Enabling Root Guard; Enabling Loop Guard - Cisco ME 3400G-2CS - Ethernet Access Switch Software Configuration Manual

Chapter 16 Configuring Optional Spanning-Tree Features
Command
Step 4 show spanning-tree summary
Step 5
copy running-config startup-config
To disable the EtherChannel guard feature, use the no spanning-tree etherchannel guard misconfig
global configuration command.
You can use the show interfaces status err-disabled privileged EXEC command to show which switch
NNIs are disabled because of an EtherChannel misconfiguration. On the remote device, you can enter
the show etherchannel summary privileged EXEC command to verify the EtherChannel configuration.
After the configuration is corrected, enter the shutdown and no shutdown interface configuration
commands on the port-channel interfaces that were misconfigured.

Enabling Root Guard

Root guard enabled on an NNI applies to all the VLANs to which the NNI belongs.
You cannot enable both root guard and loop guard at the same time.
Note
You can enable this feature if your switch is running PVST+, rapid PVST+, or MSTP.
Beginning in privileged EXEC mode, follow these steps to enable root guard on an interface. This
procedure is optional.
Command
Step 1
configure terminal
Step 2 interface interface-id
Step 3 spanning-tree guard root
Step 4
end
Step 5
show running-config
Step 6 copy running-config startup-config (Optional) Save your entries in the configuration file.
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 because of a
failure that leads to a unidirectional link. This feature is most effective when it is configured on the entire
switched network. Loop guard operates only on NNIs that are considered point-to-point by the spanning
tree.
78-17058-01
Purpose
Verify your entries.
(Optional) Save your entries in the configuration file.
Purpose
Enter global configuration mode.
Specify an interface to configure, and enter interface configuration mode. If
the interface is not an NNI, you must enter the port-type nni interface
configuration command before enabling root guard.
Enable root guard on the NNI.
By default, root guard is disabled on all interfaces.
Return to privileged EXEC mode.
Verify your entries.
Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
Configuring Optional Spanning-Tree Features
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