Reliable multicast data delivery for military networking

Multicast networking support is becoming an increasingly important technology area for both commercial and military distributed or group-based applications. The underlying delivery mechanism for IP multicast is presently the User Datagram Protocol (UDP) or raw IP packets. At present, these mechanisms provide a "best effort" delivery service. Best effort implies that IP packets are treated with essentially equal weight, and while IP makes an effort to deliver all packets to their destination, packets may be occasionally be delayed lost, duplicated, or delivered out of order. In the past such delivery mechanisms have worked fine for supporting traffic insensitive to occasional lost or missing data (e.g. voice, video). An increasing variety of distributed multimedia applications are being developed in which a consistent and/or reliable data delivery of all or a subset of data packets is a critical performance factor. In future military tactical internetworks, situational awareness data will play a major role as a critical multicast application. Reliable group file transfer (e.g. image dissemination) and interactive mission planning applications are also likely applications for military mobile units. This paper presents a taxonomy of presently available reliable multicasting solutions. The protocols are classified in terms of performance issues and scalability. Using this taxonomy, reliable multicast solutions are considered for various military applications such as mission planning, distributed interactive simulation (DIS), and situational awareness dissemination in a shared WAN environment.