In Search of Simplicity: A Self-Organizing Multi-Source Multicast Overlay

Multicast communication primitives have broad utility as building blocks for distributed applications. The challenge is to create and maintain the distributed structures that support these primitives while acc ounting for volatile end-nodes and variable network characteristics. Most solutions proposed to date rely on complex algori thms or global information, thus limiting the scale of deployments and acceptance outside the academic realm. This article introduces a low-complexity, self-orga nizing solution for maintaining multicast trees, th at we refer to as UMM (Unstructured Multi-source Multicast). UMM uses traditional distributed systems techniques: la yering, soft-state, and passive data collection to adapt to the dynamics of the physical network and maintain data dissemination trees. The result is a simple, adaptive system with lower overheads than more complex alternatives. We have implemented UMM and evaluated it on a 100-node PlanetLab testbed and on up to 102 4-node emulated ModelNet networks Extensive experimental evaluations demonstrate UMM 's low overhead, efficient network usage compared to alternative solutions, and ability to quickly adapt to network changes and to recover fro m failures.