7-49
Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7
OL-8978-04
Chapter 7 Configuring Spanning Tree
Configuring Spanning-Tree Timers on the Switch
This example shows how to display spanning-tree BPDU statistics:
Console>
show spantree statistics bpdu
Transmitted Received Processed Dropped
-------------- -------------- -------------- --------------
Total 52943073 52016589 52016422 167
Rate(/sec) 989 971 971 0
This example shows how to clear spanning-tree BPDU statistics:
Console> (enable)
clear spantree statistics bpdu
Spanning tree BPDU statistics cleared on the switch.
Console> (enable)
Configuring Spanning-Tree Timers on the Switch
The 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, or if you do not specify an MISTP instance
when the switch is in MISTP mode, MISTP instance 1 is assumed.
These sections describe how to configure the spanning-tree timers:
•
Configuring the Hello Time, page 7-50
•
Configuring the Forward Delay Time, page 7-50
•
Configuring the Maximum Aging Time, page 7-51
Caution
Be careful when 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 7-7
describes the switch variables that affect spanning tree performance.
Table 7-7
Spanning-Tree Timers
Variable
Description
Default
Hello Time
Determines how often the switch broadcasts its hello message to
other switches.
2 seconds
Maximum Age
Timer
Measures the age of the received protocol information that is
recorded for a port and ensures that this information is discarded
when its age limit exceeds the value of the maximum age parameter
that is recorded by the switch. The timeout value is the maximum
age parameter of the switches.
20 seconds
Forward Delay
Timer
Monitors the time that is spent by a port in the learning and
listening states. The timeout value is the forward delay parameter
of the switches.
15 seconds