HLA (high level architecture) is a new generation of technical framework for distributed interactive simulation which supports simulation interoperability and reusability. But distributed interactive simulations under Internet environment face the challenge of system scalability due to the limited resources of bandwidth and computation. HLA provides the possibility for system scalability through data distribution management (DDM). In this paper, the technical approach to DDM is discussed and a new strategy is proposed for multicast address allocation. This new strategy uses a hierarchical method to allocate addresses to solve the problem of contradiction between number of multicast addresses supported by hosts and the redundant data received by hosts. The new strategy also supports for the reliable transferring and data bundling of simulation data.