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Re: [802.3_4PPOE] Class Probe Presentation Review

Lennart –

I’m not sure I agree with you.  While you could go with a ‘generic’ return to IDLE for any one of a number of things,

if the standard is specifying a particular optional behavior that exits a specific state on a specific condition and returns to IDLE due to that, it should be specified as an arc.


There is a difference between ‘optional behavior’ and ‘proprietary’ or ‘implementation-specific’ behavior which is still compliant to the standard. 


Where I am uncertain is how that return to idle is specified currently in the state diagram.

Right now, I see (page 125, top level diagram) a return from the test-states, and two entries – one from the disabled state, and one conditional on (pse_enable = enable) * (pse_reset + iclass_lim_det + error_condition)


If you are referring to entry into IDLE by means of pse_reset, then the definition of pse_reset wouldn’t imply using it for something like this.  While it allows for “implementation-specific reasons require reset of PSE functionality”, that isn’t what Heath is specifying.



From: Lennart Yseboodt [mailto:lennartyseboodt@xxxxxxxxx]
Sent: Friday, September 01, 2017 1:58 AM
To: STDS-802-3-4PPOE@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_4PPOE] Class Probe Presentation Review


Hi Heath,

1. There is no need to add arcs to IDLE for optional behavior.

The PSE state diagram is at any time allowed to return to IDLE.

As such, the variable option_class_probe_only and the arc from CLASS_PROBE to IDLE are redundant.

2. Your logic for option_class_probe_only coming out of CLASS_PROBE is inverted to the meaning you assigned to it.

I really object to adding optional arcs to IDLE, since if we do this once, we open the floodgates to get arcs from every state to IDLE.

Arcs to IDLE should indicate mandatory transitions to IDLE.


Kind regards,




On Fri, Sep 1, 2017 at 2:33 AM, Heath Stewart <00000855853231d4-dmarc-request@xxxxxxxx> wrote:



As promised we are providing baseline for out class probe presentation from Berlin. Both are attached; root presentation and baseline.


It should be noted that Yair has also identified additional reasons that class probe is useful. I have not yet modified the "justification" portion of the presentation to include his comments - but will. Yair has been very collaborative on this topic.


Please consider this class probe proposal - it has a couple minor changes from what some of you have seen over the last few weeks. Also note that Yair has reflected on my approach and is offering another CLASS_PROBE baseline alternative. 


We've (David and I) tried to keep the scope as narrow as possible in this change as to limit changes to the draft.


  1) Allow class probes to determine class/detect of SS and DS PDs

  2) Limit power dissipated

  3) Ensure power is not applied after class probe by returning to IDLE_XXX

        a) IDLE_XXX will return to main IDLE using existing logic


We've been hesitant to adopt Yair's proposal in preference to this proposal:


  4) Other proposal allows asynchronous return to IDLE_XXX. This can have unintended consequences for tpon and detection sequences becoming unbounded eg you can do whatever you want.

  5) Other proposal creates a CLASS_PROBE(eg short,short,short)->CLASS_RESET->(Long,short,short)->CLASS_RESET->(Long) class event path that is not desirable.


  6) I'm not sure it is useful to have option_class_probe_pri/sec differentiation. If the room feels differently we'll be open to the consideration.





Heath Stewart
Design Center Manager, Mixed Signal

Office   (805) 560-7658
Mobile  (805) 895-0499

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