Design and implementation of a hierarchical SIP-based peer-to-peer network

Peer-to-peer (P2P) has gained popularity in Internet due to the increased number of users and distributed services such as file sharing and voice calls over IP (VoIP). Currently, the most popular P2P networks store information pertaining to its resources in a distributed manner using Distributed Hash Tables (DHT). In this type of networks, the peers are deterministically positioned and resources are also allocated to each peer for indexing in a deterministic manner. This paper presents a new hierarchical SIP based P2P network. A pure SIP solution was used because we believe that an open solution such as SIP can facilitate the creation of new types of services and permit the facilitated integration of different services. A two level hierarchy is used and is aimed towards the improvement of network efficiency where peers can move dynamically from one layer to another according to its available resources. In addition to this, the proposed implementation architecture allows the independence of the underlying DHT algorithms. The proposed architecture was implemented and tested in a realistic scenario which was created inside a Linux cluster. The DHT algorithms, Chord and EpiChord, were also implemented and used to index resources in either flat or hierarchical networks. Results indicate that the proposed two-layer hierarchy significantly improves the P2P overlay performance while in the presence of peers with limitations.