A Fast and Accurate Analytical Model of TCP Performance

Abstract — The majority of traffic on the Internet uses the Transmission Control Protocol (TCP) as a transport layer proto-col for the end-to-end control of information transfer. Accurate models of TCP performance are a key and basic step for design-ing, dimensioning and planning IP (Internet Protocol) networks. Packet-level simulation models do not scale with the growth of network capacities and number of users. Measurements also become very costly and inflexible with the growth and complexity of the Internet. This study proposes a simple, fast and accurate analytical model of TCP. The model gives Internet performance metrics, assuming that only basic network parameters such as the network topology, the number of users, link capacity, distance between network nodes and router buffer sizes are known. The TCP performance model derives performance metrics which express the network quality of service. To obtain the performance metrics, TCP and network sub-models are used. A closed network of./G/ ∞ queues is used to develop each TCP sub-model where each queue represents a state of a TCP connection. An M/M/1/K queue is used for each network sub-model which represents the output interface of an IP router with a buffer capacity of K packets. The two sub-models are iteratively solved. Based on comparisons of our results with ns2 simulation experiments and with other results from a known TCP model, our model is accurate, fast and simple