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Cisco IE 2000 Switch Software Configuration Guide
OL-25866-01
Chapter 40 Configuring EtherChannels
How to Configure EtherChannels
Do not configure a Switched Port Analyzer (SPAN) destination port as part of an Ethe rChannel.
Do not configure a secure port as part of an EtherChannel or the reverse.
Do not configure a private-VLAN port as part of an EtherChannel.
Do not configure a port that is an active or a not-yet-active member of an EtherChannel as an
IEEE 802.1x port. If you try to enable IEEE 802.1x on a n EtherChannel port, an error message
appears, and IEEE 802.1x is not enabled.
If EtherChannels are configured on switch interfaces, remove the EtherChannel con figuration from
the interfaces before globally enabling IEEE 802.1x on a sw itch by using the dot1x
system-auth-control global configuration command.
For Layer 2 EtherChannels:
Assign all ports in the EtherChannel to the same VLAN, or configure them as trunks. Ports with
different native VLANs cannot form an EtherChannel.
If you configure an EtherChannel from trunk ports, verify that the trunking mode (ISL or
IEEE 802.1Q) is the same on all the trunks. Inconsistent trunk mode s on EtherChannel ports can
have unexpected results.
An EtherChannel supports the same allowed range of VLANs on all the po rts in a trunking
Layer 2 EtherChannel. If the allowed range of VLANs is not the same, t he ports do not form an
EtherChannel even when PAgP is set to the auto or desirable mode.
Ports with different spanning-tree path costs can form an EtherChannel if they are otherwise
compatibly configured. Setting different spanning-tree path costs does not, by itself, make ports
incompatible for the formation of an EtherChannel.
How to Configure EtherChannels
Note After you configure an EtherChannel, configuration changes applied to the port-channel interface apply
to all the physical ports assigned to the port-channel interface, and configuration changes applied to the
physical port affect only the port where you apply the configuration.

Configuring Layer 2 EtherChannels

You configure Layer 2 EtherChannels by assigning ports to a channel group with the channel-group
interface configuration command. This command automatically creates the port-channel logical
interface.