The impact of non-DS domains in a multi-domain DiffServ network

Differentiated Services (DiffServ) architecture has been proposed as a scheme to provide scalable end-to-end QoS by employing a simple classification based on the DSCP in IP header. One of the major reasons that hinder ISPs to provide DiffServ is that the service level cannot be guaranteed when a specific traffic flow traverses a number of DS and non-DS domains. The issue of the impact of non-DS domains or non-DS routers in a hybrid multi-domain DiffServ network on the performance of Premium Services and Assured Services has been largely ignored by the research community. In this paper, we first present a preliminary queueing analysis of the hybrid multidomain DiffServ network based on a tandem queue model. Then we propose a performance metric called SPI (Service Provision Index) to measure the service level degradation of preferred services in a hybrid multi-domain DiffServ network with respect to an All-DS network. Network simulations and emulations are conducted on a variety of scenarios with different parameter settings to explore the performance of a hybrid multi-domain DiffServ network. Based on the quantitative analysis, the simulation and emulation results, we make some observations on the underlying problem, which could help ISPs or researchers determine the major factors of service degradation, as well as possible directions to improve the services.