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Catalyst 4500 Series, Catalyst 2948G, Catalyst 2980G Switches Software Configuration Guide
—
Release 8.1
78-15486-01
Chapter 7 Configuring Spanning Tree
Configuring Spanning Tree Timers
Configuring Spanning Tree Timers
Spanning tree timers affect the spanning tree performance. You can configure the spanning tree timers
for a VLAN in PVST+ or an MISTP instance in MISTP mode. If you do not specify a VLAN when the
switch is in PVST+ mode, VLAN 1 is assumed. If you do not specify an MISTP instance when the switch
is in MISTP mode, MISTP instance 1 is assumed.
Caution
Exercise care using these commands. For most situations, we recommend that you use the set spantree
root and set spantree root secondary commands to modify the spanning tree performance parameters.
Table 7-6
describes the switch variables that affect spanning tree performance.
Configuring the Hello Time
Enter the set spantree hello command to change the Hello time for a VLAN or for an MISTP instance.
The possible range for interval is from 1–10 seconds.
To configure the spanning tree bridge Hello time for a VLAN or an MISTP instance, perform this task
in privileged mode:
This example shows how to configure the spanning tree Hello time for VLAN 100 to 7 seconds:
Console> (enable) set spantree hello 7 100
Spantree 100 hello time set to 7 seconds.
Console> (enable)
This example shows how to set the spantree Hello time for an instance to 3 seconds:
Console> (enable) set spantree hello 3 mistp-instance 1
Spantree 1 hello time set to 3 seconds.
Console> (enable)
Table 7-6
Switch Variable Descriptions
Variable
Description
Default
Hello Time
Determines how often the switch broadcasts its Hello message to
other switches.
20 sec
Maximum Age
Timer
Measures the age of the received protocol information recorded for
a port and ensures that this information is discarded when its age
limit exceeds the value of the maximum age parameter recorded by
the switch. The timeout value is the maximum age parameter of the
switches.
2 sec
Forward Delay
Timer
Monitors the time spent by a port in learning and listening states.
The timeout value is the forward delay parameter of the switches.
15 sec
Task
Command
Step 1
Configure the Hello time for a VLAN or
MISTP instance.
set spantree hello interval [vlan] mistp-instance
[instances]
Step 2
Verify the configuration.
show spantree [vlan | mistp-instance instances]