It is usually hard to control the network conditions affecting public online game servers when studying the impact of latency, loss and jitter on user experience. This leads to a natural desire for running user-experience trials under controlled network conditions, and hence a requirement for accurate (or at least predictable) emulation of IP level latency, loss and jitter on a localized network testbed. In this short paper we reflect on some experiences with running userexperience trials, and specifically evaluate the utility and limitations of using FreeBSD’s kernel-resident dummynet module to introduce controlled jitter. We expect these insights will stimulate further userexperience trials built around low-cost, unix-based networking tools. Categories and Subject Descriptors C.2.1 [Computer-Communication Networks]: Network Architecture and Design – network communications, packet-switcing networks C.2.3 [Computer-Communication Networks]: Network Operations – network monitoring...
Grenville J. Armitage, Lawrence Stewart