Reference Guide

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R3#
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 58. RSTP Default Values
RSTP Parameter Default Value
Forward Delay 15 seconds
Hello Time 2 seconds
Max Age 20 seconds
Port Cost:
● 10-Gigabit Ethernet interfaces
● Port Channel with 10-Gigabit Ethernet interfaces
Port Cost:
● 2000
● 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.
PROTOCOL SPANNING TREE RSTP mode
hello-time seconds
NOTE:
With large configurations (especially those configurations with more ports) Dell Networking recommends
increasing the hello-time.
Rapid Spanning Tree Protocol (RSTP) 647