Author : Hussein A. Mohammed and Adnan Hussein Ali

Voice over Internet Protocol (VoIP) is an application from the internet services that allows us to communicate with each other. VoIP requires Quality of Service (QoS) because it is very sensitive to loss and delay of the information. Therefore, QoS of VoIP is needed to ensure that voice packets are not delayed or lost during the transmission over the network. The objective of this research is to study the effect some of the Security Mechanisms on the VoIP Qos. In this work, simulation tool OPNET Modeler version 14.0 is used to implement the proposed network (VoIP Network). The proposed network is a private network for a company with two locations located at different countries around the world in order to simulate the communications within the same location locally and the communications between two locations as a long distance and analyze VoIP QoS based on measuring the major factors that influence the QoS for VoIP according to international telecommunication union (ITU) standards including: delay, jitter and packet loss. In this research, a comparison was executed between some security mechanisms like Packet Filter Firewall and Virtual Private Network (VPN) and it was found that VPN gives the better QoS from the traditional firewall for VoIP networks.

Keywords: OPNET, FIFO Queue, Priority Queue, Weighted-Fair Queue, QoS, ToS.

Article published in International Journal of Current  Engineering  and Technology, Vol.3,No.5(Dec- 2013)