Cisco Catalyst 3560-X Software Configuration Manual page 569

Chapter 1 Configuring STP
Beginning in privileged EXEC mode, follow these steps to configure a switch to become the secondary
root for the specified VLAN. This procedure is optional.
Command
Step 1 configure terminal
Step 2
spanning-tree vlan vlan-id root secondary
[diameter net-diameter [hello-time
seconds]]
Step 3 end
Step 4
show spanning-tree detail
Step 5 copy running-config startup-config
To return to the default setting, use the no spanning-tree vlan vlan-id root global configuration
command.
Configuring Port Priority
If a loop occurs, spanning tree uses the port priority when selecting an interface to put into the
forwarding state. You can assign higher priority values (lower numerical values) to interfaces that you
want selected first and lower priority values (higher numerical values) that you want selected last. If all
interfaces have the same priority value, spanning tree puts the interface with the lowest interface number
in the forwarding state and blocks the other interfaces.
If your switch is a member of a switch stack, you must use the spanning-tree [vlan vlan-id] cost cost
Note
interface configuration command instead of the spanning-tree [vlan vlan-id] port-priority priority
interface configuration command to select an interface to put in the forwarding state. Assign lower cost
values to interfaces that you want selected first and higher cost values that you want selected last. For
more information, see the
OL-25303-03
Purpose
Enter global configuration mode.
Configure a switch to become the secondary root for the specified
VLAN.
For vlan-id, you can specify a single VLAN identified by VLAN
•
ID number, a range of VLANs separated by a hyphen, or a series
of VLANs separated by a comma. The range is 1 to 4094.
(Optional) For diameter net-diameter, specify the maximum
•
number of switches between any two end stations. The range is
2 to 7.
(Optional) For hello-time seconds, specify the interval in
•
seconds between the generation of configuration messages by
the root switch. The range is 1 to 10; the default is 2.
Use the same network diameter and hello-time values that you used
when configuring the primary root switch. See the
Root Switch" section on page
Return to privileged EXEC mode.
Verify your entries.
(Optional) Save your entries in the configuration file.
"Configuring Path Cost" section on page
Catalyst 3750-X and 3560-X Switch Software Configuration Guide
Configuring Spanning-Tree Features
"Configuring the
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