Modifying Interface Pvst+ Parameters - Dell S6100 Configuration Manual

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 70. 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
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.
The range is from 0 to 240, in increments of 16.
The default is 128.
690 Per-VLAN Spanning Tree Plus (PVST+)
Default Value
200000
20000
2000
1700
1400
1200
200
180000
18000
1800
1200
200
180