Alcatel Cit

Christian Roche

Jean Adrien Guezou

Serge Le Goic

The interchange system comprises stations connected to a loop link having two rings (A1, A2) making use of a token access method and operating in load sharing mode, with each ring providing all interchanges in the event of the other ring breaking down. Each station has one adapter (1, 2) per ring, a coupler (C), and a terminal (T). Each adapter performs level 1 procedures and lower layer level 2 procedures only. The coupler includes a processor and uses a protocol at the upper layer of level 2 and at level 3 for managing load sharing between the rings, for switching the station onto one ring in the event of the other ring breaking down, and for providing protection against transmisson errors, against messages being duplicated, and against messages being out of sequence, against breakdowns in the adapters and the rings, and against short traffic interruptions due to a station being inserted or withdrawn.

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Perros-Guirec, France

Christian Roche