Configuring Backbonefast; Configuring Root Guard - Cisco Catalyst 2950 Software Manual

Configuring Advanced STP Features

Configuring BackboneFast

You can enable BackboneFast to detect indirect link failures and to start the spanning-tree
reconfiguration sooner.
Note If you use BackboneFast, you must enable it on all switches in the network. BackboneFast is not
supported on Token Ring VLANs. This feature is supported for use with third-party switches.
Beginning in privileged EXEC mode, follow these steps to enable BackboneFast:
Command
Step 1 configure terminal
Step 2
spanning-tree backbonefast
Step 3
end
Step 4 show spanning-tree vlan vlan-id
Step 5 copy running-config startup-config
To disable the BackboneFast feature, use the no spanning-tree backbonefast global configuration
command.

Configuring Root Guard

Root guard enabled on an interface applies to all the VLANs to which the interface belongs. Each VLAN
has its own spannning-tree instances.
Do not enable the root guard on interfaces to be used by the UplinkFast feature. With UplinkFast, the
backup interfaces (in the blocked state) replace the root port in the case of a failure. However, if root
guard is also enabled, all the backup interfaces used by the UplinkFast feature are placed in the
root-inconsistent state (blocked) and are prevented from reaching the forwarding state.
Beginning in privileged EXEC mode, follow these steps to enable root guard on an interface:
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
To disable the root guard feature, use the no spanning-tree guard or the spanning-tree guard none
interface configuration commands.
Catalyst 2950 Desktop Switch Software Configuration Guide
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Purpose
Enter global configuration mode.
Enable BackboneFast on the switch.
Return to privileged EXEC mode.
Verify your entries.
(Optional) Save your entries in the configuration file.
Purpose
Enter global configuration mode.
Enter interface configuration mode, and specify an interface to
configure. Valid interfaces include physical interfaces and
port-channel logical interfaces (port-channel port-channel-number).
Enable root guard on the interface.
By default, root guard is disabled on all interfaces.
Return to privileged EXEC mode.
Verify your entries.
(Optional) Save your entries in the configuration file.
Chapter 9 Configuring STP
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