21-15
Cisco 7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
OL-4266-08
Chapter 21 Configuring Optional STP Features
Enabling Loop Guard
To display ports that are in the root-inconsistent state, enter the
show spanning-tree inconsistentports
command.
Enabling Loop Guard
To enable loop guard globally on the router, perform this task:
This example shows how to enable loop guard globally:
Router#
configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#
spanning-tree loopguard default
Router(config)#
^Z
Router#
show spanning-tree interface fastEthernet 4/4 detail
Port 196 (FastEthernet4/4) of VLAN0010 is forwarding
Port path cost 1000, Port priority 160, Port Identifier 160.196.
Designated root has priority 32768, address 00d0.00b8.140a
Designated bridge has priority 32768, address 00d0.00b8.140a
Designated port id is 160.196, designated path cost 0
Timers:message age 0, forward delay 0, hold 0
Number of transitions to forwarding state:1
The port is in the portfast mode by portfast trunk configuration
Link type is point-to-point by default
Bpdu filter is enabled
Loop guard is enabled by default on the port
BPDU:sent 0, received 0
To enable loop guard on a port, perform this task:
Command
Purpose
Step 1
Router(config)#
interface
{
type
1
slot/port
} |
{
port-channel
port_channel_number
}
1.
type
=
ethernet
,
fastethernet
,
gigabitethernet
, or
tengigabitethernet
Selects a port to configure.
Step 2
Router(config-if)#
spanning-tree guard root
Enables root guard.
Router(config-if)#
no
spanning-tree guard root
Disables root guard.
Step 3
Router(config-if)#
end
Exits configuration mode.
Step 4
Router#
show spanning-tree
Router#
show running interface
{
type
1
slot/port
} |
{
port-channel
port_channel_number
}
Verifies the configuration.
Command
Purpose
Step 1
Router(config)#
spanning-tree loopguard default
Enables loop guard globally on the router.
Step 2
Router(config)#
end
Exits configuration mode.
Step 3
Router#
show spanning-tree interface 4/4 detail
Verifies the configuration impact on a port.
