A Simulation Study of Tunneled Voice over Internet Protocol System


In this paper, the effects of real time traffic on non real time traffic are explained for conventional VoIP system. Also two types of Quality of Service models are applied; the End to End delay, the throughput, and the number of dropped packet are the main parameters used to evaluate the network performance. A new technique is proposed to solve the above problems. This technique is based on the tunneling process to carry the real time traffic. Some analysis is performed to expect the maximum call number served by a network. To overcome the overhead problem due the tunnel, two parameters are included; the first one is the number of real time packets tunneled in each frame, and the second one is the voice frame size. The analysis and the simulation show that as the number of the tunneled packet becomes larger, the maximum call number approaches to the non tunnel situation. On other hand, as the frame size becomes larger, the maximum call number exceeds the non tunneled situation. Of course, the maximum number of tunneled packets and the frame size affect the End to End delay which is controlled by the type of CODEC being used. A compromised value can be found to achieve the better network response. OPNET MODELER is the simulating software being used together with a dedicated program for performing some calculations related to network performance.Key Words :VOIP, Accelerator,QoS,weighted Fair Queuing, Priority Queuing, Bandwidth efficiency, Header Compression, Tunneling, OPNET Modeler.