8-19
Catalyst 4500 Series, Catalyst 2948G, Catalyst 2980G Switches Software Configuration Guide
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Release 8.1
78-15486-01
Chapter 8 Configuring Spanning Tree PortFast, BPDU Guard, BPDU Filter, UplinkFast, BackboneFast, and Loop Guard
Configuring Loop Guard
To enable loop guard on an individual port, perform this task in privileged mode:
This example shows how to enable loop guard on port 5/1:
Console> (enable) set spantree guard loop 5/1
Rootguard is enabled on port 5/1, enabling loopguard will disable rootguard on
this port.
Do you want to continue (y/n) [n]? y
Loopguard on port 5/1 is enabled.
Console> (enable)
This example shows how to enable loop guard on all the ports on a switch:
Console> (enable) set spantree mst global-defaults loop-guard enable
Spantree global loop-guard state enabled on this switch.
Disabling Loop Guard
Enter the set spantree guard command to disable the spanning tree loop guard feature on a per-port
basis. To disable loop guard on all the ports on a switch, use the set spantree mst global-defaults
loop-guard command.
To disable loop guard on the switch, perform this task in privileged mode:
This example shows how to disable loop guard on port 5/1:
Console> (enable) set spantree guard none 5/1
Rootguard is disabled on port 5/1, disabling loopguard will disable rootguard on
this port.
Do you want to continue (y/n) [n]? y
Loopguard on port 5/1 is disabled.
Console> (enable)
This example shows how to disable loop guard on all the ports on a switch:
Console> (enable) set spantree mst global-defaults loop-guard disable
Spantree global loop-guard state disabled on this switch.
Task
Command
Step 1
Enable loop guard on a port.
set spantree guard {root | loop | none} mod/port
Step 2
Verify that loop guard is enabled.
show spantree guard {mod/port | vlan} mistp-instance instance
Task
Command
Step 1
Disable loop guard on a port.
set spantree guard {root | loop | none} mod/port
Step 2
Verify that loop guard is disabled.
show spantree guard {mod/port | vlan} mistp-instance instance
