Dell PowerSwitch S4820T Configuration Guide for the S4820T System 9.100.0 - Page 720

Adding and Removing Interfaces To add and remove interfaces, use the following commands. To add an interface to the Rapid Spanning Tree topology, configure it for Layer 2 and it is automatically added. If you previously disabled RSTP on the interface using the command no spanning-tree 0 command, re-enable it using the spanning-tree 0 command. • Remove an interface from the Rapid Spanning Tree topology. no spanning-tree 0 Modifying Global Parameters You can modify RSTP 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 the Rapid Spanning Tree group. • Forward-delay - the amount of time an interface waits in the Listening state and the Learning state before it transitions to the Forwarding state. • Hello-time - the time interval in which the bridge sends RSTP BPDUs. • Max-age - the length of time the bridge maintains configuration information before it refreshes that information by recomputing the RST topology. NOTE: Dell Networking recommends that only experienced network administrators change the Rapid Spanning Tree group parameters. Poorly planned modification of the RSTP parameters can negatively affect network performance. The following table displays the default values for RSTP. Table 78. RSTP Default Values RSTP Parameter 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 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. Default Value 15 seconds 2 seconds 20 seconds Port Cost: • 200000 • 20000 • 2000 • 1400 • 180000 • 18000 • 1800 • 600 128 720 Rapid Spanning Tree Protocol (RSTP)