16- and 36-Port Ethernet Switch Module for Cisco 2600 Series, Cisco 3600 Series, and Cisco 3700 Series
Configuration Tasks
128
Cisco IOS Release 12.2(2)XT, 12.2(8)T, and 12.2(15)ZJ
Changing the Maximum-Idle Interval
If a switch does not hear BPDUs from the root switch within a specified interval, it recomputes the
spanning-tree topology.
Beginning in privileged EXEC mode, follow these steps to change the maximum-idle interval (maximum
aging time):
To return to the default setting, use the no bridge bridge-group max-age global configuration command.
Disabling the Spanning Tree on an Interface
When a loop-free path exists between any two switched subnetworks, you can prevent BPDUs generated
in one switching subnetwork from impacting devices in the other switching subnetwork, yet still permit
switching throughout the network as a whole. For example, when switched LAN subnetworks are
separated by a WAN, BPDUs can be prevented from traveling across the WAN link.
Beginning in privileged EXEC mode, follow these steps to disable spanning tree on an interface:
To reenable spanning tree on the interface, use the no bridge-group bridge-group spanning-disabled
interface configuration command.
Command
Purpose
Step 1
configure terminal
Enters global configuration mode.
Step 2
bridge bridge-group max-age seconds
Specifies the interval the switch waits to hear BPDUs from the root
switch.
•
For bridge-group, specify the bridge group number. The range is 1
to 255.
•
For seconds, enter a number from 10 to 200. The default is 30
seconds.
Step 3
end
Returns to privileged EXEC mode.
Step 4
show running-config
Verifies your entry.
Step 5
copy running-config startup-config
(Optional) Saves your entry in the configuration file.
Command
Purpose
Step 1
configure terminal
Enters global configuration mode.
Step 2
interface interface-id
Enters interface configuration mode, and specify the interface ID.
Step 3
bridge-group bridge-group
spanning-disabled
Disables spanning tree on the interface.
For bridge-group, specify the bridge group number. The range is 1
to 255.
Step 4
end
Returns to privileged EXEC mode.
Step 5
show running-config
Verifies your entry.
Step 6
copy running-config startup-config
(Optional) Saves your entry in the configuration file.