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In general, I agree with your proposal list, and I state my responses below.
(I-2) Minimizes cross-talk interference potential to Gigabit Ethernet and
unidentified future services
I think that the "future" part is kind of nebulous. We should state the requirements that exist now.
Also, I'd rather say does not interfere with 1000BASE-T, rather than minimize.
Otherwise, you could argue that a DC scheme will always minimize interference compared with an AC
scheme. And you would be right.
(I-3) Minimizes EMI
Clearly, only a true "DC" discovery scheme can do this.
Are we then done?
(R-1) Avoids "false positive" detections (quiet and noisy environments)
(R-2) Reliably delivers power to proper PEs (quiet and noisy environments)
We need to define "noisy" environment.
How about passing the EFT (electrical fast transient) test and radiated immunity at 5 volts per meter.
Also, we should use the Campbell clamp fixture to determine where the discovery process fails vs frequency,
as it is stimulated with common mode fields.
Maybe we should add these cables to test: CAT-3, CAT-5, and CAT-6.
(R-3) Avoids giving power to paralleled devices
We need further definition on this one.
No discovery method proposed so far can detect a short paralleled legacy device, depending on it's input configuration.
Also, I would add to the list:
"Avoids failure to detect a valid powerable device".
"Automatic recovery from a cable discharge or ESD event".
(D-1) Low risk of equipment damage IF power is ever inappropriately
provided
How is this an issue of the discovery method, that is not covered above under robustness?
(C-1) Leverages the necessary function of precisely monitoring current
levels to inexpensively perform detection
Doesn't this assume a fact that is not yet in evidence?
Are you saying that discovery and load current measurement must use the same method?
To repeat: Are we then done?
Other survivability tests:
Ability to survive RJ-45 Hipot test, whether DTE power is on or off, and meet the leakage resistance at the end of the test.
comments?
- Rick
-----Original Message-----
From: Donald S. Stewart [SMTP:dsstewart@xxxxxxxxx]
Sent: Monday, September 25, 2000 12:25 PM
To: 802.3af
Cc: RDLove; Donald Stewart
Subject: Re: Selection Criteria for choosing a Discovery Method
I applaud Bob's suggestion and his offer to maintain this information. I
think it will be helpful in reaching a decision. I include below my
proposals for criteria.
Regards
Don Stewart
______________________
Criteria Categories and Specific Elements:
Non Interfering
(I-1) Does not interfere with 10/100 Ethernet via cross-talk
(I-2) Minimizes cross-talk interference potential to Gigabit Ethernet and
unidentified future services
(I-3) Minimizes EMI
Detection Robustness and Flexibility
(R-1) Avoids "false positive" detections (quiet and noisy environments)
(R-2) Reliably delivers power to proper PEs (quiet and noisy environments)
(R-3) Avoids giving power to paralleled devices
(R-4) Potential for detecting multiple classes of PE
Avoids Damage to DTE
(D-1) Low risk of equipment damage IF power is ever inappropriately
provided
Efficiency
(E-1) Ability to deliver maximum, usable power to the PE
Cost
(C-1) Leverages the necessary function of precisely monitoring current
levels to inexpensively perform detection
(C-2) Amenable to integrating into the PHY
(C-3) Compact, allowing high density PSE implementations
(C-4) Compact for PE implementation
(C-5) Amenable to low cost Mid-span implementations - Env A (including main
necessary elements: sense over/under current, signature detection, power
on/off control, on/off switch for current)
(C-6) Amenable to low cost LAN-switch integrated implementations - Env A
(including main necessary elements: sense over/under current, signature
detection, power on/off control, on/off switch for current)
(C-7) Amenable to Mid-span Env B implementations
(C-8) Amenable to LAN-switch integrated Env B implementations
Survivability
(S-1) Ability to survive ESD
(S-2) Ability to survive Cable discharge
--
Donald (Don) S. Stewart Phone: 732-817-5495, FAX x4666
Avaya Inc. e-mail: dsstewart@xxxxxxxxx
(former Enterprise Networks Group of Lucent Technologies)
Cross-Product Architecture
101 Crawfords Corner Road
Holmdel, NJ 07733