Directional Gossip: Gossip in a Wide Area Network

We study the problem of reliable dissemination information in a wide area network. Traditional reliable broadcast protocols provide high reliability but do not scale well. Gossip-based protocols appear to be a viable approach. They have been developed to address scalability while still providing high reliability of message delivery. However, gossip protocols either ignore the topology of the wide-area network and thus incur a large load on some network elements or can suffer from a low reliability because they do not take the connectivity of the wide-area network into account. We present a new gossip protocol, called {\em directional gossip}, that uses flooding when necessary to attain good reliability and that uses gossip when flooding (and hence its inherent high overhead) is not needed. The determination of when to use flooding or gossip is done dynamically.