ABSTRACT PERFORMANCE PARAMETERS OF WIRELESS VIRTUAL PRIVATE NETWORK KZ, S&uuml / heyla Ms.c, Department of Information Systems Supervisor: Assoc. Prof. Dr. Nazife Baykal Co-Supervisor: Assist. Prof. Dr. Yusuf Murat Erten January 2006, 78 pages As the use of PC&rsquo / s and handheld devices increase, it expected that wireless communication would also grow. One of the major concerns in wireless communication is the security. Virtual Private Network (VPN) is the most secure solution that ensures three main aspect of security: authentication, accountability and encryption can use in wireless networks. Most VPNs have built on IP Security Protocol (IPSec) to support end-to-end secure data transmission. IPSec is a wellunderstood and widely used mechanism for wired network communication. Because, wireless networks have limited bandwidth and wireless devices have limited power and less capable CPU, the performance of the networks when VPN&rsquo / s are used is an important research area. We have investigated the use of VPNs in wireless LANs to provide end &ndash / to &ndash / end security. We have selected IPSec as the VPN protocol and investigated the effects of using IPSec on the throughput, packet loss, and delay of the wireless LANs. For this purpose, we have set up a test bed and based, our results on the actual measurements obtained from the experiments performed using the test bed. v The wireless LAN we have used is an 802.11g network and the results show that the performance of the network is adversely affected when VPN&rsquo / s are used but the degradation is not as bad as expected.