Chapter 17
  |  Spanning Tree Commands
–  444  –
spanning-tree This command enables the Spanning Tree Algorithm globally for the switch. Use 
the no form to disable it.
Syntax 
[no] spanning-tree
Default Setting 
Spanning tree is enabled.
Command Mode 
Global Configuration
Command Usage 
The Spanning Tree Algorithm (STA) can be used to detect and disable network 
loops, and to provide backup links between switches, bridges or routers. This 
allows the switch to interact with other bridging devices (that is, an STA-compliant 
switch, bridge or router) in your network to ensure that only one route exists 
between any two stations on the network, and provide backup links which 
automatically take over when a primary link goes down.
Example 
This example shows how to enable the Spanning Tree Algorithm for the switch:
Console(config)#spanning-tree
Console(config)#
spanning-tree port-priority  Configures the spanning tree priority of an interface IC
spanning-tree root-guard Prevents a designated port from passing superior BPDUs IC
spanning-tree spanning-
disabled
Disables spanning tree for an interface IC
spanning-tree tc-prop-stop Stops propagation of topology change information IC
spanning-tree protocol-
migration
Re-checks the appropriate BPDU format PE
show spanning-tree  Shows spanning tree configuration for the common 
spanning tree (i.e., overall bridge), a selected interface, or 
an instance within the multiple spanning tree
PE
show spanning-tree mst 
configuration 
Shows the multiple spanning tree configuration PE
Table 87: Spanning Tree Commands  (Continued)
Command Function Mode