What is LACP (Link Aggregation Control Protocol)?
LACP, or Link Aggregation Control Protocol, is a protocol used in link aggregation, a networking technology that combines multiple physical links between devices into a single logical link. By using link aggregation, it is possible to increase the communication bandwidth between devices. Additionally, even if one physical link experiences a failure, the logical link can be maintained using the remaining physical links, improving fault tolerance.
Other names for this kind of technology include multi-link, trunking, and EtherChannel. The variety of terms stems from manufacturers historically developing their own proprietary versions of the technology. Link aggregation was later standardized as IEEE 802.3ad, which defines the specifications for LACP.
For link aggregation to function, it must be configured properly on both switches involved in the communication. LACP is the protocol responsible for negotiating and coordinating the aggregation settings between these devices. While link aggregation can also be configured statically (manually) without using LACP, LACP is used for dynamic configuration, automating the negotiation process between devices. This dynamic approach simplifies configuration, abstracts some of the complexity, and enables automatic failure detection and recovery.