MRNet is a software overlay network that provides efficient multicast and reduction communications for parallel and distributed tools and systems. MRNet uses a tree of processes between the tool's front-end and back-ends to improve group communication performance. These internal processes are also used to distribute many important tool activities, reducing data analysis time and keeping tool front-end loads manageable.

MRNet-based tool components communicate across logical channels called streams. At MRNet internal processes, filters are bound to these streams to synchronize and aggregate dataflows. Using filters, MRNet can efficiently compute averages, sums, and other more complex aggregations and analyses on tool data. MRNet also supports facilities that allow tool developers to dynamically load new tool-specific filters into the system.