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Catalyst 4500 Series, Catalyst 2948G, Catalyst 2948G-GE-TX, and Catalyst 2980G Switches Software Configuration Guide—Release 8.2GLX
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Chapter 8 Configuring Spanning Tree PortFast, BPDU Guard, BPDU Filter, UplinkFast, BackboneFast, and Loop Guard
Configuring Loop Guard
Blocking Listening Learning Forwarding STP Active
----- -------- --------- -------- ---------- ----------
Total 0 0 0 1 1
BackboneFast statistics
-----------------------
Number of inferior BPDUs received (all VLANs) : 0
Number of RLQ req PDUs received (all VLANs) : 0
Number of RLQ res PDUs received (all VLANs) : 0
Number of RLQ req PDUs transmitted (all VLANs) : 0
Number of RLQ res PDUs transmitted (all VLANs) : 0
Console> (enable)
Disabling BackboneFast
To disable BackboneFast on the switch, perform this task in privileged mode:
This example shows how to disable BackboneFast on the switch and verify the configuration:
Console> (enable) set spantree backbonefast disable
Backbonefast enabled for all VLANs
Console> (enable) show spantree backbonefast
Backbonefast is disabled.
Console> (enable)
Configuring Loop Guard
The following sections describe how to configure loop guard.
Enabling Loop Guard
Enter the set spantree guard command to enable spanning tree loop guard on a per-port basis. To set all
the ports on the switch, use the set spantree mst global-defaults loop-guard command.
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.
Task
Command
Step 1
Disable BackboneFast on the switch.
set spantree backbonefast disable
Step 2
Verify that BackboneFast is disabled.
show spantree backbonefast
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