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[802.3_4PPOE] Re. Comment #123, #127



All,

Attached, please find a mark-up of the Type 3 and Type 4 PSE state diagrams to address...
* Comment #123: "A Type 3 or Type 4 PSE detecting an invalid signature on either alternative may perform detection on the other alternative prior to returning to IDLE."
* Comment #127: "A Type 3 or Type 4 PSE may perform classification on any alternative presenting a valid detection signature prior to returning to IDLE."

Again, per Mr. Thompson's request, changes to the state diagram have been described in text format. Modifications to transition logic have been highlighted in RED. Explanations for proposed remedies follow each item.

1) Add a new variable to 33.3.3.7:
option_det_both: This optional variable indicates that the PSE will perform detection on both alternatives. The PSE will additionally perform classification on any alternative presenting a valid detection signature.
TRUE: PSE will perform detection on both alternatives. PSE will perform classification on any alternative presenting a valid detection signature. Following detection and classification, the PSE will return to IDLE when an invalid detection or classification signature is present and power is not applied on either alternative.
FALSE: PSE will return to IDLE when an invalid detection or classification signature is present and power is not applied on either alternative.

2) Modify transition logic between ENTRY_SEC and START_DETECT_SEC:
From: ((!class_4PID_mult_events_sec * pwr_app_pri) + class_4PID_mult_events_sec ) * sism = TRUE * (CC_DET_SEQ = 0 + CC_DET_SEQ = 1)
To: (sism = TRUE) * ((CC_DET_SEQ = 0) + (CC_DET_SEQ = 1)) * (class_4PID_mult_events_sec + pwr_app_pri + (option_det_both * !det_start_pri))
Explanation for the above change:
For CC_DET_SEQ = 0 or 1 implementing sequential detection, this allows the secondary alternative state machine to perform detection once the primary alternative state machine has completed detection, regardless of detection result.
This comment also cleans up parenthesis and performs boolean reduction on class_4PID_mult_events_sec.

3) Modify transition logic between IDLE_SEC and START_DETECT_SEC:
From: !pwr_app_sec * pwr_app_pri
To: !pwr_app_sec * (pwr_app_pri + (option_det_both * !det_start_pri))
Explanation for the above change:
For CC_DET_SEQ = 3, this allows the secondary alternative state machine to perform detection once the primary alternative has finished detection, regardless of detection result.

4) Modify transition logic between CLASS_EVAL_SEC and POWER_UP_SEC:
From: (pd_req_pwr_sec <= pse_avail_pwr_sec) * ted_timer_done_sec * (PD_4pair_cand + (sig_pri != valid))
To: (pd_req_pwr_sec <= pse_avail_pwr_sec) * ted_timer_done_sec * (PD_4pair_cand + ((sig_pri != valid) * !(class_4PID_mult_events_sec + (CC_DET_SEQ = 3))))
Explanation for the above change:
This prevents the secondary alternative from applying power when sequential detection/classification are performed and an invalid signature has been detected on the primary alternative.
For CC_DET_SEQ = 0 or 1, please note that class_4PID_mult_events_sec selects between parallel and sequential detection.
** If class_4PID_mult_events_sec is TRUE, parallel detection and classification are performed.
** If class_4PID_mult_events_sec is FALSE, sequential detection and classification are performed.
For CC_DET_SEQ = 3, only sequential detection is performed and the (sig_pri != valid) term does not apply.

5) Modify transition logic between CLASS_EVAL_SEC and POWER_DENIED_SEC:
From: (pd_req_pwr_sec > pse_avail_pwr_sec) + (!PD_4pair_cand * alt_pri_pwrd) + !ted_timer_sec_done
To: (pd_req_pwr_sec > pse_avail_pwr_sec) + (!PD_4pair_cand * alt_pri_pwrd) + ((sig_pri != valid) * (class_4PID_mult_events_sec + (CC_DET_SEQ = 3))) + !ted_timer_sec_done
Explanation for the above change:
This is the companion logic for the change between CLASS_EVAL_SEC and POWER_UP_SEC, allowing the secondary alternative state machine to return to IDLE_SEC when sequential detection was performed and an invalid detection or classification signature was found on the primary alternative.

Note: In all cases, CC_DET_SEQ = 2 performs parallel detection and classification, and so it is intentionally absent from the proposed remedy.

--
Cheers,
David Stover II