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ESCON (Enterprise Systems Connection) is a data connection created byIBM, and is commonly used to connect theirmainframe computers to peripheral devices such asdisk storage,tape drives andIBM 3270 display controllers. ESCON is anoptical fiber,half-duplex,serial interface. It originally operated at a rate of 10 MB/s, which was later increased to 17 MB/s. The current maximum distance is 43 kilometers.[citation needed]
IBM introduced ESCON[1] in September 1990 as part of its System/390 announcement.[2][3] It replaced the older, slower (4.5 MB/s), copper-based, parallel,IBM System/360Bus and Tag channels technology of 1960-1990 era mainframes. Optical fiber is smaller in diameter and weight, and hence could save installation costs. Space and labor could also be reduced when fewer physical links were required - due to ESCON's switching features. ESCON is being supplanted by the substantially fasterFICON, which runs overFibre Channel.
ESCON allows the establishment and reconfiguration of channel connections dynamically, without having to take equipment off-line and manually move the cables. ESCON supports channel connections using serial transmission over a pair of fibers. The ESCON Director supports dynamic switching (which could be achieved prior to ESCON, but not with IBM-only products). It also allows the distance between units to be extended up to 60 km over a dedicated fiber. "Permanent virtual circuits" are supported through the switch.
ESCON switching has advantages over a collection of point-to-point links. A peripheral previously capable of accessing a single mainframe can now be connected simultaneously to up to eight mainframes, providing peripheral sharing.
The ESCON interface specifications were adopted as ANSI X3.296:1997 by theANSI X3T11 committee.[4][5][6]