BlockFLEX: An Adaptive and Survivable Architecture with Hierarchical Routing for LEO Satellite Networks

This paper presents $\mathbf{\text{BlockFLEX}}$, an adaptive and survivable architecture with a hierarchical routing scheme for Low Earth Orbit satellite networks, designed to address dynamic topology changes and severe link failures. By organizing satellites into autonomous blocks, BlockFLEX establishes a survivable underlay network that masks network volatility and offers a stable overlay view. The architecture employs a hierarchical routing scheme integrating both convergence-free geographic routing and convergence-isolated routing. Furthermore, BlockFLEX adaptively switches between stateful and stateless forwarding modes, enabling efficient, resilient, and stable routing via a dedicated protection mechanism and an optimized source satellite selection algorithm. Experimental evaluations on current operational LEO satellite networks (LSNs) demonstrate that under scenarios with up to 30% random link failures, the proposed method achieves a $2\times$ improvement in reachability compared to current leading schemes, while maintaining near-100% routing availability. Moreover, the overhead of control messages and forwarding information base (FIB) updates remains below $0.2\mathrm{\%}$ of that in OSPF, accompanied by a $\ge 36\mathrm{\%}$ reduction in routing computation time and a $\ge 50\mathrm{\%}$ decrease in latency jitter.