Using Eth-Trunk to Connect Two Access Switches to a Core Switch
As shown in Figure 3-14, access switches SwitchB and SwitchC of the data center connect to core switch SwitchA. SwitchB and SwitchC connect to many users, and SwitchA connects to the external network through the egress router. More and more users connecting to the network want to communicate with each other. The links between SwitchA and SwitchB, and between SwitchA and SwitchC require sufficient bandwidth and reliability. Eth-Trunk 1 and Eth-Trunk 2 are then created to provide high bandwidth and reliability.
You can determine the working mode for the Eth-Trunk according to the following situations:
If devices at both ends of the Eth-Trunk support LACP, the LACP mode is recommended.
If the device at either end of the Eth-Trunk does not support LACP, you must use the manual load balancing mode.