Introduction

Abstract

Internet has evolved from network architectures in which, general connectivity was far more important than consistent performance, and the Internet of today consequently exhibits less predictable performance. Generally, the delivery of Internet Protocol (IP) services is designed to be “Best effort” and the packets were treated equally. In case of Public Switched Telephone Network (PSTN), routing is very expensive due to higher bandwidth available for high performing and reliable interactive audio and video sessions. Whereas, in IP Networks, the routing is reasonably affordable but sharing the resources makes the IP services a real challenge. There are some fundamental issues in the audio and video services like the latency, packet loss and jitter. The basic principles of PSTN and Internet are different. The PSTN is a network that transports only the voice media with the most reliable delivery mechanism. Internet on the other hand can transport any media (voice, video and data) using the best effort delivery mechanisms. PSTN requires a simple endpoint (simple phone) and an expensive switch to transport the voice circuits along with other services. Internet uses the routers to receive the packet; forwards the packet to the next router and so on until the packet reaches the intended destination. The power of Internet is concentrated on the edges of network elements such as powerful desktop, laptop computers, cell phones and other digital hand held devices (Gurabani 2004).