IP-based virtual private networks and proportional quality of service differentiation

IP-based virtual private networks (VPNs) have the potential of delivering cost-effective, secure, and private network-like services. Having surveyed current enabling techniques, an overall picture of IP VPN implementations is presented. In order to provision the equivalent quality of service (QoS) of legacy connection-oriented layer 2 VPNs (e.g., Frame Relay and ATM), IP VPNs have to overcome the intrinsically best effort characteristics of the Internet. Subsequently, a hierarchical QoS guarantee framework for IP VPNs is proposed, stitching together development progresses from recent research and engineering work. To differentiate IP VPN QoS, the proportional QoS differentiation model, whose QoS specification granularity compromises that of IntServ and Diffserv, emerges as a potential solution. The investigation of its claimed capability of providing the predictable and controllable QoS differentiation is then conducted. With respect to the loss rate differentiation, the packet shortage phenomenon shown in two classical proportional loss rate (PLR) dropping schemes is studied. On the pursuit of a feasible solution, the potential of compromising the system resource, that is, the buffer, is ruled out; instead, an enhanced debt-aware mechanism is suggested to relieve the negative effects of packet shortage. Simulation results show that debt-aware partially curbs the biased loss rate ratios, and improves the queueing delay performance as well. With respect to the delay differentiation, the dynamic behavior of the average delay difference between successive classes is first analyzed, aiming to gain insights of system dynamics. Then, two classical delay differentiation mechanisms, that is,proportional average delay (PAD) and waiting time priority (WTP), are simulated and discussed. Based on observations on their differentiation performances over both short and long time periods, a combined delay differentiation (CDD) scheme is introduced. Simulations are utilized to validate this method. Both loss and delay differentiations are based on a series of differentiation parameters. Though previous work on the selection of delay differentiation parameters has been presented, that of loss differentiation parameters mostly relied on network operators\u27 experience. A quantitative guideline, based on the principles of queueing and optimization, is then proposed to compute loss differentiation parameters. Aside from analysis, the new approach is substantiated by numerical results

An enhanced dropping scheme for proportional differentiated services

the DiffServ architecture is gaining ground, traffic engineering requires major adjustments. In addition, the measurement-based strategy gas been widely adopted owing to its advantages of flexibility and easy adaptation. This article reviews measurement-based dropping schemes. Based on the definition and investigation of the "packet shortage" phenomenon, an enhanced dropping scheme for the proportional differentiated packet loss, referred to as "debt-aware," is proposed. Simulation parameters, as compared to a typical proportional dropping mechanism. More simulations have been applied to demonstrate the merits of this improved method

An Enhanced Dropping Scheme for Proportional Differentiated Services

As the DiffServ architecture is gaining ground, traffic engineering requires major adjustments. In addition, the measurement-based strategy has been widely adopted owing to its advantages of flexibility and easy adaptation. This article reviews measurement-based dropping schemes. Based on the definition and investigation of the "packet shortage" phenomenon, an enhanced dropping scheme for the proportional differentiated packet loss, referred to as "debt-aware," is proposed. Simulation results show that the scheme partially curbs negative effects of "packet shortage" and closely approximates loss differentiation parameters, as compared to a typical proportional dropping mechanism. More simulations have been applied to demonstrate the merits of this improved method

Traffic Isolation and Network Resource Sharing for Performance Control in Grids

International audienceWhile grids reach further to geographically separated clusters and data warehouses, grid applications pose new demands on end-to-end performance control. Data-intensive grid applications rely on the underneath network to bring together distributed computational and storage resources. From computational grids to data grids, the focus of resource utilization is shifting from computing power to network resources. This article investigates network resource sharing in grids, especially data grids. It studies traffic characteristics and quality of service (QoS) mechanisms of grid applications. A hybrid approach, which combines advance resource reservation and classical QoS differentiation, is proposed to meet grid application performance requirements. Identifying three types of resource reservation scenarios, that is, long-lived, short-lived, and flexible shortlived, the article formulates optimization problem of network resource sharing. Proven NP-complete, the problem is pursued with heuristics and simulation

An Overlay Infrastructure for Bulk Data Transfers in Grids

International audienc

Peer-to-Peer Models for Resource Discovery in Large-scale Grids: A Scalable Architecture

Abstract. As Grids enlarge their boundaries and users, some of their functions should be decentralized to avoid bottlenecks and guarantee scalability. A way to provide Grid scalability is to adopt Peer-to-Peer (P2P) models to implement non hierarchical decentralized Grid services and systems. A core Grid functionality that can be effectively redesigned using the P2P approach is resource discovery. This paper proposes a P2P resource discovery architecture aiming to manage various Grid resources and complex queries. Its goal is two-fold: to address discovery of multiple resources, and to support discovery of dynamic resources and arbitrary queries in Grids. The architecture includes a scalable technique for locating dynamic resources in large-scale Grids. Simulation results are provided to demonstrate the efficiency of the proposed technique.