Reliable multicast under error conditions

Reliable multicast protocols provide means to deliver data from one sender to many receivers with assurance. Reliable multicast is better suited than unicast for bandwidth restricted, high error rate, hostile communications environments found in the military's tactical arena. General purpose protocols ensure adaptability to the military's variety of communications suites. Acceptable multicast protocols must support varying assurance levels, from unreliable delivery to full reliability. This paper documents experimental results gathered on one implementation of the Xpress Transport Protocol, a transport protocol that provides reliable multicast as well as unicast service. The experiments observe unicast and multicast transmissions with varying numbers of induced errors. Performance measurements examine various challenges present in a communications medium subject to hostile conditions. The results demonstrate that use of reliable multicast in a tactical environment is possible. Suggestions are made for modification of the error recovery algorithm, making the protocol more responsive in a local environment.