Method and communication system for establishing a least one fail safe communication link

The invention relates to a communication system comprising several connection units, associated to each other and to which several redundant transmission lines, provided for establishing at least one communication link, are respectively connected. In each of said connection units, control functions are provided for controlling functions which are centrally executed in said communication system and/or in the respective communication unit. According to the invention, in case of failure of at least one part of said control functions in one of the connection units, at least the failed communication system-specific and/or connection unit-specific functions are controlled by the control functions of the at least one corresponding connection unit. Advantageously, the line redundancy is combined with a module redundancy for a central connection unit or module, which contains both local interface functions and central control functions of the communication system.