Administrator Guide

Table 84. RSTP Default Values
RSTP Parameter Default Value
Forward Delay 15 seconds
Hello Time 2 seconds
Max Age 20 seconds
Port Cost:
● 100-Mb/s Ethernet interfaces
● 1-Gigabit Ethernet interfaces
● 10-Gigabit Ethernet interfaces
● 40-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 40-Gigabit Ethernet interfaces
Port Cost:
● 200000
● 20000
● 2000
● 1400
● 180000
● 18000
● 1800
● 600
Port Priority 128
To change these parameters, use the following commands.
● Change the forward-delay parameter.
PROTOCOL SPANNING TREE RSTP mode
forward-delay seconds
The range is from 4 to 30.
The default is 15 seconds.
● Change the hello-time parameter.
PROTOCOL SPANNING TREE RSTP mode
hello-time seconds
NOTE:
With large configurations (especially those configurations with more ports) Dell EMC Networking recommends
increasing the hello-time.
The range is from 1 to 10.
The default is 2 seconds.
● Change the max-age parameter.
PROTOCOL SPANNING TREE RSTP mode
max-age seconds
The range is from 6 to 40.
The default is 20 seconds.
To view the current values for global parameters, use the show spanning-tree rstp command from EXEC privilege mode.
Enabling SNMP Traps for Root Elections and Topology Changes
To enable SNMP traps, use the following command.
● Enable SNMP traps for RSTP, MSTP, and PVST+ collectively.
snmp-server enable traps xstp
Modifying Interface Parameters
On interfaces in Layer 2 mode, you can set the port cost and port priority values.
● Port cost — a value that is based on the interface type. The previous table lists the default values. The greater the port
cost, the less likely the port is selected to be a forwarding port.
Rapid Spanning Tree Protocol (RSTP)
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