MAGNET II is a testbed for integrated networks. It was designed and implemented based on requirements of real-time network management and control. Quality-of-service requirements explicitly appear in the design specifications of the network on the media access level. Switching is based on the concept of asynchronous time sharing. The core of the network distinguishes between three traffic classes. The quality of service of these classes is monitored and controlled by the traffic-control architecture of the network. Monitoring is supported by observation units distributed throughout the system. The main network resources, switching bandwidth, communication bandwidth, and buffer space, are observable and controllable.>