A network management system in an aircraft for managing and maintaining a network. An aircraft maintenance computer communicates with a first device to be managed via the SNMP protocol. The first device to be comprises a description file. Within a subnetwork one or more second devices to be managed are present which are linked with the first device to be managed. These second devices to be managed enter their data into the description file via these connections. The data are necessary for managing and maintaining the respective second device to be managed by the aircraft maintenance computer. Therefore the aircraft maintenance computer is enabled to manage and maintain the first and the second devices only by means of the central MIB.