Cisco Catalyst 4500 Series Configuration Manual page 1116

spanning-tree vlan
Usage Guidelines When you are setting the max-age seconds value, if a bridge does not hear BPDUs from the root bridge
within the specified interval, it assumes that the network has changed and recomputes the spanning-tree
topology.
The spanning-tree root primary command alters the switch bridge priority to 8192. If you enter the
spanning-tree root primary command and the switch does not become root, then the bridge priority is
changed to 100 less than the bridge priority of the current bridge. If the switch does not become root, an
error will result.
The spanning-tree root secondary command alters the switch bridge priority to 16384. If the root
switch fails, this switch becomes the next root switch.
Use the spanning-tree root commands on backbone switches only.
Examples
The following example shows how to enable spanning tree on VLAN 200:
Switch(config)# spanning-tree vlan 200
Switch(config)#
The following example shows how to configure the switch as the root switch for VLAN 10 with a
network diameter of 4:
Switch(config)# spanning-tree vlan 10 root primary diameter 4
Switch(config)#
The following example shows how to configure the switch as the secondary root switch for VLAN 10
with a network diameter of 4:
Switch(config)# spanning-tree vlan 10 root secondary diameter 4
Switch(config)#
Related Commands Command
spanning-tree cost
spanning-tree port-priority
spanning-tree portfast
spanning-tree portfast (interface
configuration mode)
spanning-tree vlan
show spanning-tree
Catalyst 4500 Series Switch Cisco IOS Command Reference—Release XE 3.9.xE and 15.2(5)Ex
2-1066
Description
Calculates the path cost of STP on an interface.
Prioritizes an interface when two bridges compete for
position as the root bridge.
Enables PortFast by default on all access ports.
Enables PortFast mode.
Configures STP on a per-VLAN basis.
Displays spanning-tree state information.
Chapter 2