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Spanning-Tree Commands
335
DELL CONFIDENTIAL – PRELIMINARY 9/13/06 – FOR PROOF ONLY
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Use the
spanning-tree guard root
interface configuration command to enable root guard on all the
spanning tree instances on that interface. Root guard restricts the interface to be the root port for
the switch. Use the
no
form of this command to disable root guard on the interface.
Syntax
spanning-tree guard root
no spanning-tree guard root
Default Configuration
Root guard is disabled.
Command Modes
Interface configuration (Ethernet, port-channel).
User Guidelines
Root guard can be enabled when the switch works in STP, RSTP and MSTP.
When root guard is enabled, if spanning-tree calculations cause a port to be selected as the root
port, the port transitions to the alternate state.
Example
The following example enable root guard on port e8.
###### MST 0 Vlans Mapped: 1-9, 21-4094
CST Root ID
Priority
32768
Address
00:01:42:97:e0:00
This switch is root for CST and IST master.
Root Port
1 (1/e1)
Hello Time 2 sec
Max Age 20 sec
Forward Delay 15 sec
Max hops
20
Console(config)#
interface ethernet
1/e8
Console(config-if)#
spanning-tree guard root