<Li> JXTA, a peer - to - peer protocol designed for the Java platform . </Li> <Li> FAROO, a peer - to - peer web search engine </Li> <Li> The U.S. Department of Defense is conducting research on P2P networks as part of its modern network warfare strategy . In May, 2003, Anthony Tether, then director of DARPA, testified that the United States military uses P2P networks . </Li> <P> Cooperation among a community of participants is key to the continued success of P2P systems aimed at casual human users; these reach their full potential only when large numbers of nodes contribute resources . But in current practice, P2P networks often contain large numbers of users who utilize resources shared by other nodes, but who do not share anything themselves (often referred to as the "freeloader problem"). Freeloading can have a profound impact on the network and in some cases can cause the community to collapse . In these types of networks "users have natural disincentives to cooperate because cooperation consumes their own resources and may degrade their own performance ." Studying the social attributes of P2P networks is challenging due to large populations of turnover, asymmetry of interest and zero - cost identity . A variety of incentive mechanisms have been implemented to encourage or even force nodes to contribute resources . </P>

Distinguish between ip and overlay routing for peer-to-peer applications