5.4 STP in the Campus Network
5.4.4 Modifying port priority
You can change the port priority of switch ports. The port with the lowest priority value for a specific VLAN forwards frames for that VLAN. If all ports have the same priority value for a particular VLAN, the port with the lowest port number forwards frames for that VLAN. The possible port priority range is 0 through 63. The default is 32. To change the port priority for a port on a set command-based switch, enter the set spantree portpri mod_num/port_num priority [vlans] command in privileged mode.

Verify the port priority setting by entering the show spantree [mod_num/port_num] command. The example in the Figure shows how to change the port priority for a port and verify the configuration on a set command-based switch.

Lab Activity
  In this lab activity, you will learn how to configure a port on your switch to monitor another port on the switch. This will be used to capture data from one port to a protocol analyzer.