The Bluetooth protocol stack vs the OSI model
The reason for comparing the Bluetooth protocol stack with the Open Systems Interconnection (OSI) model is to understand the former, better. Knowledge of the OSI model is assumed.
The radio, baseband and link manager layer are the hardware part of the Bluetooth architecture which is implemented on the Bluetooth chipset. These layers roughly map to the physical, data link and network layers in the OSI model. The host control interface (HCI) maps to the transport layer, and transports data between the L2CAP layer and the Bluetooth chipset. The Logical Link Control and Adaptation Protocol (L2CAP) maps to the session layer. Serial port emulation using radio frequency communication (RFCOMM), Ethernet emulation using Bluetooth Network Encapsulation Protocol (BNEP) and the Service Discovery Protocol (SDP) are part of the feature-rich presentation layer. At the top of the stack reside various application environments called profiles. Since the radio, baseband and link manager are usually part of
Figure 3: Bluetooth protocol layers mapped to BlueZ kernel modules