Port-Channel Interfaces - Cisco Catalyst 3750 Software Configuration Manual

Chapter 27 Configuring EtherChannels

Port-Channel Interfaces

When you create an EtherChannel, a port-channel logical interface is involved:
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For both Layer 2 and Layer 3 ports, the channel-group command binds the physical port and the logical
interface together as shown in
Each EtherChannel has a port-channel logical interface numbered from 1 to 12. This port-channel
interface number corresponds to the one specified with the channel-group interface configuration
command.
Figure 27-2 Relationship of Physical Ports, Logical Port Channels, and Channel Groups
After you configure an EtherChannel, configuration changes applied to the port-channel apply to all the
physical ports assigned to the port-channel. Configuration changes applied to the physical port affect
only the port where you apply the configuration. To change the parameters of all ports in an
EtherChannel, apply configuration commands to the port-channel interface, for example, spanning-tree
commands or commands to configure a Layer 2 EtherChannel as a trunk.
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With Layer 2 ports, use the channel-group interface configuration command to dynamically create
the port-channel logical interface.
You also can use the interface port-channel port-channel-number global configuration command
to manually create the port-channel logical interface, but then you must use the channel-group
channel-group-number command to bind the logical interface to a physical port. The
channel-group-number can be the same as the port-channel-number, or you can use a new number.
If you use a new number, the channel-group command dynamically creates a new port channel.
With Layer 3 ports, you should manually create the logical interface by using the interface
port-channel global configuration command followed by the no switchport interface configuration
command. Then you manually assign an interface to the EtherChannel by using the channel-group
interface configuration command.
Logical
port-channel
Figure 27-2.
Channel-group
binding
Physical ports
Catalyst 3750 Metro Switch Software Configuration Guide
Understanding EtherChannels
27-3