Hardware upgrades can increase Ethernet link bandwidth but at high costs. In addition, hardware upgrades are less flexible than software upgrades. Ethernet link aggregation addresses these issues and supports the following functions:
The maximum bandwidth of a link aggregation group (LAG) is equal to the total bandwidths of all links in a LAG. Hardware upgrades are not required and costs are curtailed.
Traffic in a LAG is distributed to member links using the load-sharing algorithm, implementing load sharing and improving link usage.
Member links in a LAG dynamically backs up each other. When one link is interrupted, a backup link immediately takes over.
Link aggregation functions between interconnected devices only and are independent of the network topology. A logical link aggregating several physical links is called a LAG.
PS: Link aggregation is also called port aggregation because each link corresponds to two specific ports on an Ethernet network.