Administrator Guide

Table Of Contents
Modifying Global Parameters
You can modify the spanning tree parameters. The root bridge sets the values for forward-delay, hello-time, and max-age and
overwrites the values set on other bridges participating in STP.
NOTE: Dell EMC Networking recommends that only experienced network administrators change the spanning tree
parameters. Poorly planned modification of the spanning tree parameters can negatively affect network performance.
The following table displays the default values for STP.
Table 138. STP Default Values
STP Parameters 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
25-Gigabit Ethernet interfaces
40-Gigabit Ethernet interfaces
50-Gigabit Ethernet interfaces
100-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 Channel with 25-Gigabit Ethernet interfaces
Port Channel with 50-Gigabit Ethernet interfaces
Port Channel with 100-Gigabit Ethernet interfaces
200000
20000
2000
1700
1400
1200
200
180000
18000
1800
600
1200
200
180
Port Priority 8
Change the forward-delay parameter (the wait time before the interface enters the Forwarding state).
PROTOCOL SPANNING TREE mode
forward-delay seconds
The range is from 4 to 30.
The default is 15 seconds.
Change the hello-time parameter (the BPDU transmission interval).
PROTOCOL SPANNING TREE mode
hello-time seconds
NOTE:
With large configurations (especially those 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 (the refresh interval for configuration information that is generated by recomputing the
spanning tree topology).
PROTOCOL SPANNING TREE mode
max-age seconds
The range is from 6 to 40.
The default is 20 seconds.
Spanning Tree Protocol (STP)
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