ATM communication system

A communication method for transmission of message cells according to an asynchronous transfer mode during the course of virtual connections, comprising the steps of:

• providing ATM communication equipment units connected to one another;
• providing concentrator equipment units connected to at least one of the communication equipment units;
• providing a plurality of ATM subscriber equipment units connected to respective concentrator equipment units;
• arranging the concentrator equipment units together with the corresponding communication equipment unit in a ring line system;
• connecting each of the concentrator equipment units via separate virtual paths within the ring line system to the corresponding communication equipment unit and connecting each of the concentrator equipment units to each other via separate virtual paths in the ring line system;
• individually keeping, for individual virtual paths in the corresponding communication equipment unit, a current transmission bit rate occurring on each respective virtual path which is already occupied by currently established virtual connections, the current transmission bit rate being derived from bit rates of each of the currently existing virtual connections so that said current transmission bit rate represents a measure of momentary traffic volume, said current transmission bit rate dynamically changing as traffic volume changes;
• updating the current transmission bit rate for an associated virtual path with every set-up and clear-down of a virtual connection;
• centrally controlling by the corresponding communication equipment unit the set-up of virtual connections within the virtual paths such that, given presence of a request for a new virtual connection, identifying a virtual path coming into consideration for the new virtual connection, comparing for that virtual path a current transmission bit rate with a maximum capacity transmission bit rate for that virtual path to determine whether sufficient capacity for the new virtual connection is still available;
• if the transmission bit rate capacity is still available on the particular virtual path, only then setting up the new virtual connection on that virtual path;
• and
• exclusively monitoring the bit rate of the currently existing virtual connections in the respective concentrator connected to the respective calling subscriber equipment unit coming into consideration for the respective virtual connection so that the at least one communication equipment unit to which the concentrator equipment units are connected is relieved of said monitoring.