Availability of real time Internet services

The Internet has seen dramatic growth over the last few years aided by the increasing popularity of the World Wide Web. Businesses are rushing to provide a presence on the Web and the number of consumers surfing the Web grows daily. This growth in traffic and applications has implications on the expected quality of services. As competition for services increases and customers are asked to pay for these services, performance will become a key differentiator. We consider quality of service issues for real time Internet applications. In particular we define service availability, the probability that a customer will be properly serviced by a given application at a given point in time, as a key measure of service quality. We discuss the network and service factors affecting the performance of new real time applications and then develop a system availability model for the Internet and use it to provide initial estimates of service availability for telephony over the Internet.