Data Flow Control Layer

The data flow control (DFC) layer of SNA controls the flow of function management data (FMD) requests and FMD responses between FMD pairs that are in sessions and between sessions. The data flow control layer supplies various functions, such as request/response formatting, data-chaining protocol, request/response correlation, send- and receive-mode protocols, bracket protocol, error-recovery protocol, stop-bracket-initiation protocol, and queued-response protocol. LUA contains an implementation of the data flow control layer for LU types 0, 1, 2, and 3 within Personal Communications.