Communicating with SNA Hosts Using DLC

A major use of the DLC protocol is connecting personal computers to Systems Network Architecture (SNA) hosts, such as IBM mainframes or midrange computers such as the AS/400.

SNA provides functionality that is equivalent to the Open System Interconnection (OSI) Model Network, Transport, Session, and Presentation layers (although functionality might differ at each level). The DLC layer and the OSI Data Link layer are almost identical in functionality, and a programming interface is available for programmers who want to work with the interface at the DLC layer level. The interface is described in the IEEE 802.2 standard.

Note

DLC is not robust enough to handle multithreaded programming.

Figure 17.1 shows a comparison of the SNA and OSI models.

Figure 17.1 Comparison of SNA and OSI Models

Microsoft® SNA Server uses the DLC protocol device driver when communicating to mainframes.