Request-based gossiping

By the distributed averaging problem is meant the problem of computing the average value of a set of numbers possessed by the agents in a distributed network using only communication between neighboring agents. Gossiping is a well-known approach to the problem which seeks to iteratively arrive at a solution by allowing each agent to interchange information with at most one neighbor at each iterative step. Crafting a gossiping protocol which accomplishes this is challenging because gossiping is an inherently collaborative process which can lead to deadlock unless careful precautions are taken to ensure that it does not. In this paper we present three gossiping protocols. We show by example that the first can deadlock. While the second cannot, it requires a degree of network-wide coordination which may not be possible to secure in some applications. The third protocol uses only local information, is guaranteed to avoid deadlock, and requires fewer transmissions per iteration than standard broadcast-based distributed averaging protocols.