Modifying The Interface Parameters - Dell S4820T Configuration Manual

The default is 20.
Example of the forward-delay Parameter
To view the current values for MSTP parameters, use the show running-config spanning-tree
mstp command from EXEC privilege mode.
Dell(conf-mstp)#forward-delay 16
Dell(conf-mstp)#exit
Dell(conf)#do show running-config spanning-tree mstp
!
protocol spanning-tree mstp
no disable
name my-mstp-region
MSTI 1 VLAN 100
MSTI 2 VLAN 200-300
forward-delay 16
MSTI 2 bridge-priority 4096
Dell(conf)#

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 53. Default Values for Port Costs by Interface
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
To change the port cost or priority of an interface, use the following commands.
1. Change the port cost of an interface.
INTERFACE mode
spanning-tree msti number cost cost
The range is from 0 to 200000.
Multiple Spanning Tree Protocol (MSTP)
Default Value
200000
20000
2000
180000
18000
1800
653