Cisco Systems 3560X Manual De Usuario
20-15
Catalyst 3750-X and 3560-X Switch Software Configuration Guide
OL-21521-01
Chapter 20 Configuring STP
Configuring Spanning-Tree Features
To return to the default setting, use the no spanning-tree mode global configuration command. To return
the port to its default setting, use the no spanning-tree link-type interface configuration command.
the port to its default setting, use the no spanning-tree link-type interface configuration command.
Disabling Spanning Tree
Spanning tree is enabled by default on VLAN 1 and on all newly created VLANs up to the spanning-tree
limit specified in the
limit specified in the
. Disable spanning tree
only if you are sure there are no loops in the network topology.
Caution
When spanning tree is disabled and loops are present in the topology, excessive traffic and indefinite
packet duplication can drastically reduce network performance.
packet duplication can drastically reduce network performance.
Beginning in privileged EXEC mode, follow these steps to disable spanning-tree on a per-VLAN basis.
This procedure is optional.
This procedure is optional.
To re-enable spanning-tree, use the spanning-tree vlan vlan-id global configuration command.
Configuring the Root Switch
The switch maintains a separate spanning-tree instance for each active VLAN configured on it. A bridge
ID, consisting of the switch priority and the switch MAC address, is associated with each instance. For
each VLAN, the switch with the lowest bridge ID becomes the root switch for that VLAN.
ID, consisting of the switch priority and the switch MAC address, is associated with each instance. For
each VLAN, the switch with the lowest bridge ID becomes the root switch for that VLAN.
Step 6
clear spanning-tree detected-protocols
(Recommended for rapid-PVST+ mode only) If any port on the switch
is connected to a port on a legacy IEEE 802.1D switch, restart the
protocol migration process on the entire switch.
is connected to a port on a legacy IEEE 802.1D switch, restart the
protocol migration process on the entire switch.
This step is optional if the designated switch detects that this switch is
running rapid PVST+.
running rapid PVST+.
Step 7
show spanning-tree summary
and
show spanning-tree interface
interface-id
Verify your entries.
Step 8
copy running-config startup-config
(Optional) Save your entries in the configuration file.
Command
Purpose
Command
Purpose
Step 1
configure terminal
Enter global configuration mode.
Step 2
no
spanning-tree vlan vlan-id
For vlan-id, the range is 1 to 4094.
Step 3
end
Return to privileged EXEC mode.
Step 4
show spanning-tree vlan
vlan-id
Verify your entries.
Step 5
copy running-config startup-config
(Optional) Save your entries in the configuration file.