The Study Of Connectionless Quality-of-Service Routing

The continuous growth in both commercial and public network traffic with quality-of-service (QoS) requirements is calling for the evolution of the Internet from a simple best-effort network towards a converged one that can provide various levels of QoS guarantees and/or differentiations to voice, video, and data applications. However, existing QoS architectures (such as IntServ, DiffServ, etc.) mostly suffer from the unscalability problem. In IntServ, all routers have to maintain per-flow states and perform numerous and burdensome tasks, and thus the huge number of flows in core routers makes IntServ unscalable. In the case of DiffServ, QoS control is based on flow aggregates rather than individual flows and it only supports a limited number of priority-based services. Therefore, next generation networks call for novel network architectures in order to support any underlying type of QoS-oriented applications.This paper proposes a novel connectionless QoS routing framework for high-speed core networks. Unlike traditional QoS architectures, neither resource reservation nor per-flow management exists in the proposed routing framework, so it has good scalability. In this framework, QoS constraints are carried by every packet and routing decisions are made hop by hop at the packet level. Therefore, it can satisfy explicit QoS requirements of end-to-end individual packet flows. This paper centers on the connectionless QoS routing framework and works on its definitions, model designs, related algorithms and experiments. The main contributions include:(1) Establish a theoretical model for the connectionless QoS routing framework. Focusing on two types of QoS traffic: the strictly inelastic traffic and the adaptive traffic, this model formalizes the expected network utility of three QoS control frameworks: the Best-Effort framework, the connection-oriented QoS control framework and the proposed connectionless QoS routing framework. Perfrormance of these three frameworks are compared with each other by this model in the case of each traffic type, respectively.(2) Propose the connectionless QoS routing framework. This paper first defines six design principles for devising a modern routing system. These principles take into consideration both the QoS-surpport and scalability problem. Then based on these design principles, the connectionless QoS routing framework is proposed with three key components: QoS routing table establishment, connectionless admission control and QoS packet forward. In order to support multiple constraints in inter-domain routing, a QoS extension scheme to the current inter-domain routing protocol (BGP) is proposed. This extension makes BGP support multiple QoS metrics. This paper describes the big picture with regard to how the BGP speakers cooperate with each other.(3) Design several path reduction algorithms to save on the QoS routing table storage and at the same time to reduce the routing message overhead of the QoS-aware routing protocol. These algotithms make the QoS extension to the routing protocols scalabele in the connectionless framework. This paper provides the related definitions, theorems and algorithm description.(4) Implement a simulation system to acquire performance evaluation. This paper collects a lot of experiment data which are valuable to further research work, and evaluates the connectionless QoS routing framework, the QoS extension schemes to BGP and all the path reduction algorithms according to experiment results.