A NETWORK ARCHITECTURE FOR HETEROGENEOUS MOBILE COMPUTING

This article summarizes the results of the BARWAN project, which focus ed on enabling truly useful mobile networking across an extremely wide variety of real-world networks and mobile devices. We present the ove rall architecture, summarize key results, and discuss four broad lesso ns learned along the way. The architecture enables seamless roaming in a single logical overlay network composed of many heterogeneous (most ly wireless) physical networks, and provides significantly better TCP performance for these networks. It also provides complex scalable and highly available services to enable powerful capabilities across a ver y wide range of mobile devices, and mechanisms for automated discovery and configuration of localized services. Four broad themes arose from the project: 1) the power of dynamic adaptation as a generic solution to heterogeneity, 2) the importance of cross-layer information, such as the exploitation of TCP semantics in the link layer, 3) the use of agents in the infrastructure to enable new abilities and to hide new p roblems from legacy servers and protocol stacks, and 4) the importance of soft state for such agents for simplicity, ease of fault recovery, and scalability.