Research Of SBC Networking And Load Balance Based On DHT Algorithm

P2P (Peer-to-Peer) technology is popular in network application now, and has gained great success in file sharing, distributed calculation, distributed storage and so on. SBC (Session Border Controller) is also a primary technology of firewall/NAT traversal which has been developed rapidly in recent years. With single and centralized architecture, SBC is in charge of all the signaling and media flow forwarding, and thus SBC becomes the bottleneck of the communication system. In order to solve the problem of scalability and reliability in SBC system, the thesis mainly focuses on SBC networking with SIP, which integrated with distributed architecture of P2P network. And an algorithm for load balance has been designed for SBC networking based on DHT algorithm.In comparison with the traditional C/S model, P2P model itself contains both good scalability and reliability. The structured P2P network, based on DHT (Distributed Hash Table) technology, has positive significance to resolve the problem of single point invalidation and system bottleneck in the existing SBC system. After having compared and analyzed some DHT structure algorithm, the thesis takes Chord algorithm as example and gives the SBC networking architecture based on DHT algorithm. SBCs are considered as super peers in P2P network which form a Chord ring, while terminal users are considered as ordinary peers in P2P network and user information is considered as the resources distributed on super peers. Key technologies have been discussed, such as peer key selection, peer location using DHT, peer communication using SIP messages. Then a set of the working mechanism about DHT-based SBC networking has been designed, which is composed of the procedures of discovery, insertion, stabilization and leaving for SBC, as well as the processing of registration and call establishing for terminal user.However, there are still some issues of load balance such as load distribution, peer heterogeneity and routing congestion in DHT system. After analyzing the problems and shortages of the existing load balance schemes in DHT system, an algorithm based on dynamic identifier space (DIS) is proposed to improve the performance of load balance in DHT-based SBC networking. According to the history information about user accessing, the algorithm predicts the load variation trend in the future, and also takes SBC capacity into account to dynamically adjust peer identifier space which is adapted to its load variation. This algorithm is composed of load distribution when a new peer joins in and load redistribution if overload peer appears. Finally, it is demonstrated that the algorithm has excellent performances on load balancing distribution and alleviation of overload peer.