Dell PowerSwitch S4820T Configuration Guide for the S4820T System 9.100.0 - Page 662

The 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 pvst command. Modifying Interface PVST+ Parameters You can adjust two interface parameters (port cost and port priority) to increase or decrease the probability 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 the port is selected to be a forwarding port. • Port priority - influences the likelihood that a port is selected to be a forwarding port in case that several ports have the same port cost. The following tables lists the default values for port cost by interface. Table 67. Default Values for Port Cost Port Cost 100-Mb/s Ethernet interfaces 1-Gigabit Ethernet interfaces 10-Gigabit Ethernet interfaces 25-Gigabit Ethernet interfaces 40-Gigabit Ethernet interfaces 50-Gigabit Ethernet interfaces 100-Gigabit Ethernet interfaces Port Channel with 100 Mb/s Ethernet interfaces Port Channel with 1-Gigabit Ethernet interfaces Port Channel with 10-Gigabit Ethernet interfaces Port Channel with 25-Gigabit Ethernet interfaces Port Channel with 50-Gigabit Ethernet interfaces Port Channel with 100-Gigabit Ethernet interfaces Default Value 200000 20000 2000 1700 1400 1200 200 180000 18000 1800 1200 200 180 NOTE: The Dell Networking OS implementation of PVST+ uses IEEE 802.1s costs as the default costs. Other implementations use IEEE 802.1w costs as the default costs. If you are using Dell Networking 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 mode spanning-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 mode spanning-tree pvst vlan priority. 662 Per-VLAN Spanning Tree Plus (PVST+)