[Tfug] PoE supplies/injectors

[Zack Williams]

> I'm curious as to the type of *typical* support provided PoE.
> I assume legacy installations use midpoint injectors on
> *select* drops (to eliminate the cost of replacing existing
> switches)?

Correct.

> Or, is it more typical for the switch to be replaced to
> provide PoE to *all* drops?

Usually I've seen a small dedicated PoE switch installed in addition
to any existing switch.

> Are there any "smart" injectors (midpoint or endpoint) where
> "something" can control the delivery of power *to* the PD's?

Some switches have a per-port PoE setting you can turn on and off.  If
the switch or power injector had a CLI you could probably script it so
that specific MAC addresses would get power, but...

> I.e., so that I can selectively apply/remove power from
> individual drops?  And, ideally sense/control the class
> negotiated by the PD (i.e., so I can *manage* power instead
> of just providing it)?

In terms of being plug and play, and full autosense this is a
chicken/egg problem.  How does the switch known that the device
connected to it if said device has to be powered in order for it to
inform the switch that it needs power?

- Zack