But this
is exactly the argument FOR allowance of Mike’s underpowered PSE.
The spec
already allows for a designer to make a multiport PSE and underpower it for
full power on every port. It is
wholly legal to make a 48 port PSE and put one 15.4W power supply in for POE. Of course this is a ridiculous
theoretical product, but it is allow in the text.
It would
also require a label to explain that only one port is able to provide full
power and/or a page full of text in the product docs to cover it fully for the
end user. The only difference between
what Mike is asking for and a multiport port PSE with only 15.4W available is
the spec allows the latter. This was
added to the spec to ease the cost requirement on the power supply for a
multiport PSE. Mike is just asking
for some leeway for a single port PSE.
My half-a-cent.
Chad Jones
-----Original
Message-----
From:
owner-stds-802-3-pwrviamdi@xxxxxxxxxxxxxxxxxx [mailto:owner-stds-802-3-pwrviamdi@xxxxxxxxxxxxxxxxxx]On Behalf Of Roger Karam
Sent: Thursday, January 23, 2003
3:20 PM
To: Geoff Thompson
Cc: Steve Jackson;
Scott_Burton@xxxxxxxxx; stds-802-3-pwrviamdi@xxxxxxxxxxxxx
Subject: Re: [802.3af] inadequate
power PSEs
Hi
I am with Goeff on the plug and play issue if we open this up to labeling
then everyone will get 'creative' about going around the power supply issue
but not by doing the right design to account for power - but by shipping
1/2 the wattage needed and claiming compliance .... Then again chances
are Mike will come up with argument that tempts me to reconsider.
to me that fact this is NOT too clear, and is debatable, proves that
the risk of it making a mess are great.... my 2c anyway....
also we run hard to 'graduate' and we seem to go back and open up subjects that
were sweated for months before.. just because we can not recall the details:
classification and class zero though not too sophisticated gave us a start
for hooks into the phy later, a back up plan for discovery that was plagued
with
low current suseptibility to noise, and leackage of diodes and power FETs.
these were real concerns that we tackled for months.... I shall invite
Rick to refresh our memory ....
also we have increased the detection signature to a much wider value than
the one the hazard matrix was based on... so can we stop fixing 'unbroken
things'
and move on....
at the end of the day, it may be hard to tell the exact right thing to do.
but the is what voting is for....
rk
At 10:49 AM 1/23/2003, Geoff Thompson wrote:
Folks-
I think I will stick to my position. Steve's arguments for the other side below
only (in my opinion) prove my point.
20 AMPs in the guest bathroom is just fine. It corresponds to our full power
situation. You can run an iron or an electric heater off a 20 AMP circuit. If
you try to do both then you deserve to have the breaker trip. The breaker BTW,
these days is a GFI in the bathroom. You don't have to go down to the basement
to reset.
The cigarette lighter socket in Steve'car is the 2nd socket. There is still a
high amperage socket for the lighter within reach of the driver and the car
came with a lighter in that socket. When additional socket started appearing in
cars it was in a mature socket situation and nobody (well, there was probably
some fool somewhere) was looking to add more cigarette lighters, they were
looking for a place to plug in their cell phones. The bulk of the market
understood the situation quite well.
Our situation, on the other hand is somewhat different (Opinion piece).
1) The market we
are approaching is used to wall warts. The market expectation for those is that
they are absolutely not interchangeable between products. Our goal is that DTE
Power just works everywhere. Kill wall warts!
2) I am of the
opinion that if we had not had Auto-Negotiation for 10/100 Ethernet then
100BASE-TX would have been a bust, or at least a slug. This would have been
true even if product had Auto-Negotiation but what was sold was like to not be
able to find a common operating mode between the 2 ends. One of the reasons
(albeit probably a minor one) that 100VG-AnyLAN failed was that you had to
manually configure it to match the two ends of the wire. It wasn't plug and
play.
Therefore, I am still of the opinion that we should position the front end of
the market so that everything just works. When folks understand it a
little better, a couple of years down the road, then we can back down.
Geoff
At 12:09 PM 1/23/2003 -0500, Steve Jackson wrote:
... pardon
the tongue-in-cheek title ...
This issue really has me torn.
Mike's rationale is great, and Geoff's concerns are also 110% valid.
I'm going to speak up, since I haven't for a long time. I support the
low-power-warning label "deal" for the following reasons:
1. Power-limit-at-the-socket paradigms are a fact of life in our consumer
society. Having a label stating this is a bonus that isn't always offered; my
car's cigarette lighter socket, which cannot source enough power to perform
that function, is so labeled. The AC outlet in the guest bathroom can't source
20A, and isn't labeled. The circuit breaker is. Mike cites some .3 precedent
but that isn't a concern to me. A 4 watt port is OK as long as you tell me
about it, and besides, that's why they make polyfuses.
2. I didn't like the classification idea from the get-go, which, as you'll
recall, started out as an optional feature. Having this 'feature' opens up
(encourages) the possibility of deployment of poorly-architected .af systems,
defined by me as those not capable of delivering battery-backed-up full power
on all ports. Now that someone WANTS to sell such a system ON PURPOSE (even
worse than the power allocation scheme) I say, go ahead. As long as it's
labeled. Make sure the warning-label color is specified as bright yellow;
caveat emptor. I also think that power-allocated ports ought to be so indicated
by a blinking yellow port-status LED, but I never thought I'd get anywhere with
such a proposal.
3. Oh, yeah: I mentioned power-allocated systems in #2. If we allow them, we
have explicitly already allowed what Mike wants. I admit ignorance of the
discussion-goings-on since I no longer can attend the .af meetings, but, heck.
Why the fuss?
Nomex suit on.
/steve