Structured peer-to-peer (p2p) overlay networks provide a useful substrate for building distributed applications. They assign object keys to overlay nodes and provide a primitive to route a message to the node responsible for a key. Proximity neighbor selection (PNS) can be used to achieve both low delay routes and low bandwidth usage but it introduces high overhead. This paper presents a detailed evaluation of PNS and heuristic approximations. We describe a new heuristic called constrained gossiping (PNS-CG) and show that it achieves performance similar to perfect PNS with low overhead. We also compare constrained gossiping with previous heuristics and show that it achieves better performance with lower overhead.

It is a well-known fact that the partition is one of the main problems in p2p group membership. This problem rises when failures and dynamics of peer participation, or churn, occur in the overlay topology created by a group membership protocol connecting the group of peers. Solutions based on Gossip-based Group Membership (GGM) cope well with the failures while suffer from network dynamics. This paper shows a performance analysis of SCAMP, one of the most interesting GGM protocol. The analysis points out that the probability of partitioning of the overlay topology created by SCAMP increases as the churn rate increases. We also compare SCAMP with another protocol, namely DET, that deterministically avoids partitions of the overlay. The comparison points out an interesting trade-off between reliability, in terms of guaranteeing overlay connectivity at any churn rate, and scalability in terms of creating scalable overlay topologies where latencies experienced by a peer during join and leave operations do not increase linearly with the number of peers in the group. 1