Dell Configuration Guide for the S4048–ON System 9.14.2.5

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Modifying the Interface Parameters

You can adjust two interface parameters to increase or decrease the probability that a port becomes a forwarding port.

Port cost is 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 lists the default values for port cost by interface.

Table 1. Default Values for Port Costs by InterfaceDefault Values for Port Costs by Interface
Port Cost	Default Value
100-Mb/s Ethernet interfaces	200000
1-Gigabit Ethernet interfaces	20000
10-Gigabit Ethernet interfaces	2000
25-Gigabit Ethernet interfaces	800
40-Gigabit Ethernet interfaces	500
50-Gigabit Ethernet interfaces	400
100-Gigabit Ethernet interfaces	200
Port Channel with 100 Mb/s Ethernet interfaces	100000
Port Channel with 1-Gigabit Ethernet interfaces	10000
Port Channel with 10-Gigabit Ethernet interfaces	1000
Port Channel with 25-Gigabit Ethernet interfaces	400
Port Channel with 50-Gigabit Ethernet interfaces	200
Port Channel with 100-Gigabit Ethernet interfaces	100

To change the port cost or priority of an interface, use the following commands.

Change the port cost of an interface.
INTERFACE mode

spanning-tree msti number cost cost

The range is from 0 to 200000.

For the default, refer to the default values shown in the table..
Change the port priority of an interface.
INTERFACE mode

spanning-tree msti number priority priority

The range is from 0 to 240, in increments of 16.

The default is 128.

To view the current values for these interface parameters, use the show config command from INTERFACE mode.