[Asterisk-Users] cisco poe

[Joe Greco]

> I know this is on the wiki, I just want to confirm so I don't blow up my 
> cisco phones.  I've got several cisco 7940's all running using cisco 
> power cubes.  However, my boss wants me to switch just a few over to 
> poe, but doesn't want to fork out the dough for a nice cisco poe switch, 
> or anybody else's poe switch for that matter.
> 
> So my question is, what is the '99.999% sure/safe' poe injector solution 
> that most people are using for the cisco phones?
> 
> Right now I'm looking at buying the 3-Com 3CNJPSE (qty 2-3) to power the 
> few specific locations where a power cube just wouldn't look right, like 
> a conference room table for example. :)  I know this solution, thanks to 
> the fact that it is a 'hack', is far from the 99.999% I just stated, but 
>   it also seems to be the only low-end solution for poe.  Am I right, or 
> just plain blind?

The thing you need to watch out for is that the 7940/7960 do not do PoE,
or (more specifically) do not do standard PoE.  They use the Cisco variant,
a pre-standard PoE which has reversed polarity.

This means that, unless a switch actually claims to be compatible with the
Cisco variant, a non-Cisco PoE switch will not power the 7940/7960.
Likewise, injectors probably won't work, though some people report success
with various hacks such as wiring up a cable to provide a Cisco-compatible
layout.  Beware that there are severe risks in doing this, in that if you
inadvertently plug in some other PoE device to such a port, or don't
clearly mark such cables, that you are likely to burn up some other PoE
device at a future point in time.

Bad Cisco, very bad Cisco...

... JG
-- 
Joe Greco - sol.net Network Services - Milwaukee, WI - http://www.sol.net
"We call it the 'one bite at the apple' rule. Give me one chance [and] then I
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