13-16
Cisco ME 3800X and 3600X Switch Software Configuration Guide
OL-23400-01
Chapter 13 Configuring STP
Configuring Spanning-Tree Features
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.
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 a spanning-tree port to put into the
forwarding state. You can assign higher priority values (lower numerical values) to ports that you want
selected first and lower priority values (higher numerical values) to ones that you want selected last. If
all spanning-tree ports have the same priority value, spanning tree puts the port with the lowest interface
number in the forwarding state and blocks the other interfaces.
Command
Purpose
Step 1
configure terminal
Enter global configuration mode.
Step 2
spanning-tree vlan vlan-id root secondary
[diameter net-diameter [hello-time
seconds]]
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
“Configuring the
Root Switch” section on page 13-14
.
Step 3
end
Return to privileged EXEC mode.
Step 4
show spanning-tree detail
Verify your entries.
Step 5
copy running-config startup-config
(Optional) Save your entries in the configuration file.
