[PLUG] question: low power CAT5 switches

[Keith Lofstrom]

I spent way too much time yesterday "rationalizing" a 15 year 
accumulation of cat5 and coax ethernet cables in my office and
the house (among other things).   Now my ALIX firewall/router
and 2 out of 6 ethernet switches are stacked together in one
place (talking to 3 other switches and up to 7 other computers), 
cables are shorter and labelled at the ends, unused cables are
eliminated, etc.  After all the work optimizing power on the 4
watt ALIX, the power drawn by the 8 port Linksys EZXS88W switches
are now the most significant power usage in the network - they
draw around 6W each, idle.

In theory, an ideal 802.3 ethernet PHY driver uses around 80mW
when transmitting a packet (2.8V into 100 ohms) and nothing 
when idle.  The high signalling voltages are legacy, from the
days when ethernet and analog telephones shared cable bundles -
an analog phone going on or off hook can inject a 250mV crosstalk
spike into the ethernet pairs.

A 100% active 8 port switch transmitting on half its ports
should ideally consume less than 0.4W peak, much less idling.
Of course, the internals will take some power, but modern
electronics consumes less and less per digital function than
the old stuff.

There is a new standard coming, 802.3az energy efficient
ethernet, that will reduce the power still more in data
centers.  That probably will not interoperate with existing
gear, so it is not a consideration for me.  Still, it should
be possible to reduce the power a lot for plain old 802.3.

So, I would like to find new switches (4, 8, and 16 port)
that reduce the power.  Suggestions?

Keith


-- 
Keith Lofstrom          keithl at keithl.com         Voice (503)-520-1993
KLIC --- Keith Lofstrom Integrated Circuits --- "Your Ideas in Silicon"
Design Contracting in Bipolar and CMOS - Analog, Digital, and Scan ICs