DLCSDLC Device Manager Functions

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Synchronous data link control (SDLC) is split between a physical adapter with its associated device handler and a data link control (DLC) component.

The synchronous data link control (DLCSDLC) device manager is responsible for functions that include:

  • Sequencing information frames
  • Creating address and control for transmit frames
  • Servicing control for receive frames
  • Handling repoll and inactivity time outs
  • Generating frame-rejects
  • Handling transmit windows
  • Handling reliability counters, availability counters, serviceability counters, error logs, and link traces.

The device handler and adapter are jointly responsible for the remaining SDLC functions:

  • Recognizing station addresses
  • Encoding and decoding non-return-to-zero (inverted) recording (NRZI) and non-return-to-zero (NRZ)
  • Inserting and deleting 0 bits
  • Generating and checking frame-check sequences
  • Generating and checking flags and pads
  • Filling interframe time
  • Handling line-attachment protocols, such as RS-232C, X.21, and Smartmodem
  • Handling fail-safe time outs
  • Handling autoresponse for nonproductive supervisory command frames.