Safety and Observibility of Distributed Broadcast Algorithms

In this paper, we first show the condition under which the transient faults are observable and the safety requirements are satisfied for a broadcast algorithm. Then we propose the first safe fault-containing and self-healing broadcast algorithm for locally observable faults in tree networks. A locally observable transient fault refers to a transient fault that perturbs the state of a process such that a faulty state of a process could be distinguished from a non-faulty state by all neighbours of the faulty process, and locally non-observable transient faults, otherwise. Our proposed algorithm contains and self-heals an unlimited number of transient faults in at most O(3) rounds provided that any two faulty processes are separated by two non-faulty processes.