User's Manual

20-22
Catalyst 3750-X and 3560-X Switch Software Configuration Guide
OL-21521-01
Chapter 20 Configuring STP
Configuring Spanning-Tree Features
Configuring Spanning-Tree Timers
Table 20-4 describes the timers that affect the entire spanning-tree performance.
The sections that follow provide the configuration steps.
Configuring the Hello Time
You can configure the interval between the generation of configuration messages by the root switch by
changing the hello time.
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 hello time.
Beginning in privileged EXEC mode, follow these steps to configure the hello time of a VLAN. This
procedure is optional.
To return to the default setting, use the no spanning-tr
ee vlan vlan-id hello-time global configuration
command.
Ta ble 20-4 Spanning-Tree Timers
Variable Description
Hello timer Controls how often the switch broadcasts hello messages to other switches.
Forward-delay timer Controls how long each of the listening and learning states last before the interf
ace begins
forwarding.
Maximum-age timer Controls the amount of time the switch stores protocol information received on an interface.
Transmit hold count Controls the number of BPDUs that can be sent before pausing for 1 second.
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
spanning-tree vlan vlan-id hello-time seconds Configure the hello time of a VLAN. The hello time is the
interval between the generation of configuration messages by
the root switch. These messages mean that the switch is alive.
• 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 seconds, the range is 1 to 10; the default is 2.
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.