Spanning Tree Commands4-1714The recommended range is:•Ethernet: 200,000-20,000,000•Fast Ethernet: 20,000-2,000,000•Gigabit Ethernet: 2,000-200,000Default SettingBy default, the system automatically detects the speed and duplex mode usedon each port, and configures the path cost according to the values shownbelow. Path cost “0” is used to indicate auto-configuration mode. When theshort path cost method is selected and the default path cost recommended bythe IEEE 8021w standard exceeds 65,535, the default is set to 65,535.• Ethernet – half duplex: 2,000,000; full duplex: 1,000,000; trunk: 500,000• Fast Ethernet – half duplex: 200,000; full duplex: 100,000; trunk: 50,000• Gigabit Ethernet – full duplex: 10,000; trunk: 5,000Command ModeInterface Configuration (Ethernet, Port Channel)Command Usage• This command is used by the Spanning Tree Algorithm to determine the bestpath between devices. Therefore, lower values should be assigned to portsattached to faster media, and higher values assigned to ports with slowermedia.• Path cost takes precedence over port priority.• When the spanning-tree pathcost method (page 4-165) is set to short, themaximum value for path cost is 65,535.Examplespanning-tree port-priorityThis command configures the priority for the specified interface. Use the no form torestore the default.Syntaxspanning-tree port-priority priorityno spanning-tree port-prioritypriority - The priority for a port. (Range: 0-240, in steps of 16)Default Setting128Command ModeInterface Configuration (Ethernet, Port Channel)Console(config)#interface ethernet 1/5Console(config-if)#spanning-tree cost 50Console(config-if)#
