Modifying the Interface ParametersYou can adjust two interface parameters to increase or decrease the probability that a port becomes aforwarding port.• Port cost is a value that is based on the interface type. The greater the port cost, the less likely theport is selected to be a forwarding port.• Port priority influences the likelihood that a port is selected to be a forwarding port in case thatseveral ports have the same port cost.The following lists the default values for port cost by interface.Table 32. Default Values for Port Costs by InterfacePort Cost Default Value100-Mb/s Ethernet interfaces 2000001-Gigabit Ethernet interfaces 2000010-Gigabit Ethernet interfaces 2000Port Channel with 100 Mb/s Ethernet interfaces 180000Port Channel with 1-Gigabit Ethernet interfaces 18000Port Channel with 10-Gigabit Ethernet interfaces 1800To change the port cost or priority of an interface, use the following commands.1. Change the port cost of an interface.INTERFACE modespanning-tree msti number cost costThe range is from 0 to 200000.For the default, refer to the default values shown in the table..2. Change the port priority of an interface.INTERFACE modespanning-tree msti number priority priorityThe range is from 0 to 240, in increments of 16.The default is 128.To view the current values for these interface parameters, use the show config command fromINTERFACE mode.Configuring an EdgePortThe EdgePort feature enables interfaces to begin forwarding traffic approximately 30 seconds sooner.In this mode, an interface forwards frames by default until it receives a BPDU that indicates that it shouldbehave otherwise; it does not go through the Learning and Listening states. The bpduguard shutdown-on-violation option causes the interface hardware to be shut down when it receives a BPDU. When524 Multiple Spanning Tree Protocol (MSTP)
