Method and circuit arrangement for transmitting message cells via

Abstract

An ATM communication system (ATMK) has communication equipment (K1, K2, K3) that are arranged in a ring circuit system (RS) formed of two ring circuits (RING0, RING1) operated in opposite directions. Ring loops can thereby be established via the communication equipment in order to be able to switch from an active path to an alternate path as needed in the transmission of message cells. In the respective communication equipment, the message cells are respectively preceded by an internal cell header wherein, among other things, a path-associated sequence number is contained. Over and above this, the sequence number anticipated next or, respectively, the sequence number that most recently appeared is retained and path-associated in the respective communication equipment. Upon establishment or, respectively, clear down of a ring loop, the retained sequence number coming into consideration is updated while forwarding the message cell on the basis of the sequence number of the next message cell of the respective path to arrive. Following message cells of the same path are only forwarded when the sequence number respectively contained in these corresponds to the retained sequence number.