The cost of application-level broadcast in a fully decentralized peer-to-peer network

Recently, there has been a growing interest in peer-to-peer networks such as Gnutella. A typical characteristic of Gnutella is that it is a 'pure' peer-to-peer system, with all nodes being equal participants in the network. Due to its decentralized nature, Gnutella implements services such as searching and peer discovery via flooding-based application-level broadcast. In this paper, we study the cost of Gnutella's version of broadcast, based on the total number of messages generated and forwarded as the metric of cost. We further propose the use of Rumor Mongering (or Gossip) as an alternative routing method in decentralized peer-to-peer networks. Using simulation, we show that this probabilistic protocol significantly reduces the cost of broadcast.