Modifying Interface PVST+ ParametersYou can adjust two interface parameters (port cost and port priority) to increase or decrease the probability that a port becomes aforwarding port.• Port cost — a value that is based on the interface type. The greater the port cost, the less likely the port is selected to be a forwardingport.• Port priority — influences the likelihood that a port is selected to be a forwarding port in case that several ports have the same portcost.The following tables lists the default values for port cost by interface.Table 71. Default Values for Port CostPort Cost Default Value100-Mb/s Ethernet interfaces 2000001-Gigabit Ethernet interfaces 2000010-Gigabit Ethernet interfaces 200025-Gigabit Ethernet interfaces 170040-Gigabit Ethernet interfaces 140050-Gigabit Ethernet interfaces 1200100-Gigabit Ethernet interfaces 200Port Channel with 100 Mb/s Ethernet interfaces 180000Port Channel with 1-Gigabit Ethernet interfaces 18000Port Channel with 10-Gigabit Ethernet interfaces 1800Port Channel with 25-Gigabit Ethernet interfaces 1200Port Channel with 50-Gigabit Ethernet interfaces 200Port Channel with 100-Gigabit Ethernet interfaces 180NOTE: The Dell Networking OS implementation of PVST+ uses IEEE 802.1s costs as the default costs. Other implementationsuse IEEE 802.1w costs as the default costs. If you are using Dell Networking systems in a multi-vendor network, verify that thecosts are values you intended.To change the port cost or port priority of an interface, use the following commands.• Change the port cost of an interface.INTERFACE modespanning-tree pvst vlan cost.The range is from 0 to 200000.Refer to the table for the default values.• Change the port priority of an interface.INTERFACE modespanning-tree pvst vlan priority.The range is from 0 to 240, in increments of 16.The default is 128.Per-VLAN Spanning Tree Plus (PVST+) 725
