when swich is power on it boots all ports are off . after the boot process it turns on the ports on a poe each port is check to see 1) if device is connected to it , if not power turn off
2) if device is connected it trys test what ports data sent over cisco poe runs on pins 1 throw 4
throw some devices has abuilt to change this the more highend swichs has abuilty to change ports so it checks to see what pins has load on them it one of two it eather 1and 3 or 4 and 8 this tells device what pins send the power next how much power dose it take to say that these devices u dont know. these devices wont blow out a device unpower
they not able to , unlike cheaper swichs there is a must have to provent this bad cable or some other reason the swich can be damage so that port is turn off and u cant turn back on untill fault is cleared. these devices boot in a order its very clear as to what it is doing just waching it in my case it has 4 cards one is wism2 one is poe one card is not and there reason this was done poe card dose not handle enciprtion only none poe boards do , so when swich powers up first sup is check it comes on line then tells boards come on line wism2 card is last to come on becuase it must have all other ports online for it to even work so it will wait till system wired ports is on and running then it will boot, throw wism2 dose not need poe ports to run the aps do, now intesting fack is if a device is plug in and for some reason it cant figger out how its wired wont power on at all port will stay on but power will remain off
