[Asterisk-Users] Cheap PoE switches/injectors?

[Kevin P. Fleming]

Greg Hill wrote:

> officially, a POE capable switch/etc is supposed to do a discovery routine
> to detect, when a device is plugged into it, whether that device requires
> POE. Right? And the single-port POE injectors are usually nothing more
> than two RJ45 packs with a dc power connector, right? That could be the
> difference in price there: the detection circuitry. Or am I way off?

No, even the single-port injectors have to have that circuitry, I 
believe. Otherwise power on the extra pins would be live all the time, 
which could be damaging to any non-PoE equipment you plugged in there. 
Also, the PoE device itself wants to negotiate its power usage with the 
power supplier, and if the injector didn't respond I don't know if the 
PoE device would ever come up.