Port-Channel Interfaces - Cisco 3845 - Security Bundle Router Software Manual

Chapter 28 Configuring EtherChannels
If a link within an EtherChannel fails, traffic previously carried over that failed link changes to the
remaining links within the EtherChannel. A trap is sent for a failure, identifying the switch, the
EtherChannel, and the failed link. Inbound broadcast and multicast packets on one link in an
EtherChannel are blocked from returning on any other link of the EtherChannel.

Port-Channel Interfaces

When you create an EtherChannel, a port-channel logical interface is involved:
•
•
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 48. This port-channel
interface number corresponds to the one specified with the channel-group interface configuration
command.
Figure 28-2
OL-23400-01
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.
Relationship of Physical Ports, Logical Port Channels, and Channel Groups
Logical
port-channel
Figure 28-2.
Channel-group
binding
Physical ports
Cisco ME 3800X and 3600X Switch Software Configuration Guide
Understanding EtherChannels
28-3