The Military Technical College
The prevalence and ease of packet sniffing and other techniques for capturing packets on an IP based network makes encryption a necessity for VOIP (Voice Over Internet Protocol). Security in VOIP is concerned both with protecting what a person says (by Encryption) as well as to whom the person is speaking (by Authentication). IPsec can be used to achieve both of these goals as long as it is applied with ESP (Encapsulating Security Payload) using the tunnel method. In this paper the negative effect of adding security to VoIP networks has been measured for different simulation times using OPNET (Network Simulation Tool).