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Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter 10 Configuring STP
Configuring Basic STP Features
To return the switch to its default setting, use the no spanning-tree vlan vlan-id forward-time global
configuration command.
Configuring the Maximum-Aging Time for a VLAN
Beginning in privileged EXEC mode, follow these steps to configure the STP maximum-aging time for
a VLAN:
To return the switch to its default setting, use the no spanning-tree vlan vlan-id max-age global
configuration command.
Configuring STP for Use in a Cascaded Stack
STP uses default values that can be reduced when configuring your switch in cascaded configurations.
If an STP root switch is part of a cluster that is one switch from a cascaded stack, you can customize
STP to reconverge more quickly after a switch failure.
Figure 10-14
shows switches in three cascaded
stacks that use the GigaStack GBIC.
Table 10-4
shows the default STP settings and those that are
acceptable for these configurations.
Command
Purpose
Step 1
configure terminal
Enter global configuration mode.
Step 2
spanning-tree vlan vlan-id max-age seconds
Configure the maximum-aging time of a VLAN. The
maximum-aging time is the number of seconds a switch waits
without receiving STP configuration messages before
attempting a reconfiguration.
•
For vlan-id, the range is 1 to 1005. Do not enter leading
zeros.
•
For seconds, the range is 6 to 40 seconds; the default is 20
seconds.
Step 3
end
Return to privileged EXEC mode.
Step 4
show spanning-tree vlan vlan-id bridge [brief]
Verify your entries.
Step 5
copy running-config startup-config
(Optional) Save your entries in the configuration file.
Table 10-4
Default and Acceptable STP Parameter Settings (in seconds)
STP Parameter
STP Default
Acceptable for Option 1
Acceptable for Option 2
Acceptable for Option 3
Hello Time
2
1
1
1
Max Age
20
6
10
6
Forwarding Delay
15
4
7
4