Link aggregation
lastmod 2026-02-24created 2023-02-014 edits
In computer networking, link aggregation (link Aggregation) applies to various methods of combining multiple network connections in parallel in order to increase throughput beyond what a single connection could sustain, and to provide redundancy in case one of the links should fail. A link aggregation group (LAG) combines a number of physical ports together to make a single high-bandwidth data path, so as to implement traffic load sharing among the member ports in the group and to enhance connection reliability.
Other umbrella terms used to describe the method include port trunking, link bundling, Ethernet/network/NIC bonding, NIC teaming, network redundancy, and network multiplexing.
Overview
Link aggregation addresses two problems with Ethernet connections: bandwidth limitations and lack of resilience.
With regard to the first problem, bandwidth requirements do not scale linearly. Ethernet bandwidths have historically increased tenfold each generation: 10 Mbit/s, 100 Mbit/s, 1000 Mbit/s, 10,000 Mbit/s. Once you start hitting bandwidth ceilings, the only option is to move to the next generation, which can be cost-prohibitive. An alternative solution, introduced by many network manufacturers in the early 1990s, is to combine two physical Ethernet links into one logical link via channel bonding. Most of these solutions required manual configuration and identical equipment on both sides of the aggregation.
The second problem involves the three single points of failure in a typical port-cable-port connection.