Applying adaptive virtual queue to improve the performance of the assured forwarding service

Recent research studies in over-provisioned networks have shown that the assured forwarding (AF) service in the current differentiated services (DiffServ) architecture fails to provide bandwidth assurance in some situations. The paper focuses on the situation where adaptive and non-adaptive traffic coexist in the same real queue at routers and the buffer management scheme treats the traffic of the same priority in the same AF class indiscriminately. An enhanced RIO is introduced, which, without excessively penalizing non-adaptive flows, can: (1) significantly improve bandwidth assurance of adaptive AF flows; (2) alleviate the starvation imposed on adaptive best-effort flows. These goals are achieved by doing the following when the failure of bandwidth assurance is detected: (1) mapping adaptive OUT traffic and non-adaptive OUT traffic to different virtual queues; (2) adapting the queue length thresholds according to whether bandwidth assurance is achieved. We validate our design through simulations.