[PLUG] What is POE?

Russell Senior russell at personaltelco.net
Fri Dec 11 22:22:22 UTC 2009


>>>>> "Joe" == Joe Pruett <joey at clean.q7.com> writes:

>> Power over Ethernet and how is it implemented?  I'm tempted to grab
>> 2 Invictus wireless outdoor WAPS, but I'm concerned about what POE
>> is since they use it.
>> 
>> http://www.invictuswireless.com/ProductDetails.asp?ProductCode=NS2

Joe> poe is quite nice.  it lets you use the standard ethernet twisted
Joe> pair connection to deliver power to small bits of hardware (voip
Joe> phones, waps, etc).  you can get a poe switch to provide power,
Joe> or poe injectors to add poe to a single run.

Just beware that not all PoE powered devices are IEEE Standard 802.3af
PoE.  Lots of devices I deal with are something called "passive" poe
where there is no handshaking protocols, and the end devices are
typically expecting less than the "standard" 48V.  For example,
virtually all of the Ubiquiti gear uses "passive" PoE in the range
from about 10-24 Volts or something (from memory, please check).  The
Nanostation comes with a little injector that just puts a nominally
12V DC power supply on the ethernet cable (two wires +12V, two wires
ground).  There is some resistive voltage loss in long runs of
cabling.  It is not uncommon for people to use 15V or 18V in
situations like that.  In anything under about 100 feet, the supplied
12V adapter is going to be just fine.


-- 
Russell Senior, President
russell at personaltelco.net




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