A Multicast Protocol Based on a Single Logical Ring Using a Virtual Token and Logical Clocks

A novel and efficient protocol based on a single logical ring for multicast communication among a group of processes is presented. The senders and receivers are merged in the same group and this peer group reflects a cooperative (mirror) group of information servers. The protocol maintains consistency in the group by using two strategies. First, by placing a total sequence number in each of the multicast messages, it guarantees total ordering of message delivery for each member. Second, in contrast to other ring protocols which are based on real token passing, it uses a virtual token and achieves message atomicity by using up to n point-to-point control messages. Since no real token passing messages are rotating on the ring, the position of the token holder is calculated by using a logical clock located in each of the processes. The protocol can tolerate communication faults, process crash failures and network partitioning. The protocol has been implemented and experimental results show that the protocol achieves satisfactory performance.