Probing-Based Topology Discovery in SDN-enabled Mega-Constellation Network

To provide low-latency broadband Internet globally, SpaceX, Amazon, and other companies plan to launch thousands of satellites into low Earth orbit. The proposed constellations hold great promise, but they also present new networking challenges. It is crucial that mega-constellation networks discover their topology accurately and in a timely manner. Due to the mobility of LEO satellites, it is particularly difficult to solve the problem in the network. This paper proposes a new SDN-based topology discovery scheme for satellite networks called SSTD, which uses a small set of ground terminals/gateways to probe the mega-constellation network with low-bandwidth and low-flow rule consumption. By minimizing the dedicated forwarding rules cost, SSTD's probing paths are light-weight and efficient. A fast heuristic path solving algorithm is also provided to get the path quickly. The results of our evaluation of SSTD on three real satellite topologies show that it can produce accurate topology discovery with 53% fewer probing packets than LLDP-based solutions and 34% fewer routing rules than logic rings.