An Experimental Study on the Performance and Fairness of Loss Differentiation for TCP

This paper investigates the performance and fairness of receiver-based loss differentiation for TCP. Experiments have been performed with a FreeBSD kernel implementation. As expected, the results verify the effectiveness of receiver-based loss differentiation when corruption losses are present. However, if the the corrupting link is shared with users that do not employ loss differentiation, the performance gain typically comes at the expense of increased unfairness. The results show that a single loss differentiating user may in some cases reduce the bandwidth of users without loss differentiation with up to 35 percent, but there are also cases where loss differentiation has limited fairness implications. The results further show that if a user employs multiple TCP connections over the corrupting link the negative effects of corruption losses are reduced. This is true even if all connections employ regular TCP. Hence, multiple connections at the application level can to some extent be used as a simple mechanism to limit the impact of corruption losses.