Voltage In Cisco Switch (PoE)

[silver.root]

I want to learn how a Cisco PoE switch sends the voltage on its ports ...

I plug in two IP cameras. One camera runs, if you power it from a transformer, 5VDC at 800mA. The other, if you power it from a transformer, runs 9VDC at 1000mA ...

How does a Cisco PoE switch know how much voltage it's supposed to be sending??

Is there a negotiation process  between the POE switch and the POE device ??

[Collin Clark]

Yes there is a negotiation process-

http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst6500/ios/12-2SX/configuration/guide/book/power_over_ethernet.html

[chinpohpang851]

PoE is for IPPhone and those PoE powered devices?