Setup Guide

MSTI 2 bridge-priority 4096
DellEMC(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 64. Default 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.
1. 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..
2. 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.
Setting STP path cost as constant
You can set the path cost to be constant for port-channel regardless of the operation status of the port-channel member ports.
To set the STP path cost, use the port-channel path-cost custom command from the PROTOCOL SPANNING-TREE mode.
Multiple Spanning Tree Protocol (MSTP)
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