Implementing Uniform Reliable Broadcast in Anonymous Distributed Systems with Fair Lossy Channels

Abstract

Uniform Reliable Broadcast (URB) is an important abstraction in distributed systems, offering delivery guarantee when spreading messages among processes. Informally, URB guarantees that if a process (correct or not) delivers a message m, then all correct processes deliver m. This abstraction has been extensively investigated in distributed systems where all processes have different identifiers. Furthermore, the majority of papers in the literature usually assume that the communication channels of the system are reliable, which is not always the case in real systems. In this paper, the URB abstraction is investigated in anonymous asynchronous message passing systems with fair lossy communication channels. Firstly, a simple algorithm is given to solve URB in such system model assuming a majority of correct processes. Then a new failure detector class AT is proposed. With AT, URB can be implemented with any number of correct processes. Due to the message loss caused by fair lossy communication channels, every correct process in this first algorithm has to broadcast all URB delivered messages forever, which makes the algorithm to be non-quiescent. In order to get a quiescent URB algorithm in anonymous asynchronous systems, a perfect anonymous failure detector AP* is proposed. Finally, a quiescent URB algorithm using AT and AP* is given.