Cisco Systems EA6500 Manual De Usuario

STP is enabled by default on VLAN 1 and on all newly created VLANs.

You can enable STP on a per-VLAN basis. The Catalyst 6500 series switch maintains a separate instance 
of STP for each VLAN (except on VLANs on which you disable STP).

To enable STP on a per-VLAN basis, perform this task:

Do not disable spanning tree on a VLAN unless all switches and bridges in the VLAN have spanning 
tree disabled. You cannot disable spanning tree on some switches and bridges in a VLAN and leave it 
enabled on other switches and bridges in the VLAN. This action can have unexpected results because 
switches and bridges with spanning tree enabled will have incomplete information regarding the physical 
topology of the network. 

We do not recommend disabling spanning tree, even in a topology that is free of physical loops. Spanning 
tree serves as a safeguard against misconfigurations and cabling errors. Do not disable spanning tree in 
a VLAN without ensuring that there are no physical loops present in the VLAN.

This example shows how to enable STP on VLAN 200:

Router# configure terminal 

Router(config)# spanning-tree vlan 200 

Router(config)# end 

Router#

Because STP is enabled by default, entering a show running command to view the resulting 
configuration does not display the command you entered to enable STP.

Router(config)# spanning-tree vlan vlan_ID 

Enables STP on a per-VLAN basis. The vlan_ID value 
can be 1 through 4094, except reserved VLANs (see 

).

Router(config)# default spanning-tree vlan 

vlan_ID 

Reverts all STP parameters to default values for the 
specified VLAN. 

Router(config)# no spanning-tree vlan vlan_ID 

Disables STP on the specified VLAN; see the following 
Cautions for information regarding this command.

Router(config)# end 

Exits configuration mode.

Router# show spanning-tree vlan vlan_ID 

Verifies that STP is enabled.