Latency Improvement in Virtual Multicasting

Virtual Multicasting (VMC) is a specific instance of a more general idea, Information Mass Transit (IMT). IMT aims to reduce the waste of bandwidth resulting from individual streams of data, while improving user-level latency. By analogy with mass transit where shared transport reduces the load on infrastructure, IMT aims to use networks and other infrastructure more efficiently. VMC combines some of the benefits of caching (transparency, dynamic adaptation to workload) and multicasting (reducing duplicated traffic). Virtual multicasting is intended to save bandwidth in cases of high load, resulting from unpredictable but high demands for similar traffic. However, even in cases where relatively low fractions of traffic are similar (hence offering few opportunities for VMC), introducing VMC can have a disproportionate effect on latency reduction because of the generally beneficial effect of reduction in traffic, including reduced contention. This paper presents results of a study of latency reduction across a range of workloads, illustrating the potential for VMC even in situations where the extent of overlapped traffic is light