The Data Link Control Interface

The data link control interface (DLC) defines the interface between the local 2.1 node and an SNALink. The DLC interface is defined in terms of the messages that are sent across the interface. Note that this is logically distinct from the definition of the Base/DMOD interface, which defines the API used to send messages between two components in Microsoft® SNA Server (for example, between the local node and an SNALink).

DLC messages are exchanged between the local node and an SNALink across LPI connections (see Structure of SNA Server Components).

The local node uses the DLC interface to:

• Activate DLC connections.
• Exchange format 0 or format 3 XIDs for station activation.
• Exchange DLC information frames.
• Handle DLC error notification.