Configuring A Secondary Root Bridge-Cli Version - Cisco Nexus 7000 Series Configuration Manual

Configuring Rapid PVST+ Using Cisco NX-OS
Command or Action
Example:
switch(config)# spanning-tree vlan 5 root
primary diameter 4
Step 3
exit
Example:
switch(config)# exit
switch#
Step 4 show spanning-tree
Example:
switch# show spanning-tree
Step 5
copy running-config startup-config
Example:
switch# copy running-config startup-config
This example shows how to configure the device as the root bridge for VLAN 5 with a network diameter of
4:
switch# config t
switch(config)# spanning-tree vlan 5 root primary
diameter 4
switch(config)# exit
switch#
Configuring a Secondary Root Bridge—CLI Version
When you configure a device as the secondary root, the STP bridge priority is modified from the default value
(32768) so that the device is likely to become the root bridge for the specified VLANs if the primary root
bridge fails (assuming the other network devices in the network use the default bridge priority of 32768). STP
sets the bridge priority to 28672.
Enter the diameter keyword to specify the Layer 2 network diameter (that is, the maximum number of bridge
hops between any two end stations in the Layer 2 network). When you specify the network diameter, the
software automatically selects an optimal hello time, forward delay time, and maximum age time for a network
of that diameter, which can significantly reduce the STP convergence time. You can enter the hello-time
keyword to override the automatically calculated hello time.
You can configure more than one device in this manner to have multiple backup root bridges. Enter the same
network diameter and hello time values that you used when configuring the primary root bridge.
Purpose
Exits global configuration mode.
(Optional)
Displays the STP configuration.
(Optional)
Copies the running configuration to the startup
configuration.
Cisco Nexus 7000 Series NX-OS Layer 2 Switching Configuration Guide, Release 5.x
Configuring a Secondary Root Bridge—CLI Version
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