About Etherchannel Guard - Cisco Catalyst 4500 Series Software Configuration Manual

About EtherChannel Guard

This example shows how to verify the configuration impact on port 4/4:
Switch# show spanning-tree interface fastEthernet 4/4 detail
Port 196 (FastEthernet4/4) of VLAN0010 is forwarding
Port path cost 1000, Port priority 160, Port Identifier 160.196.
Designated root has priority 32768, address 00d0.00b8.140a
Designated bridge has priority 32768, address 00d0.00b8.140a
Designated port id is 160.196, designated path cost 0
Timers:message age 0, forward delay 0, hold 0
Number of transitions to forwarding state:1
The port is in the portfast mode by portfast trunk configuration
Link type is point-to-point by default
Bpdu filter is enabled
Loop guard is enabled on the port
BPDU:sent 0, received 0
Switch#
About EtherChannel Guard
EtherChannel guard allows you to detect an EtherChannel misconfiguration between the switch and a
connected device. A misconfiguration can occur if the interfaces of a switch are manually configured in
an EtherChannel, and one or more interfaces on the other device are not. For EtherChannel configuration
guidelines, see the
EtherChannel guard applies only to EtherChannels in forced mode (that is, manually configured) rather
Note
than through PAgP or LACP.
If the switch detects a misconfiguration on the other device, EtherChannel guard error-disables all
interfaces in the EtherChannel bundle, and displays an error message.
You can enable this feature with the spanning-tree etherchannel guard misconfig global configuration
command.
Enabling EtherChannel Guard (Optional)
You can enable EtherChannel guard to detect an EtherChannel misconfiguration if your switch is
running PVST+, rapid PVST+, or MSTP.
To enable EtherChannel guard, perform this task:
Command
Step 1
Switch(config)# configure terminal
Step 2
Switch(config)# spanning-tree etherchannel guard
misconfig
Step 3
Switch(config)# end
Step 4
Switch(config)# show spanning-tree summary
Step 5
Switch(config)# copy running-config
startup-config
Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
26-6
"EtherChannel Configuration Guidelines and Restrictions" section on page
Chapter 26
Purpose
Enters global configuration mode.
Enables EtherChannel guard.
Returns to privileged EXEC mode.
Verifies your entries.
(Optional) Saves your entries in the configuration file.
Configuring Optional STP Features
27-6.