1、外文原文 LOGICAL LINK CONTROL AND ADAPTATION PROTOCOL SPECIFICATION 1 INTRODUCTION This section of the Bluetooth Specification defines the Logical Link Control and Adaptation Layer Protocol, referred to as L2CAP. L2CAP is layered over the Link Controller Protocol and resides in the data link layer as sh
2、own in Figure 1.1. L2CAP provides connection-oriented and connectionless data services to upper layer protocols with protocol multiplexing capability, segmentation and reassembly operation, and group abstractions. L2CAP permits higher level protocols and applications to transmit and receive upper la
3、yer data packets (L2CAP Service Data Units, SDU) up to 64 kilobytes in length. L2CAP also permits per-channel flow control and retransmission via the Flow Control and Retransmission Modes. Figure 1.1: L2CAP within protocol layers The L2CAP layer provides logical channels, named L2CAP channels, which
4、 are mapped to L2CAP logical links supported by an ACL logical transport, see baseband specification vol.2, part B Section 4.4 on page 86. 1.1 L2CAP FEATURES The functional requirements for L2CAP include protocol/channel multiplexing, segmentation and reassembly (SAR), per-channel flow control, error control and group management. Figure 1.2 on page 22 illustrates how L2CAP data flows fit into the Bluetooth Protocol Stack. L2CAP lies above the Link Controller Protocol and interfaces with other
