Study Of Fairness Of Bandwidth Sharing In Differentiated Services

With the appearances of many multimedia applies via network such as video conference,video frequency,IP phone and tel-education,the Business volume of Internet grows very quickly.Traditional "Best effort" services can't meet the users' requirement. So, IP QoS (Quality of Service) becomes an important issue.Various of QoS networks architectures are provided by international organizes, research centers, universities and companies.In these QoS networks architectures, Differentiated services model offered by IETF is valued.In DiffServ networks, edge routers classify each packet based on it's profile specifies and mark it in it's DSCP (Differentiated Services CodePoint).Core routers determine the particular forwarding treatment with each packet's DSCP.DiffServ has several advantages.First, it is performs congestion control on an aggregate traffic, so it can be realized simply. Second, it is easy to be extended to new applications. But the fairness of resource sharing is a important problem in the DiffServ.This problem contains two aspects.One is that the different micro-flow with different profile specifies such as congestion control manshanism, and traffic rate always can't obtain the fairness of resource sharing.The other one is that the different aggregated traffics with different number of microflows, packet size and target rate usually can't obtain the fairness of resource sharing. Lots of recent studies focus on the unfairness of resource sharing between different micro-flow, but not that between different macro-flow.In this paper, we design a Differentiated RIO (DRIO) based on ARIO.The aggregated traffics with different target rate are dealt with differently in DRIO. So that DRIO can assure the fairness of bandwidth sharing among aggregated traffics very well. Otherwise, the algorithm can be put in practice simply. The simulation results indicate that the DRIO algorithm has best effect on improving the fairness of bandwidth sharing between aggregated traffics. Moreover, we propose an overlay-based feedback congestion control mechanism (OFCCM).The simulation results indicate that the OFCCM not only reduces packet loss ratio greatly, but also improving the fairness of bandwidth sharing between aggregated.