This is the sixth conference in the series which started in 1981 in Paris, followed by conferences held in Zurich (1984), Rio de Janeirio (1987), Barcelona (1991), and Raleigh (1993). The main objective of this IFIP conference series is to provide a platform for the exchange of recent and original contributions in communications systems in the areas of performance analysis, architectures, and applications. There are many exiciting trends and developments in the communications industry, several of which are related to advances in Asynchronous Transfer Mode·(ATM), multimedia services, and high speed protocols. It is commonly believed in the communications industry that ATM represents the next generation of networking. Yet, there are a number of issues that has been worked on in various standards bodies, government and industry research and development labs, and universities towards enabling high speed networks in general and ATM networks in particular. Reflecting these trends, the technical program of the Sixth IFIP W.G. 6.3 Conference on Performance of Computer Networks consists of papers addressing a wide range of technical challenges and proposing various state of the art solutions to a subset of them. The program includes 25 papers selected by the program committee out of 57 papers submitted.