24-2
Cisco Systems IntelligentGigabit Ethernet Switch Modules for the IBMBladeCenter, Software Configuration Guide
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Chapter24 Configuring EtherChannels and Layer2 Trunk Failover
Understanding EtherChannels
Figure24-1 Typical EtherChannel Configuration
Note The network device to which your switch is connected can im pose its own limits on the number of
interfaces in the EtherChannel. The number of EtherChannels is limited to six with eight ports per
EtherChannel.
You can configure an EtherChannel in one of these modes: Port Aggregation Protocol (PAgP), Link
Aggregation Control Protocol (LACP), or On mode. Configure both ends of th e EtherChannel in the
same mode:
•When you configure one end of an EtherChannel in either PAgP or LACP mode, the system
negotiates with the other end of the channel to determine which ports should become active.
Incompatible ports are suspended.
•When you configure an EtherChannel in the on mode, no negotiations take place. The switch forces
all compatible ports to become active in the EtherChannel. The other end of the channel (on the other
switch) must also be configured in the on mode; otherwise, packet loss can occur.
If a link within an EtherChannel fails, traffic previously carried over that failed link moves to the
remaining links within the EtherChannel. If traps are enabled on the switch, a trap is sent for a failure
that identifies 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
When you create an EtherChannel for Layer 2 interfaces, a logical interface is dynamically created, as
shown in Figure 24-2. You then manually assign an interface to the EtherChannel by using the
channel-group interface configuration command.
Each EtherChannel has a logical port-channel interface numbered from 1 to 6.
BladeCenter
Catalyst 8500, 6000,
5500, or 4000
series switch
Gigabit EtherChannel
92432
1000BASE-X