Configuring The Root Bridge - Cisco Nexus 5000 Series Configuration Manual

Configuring the Root Bridge

DETAILED STEPS
Command or Action
Step 1
switch# configure terminal
Step 2
switch(config)# spanning-tree mst configuration
Step 3 switch(config-mst)# private-vlan synchronize
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
Note
switch as the spanning tree primary root bridge.
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
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.
SUMMARY STEPS
1. switch# configure terminal
2. switch(config)# spanning-tree mst instance-id root {primary | secondary} [diameter dia [hello-time
hello-time]]
3. (Optional) switch(config)# no spanning-tree mst instance-id root
Cisco Nexus 5000 Series NX-OS Layer 2 Switching Configuration Guide, Release 5.0(3)N1(1)
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Configuring Multiple Spanning Tree
Purpose
Enters configuration mode.
Enters MST configuration submode.
Automatically maps all secondary VLANs to the same MSTI
and their associated primary VLAN for all private VLANs.