Nemo: Resilient Peer-to-Peer Multicast without the Cost
Stefan Birrer and Fabián E. Bustamante
In Proc. of the 12th Annual Multimedia Computing and Networking Conference (MMCN'05), January 2005. Also published as Tech. Report NWU-CS-04-36.
Department of Computer Science
Evanston, IL 60201, USA
We introduce Nemo, a novel peer-to-peer multicast protocol that achieves high delivery ratio without sacrificing end-to-end latency or incurring additional costs. Based on two simple techniques: (1) co-leaders to minimize dependencies and, (2) triggered negative acknowledgments (NACKs) to detect lost packets, Nemo's design emphasizes conceptual simplicity and minimum dependencies, thus achieving performance characteristics capable of withstanding the natural instability of its target environment. We present an extensive comparative evaluation of our protocol through simulation and wide-area experimentation. We contrast the scalability and performance of Nemo with that of three alternative protocols: Narada, Nice and Nice-PRM. Our results show that Nemo can achieve delivery ratios (up to 99.9%) similar to those of comparable protocols under high failure rates, but at a fraction of their cost in terms of duplicate packets (reductions > 90%) and control-related traffic (reductions > 20%).