| has gloss | eng: In telecommunication, an Extended Super Frame (ESF) is a T1 framing standard, sometimes called D5 framing because it was first used in the D5 Channel Bank, invented in the 1980s. It is preferred to its predecessor, Super Frame, because it includes a cyclic redundancy check (CRC) and 4000 bit/s channel capacity for a data link channel (used to pass out-of-band data between equipment.) It requires less frequent synchronization than the earlier superframe or D-4 format, and provides on-line, real-time testing of circuit capability and operating condition. |