Configuring Spanning-Tree Features
Configuring the Switch Priority of a VLAN
You can configure the switch priority and make it more likely that the switch will be chosen as the root
switch.
Note
Exercise care when using this command. For most situations, we recommend that you use the
spanning-tree vlan vlan-id root primary and the spanning-tree vlan vlan-id root secondary global
configuration commands to modify the switch priority.
Beginning in privileged EXEC mode, follow these steps to configure the switch priority of a VLAN. This
procedure is optional.
Command
Step 1
configure terminal
Step 2
spanning-tree vlan vlan-id priority priority
Step 3
end
Step 4
show spanning-tree vlan vlan-id
Step 5
copy running-config startup-config
To return the switch to its default setting, use the no spanning-tree vlan vlan-id priority global
configuration command.
Configuring Spanning-Tree Timers
Table 13-4
Table 13-4
Spanning-Tree Timers
Variable
Description
Hello timer
Determines how often the switch broadcasts hello messages to other switches.
Forward-delay timer
Determines how long each of the listening and learning states last before the interface begins
forwarding.
Maximum-age timer
Determines the amount of time the switch stores protocol information received on an interface.
Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide
13-20
describes the timers that affect the entire spanning-tree performance.
Purpose
Enter global configuration mode.
Configure the switch priority of a 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.
For priority, the range is 0 to 61440 in increments of
•
4096; the default is 32768. The lower the number, the
more likely the switch will be chosen as the root switch.
Valid priority values are 4096, 8192, 12288, 16384,
20480, 24576, 28672, 32768, 36864, 40960, 45056,
49152, 53248, 57344, and 61440. All other values are
rejected.
Return to privileged EXEC mode.
Verify your entries.
(Optional) Save your entries in the configuration file.
Chapter 13
Configuring STP
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