Terminology Link Aggregation:
It is a method to have multiple physical links with the same media and speed bundled to be a logical link forming a Link Aggregation Group with a group ID. With the viewpoint of MAC client, each Link Aggregation Group is an independent link.
There are three cases of link used in the network, which are switch to switch, switch to station and station to station. Here station may be a host or a router.
Link Aggregation, called port trunking sometimes, has two types of link configuration, including static port trunk and dynamic port trunk.
Static Port Trunk:
When physical links are changed, administrator needs to manually configure the switches one by one.
Dynamic Port Trunk:
When physical links are changed, LACP takes over and automatically reconfigure. Administrator does not have to do anything and may see the trap message of LACP changed in NMS.
Fig. 3-10 Example of Link Aggregation Application
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