Systems and methods for employing opportunistic data transfer to create a dynamically mobile data communication system. Implementation of the present invention takes place in association with a computer environment with many possible types of computer system configurations such as personal computers, hand-held devices, multi-processor systems, microprocessor-based or programmable consumer electronics, networked PCs, minicomputers, mainframe computers, and the like. Data is automatically compared and replicated between communication nodes when the nodes are within transmission range in order to move the data by creating redundant copies ofthe data. Communication between communication nodes is enabled by one or more network interfaces that include an opportunistic data transfer protocol ("ODTP") component. Because ODTP components are opportunistic, establishing network connections whenever possible and utilizing the connection for as long as the connection exists, reliable connections are not required to carry out network functions. When a connection is lost, the ODTP component waits for another connection to be established or for a re-connection, in which case the ODTP component will resume from the point that it left off with the previous connection.
 This invention was made with United States Government support under Contract No. DE-AC07-94ID13223, now Contract No. DE-AC07-99ID13727 awarded by the United States Department of Energy. The United States Government has certain rights in the invention.