Method for operating an industrial automation system communication network comprising a plurality of communication devices, in which - at least one control unit (101, 102) controls functions of a plurality of communication devices which are assigned to the control unit, - the communication network is divided into a plurality of partitions, which each comprise a plurality of end nodes as service access points and predeterminable shares of system resources of communication devices, which are assigned to the respective partition, - guaranteeable service quality parameters are determined for a data transmission within the partitions, in each case by pairs of end nodes and in a direction-dependent manner, which may be mapped in a multi-dimensional service quality parameter matrix for each partition, - each partition together with the guaranteeable service quality parameters is uniquely assigned in each case to a user, wherein potentially available system resources and/or permissions for the users are defined by the assigned partition in each case, - for user-side communication service requests within a partition the control unit (101, 102) determines in each case a path between a first communication device at a first end node and a second communication device at a second end node via third communication devices within the partition assigned to the respective user, - the control unit (101, 102) verifies whether in each case necessary system resources are available along the determined paths within the partition assigned to the respective user during a planned usage period, - the control unit (101, 102) reserves system resources necessary for the communication service requests in each case in the event of a positive verification result and controls routing or switching functions of the third communication devices in accordance with the determined paths. - at least one control unit (101, 102) controls functions of a plurality of communication devices which are assigned to the control unit, - the communication network is divided into a plurality of partitions, which each comprise a plurality of end nodes as service access points and predeterminable shares of system resources of communication devices, which are assigned to the respective partition, - guaranteeable service quality parameters are determined for a data transmission within the partitions, in each case by pairs of end nodes and in a direction-dependent manner, which may be mapped in a multi-dimensional service quality parameter matrix for each partition, - each partition together with the guaranteeable service quality parameters is uniquely assigned in each case to a user, wherein potentially available system resources and/or permissions for the users are defined by the assigned partition in each case, - for user-side communication service requests within a partition the control unit (101, 102) determines in each case a path between a first communication device at a first end node and a second communication device at a second end node via third communication devices within the partition assigned to the respective user, - the control unit (101, 102) verifies whether in each case necessary system resources are available along the determined paths within the partition assigned to the respective user during a planned usage period, - the control unit (101, 102) reserves system resources necessary for the communication service requests in each case in the event of a positive verification result and controls routing or switching functions of the third communication devices in accordance with the determined paths.