A T-carrier framing convention that extends the superframe sequence from 12 to 24 frames; with signaling performed in frames 6, 12, 18, and 24. ESF offers the advantages of non-disruptive error detection through a six-bit cyclic redundancy check (CRC), and an embedded operations channel (EOC) for network management. See also CRC, D1, D2, D4, D4, frame, network management, superframe, and T-carrier.
(1) (Extended SuperFrame) An enhanced T1 format that allows a line to be monitored during normal operation. It uses 24 frames grouped together (instead of the 12-frame D4 superframe) and provides room for CRC bits and other diagnostic commands.
(2) (External Source Format) A specification language for defining an application in IBM's CSP/AD application generator.