Dell PowerSwitch S4820T Configuration Guide for the S4820T System 9.112.0P1 - Page 894

Adding an Interface to the Spanning Tree Group To add a Layer 2 interface to the spanning tree topology, use the following command. • Enable spanning tree on a Layer 2 interface. INTERFACE mode spanning-tree 0 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 104. STP Default Values STP Parameters Forward Delay Hello Time Max Age 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 Priority Default Value 15 seconds 2 seconds 20 seconds • 200000 • 20000 • 2000 • 1400 • 180000 • 18000 • 1800 • 600 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 hellotime. 894 Spanning Tree Protocol (STP)