Timer-based composition of fault-containing self-stabilizing protocols

One of the desired properties of distributed systems is self-adaptability against faults. Self-stabilizing protocols provide autonomous recovery from any finite number of transient faults. However, in practice, catastrophic faults rarely occur, while small-scale faults are more likely to occur. Fault-containing self-stabilizing protocols promise not only self-stabilization but also containment of the effect of small-scale faults, i.e., they promise quick recovery and small effect for small-scale faults. Hierarchical composition of self-stabilizing protocols is expected to ease the design of new self-stabilizing protocols. However, existing composition techniques for self-stabilizing protocols cannot preserve the fault-containment property of source protocols. In this paper, we propose a novel timer-based hierarchical composition of fault-containing self-stabilizing protocols that preserves the fault-containment property of source protocols. To implement timers, we propose a local neighborhood synchronizer that synchronizes limited number of processes during a short time after a fault without involving the entire network into the synchronization. The proposed composition technique facilitates the design of new fault-containing self-stabilizing protocols and enhances the reusability of existing fault-containing self-stabilizing protocols.