A survey and comparison of peer-to-peer group communication systems suitable for network-centric warfare

In this paper we describe state-of-the-art peer-to-peer systems and analyze them according to multiple characteristics highlighting (1) scalability, (2) security and (3) fault tolerance. Peer-to-Peer systems are inherently scalable since they create fully decentralized environments across the Internet while simultaneously reducing complexity because each server handles a local set of clients. Peer-to-peer system security has depended primarily on user trust - the fact that any peer can contact any other peer in the system introduces issues of insider attacks from malicious users or external attacks through the Internet. Lastly, while peer-to-peer systems are evolving in response to peer unreliability, fault tolerance/survivability for general-purpose military group communications may require additional middleware. Comparing these characteristics across different peer-to-peer systems is a step towards understanding which system may be appropriate for military group communications and where further research is needed. A secondary result of our comparison is an attempt to move towards common terminology and models between peer-to-peer, application-layer multicast, IP layer multicast, and distributed systems approaches for group communications.