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Advanced STP Tuning

Chapter Description

In this sample chapter from CCNP and CCIE Enterprise Core ENCOR 350-401 Official Cert Guide, you will review techniques for configuring a switch to be guaranteed as the root bridge or as a backup root bridge for a Layer 2 topology.

Use the Command Reference to Check Your Memory

Table 3-3 lists the important commands from this chapter. To test your memory, cover the right side of the table with a piece of paper, read the description on the left side, and see how much of the command you can remember.

Table 3-3 Command Reference

Task

Command Syntax

Configure the STP priority for a switch so that it is a root bridge or a backup root bridge

spanning-tree vlan vlan-id root {primary | secondary} [diameter diameter]

OR

spanning-tree vlan vlan-id priority priority

Configure the STP port cost

spanning tree [vlan vlan-id] cost cost

Configure the STP port priority on the downstream port

spanning-tree [vlan vlan-id] port-priority priority

Enable root guard on an interface

spanning-tree guard root

Enable STP portfast globally, for a specific port, or for a trunk port

spanning-tree portfast default

OR

spanning-tree portfast

OR

spanning-tree portfast trunk

Enable BPDU guard globally or for a specific switch port

spanning-tree portfast bpduguard default

OR

spanning-tree bpduguard {enable | disable}

Enable BPDU guard globally or for a specific interface

spanning-tree portfast bpdufilter default

OR

spanning-tree bpdufilter enable

Enable STP loop guard globally or for a specific interface

spanning-tree loopguard default

OR

spanning-tree guard loop

Enable automatic error recovery for BPDU guard.

errdisable recovery cause bpduguard

Change the automatic error recovery time

errdisable recovery interval time-seconds

Enable UDLD globally or for a specific port

udld enable [aggressive]

OR

udld port [aggressive]

Display the list of STP ports in an inconsistent state

show spanning-tree inconsistentports

Display the list of neighbor devices running UDLD

show udld neighbors

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