Dell PowerEdge FN I/O Module Configuration Guide 9.10(0.0)

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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 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 1. STP Default Values
STP Parameters	Default Value
Forward Delay	15 seconds
Hello Time	2 seconds
Max Age	20 seconds
Port Cost 40-Gigabit Ethernet interfaces 10-Gigabit Ethernet interfaces Port Channel with 40-Gigabit Ethernet interfaces Port Channel with 10-Gigabit Ethernet interfaces	1 2 1 1
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 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.

To view the current values for global parameters, use the show spanning-tree 0 command from EXEC privilege mode. Refer to the second example in Enabling Spanning Tree Protocol Globally.