ITR: Multiple Time Scale Traffic Control for Next Generation Internets

Purdue Research Foundation, West Lafayette IN

Investigators

Abstract

The Internet is governed by a compendium of protocols spanning a number of functionalities including congestion control, routing, multicast, label switching, resource reservation and admission control, error control, and network management. These protocols engage in control actions at multiple time scales, from microseconds for routing and label switching, to milliseconds for congestion control, and the several second range for multicast, routing table updates, and network management. The behavior and performance of a network system is influenced by the workload that drive the protocols - reliable transport of heavy-tailed files, QoS-sensitive streaming of VBR video and audio, burstiness of connection arrivals, skewed make-up of short- and long-lived flows, and self-similar burstiness of multiplexed traffic - with Internet workload exhibiting variability and correlation at multiple time scales, from multiplicative scaling observed for IP flows in the millisecond range, to long-range correlations present in the second range. With QoS emerging as a unifying umbrella under which the various network subsystems can be organized and viewed as provisioning user-specified services, the need arises to coordinate and integrate the control activities - many of whom have direct impact on end-to-end QoS - such that both effective and efficient services can be rendered. In tandem with the QoS integration challenge, the PIs are presented with the opportunity to explicitly exploit the multiple time scale nature of network protocols and Internet workload to affect seemless and predictable services. In the proposed project, the PIs plan to address the following two-pronged problem: (1) exploit multiple time scale property of network protocols to facilitate effective coordination and integration of disjoint network controls for end-to-end QoS, and (2) exploit multiple time scale nature of Internet workload to achieve workload-sensitive traffic controls. Problem (1), in turn, is comprised of two key issues: sufficiency or separation conditions under which two network controls - e.g., routing and congestion control-acting at different time scales can be integrated without causing harmful effects with respect to stability and efficiency, and the effective coupling of protocols when time scale separation is not available - e.g., label control and congestion control. Problem (2) consists of three key issues: short-lived connection management using lightweight optimistic control, long-lived connection management using connection duration prediction and multi-layered feedback control, and QoS amplification through workload-sensitive, end-to-end and per-hop control. The two-fold challenge that the PIs plan to attack is grounded in well-defined technical problems, and at the same time, represents an innovative traffic control dimension with broader implications to the next generation Internet. The PIs bring expertise in core traffic control areas spanning congestion control (Park), QoS routing (Hou), multicast (Hou), label switching (Park), and traffic modeling (Park). Both PIs have significant experience in performance analysis and protocol design, and they complement each other's strengths with respect to simulation (Hou) and implementation (Park) based performance evaluation. The PIs will leverage existing benchmarking platforms - the Purdue Infobahn QoS testbed comprised of Cisco 7206 routers (Park) and the NetSim performance evaluation environment (Hou) - to implement, test, and benchmark the protocols. The research results, technology demonstration, and software prototypes will be made available through the Web to academic institutions, industrial affiliates, and the networking community at large.