Differentiated Services (DiffServ) is a mechanism for supporting network Quality of Service (or QoS) whereby packets that are transmitted by a client program are marked with a priority setting that can be interpreted by the router to effect special treatment of the packet. In particular the marked packets are promoted to a higher priority queue in the router and, as a result, spend a minimum amount of time in the router. Packets that are not marked are attached to a lower priority queue, and in some cases may be dropped when congestion arises. A more detailed description of DiffServ may be found in the paper by Sander et al [Sander et al 2000].

A series of experiments were performed over a wide area DiffServ testbed as part of the EMERGE project. EMERGE (www.evl.uic.edu/cavern/EMERGE) is a Department of Energy funded project for designing, deploying and testing Differentiated Services on an IP/ATM Regional GigaPoP Network interoperating with ESnet for applications in Combustion, Climate and High-Energy Physics. The main participants of the experiments in this report were EVL and Argonne National Laboratory(ANL).