The Standards for the Interoperability of Defense Simulations, also known as the Distributed Interactive Simulation (DIS) standards, have been under development since 1989 and currently define a set of protocol data units (PDUs) by which dissimilar simulators and simulations can communicate in a networked environment. A series of workshops have provided the forum for industry, government, and academia to develop these standards. The Communication Architecture/Security Subgroup (CASS) of these workshops is responsible for defining the communication architecture to be used for networking dissimilar systems together. This paper will present issues that have been brought to the surface by CASS in the process of defining the communication architecture for DIS.

The government mandate for the use of Government Open Systems Interconnection Profile (GOSIP) for all communication architectures has driven the DIS requirements. The concept of distributed simulations requiring interaction has led to the definition of service requirements which must be met by the communication architecture. Two of these, real-time and multicast, are not provided for by GOSIP at this time. Another issue is the need for reliable communications within the real-time multicast setting. These issues lead to the question of what type of performance can be expected and is needed to accomplish some level of fidelity for applications within DIS. Other issues include (1) the incorporation of security into DIS and (2) the connection of existing devices to DIS compliant networks. As these issues are examined, the objective of interoperability among systems leads to the use of existing standards, where available. This paper will address the role of communication architecture in DIS, service and security requirements, requirements for interfacing dissimilar systems, the use of existing standards, and the overall CASS approach for defining communication architecture for DIS.