Uniform reliable broadcast in anonymous distributed systems with fair lossy channels

Uniform reliable broadcast (URB) is an important abstraction in distributed systems, offering delivery guarantee when spreading messages between 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 unique 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 distributed systems with process crash failures and fair lossy channels. For that, we assume the availability of a random number generator that generates unique global values with very high probability. Firstly, a simple URB algorithm is given assuming a majority of correct processes. Then, we prove the impossibility of solving URB without a majority of correct processes if no failure detector is used. Subsequently, a new failure detector class \(A{\varTheta }\) is proposed, which can be used to implement URB with any number of correct processes. However, the two previous URB algorithms are non-quiescent because every correct process, to offset the loss of messages caused by fair lossy channels, has to broadcast all URB\(\_\)delivered messages forever. Hence, a perfect anonymous failure detector \(AP^*\) is proposed, together with \(A{\varTheta }\), to make the URB algorithm quiescent. Finally, we discuss an alternative failure detector \(A{\varTheta }P^*\), which combines the properties of \(A{\varTheta }\) and \(AP^*\).