Real-time applications, such as process control signals and multimedia transmission, are more and more deployed in current networks. These applications produce a type of trafic with stringent timing requirements whose transmission is critical as it has to be completed within its deadline. This can be performed only using protocols that support real-time trafic transmissions. In this paper we propose a new real-time protocol, called RT-Ring, able to support transmissions of both real-time and generic traf-$c over a ring network. RT-Ring provides both network guarantees and high network resource utilization, while ensuring the compatibility with the emerging Differentiated Service Architecture. Network guarantees are fully proved and high network utilization is highlighted by a comparison study with the FDDI protocol. This compar-ison shows that RT-Ring network capacities are greater than the corresponding FDDI capacities.