When group applications such as virtual environments, multiplayer games and battlefield simulations are distributed, they generate communication needs that are not met by today’s communication infrastructure. The current Internet infrastructure is built around point-to-point best effort packet switching design for unicast applications, whereas the above family of applications require reliable, low latency, ordered multicast. The introduction of Active Networking resources into the switching fabric opens the door to a new genre of protocols that are better able to meet these needs. By using the services provided by this new infrastructure we have created a novel protocol, ATOM, which addresses the needs of such applications and provides a totally ordered reliable multicast service with optimal fairness. We begin this paper by exploring the context of this application domain and the relevant technologies. We continue by showing the ATOM design. We finish by comparing ATOM against other approaches available and show the improvements that can be gained through its use.