TOPLUS is a lookup service for structured peer-to-peer networks that is based on the hierarchical grouping of peers according to network IP prefixes. In this paper we present MULTI+, an application-level multicast protocol for content distribution over a peer-to-peer (P2P) TOPLUS-based network. We use the characteristics of TOPLUS to design a protocol that allows for every peer to connect to an available peer that is close. MULTI+ trees also reduce the amount of redundant flows leaving and entering each network, making more efficient bandwidth usage. We use different procedures to measure or calculate the distances among peers, in order to validate the algorithms in MULTI+.

Abstract—Overlay multicast is becoming increasingly popular for multimedia delivery over Internet. The available bandwidths between sender and different receivers are generally heterogeneous. In this paper, we propose a scheme to improve the throughput of a media delivery session with heterogeneous receivers by organizing the receivers into layered data distribution meshes and sending substreams to each mesh using layered coding. Our solution utilizes alternative paths and network coding in each mesh. We first formulate the problem into a mathematical programming, whose optimal solution requires global information. We therefore present a distributed heuristic algorithm. The heuristic progressively organizes the receivers into layered meshes. Each receiver can subscribe to a proper number of meshes to maximize its throughput by fully utilizing its available bandwidth. The benefits of organizing the topology into layered mesh and using network coding are demonstrated through extensive simulations. Numerical results indicate that the average throughput of a media delivery session is significantly improved. Keywords- Overlay multicast;network coding;heterogeneity I.