Simulation model for evaluation of packet sequence changed order of stream in DiffServ network

Current packet networks use a large variety of mechanisms which should support QoS (Quality of Service). One of those mechanisms is routing (calculating connection paths for incoming service requests). The most effective mechanism in QoS context is dynamic routing, based on the current network state described by the offered traffic matrix and link states. After switching between calculated available paths, connection path changes may cause received packets to change order within a single stream. This paper includes the problem definition and the analysis of all additional effects. A combined simulation/analytic model was proposed in order to answer whether the number of changed-order packets is significant and if it should be considered when calculating the end-to-end delay balance in analytical models for packet networks with differentiated services. Furthermore, the proposed model gave the answer on how often calculated paths may be switched to avoid the network beingout of tune.