Research And Implemention Of Super Node In The Lightweight Voip System

VoIP service as one of typical application in the Internet, quickly occupies an important position in the field of voice business with its cheap properties. VoIP systems combined with P2P technology, has become an important development direction of the field of VoIP services because of its good scalability and high availability, such as Skype system. However, all existing systems use proprietary protocols based on the custom networking structure, with poor interoperability. In addition, the location operation as the most basic and important operation, must be completely re-developed by each system and the reusability is extremely poor. Based on this, the P2PSIP Working Group of IETF proposed RELOAD protocol which committed to standardize P2P network communication protocol in2006. It provides the resource location and storage as its basic function to meet the demand of most of Internet applications requirements. RELOAD has a great significance for solving the closed nature, poor reusablity of the VoIP systems combined with P2P technology.This paper proposes a lightweight VoIP system based on the distributed network architecture.It supports RELOAD protocol. Super nodes as the core network entity in the system, have an important role for the entire VoIP system. In order to design the SN effectively, the following three aspects will be researched:1, research how to combine RELOAD with SIP in one system to guarantee that SIP protocol can use the storage and location function provided by RELOAD correctly and effectively.2, research the session control function of SIP to ensure SN can control the session in the NAT and cross-domain environments.3, research the adaptive network capacity expansion programs and related algorithms, ensure SN in the heavy load, can adaptively select performance UE to upgrade as SN, which can unload the system and boost the network capacity.This paper focuses on the access control, session control and network adaptive expansion functions and puts forward a complete network adaptive capacity expansion program, describe the implementation of SN in detail. With MCF which is a middleware based on message-driven, the implemetion of SN is converted to the upper application component development in the MCF. Finally, the test results have verified the effectiveness of SN in the lightweight VoIP system.