Research And Design Of The VoIP Network Border Access QoS Based On Policy

Voice over IP technology has been widely developed with the rapid development of network applications, so the QoS requirements are increasingly high. Currently access technologies are various, the QoS technologies of different access networks are obvious different from each other. There are some problems and shortcomings on traditional QoS technology for solving the QoS of access network. And besides, there is a lack of policy service and QoS guarantee on the traditional SIP servers. Based on the research on the Session Initiation Protocol, SBC (Session Border Controller) technology, and QoS technology as well as policy service, this thesis presents policy-based network border access QoS solution in VoIP system which is developed from a new technology named SBC.As SBC locates at the network access layer, it provides the feasibility for unified QoS policy on network border access, further more it can provide the QoS ensure which integrates load-bearing layer with traffic layer according to the identities of conversations. So this solution expands the ability of the SBC system, makes it have the ability of policy service and quality of service ensure besides session control and NAT traversing. This solution realizes the convergence of service quality control and session control by the inter-work of QoS signaling and policy service management. It integrates the IntServ and DiffServ way, and provides the calls access control, setting and update to the system limit by policy-based dynamic resource management; moreover it also provides different levels of service by classified resource reservation, resource borrow-return mechanism, classified media channel to resource isolation and PQWFQ.This thesis gives a prototype of the SBC system which supports QoS ensure, and expatiates on the key technologies of the SBC system, including the QoS expanding on SIP which is named Q-SIP, the realization of QoS signaling, and the detail realization of SAG (Signaling Access Gateway), MCC (Media Channel Controller), NMC (Network Manage Center) and QoS module in the SBC system.At last, an independently developed test program is used to test the performance of the SBC system; the contrast can be seen through the test data. The results demonstrate that the SBC system which supports policy-based QoS ensures can provide the calls access control to traffic, the bandwidth occupancy ratio is kept on 85% around, and so it avoids the system congestion. The quality of service is also improved in this system, the highest class users'average response time keeps around 10ms, and the packet loss is kept below 4%. The system can ensure that different class users experience different class service correspondingly.