Dell EMC Configuration Guide for the S3100 Series 9.14.2.4

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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 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 1. STP Default ValuesSTP 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 Port Channel with 100 Mb/s Ethernet interfaces Port Channel with 1-Gigabit Ethernet interfaces Port Channel with 10-Gigabit Ethernet interfaces	200000 20000 2000 180000 18000 1800
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.

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.