Re: [802.3EEESG] 10BASE-T question
I believe the conversation about changing voltages was stimulated when
10BASE-T was mentioned as candidate for the minimum operating speed.
Legacy 10BASE-T voltages are indeed a problem for current silicon
processes. I think the real question is not the level of difficulty to
modify the standard but rather what is the motivation to do that and are
there alternatives.
The advantage of 10BASE-T was that during idle periods it only sends
link pulses. One suggestion might be to exclude 10BASE-T due to voltages
and adopt a 0M mode which exchanges a modified link pulse. Indeed I
would suggest a "chirp pulse." The idea is to send a very low energy
signal that would not be confused with link pulse but would permit the
collection of enough information about the channel so that the startup
time for 100M or even potentially a 1G PHY could be reduced. Of course
timing and phase information is necessary too but maybe that acquisition
time could be reduced too with a cleverly design chirp. I'm thinking
radar link pulses - low energy, broad spectrum, spread over time.
I don't know if this is technically feasible or what kind of power it
would take to implement it but it seems to be worth a look and
completely side steps the questions about modifying any legacy modes
beyond the creation of alternative entry points in the startup state
machines as already discussed.
Mike
-----Original Message-----
From: Mike Bennett [mailto:mjbennett@LBL.GOV]
Sent: Wednesday, March 28, 2007 1:46 PM
To: STDS-802-3-EEE@listserv.ieee.org
Subject: [802.3EEESG] 10BASE-T question
Folks,
For those of you who were able to attend the March meeting, you may
recall we had a discussion on 10BASE-T (in the context of having a low
energy state mode) and what we might change to specify this, which
included possibly changing the output voltage. Concern was raised that
the work required to specify a new output voltage for 10BASE-T would far
outweigh the benefit. Additionally, there was a question regarding the
use of 100BASE-TX instead of doing anything with 10BASE-T. Would
someone please explain just how much work it would be to change 10BASE-T
and what the benefit would be compared to using 10BASE-T with the
originally specified voltage or 100BASE-TX for a low energy (aka
"0BASE-T" or "sleep") state?
Thanks,
Mike