Cisco SD2008T-NA Configuration Manual page 82

Chapter 3 Configuring Ports and Interfaces
Enabling Link Aggregation
Figure 3-11 Link Aggregation
LAG simplifies controller configuration because you no longer need to configure primary and secondary
ports for each interface. If any of the controller ports fail, traffic is automatically migrated to one of the
other ports. As long as at least one controller port is functioning, the system continues to operate, access
points remain connected to the network, and wireless clients continue to send and receive data.
When configuring bundled ports on the controller, you may want to consider terminating on two different
modules within a modular switch such as the Catalyst 6500; however, we do not recommend connecting
LAG ports of a 4400 controller to multiple Catalyst 6500 or 3750G switches.
Terminating on two different modules within a single Catalyst 6500 switch provides redundancy and
ensures that connectivity between the switch and the controller is maintained when one module fails.
Figure 3-12 illustrates this use of redundant modules. A 4402-50 controller is connected to two different
gigabit modules (slots 2 and 3) within the Catalyst 6500. The controller's port 1 is connected to gigabit
interface 3/1, and the controller's port 2 is connected to gigabit interface 2/1 on the Catalyst 6500. Both
switch ports are assigned to the same channel group.
Cisco Wireless LAN Controller Configuration Guide
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