Controlling PoE allocation

Syntax:


[no] int <port-list> poe-allocate-by [usage | class | value]

Allows you to manually allocate the amount of PoE power for a port by either its class or a defined value.

The default option for PoE allocation is usage, which is what a PD attached to the port is allocated. You can override this value by specifying the amount of power allocated to a port by using the class or value options.

usage

(Default) The automatic allocation by a PD.

class

Uses the power ramp-up signature of the PD to identify which power class the device will be in. Classes and their ranges are shown in the following table.

value

A user-defined level of PoE power allocated for that port.

NOTE:

The allowable PD requirements are lower than those specified for PSEs to allow for power losses along the Cat-5 cable.

Power classes and their values

Power class

Value

0

Depends on cable type and PoE architecture. Maximum power level output of 15.4 watts at the PSE.This is the default class; if there is not enough information about the load for a specific classification, the PSE classifies the load as class 0 (zero).

1

Requires at least 4 watts at the PSE.

2

Requires at least 7 watts at the PSE.

3

15.4 watts

4

For PoE+Maximum power level output of 30 watts at the PSE.

Example:

To allocate by class for ports 6 to 8:

switch(config)# int 6-8 PoE-allocate-by class