sVIRGO: A Scalable Virtual Tree Hierarchical Framework for Distributed Systems

We propose sVIRGO, a scalable virtual tree hierarchical framework for large-scale distributed systems. sVIRGO constructs virtual hierarchical trees directly on physical nodes, allowing each node to assume multiple hierarchical roles without overlay networks. The hierarchy preserves locality and is organized into configurable layers within regions. Coordination across thousands of regions is achieved via virtual upper-layer roles dynamically mapped onto nodes up to the top layer. Each region maintains multiple active coordinators that monitor local health and perform dynamic re-selection if failures occur. Temporary drops below the minimum threshold do not compromise coordination, ensuring near-zero recovery latency, bounded communication overhead, and exponentially reduced failure probability while maintaining safety, liveness, and robustness under mobile, interference-prone, or adversarial conditions. Communication is decoupled from the hierarchy and may use multi-frequency wireless links. Two message hop strategies are supported: (i) with long-distance infrastructure-assisted channels, coordinators exploit the virtual tree to minimize hops; (ii) without such channels, messages propagate via adjacent regions. sVIRGO also supports Layer-Scoped Command Execution. Commands and coordination actions are executed within the scope of each hierarchical layer, enabling efficient local and regional decision-making while limiting unnecessary global propagation.