Cisco Catalyst 3550 Series User Manual

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Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter 36 Configuring Fallback Bridging
Monitoring and Maintaining Fallback Bridging
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 re-enable spanning tree on the interface, use the no bridge-group bridge-group spanning-disabled
interface configuration command.
This example shows how to disable spanning tree on an interface in bridge group 10:
Switch(config)# interface gigabitethernet0/1
Switch(config-if)# bridge group 10 spanning-disabled
Monitoring and Maintaining Fallback Bridging
To monitor and maintain fallback bridging, use one or more of the privileged EXEC commands in
Table 36-2:
For information about the fields in these displays, refer to the Cisco IOS Bridging and IBM Networking
Command Reference for Release 12.1.
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
interface interface-id Enter interface configuration mode, and specify the interface ID.
Step 3
bridge-group bridge-group
spanning-disabled
Disable spanning tree on the interface.
For bridge-group, specify the bridge group number. The range is 1
to 255.
Step 4
end Return to privileged EXEC mode.
Step 5
show running-config Verify your entry.
Step 6
copy running-config startup-config (Optional) Save your entry in the configuration file.
Table 36-2 Commands for Monitoring and Maintaining Fallback Bridging
Command Purpose
clear bridge bridge-group Removes any learned entries from the forwarding
database and clears the transmit and receive counts for
any statically configured entries.
show bridge [bridge-group] Displays details about the bridge group.
show bridge [bridge-group] [interface-id]
[address] [group] [verbose]
Displays classes of entries in the bridge forwarding
database.

Cisco Catalyst 3550 Series Specifications

General

Form Factor	Rack-mountable
Manageable	Yes
RAM	64 MB
Device Type	Switch
MAC Address Table Size	12000 entries
Routing Protocol	RIP
Features	VLAN support
Power Supply	AC 120/230 V (50/60 Hz)
Ports	24 or 48 x 10/100Base-TX, 1 x GBIC, 2 x 10/100/1000Base-T
Operating Temperature	32 to 113°F (0 to 45°C)