Logical Link Control and Adaptation Protocol
This is the protocol with which most applications would interact,
unless a host controller is used. The basic functions of the L2CAP are:
Multiplexing: The protocol must allow multiple applications to use a link between two devices simultaneously.
Quality of Service: L2CAP allows applications to demand QoS on certain parameters like peak bandwidth, latency and delay variation. L2CAP checks if the link is capable of providing it and
provides it if possible.
Segmentation and Reassembly: The protocol must reduce the
size of packets provided by applications to the size of packets
accepted by baseband. L2CAP itself accepts packet sizes up to
64kb but the baseband packets can accept a payload of at most
2745 bits. The reverse procedure, that of combining the
segmented packets in the proper order, has to be carried
out for received packets.