PROTOCOL PVST modevlan max-ageThe range is from 6 to 40.The default is 20 seconds.The values for global PVST+ parameters are given in the output of the show spanning-tree pvstcommand.Modifying Interface PVST+ ParametersYou can adjust two interface parameters (port cost and port priority) to increase or decrease theprobability that a port becomes a forwarding port.• Port cost — 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 tables lists the default values for port cost by interface.Table 38. Default Values for Port CostPort 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 1800NOTE: The Dell Networking OS implementation of PVST+ uses IEEE 802.1s costs as the defaultcosts. Other implementations use IEEE 802.1w costs as the default costs. If you are using DellNetworking systems in a multi-vendor network, verify that the costs 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.Per-VLAN Spanning Tree Plus (PVST+) 647
