On How to Provision Quality of Service (QoS) for Large Dataset Transfers

There is recent interest in using traffic-engineered, QoS-controlled paths for large-sized, high-rate dataset transfers in the scientific community. We refer to TCP flows created by such transfers as flows. Research-and-education network providers are interested in intra-domain traffic engineering systems for identifying flows at ingress routers within their networks, and redirecting them to traffic-engineered paths. This is primarily because of the adverse effects these flows have on delay-sensitive multimedia flows. The focus of this work is to determine what QoS mechanisms are suitable to achieve the dual goals of preventing flows from adversely affecting delay- sensitive flows, while simultaneously allowing them to enjoy high throughput. The interaction between policing schemes on the ingress interfaces and scheduling schemes on the egress interfaces was studied through a set of experiments on a high-speed router testbed. Our conclusions are that a scheduling-only mechanism, with no policing, is well suited to achieve these dual goals if the level of fairness offered by today's IP-routed service is sufficient for simultaneous flows. Keywords—policing; scheduling; high-speed networks; traffic- engineering; virtual-circuit networks