Users Guide

Adding and Removing Interfaces
To add and remove interfaces, use the following commands.
To add an interface to the Rapid Spanning Tree topology, congure 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 conguration 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 modication of the RSTP parameters can negatively aect network performance.
The following table displays the default values for RSTP.
Table 68. RSTP Default Values
RSTP Parameter 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
Port Cost:
• 200000
• 20000
• 2000
• 180000
• 18000
• 1800
Port Priority 128
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.
• Change the hello-time parameter.
720
Rapid Spanning Tree Protocol (RSTP)