The Research On Fairness Of Markers In DiffServ Environments

The traditional Internet uses 'best-effort' mechanism to server received traffic, and cannot support the traffic that needs quality of service effectively. In present, researchers and service providers have been searching ways to overcome the shortcomings of the Internet Best Effort Service. Two approaches have been widely touted as the solution to QoS requirements: IntServ and DiffServ. Unlike IntServ, DiffServ handles flow aggregates, performs packet classification into classes at the network ingress and supports different per-class guarantees at every hop in the network core. Traditionally, DiffServ comes in two flavors: Expedited Forwarding (EF) and Assured Forwarding (AF). The former provides an almost airtight separation between premium and non-premium traffic; the latter, where different classes are given different forwarding or dropping treatments, although they share the same network resources. DiffServ is widely recognized for its excellent scalability properties.The fairness problems exist in the flows when sharing the network resources. For DiffServ, not only the aggregate classes but also every micro-flow of the same aggregate flow can't share the resources fairly. The research works show that the web traffic, which takes most proportion in recent network, couldn't get effective protection. Therefore, to promote the performance of the web traffic among the aggregate flow is of great practical significance.In this paper, many works have been done in the following fields. Firstly, We present the definitions and the existing problems of the Internet Service Quality. Secondly, we make an exposition of the DiffServ protocol and study the realizing scheme of the DiffServ routers. Thirdly, base on the analysis of the existing packets marking algorithm, we explain the reasons why the markers bring unfairness. Consider the shortcomings of the web traffic, we propose a new mechanism named web traffic-friendly moving rate threshold scheme. Fourthly, we introduce the principle and the characteristics of OPNET simulation environment, analyze the realizing details of DiffServ mechanism on OPNET, The simulation steps of QoS is given too. In order to prove the performance of our new scheme, we add the new algorithm to OPNET modelers. Compare with other markers, our results show that the new scheme can provide better fairness guarantee to web traffic. At last the paper summarizes the results of our study and puts forward the research direction in future.