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Catalyst 3750-E and 3560-E Switch Software Configuration Guide
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Chapter37 Configuring EtherChannels and Link-State Tracking
Understanding EtherChannels
Figure37-3 Cross-Stack EtherChannel
Port-Channel Interfaces
When you create an EtherChannel, a port-channel lo gical interface is involved:
•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 inte rface 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.
For both Layer 2 and Layer 3 ports, the channel-group command binds the physical por t and the logical
interface together as shown in Figure37-4.
Each EtherChannel has a port-channel logical interface numbered from 1 to 48. This port-c hannel
interface number corresponds to the one specified with the channel-group interface configuration
command.
Switch 1
Catalyst 3750-E switch stack
Switch 2
Channel
group 1
StackWise Plus
port
connections
Switch 3
Switch A
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