Design and Implementation of DiffServ Routers in OPNET

Differentiated Service Model (DiffServ) is currently a popular research topic as a low-cost method to bring QoS to today’s Internet backbone network. Simulation is the best way to study DiffServ before deploying it to the real Internet. In this paper, we introduce the techniques and methodologies that we used to design and implement DiffServ-enabled (DS-enabled) routers by using OPNET. We have implemented the Token Bucket and Leaky Bucket algorithms, RIO and PS queueing schemes, RED dropping schemes and other components in OPNET IP modules. Based on these DiffServ-enabled routers, we set up a large scale network to study DiffServ QoS features: priority dropping (discrimination among different service classes), QoS guarantees, token bucket effects, and fragmentation/de-fragmentation effects. Furthermore, we present problems we encountered during our study, and their solutions.