Modifying Interface Pvst+ Parameters - Dell S4820T Configuration Manual

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PROTOCOL PVST mode

vlan max-age

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

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 57. Default Values for Port Cost

100-Mb/s Ethernet interfaces

1-Gigabit Ethernet interfaces

10-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

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.

Per-VLAN Spanning Tree Plus (PVST+)

Default Value