A modified RIO algorithm that alleviates the bandwidth skew problem in Internet differentiated service

The assured service is a service model that can be offered within Internet differentiated services (Diff-Serv) architecture. It provides a statistical bandwidth guarantee to its subscribers, and allows the subscribers to claim a share of the excess network bandwidth in addition to the subscribed bandwidth. It has been observed that assured service does not meet the bandwidth guarantee for high-profile flows in the presence of numerous low-profile flows (such as best-effort). We demonstrate that there is an inadequacy in the packet differentiation algorithm used in the Diff-Serv routers, RIO ("RED with In and Out"), that contributes to the problem. We propose a modified RIO algorithm called RI+O to reduce the effect, and show that it significantly alleviates the problem. Our approach of modifying a router algorithm incurs much less deployment cost than other approaches.