Manifold – a new networking infrastructure for rtndf

While I have been using MQTT so far for rtndf, I always had in mind using my own infrastructure. I have been developing the concepts on and off since about 2003 and there’s a direct line from the early versions (intended for clusters of robots to form ad-hoc meshes), through SyntroNet and SNC to the latest incarnation called Manifold. It has some nice features such as auto-discovery, optimized distributed multicast, easy resilience and a distributed directory system that makes node discovery really easy.

The Manifold is made up of nodes. The most important node is ManifoldNexus which forms the hyper-connected fabric of the Manifold. The plan is for rtndf apps to become Manifold nodes to take advantage of the capabilities of Manifold. Manifold has APIs for C++ and Python.

Even though it is very new, Manifold is working quite well. Using Python source and sink scripts, it’s possible get throughput of around 2G bytes per second for both end to end (E2E) and multicast traffic. This figure was obtained using 5000 400,000 byte packets per second on an I7 5820K machine. Between machines, rates are obviously limited by link speeds for large packets. Round-trip E2E latency is around 50uS for small packets which could probably be improved. Maximum E2E message rate is about 100,000 per second between two nodes.

Manifold does potentially lend itself to being used with poll mode Ethernet links and shared memory links. Poll mode shared memory links are especially effective as latency is minimized and data predominately bounces off the CPU’s caches, not to mention DPDK links for inter-machine connectivity. Plenty of work left to do…

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