priority ports to meet the power demand on other, higher-priority ports. This operation occurs regardless of the
order in which PDs connect to the switch’s PoE-enabled ports.
How is power allocation prioritized?
There are two ways that PoE power is prioritized:
• Using a priority class method, a power priority of Low (the default), High, or Critical is assigned to each
enabled PoE port.
• Using a port-number priority method, a lower-numbered port has priority over a higher-numbered port within
the same configured priority class, For example, port A1 has priority over port A5 if both are configured with
High priority.
Configuring PoE operation
In the default configuration, PoE support is enabled on the ports in a PoE switch. The default priority for all ports
is Low and the default power notification threshold is 80 (%).
Using the CLI, you can:
• Disable or re-enable PoE operation on individual PoE ports
• Enable support for pre-standard devices
• Change the PoE priority level on individual PoE ports
• Change the threshold for generating a power level notice
• Manually allocate the amount of PoE power for a port by usage, value, or class
• Allocate PoE power based on the link-partner’s capabilities via LLDP
Disabling or re-enabling PoE port operation
Syntax:
[no] interface <port-list> power-over-ethernet
Re-enables PoE operation on <port-list> and restores the priority setting in effect when PoE was disabled on
<port-list>.
The no form of the command disables PoE operation on <port-list>.
Default: All PoE ports are initially enabled for PoE operation at Low priority. If you configure a higher priority, this
priority is retained until you change it.
Enabling support for pre-standard devices
The switches covered in this guide also support some pre-802.3af devices. For a list of the supported devices,
see the FAQ for your switch model.
Syntax:
[no] power-over-ethernet pre-std-detect
Detects and powers pre-802.3af standard devices.
Chapter 4 Power Over Ethernet (PoE/PoE+) Operation 109
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