You can plug any IEEE 802.3af-compliant, 802.3at-compliant, or 802.3bt-compliant (Type 3 and Type 4) for PWR+ powered device into a front-panel port and receive power in that port. Data also can pass simultaneously on that port. This capability is called PoE.
For more information about PoE and power supplies, see your hardware documentation.
The IEEE 802.3af draft standard regulates a maximum of 15.4 W of power for each port; that is, a power device cannot request more than 15.4 W of power. As different network devices require different levels of power, the overall available power budget of the switch depends on your power configuration and the particular connected network devices. If you connect an IP device that requires more than 16 W of power, you see an error on that port notifying you of an overload.
The switch automatically detects each IEEE 802.3af-compliant powered device attached to each front-panel port and immediately sends power to that appliance. The switch also automatically detects how much power each device requires and supply the required DC voltage at a set current based on the load conditions and current availability. The switch supports both PoE and standard LAN devices.
Similarly, the switch automatically detects any IEEE 802.3at-compliant (maximum 25.5 W) or IEEE 802.3bt-compliant (maximum 60W for Type 3, maximum 90W for Type 4) powered device attached to any PoE front panel port and immediately sends power to that appliance.
The power detection function of the switch operates independently of the data link status. A device that is already operating the link for data or a device that is not yet operational can request power. That is, the switch provides power to a requesting device even if the data link for that port is disabled. The switch monitors the connection and automatically disconnects power from a port when you remove or change the device, as well as when a short occurs.
The switch automatically detects devices that require no power connections from them, such as laptop computers or other switching devices, and sends no power to those devices. You control the supply of power to specific ports by setting the maximum allowed power to each port in 1 W increments, from 3 W to 98W.
Important
Wait for 30 seconds between unplugging and replugging an IP device to the switch to enable the IP device to discharge. If you attempt to connect earlier, the switch cannot detect the IP device.
The switch provides the capability to set a PoE power threshold, which lets you set a percentage of the total PoE power usage at which the switch sends a warning message. If the power consumption is below the threshold, the switch logs an information message.
Important
After you enable Fast PoE or Perpetual PoE or both, you must save the running configuration file.
If Fast PoE or Perpetual PoE are enabled and you change any other global or port-specific PoE settings (for example, power limits, or port power priority), you must resave the running configuration file.