Research Of QoS Mechanism Based On SIP Of VoIP System

VoIP generally refers to the system carrying on voice communication through IP protocol, which is hot application of the technology of computer and CTI (Telephone Integration of Computer). Severing as the provision of telephone over the Internet,VoIP is regarded as the milestone of the development of the telephone network and the rudiment of "Integrated Services" network.It is a very complicated system to carry on voice communication through Internet. Though technology involved is various, the core technology is VoIP (Voice over IP) .We can argue that the voice communication of Internet is the most typical and promising application of VoIP.This paper elaborates the technological background of IP telephone and its foreground at first. Secondly, we introduce the design principle, key technology and system architecture of VoIP system. We also describe SIP by comparing with H. 323. By introducing the process of one VoIP system, we have carefully researched SIP and QoS.In this paper, we study the feature of VoIP and proposed a new approach called Hierarchical Service Based on RSVP.The policy server is put forward, which implements our approach and can offer resources to keep the policy in advance. The fundamental theory of Policy server is providing hierarchical services. When the senior user has a request of resources reservation, if there have no enough resource toallocate, system will cut off conversations of junior users according to policy server to free abundant network resources in order to satisfying the need of the senior user.Through exploring QoS mechanism of VoIP based on SIP, we presents a new QoS mechanism which improves the functions of VoIP system and makes it more flexible. We also develop an instance of this mechanism in this paper.