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30-2
Catalyst 3550 Multilayer Switch Software Configuration Guide
78-11194-09
Chapter 30 Configuring EtherChannels
Understanding EtherChannels
Figure 30-1 Typical EtherChannel Configuration
Each EtherChannel can consist of up to eight compatibly configured Ethernet interfaces. All interfaces
in each EtherChannel must be the same speed, and all must be configured as either Layer 2 or Layer 3
interfaces.
Note
The network device to which your switch is connected can impose its own limits on the number of
interfaces in the EtherChannel. For Catalyst 3550 switches, the number of EtherChannels is limited to
the number of ports of the same type.
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.
Understanding Port-Channel Interfaces
You create an EtherChannel for Layer 2 interfaces differently from Layer 3 interfaces. Both
configurations involve logical interfaces.
•
With Layer 3 interfaces, you manually create the logical interface by using the interface
port-channel global configuration command.
•
With Layer 2 interfaces, the logical interface is dynamically created.
•
With both Layer 3 and 2 interfaces, you manually assign an interface to the EtherChannel by using
the channel-group interface configuration command. This command binds the physical and logical
ports together as shown in
Catalyst 8500, 6000,
5500, or 4000
series switch
Catalyst 3550-12T
switch
Gigabit EtherChannel
Catalyst 3550-12T
switch
Workstations
10/100
Switched
links
74618
Catalyst 2950G-24
switch
Workstations
10/100
Switched
links
1000BASE-X
1000BASE-X