Cisco Systems 2950 Enabling Loop Guard

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Catalyst2950 Desktop Switch Software Configuration Guide
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Chapter12 Configuring Optional Spanning-Tree Features
Configuring Optional Spanning-Tree Features
To disable root guard, use the no spanning-tree guard interface configuration command.
Enabling Loop Guard
You can use loop guard to prevent alternate or root ports from becoming designated ports b eca use o f a
failure that leads to a unidirectional link. This feature is most effective when it is conf igured on th e entire
switched network. Loop guard operates only on ports that are considered point-to-point by the spanning
tree.
Note You cannot enable both loop guard and root guard at the same time.
You can enable this feature if your switch is running PVST or MSTP. The MSTP is available only if you
have the EI installed on your switch.
Beginning in privileged EXEC mode, follow these steps to enable loop guard:
To globally disable loop guard, use the no spanning-tree loopguard default global configuration
command. You can override the setting of the no spanning-tree loopguard def ault global configuration
command by using the spanning-tree guard loop interface configuration command.
Step5 show running-config Verify your entries.
Step6 copy running-config startup-config (Optional) Save your entries in the configuration file.
Command Purpose
Command Purpose
Step1 show spanning-tree active
or
show spanning-tree mst
Determine which ports are alternate or root ports.
Step2 configure terminal Enter global configuration mode.
Step3 spanning-tree loopguard default Enable loop guard.
By default, loop guard is disabled.
Step4 end Return to privileged EXEC mode.
Step5 show running-config Verify your entries.
Step6 copy running-config startup-config (Optional) Save your entries in the configuration file.