OpenSN: open-source emulator for large LEO satellite networks

What it is

OpenSN is an open-source library for emulating large satellite networks, developed at Beihang University in Beijing and described in "OpenSN: An Open Source Library for Emulating LEO Satellite Networks" (Wenhao Lu, Zhiyuan Wang, Hefan Zhang, Shan Zhang and Hongbin Luo), published in IEEE Transactions on Parallel and Distributed Systems, volume 36, issue 8, August 2025. The code is on GitHub under the OpenSN-Library organisation; the documentation site is licensed under Creative Commons BY-SA 4.0.

Unlike simulators that model a constellation mathematically, OpenSN is an emulator: every satellite and ground node is a container running real network software, and the links between containers are reconfigured as the orbits move. The authors' design choices are a container-based rather than Mininet-based architecture, a key-value database that separates user configuration from container management, and horizontal scaling across several machines. They report constructing mega-constellations five to ten times faster than StarryNet and updating link state two to four times faster than Mininet-based tools.

What you can do with it

• Run an actual routing daemon (OSPF, BGP or a custom protocol) on each emulated satellite and measure convergence when inter-satellite links come and go.
• Emulate a Starlink-like shell with thousands of nodes spread over a cluster, and inject traffic between gateways and user terminals.
• Compare topologies (+Grid, Walker Delta versus Walker Star, see Walker constellation) on the same routing code.

Who it is for

Network researchers and the engineering teams of operators or large integrators who design routing and traffic engineering for LEO systems. It is not a tool for buyers or installers. If you need to understand why a provider's latency varies with the number of satellite hops, or how a constellation routes around a failed gateway, OpenSN and its sibling Hypatia are the two open frameworks that let you test the answer instead of taking the marketing word for it. Hypatia pre-computes state and simulates packets in ns-3; OpenSN runs real software in containers. They are complementary.

How to use it

1. Clone the OpenSN-Library repository and follow the documentation site's installation guide (Linux hosts with Docker; several hosts for large constellations).
2. Describe the constellation (planes, satellites per plane, altitude, inclination) and the ground stations in the configuration files.
3. Choose the routing software image for the nodes, start the emulation and drive it through the key-value store.
4. Capture traffic with standard tools inside the containers; export link-state timelines for analysis.

Limits

OpenSN emulates the network layer, not the radio: no beam scheduling, no link budget, no rain fade. Resource needs grow with constellation size, and the project is young (2025), so documentation and community are thinner than for ns-3. Read the TPDS paper before relying on the performance figures for your own hardware.

Related

Definitions: satellite constellation, low Earth orbit, non-terrestrial network. Directory: LEO providers.