Design and Analysis of RT-Ring: a protocol for supporting real-time communications

Distributed applications with quality of service (QoS) requirements are more and more used in several areas (e.g.,automated factory networks, embedded systems, conferencingsystems). These applications produce a type of traffic with hardtiming requirements, i.e., transmissions must be completedwithin specified deadlines. To handle these transmissions, thecommunication system must use real-time protocols to provide acommunication service that is able to satisfy the QoS requirements of the distributed applications. In this paper, we propose a new real-time protocol, called RT-Ring, able to support transmissions of both real-time and generic traffic over a ring network. RT-Ring provides both network guarantees and high network resource utilization, while ensuring the compatibility with the emerging differentiated service architectures. Network guarantees are fully proved and high network utilization is highlighted by a comparative study with the FDDI protocol. This comparison shows that RT-Ring network capacities are greater than the corresponding FDDI capacities. In fact, by assuming the FDDI frames with a length equal to the RT-Ring slot size and by using the same traffic load we show that the capacities of FDDI are equal to the lower bound capacities of RT-Ring.