In clause 33 we add a text Transients less than 30 μs in duration may cause the voltage at the PI to fall below VTran-2P.” that was not appeared in clause 33.

The addition of it creates a valid question i.e. what to do with this piece of information?

I am asking to explicitly say what to do with it. To say “No requirements are specified for transients <30usec” is also clear statement which makes it similar to clause 33.

 

We can’t be worse than clause 33 in terms of clarity.

 

That is why I disagree with your statement “If we listed everything that wasn’t specified, we’d never finish”  since I am not asking to specify new requirement. I am asking to clarify what was clear in clause 33 and now in clause 145 it is not.

 

Yair

 

From: Chad Jones (cmjones) [mailto:cmjones@xxxxxxxxx]
Sent: Tuesday, June 12, 2018 8:27 PM
To: Yair Darshan <YDarshan@xxxxxxxxxxxxx>; STDS-802-3-4PPOE@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_4PPOE] Summary of the missing requirements for Transients for <=30uS

 

EXTERNAL EMAIL

Yair, we’ve be at this specification stuff for 15 years (you and I). Many, many times we have talked about how we don’t address what’s not addressed (and yes, that circular text was intentional). If we listed everything that wasn’t specified, we’d never finish. I cannot support the addition of this statement.

 

 

 

Chad Jones

Tech Lead, Cisco Systems

Chair, IEEE P802.3bt 4PPoE Task Force

Principal, NFPA 70 CMP3

From: Yair Darshan <YDarshan@xxxxxxxxxxxxx>
Reply-To: Yair Darshan <YDarshan@xxxxxxxxxxxxx>
Date: Tuesday, June 12, 2018 at 10:00 AM
To: 4PPOE Reflector <STDS-802-3-4PPOE@xxxxxxxxxxxxxxxxx>
Subject: [802.3_4PPOE] Summary of the missing requirements for Transients for <=30uS

 

Hi all,

After seeing all the responses, I propose the following remedy to my comment below.

 

The concept is to make it similar to what we have in clause 33 which is no PSE requirements for transients below 30usec

Make the following changes:

"Transients less than 30 μs in duration may cause the voltage at the PI to fall below VTran-2P. Requirements for Transients less than 30 μs in duration are not specified. See 145.3.8.6 for PD transient requirements."

 

Other option is to delete “"Transients less than 30 μs in duration may cause the voltage at the PI to fall below VTran-2P.” however I see the value with keeping this text but to complete explicitly the needed requirements which is in this case “no requirements are specified”.

 

Yair

--------------------------------------------------------------------------------------------

In clause 145 in the PD side we have clear requirements for what to do below 30usec and what to do between 30-250usec.

In the PSE side, it is only clear what to do between 30usec to 250usec.

Below 30usec the spec just giving us the info that the voltage can be lower than Vtran-2P but doesnt say what to do in this case.

If for example we didn’t have this text "Transients less than 30 μs in duration may cause the voltage at the PI to fall below VTran-2P” as we don’t have in clause 33, that it will not be raising the question OK so what netx? What is the requirement from PSE in that case. Should we keep the power? Should we remove power? We dont care? Or It is system decision? (i.e. may or may not remove power or “no requirements are specified” ? This is the problem that I am trying to resolve.

 

Yair

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