QoS Research For Broadband Network

The original idea of IP network is to use the "best effort" mechanism on transmitting packets. So, for the multimedia application which require strict QoS guarantee, if we don't use new technologies to improve the networking capability, these new applications will not be able to be deployed widely on the Internet.Fundamentally, all of the QoS problems are caused by un-enough bandwidth. The simplest and the most effective way of solving Internet QoS problem is to increase the network bandwidth to meet users' need. But the incoming new applications always used all of the increasing bandwidth very soon and made the bandwidth will never meet the requirement of the new service deployment. Therefore, how to efficiently use the limited bandwith of IP network is the key to solve the problem and meet the strict QoS requirements of the real-time applications.Right now, the telecommunication network is changing to IP technology, for example the development of NGN and IMS. Someone even said, the key of the next generation telecommunication network is the IMS technology. But the QoS problem of the NGN network is the un-avoidable problem facing every standard and research groups. And NGN introduced new QoS problems, which are different from the normal IP QoS problems, because NGN QoS is expected to provide the telecommunication quality level guarantee.The goal of NGN QoS is to meet the QoS requirements of specific services using IP processing technology. In specific, it needs to solve the following issues: how to coordinate between the service layer and transport layer? How to map the service QoS requirements to the transport IP layer? How to meet the different QoS requirements using the same network? How to separate the impact of different services?, etcIn this dissertation, the fundamental theory and algorithms on network QoS problem are researched and studied. The detailed of QoS mechanisms for high-speed (10Gbps) core router are implemented and discussed. The major research context and the innovative ideas are below:1) Researched on QoS fundmental theories, including the QoS definition, service models and its impact on network design, ATM QoS technologies and the functional model.2) Researched on the IntServ and DiffServ technologies and the basic MPLS ideas and it QoS capabilities. Studied and compared their pros and cons.3) Proposed an end-to-end QoS model for Internet, which embrace the advantages of IntServ, DiffServ and MPLS traffic engineering capabilities. IntServ is used in the access network and DiffServ and MPLS with TE are used in the core network. It has better scalability and different QOS granularities.4) Proposed a new bi-directional resource reservation technology for improving TCP performance. Because of the mechanism of TCP protocol, the one-way resource reservation is not enough. From the simulation, the TCP performance is improved a lot using this technology.5) Implemented several QoS modules with 10Gbps line rate processing capability for core router (discussed METER, WRED and hierarchical packet scheduling mechanism in this dissertation). Every module only has 57-cycle budget so every instruction should be considered carefully. Discussed the difficulities of implementing QoS mechanism, which can provide the reference and guide for future QoS research on broadband network. This implementation is under product development now.6) Discussed the NGN development status of several standardize groups and analyzed the new QoS problems facing the NGN network which has decoupled server layer and transport layer.7) Proposed a new solution to map the service QoS requirement (loss probability) onto DiffServ router. Analyzed the loss probability of a single flow within an aggregated flow and proposed a new mechanism for access control. From the analysis, this solution works well and should be useful for future NGN technology.This dissertation covers lots of QoS theories and mechanisms in ATM, IP and NGN network, proposes several new solutions and mechnisms. The implementation of QoS on high-speed core router is also discussed.