Logical Link Control and Adaptation Protocol (L2CAP) is a protocol used in the Bluetooth standard that provides adaption between higher layers and the baseband layer of the Bluetooth stack. It operates just above the host-controller interface (HCI) passing data frames from the higher layers to either HCI or Link Manager.
The following diagram shows the position of L2CAP in Bluetooth protocol architecture −
Adaptation between higher-layer frames and lower layer frames of the Bluetooth protocol stack.
Support for both connection-oriented as well as connectionless services.
Supporting two links for the Baseband layer −
Synchronous Connection-Oriented (SCO) links for real-time voice traffic using reserved bandwidth.
Asynchronous Connection-Less (ACL) links for best-effort traffic.
Multiplexing of higher layer protocols, which allows them to use the links provided by the lower layers.
Segmentation and reassembly of data packets of the upper layer that are larger than the capacity of the radio layer underneath.
Quality of Service (QoS) for upper-layer protocols.