Scaling Unstructured Peer-to-Peer Networks with Heterogeneity-Aware Topology And Routing

Peer-to-peer (P2P) file sharing systems such as Gnutella have been widely acknowledged as the fastest growing Internet applications ever. The P2P model has many potential advantages including high flexibility and server-less management. However, these systems suffer from the well-known performance mismatch between the randomly constructed overlay network topology and the underlying IP-layer topology. This paper proposes to structure the P2P overlay topology using a heterogeneity-aware multi-tier topology to better balance the load at peers with heterogeneous capacities and to prevent low capability nodes from throttling the performance of the system. An analytical model is developed to enable the construction and maintenance of heterogeneity-aware overlay topologies with good node connectivity and better load balance. We also develop an efficient routing scheme, called probabilistic selective routing, that further utilizes heterogeneity-awareness to enhance the routing performance. We evaluate our design through simulations. The results show that our multi-tier topologies alone can provide eight to ten times improvements in the messaging cost, two to three orders of magnitude improvement in terms of load balancing, and seven to eight times lower topology construction and maintenance costs when compared to Gnutella’s random power-law topology. Moreover, our heterogeneity-aware routing scheme provides further improvements on all evaluation metrics, when used with our heterogeneity-aware overlay