Cisco Nexus 5000 Series Switch CLI Software Configuration Guide (OL-16597-01, July 2009)
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# configure terminal
switch(config)# spanning-tree mst configuration
switch(config-mst)# private-vlan synchronize
Configuring the Root Bridge
You can configure the switch to become the root bridge.
The root bridge for each MSTI should be a backbone or distribution switch. Do not configure an access
switch as the spanning tree primary root bridge.
Note
Enter the diameter keyword, which is available only for MSTI 0 (or the IST), to specify the network diameter
(that is, the maximum number of hops between any two end stations in the network). When you specify the
network diameter, the switch 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 switch configured as the root bridge, do not manually configure the hello time, forward-delay
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.
Note
Procedure
PurposeCommand or Action
Enters configuration mode.switch# configure terminal
Step 1
Configures a switch as the root bridge as follows:switch(config)# spanning-tree mst
instance-id root {primary |
Step 2
•
For instance-id, you can specify a single instance, a range
of instances separated by a hyphen, or a series of instances
separated by a comma. The range is from 1 to 4094.
secondary} [diameter dia
[hello-time hello-time]]
•
For diameter net-diameter, specify the maximum number
of hops between any two end stations. The default is 7.
This keyword is available only for MST instance 0.
•
For hello-time seconds, specify the interval in seconds
between the generation of configuration messages by the
root bridge. The range is from 1 to 10 seconds; the default
is 2 seconds.
(Optional)
Returns the switch priority, diameter, and hello time to default
values.
switch(config)# no spanning-tree
mst instance-id root
Step 3
Cisco Nexus 5000 Series Switch CLI Software Configuration Guide
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Configuring MST
Configuring the Root Bridge