Collecting network status information for network-aware applications

Network-aware applications, i.e., applications that adapt to network conditions in an application-specific way, need both static and dynamic information about the network to be able to adapt intelligently to network conditions. The CMU Remos interface gives applications access to a wide range of information in a network-independent fashion. Remos uses a logical topology to capture the network information that is relevant to applications in a concise way. However, collecting this information efficiently is challenging for several reasons: networks use diverse technologies and can be very large (Internet); applications need diverse information; and network managers might have concerns about leaking confidential information. In this paper we present an architecture for a hierarchical collector of network information. The decentralized architecture relies on data collectors that collect information on individual subnets; data collectors can collect information in manner that is appropriate for that subnet and can control the distribution of the information. For application queries that involve multiple subnets, we use a set of master collectors to partition requests and distribute subrequests to individual data collectors and to combine the results. Collectors cache recent network information to improve efficiency and responsiveness. This paper presents and justifies the collector architecture, describes a prototype implementation, and presents preliminary measurements characterizing its operation