These sections describe how to configure EtherChannels:
Catalyst 6500 Series Switch Cisco IOS Software Configuration Guide—Release 12.1 E
Enable all LAN ports in an EtherChannel. If you shut down a LAN port in an EtherChannel, it is
treated as a link failure and its traffic is transferred to one of the remaining ports in the
An EtherChannel will not form if one of the LAN ports is a Switched Port Analyzer (SPAN)
For Layer 3 EtherChannels, assign Layer 3 addresses to the port channel logical interface, not to the
LAN ports in the channel.
For Layer 2 EtherChannels:
Assign all LAN ports in the EtherChannel to the same VLAN or configure them as trunks.
If you configure an EtherChannel from trunking LAN ports, verify that the trunking mode is the
same on all the trunks. LAN ports in an EtherChannel with different trunk modes can operate
An EtherChannel supports the same allowed range of VLANs on all the LAN ports in a trunking
Layer 2 EtherChannel. If the allowed range of VLANs is not the same, the LAN ports do not
form an EtherChannel.
LAN ports with different STP port path costs can form an EtherChannel as long they are
compatibly configured with each other. If you set different STP port path costs, the LAN ports
are not incompatible for the formation of an EtherChannel.
An EtherChannel will not form if protocol filtering is set differently on the LAN ports.
After you configure an EtherChannel, the configuration that you apply to the port channel interface
affects the EtherChannel. The configuration that you apply to the LAN ports affects only the LAN
port where you apply the configuration.
With Release 12.1(12c)E1 and later releases, when QoS is enabled, enter the no mls qos
channel-consistency port-channel interface command to support EtherChannels that have ports
with and without strict-priority queues.
Configuring Port Channel Logical Interfaces for Layer 3 EtherChannels, page 13-7
Configuring Channel Groups, page 13-8
Configuring EtherChannel Load Balancing, page 13-11
Make sure that the LAN ports are configured correctly (see the
Configuration Guidelines and Restrictions" section on page
With Release 12.1(11b)E and later, when you are in configuration mode you can enter EXEC mode
commands by entering the do keyword before the EXEC mode command.