Configuring The Root Bridge - Cisco Nexus 7000 Series Configuration Manual

Configuring MST Using Cisco NX-OS
Command or Action
Step 6
copy running-config startup-config
Example:
switch(config)# copy running-config startup-config
This example shows how to automatically map all the secondary VLANs to the same MSTI as their associated
primary VLANs in all private VLANs:
switch# config t
switch(config)# spanning-tree mst configuration
switch(config-mst)# private-vlan synchronize
switch(config-mst)# exit
switch(config)#

Configuring the Root Bridge

You can configure the device to become the MST root bridge.
The spanning-tree vlan vlan_ID primary root command fails if the value required to be the root bridge is
less than 4096. If the software cannot lower the bridge priority any lower, the device returns the following
message:
Error: Failed to set root bridge for VLAN 1
It may be possible to make the bridge root by setting the priority
for some (or all) of these instances to zero.
The root bridge for each MSTI should be a backbone or distribution device. Do not configure an access
Note
device as the spanning tree primary root bridge.
Enter the diameter keyword, which is available only for MSTI 0 (or the IST), to specify the Layer 2 network
diameter (that is, the maximum number of Layer 2 hops between any two end stations in the Layer 2 network).
When you specify the network diameter, the device automatically sets an optimal hello time, forward-delay
time, and maximum-age time for a network of that diameter, which can significantly reduce the convergence
time. You can enter the hello keyword to override the automatically calculated hello time.
With the device configured as the root bridge, do not manually configure the hello time, forward-delay
Note
time, and maximum-age time using the spanning-tree mst hello-time, spanning-tree mst forward-time,
and spanning-tree mst max-age global configuration commands.
Before You Begin
Ensure that you are in the correct VDC (or enter the switchto vdc command).
Cisco Nexus 7000 Series NX-OS Layer 2 Switching Configuration Guide, Release 5.x
Configuring the Root Bridge
Purpose
(Optional)
Copies the running configuration to the startup
configuration.
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