Cisco Catalyst 3550 Series User Manual

36-10
Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter 36 Configuring Fallback Bridging
Configuring Fallback Bridging
Adjusting BPDU Intervals
You can adjust BPDU intervals as described in these sections:
• Adjusting the Interval between Hello BPDUs, page 36-10
• Changing the Forward-Delay Interval, page 36-10
• Changing the Maximum-Idle Interval, page 36-11
Note Each switch in a spanning tree adopts the interval between hello BPDUs, the forward delay interval, and
the maximum idle interval parameters of the root switch, regardless of what its individual configuration
might be.
Adjusting the Interval between Hello BPDUs
Beginning in privileged EXEC mode, follow these step to adjust the interval between hello BPDUs:
To return to the default setting, use the no bridge bridge-group hello-time global configuration
command.
This example shows how to change the hello interval to 5 seconds in bridge group 10:
Switch(config)# bridge 10 hello-time 5
Changing the Forward-Delay Interval
The forward-delay interval is the amount of time spent listening for topology change information after
an interface has been activated for switching and before forwarding actually begins.
Beginning in privileged EXEC mode, follow these steps to change the forward-delay interval:
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
bridge bridge-group hello-time seconds Specify the interval between hello BPDUs.
• For bridge-group, specify the bridge group number. The range is 1
to 255.
• For seconds, enter a number from 1 to 10. The default is 2 seconds.
Step 3
end Return to privileged EXEC mode.
Step 4
show running-config Verify your entry.
Step 5
copy running-config startup-config (Optional) Save your entry in the configuration file.
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
bridge bridge-group forward-time
seconds
Specify the forward-delay interval.
• 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 20
seconds.

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)