C
HAPTER
33
| Spanning Tree Commands
– 758 –
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 loopback-
detection release
Manually releases a port placed in discarding state by
loopback-detection
PE
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 99: Spanning Tree Commands (Continued)
Command Function Mode