Performance Comparison of Different Class-and-Drop Treatment of Data and Acknowledgements in DiffServ IP Networks

In differentiated services IP networks the sender of a TCP connection determines the class of data packets he emits. The receiver chooses the class of the acknowledgements sent back, independently of the received class. In this work, we examine the impact of different drop precedence within a class and the assignment of different classes for data and acknowledgements. The results show that the throughput of a TCP connection depends not only on the data class, but also on the right choice for the acknowledgements. Some combinations of classes for data and ACKs could even lead to an “unfair” use of bandwidth. On the other hand, for a high throughput the selection of the drop precedence is in most cases only important for data packets.