Admission control and overload handling in FTT-CAN

The paper presents new protocols for admission control and handling of overload conditions when scheduling real-time messages on CAN networks. The proposed solution builds incrementally on the FTT-CAN protocol, which provides guaranteed scheduling for cyclic (periodic) and aperiodic message streams as defined at design time and best effort scheduling for signalling (including admission requests) and scheduling of dynamically arriving message streams. FTT-CAN does not specify any particular admission control or overload management methods but provides mechanisms that support their implementation. This work exploits such mechanisms and provides the description of protocols related to admission control, guarantee of dynamic message streams, temporary overload management and fault containment. This work provides the description of protocols and implementation related issues that allow for guaranteed bandwidth and bounded response time for admission requests, and graceful recovery from temporary overload of event-based messages. The proposed approach has been implemented and validated by means of simulation.