Guérin, Roch A
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Publication Modeling the dynamics of network technology adoption and the role of converters(2009-06-22) Sen, Soumya; Guérin, Roch; Hosanagar, Kartik; Jin, YoungmiNew network technologies constantly seek to displace incumbents. Their success depends on technological superiority, the size of the incumbent's installed base, users' adoption behaviors, and various other factors. The goal of this paper is to develop an understanding of competition between network technologies, and identify the extent to which different factors, in particular converters (a.k.a. gateways), affect the outcome. Converters can help entrants overcome the influence of the incumbent's installed base by enabling cross-technology inter-operability. However, they have development, deployment, and operations costs, and can introduce performance degradations and functionality limitations, so that if, when, why, and how they help is often unclear. To this end, the paper proposes and solves a model for adoption of competing network technologies by individual users. The model incorporates a simple utility function that captures key aspects of users' adoption decisions. Its solution reveals a number of interesting and at times unexpected behaviors, including the possibility for converters to reduce overall market penetration of the technologies and to prevent convergence to a stable state; something that never arises in their absence. The findings were tested for robustness, e.g., different utility functions and adoption models, and found to remain valid across a broad range of scenarios.Publication SICAP, A Shared-segment Inter-domain Control Aggregation Protocol(2003-06-24) Sofia, Rute; Guérin, Roch A; Veiga, PedroExisting Quality of Service models are well defined in the data path, but lack an end-to-end control path mechanism that guarantees the required resources to bandwidth intensive services, such as video streaming. Current reservation protocols provide scalable resource reservation inside routing domains. However, it is primarily between such domains that scalability becomes a major issue, since inter-domain links experience large volumes of reservation requests. As a possible solution, we present and evaluate the Shared-segment based Inter-domain Control Aggregation Protocol, (SICAP) which affords the benefits of shared-segment aggregation, while avoiding its major drawback, namely, its sensitivity to the intensity of requests [l]. We present results of simulations that compare the performance of SICAP against that of the Border Gateway Reservation Protocol, (BGRP) which relies on sink-tree aggregation to achieve scalability.Publication Individual QoS versus Aggregate QoS: A Loss Performance Study(2002-06-23) Xu, Ying; Guérin, Roch AThis papers explores, primarily by means of analysis, the differences that can exist between individual and aggregate loss guarantees in an environment where guarantees are only provided at an aggregate level. The focus is on understanding which traffic parameters are responsible for inducing possible deviations and to what extent. In addition, we seek to evaluate the level of additional resources, e.g., bandwidth or buffer, required to ensure that all individual loss measures remain below their desired target. The paper’s contributions are in developing analytical models that enable the evaluation of individual loss probabilities in settings where only aggregate losses are controlled, and in identifying traffic parameters that play a dominant role in causing differences between individual and aggregate losses. The latter allows the construction of guidelines identifying what kind of traffic can be safely multiplexed into a common service class.Publication Making IGP Routing Robust to Link Failures(2005-05-02) Sridharan, Ashwin; Guérin, Roch AAn important requirement of a robust traffic engineering solution is insensitivity to changes, be they in the form of traffic fluctuations or changes in the network topology because of link failures. In this paper we focus on developing a fast and effective technique to compute traffic engineering solutions for OSPF/IS-IS environments that are robust to link failures in the logical topology. OSPF and IS-IS are the dominant intra-domain routing protocols where traffic engineering is primarily governed by link weights. Our focus is on computing a single set of link weights for a traffic engineering instance that performs well over all single logical link failures. Such types of failures, although usually not long lasting, of the order of tens of minutes, can occur with high enough frequency, of the order of several a day, to significantly affect network performance. The relatively short duration of such failures coupled with issues of computational complexity and convergence time due to the size of current day networks discourage adaptive reactions to such events. Consequently, it is desirable to a priori compute a routing solution that performs well in all such scenarios. Through computational evaluations we demonstrate that our technique yields link weights that perform well over all single link failures and also scales well, in terms of computational complexity, with the size of the network.Publication Achieving Near-Optimal Traffic Engineering Solutions for Current OSPF/IS-IS Networks(2003-03-30) Sridharan, Ashwin; Guérin, Roch A; Diot, ChristopheTraffic engineering is aimed at distributing traffic so as to "optimize" a given performance criterion. The ability to carry out such an optimal distribution depends on both the routing protocol and the forwarding mechanisms in use in the network. In IP networks running the OSPF or IS-IS protocols, routing is over shortest paths, and forwarding mechanisms are constrained to distributing traffic uniformly over equal cost shortest paths. These constraints often make achieving an optimal distribution of traffic impossible. In this paper, we propose and evaluate an approach, based on manipulating the set of next hops for routing prefixes, that is capable of realizing near optimal traffic distribution without any change to existing routing protocols and forwarding mechanisms. In addition, we explore the tradeoff that exists between performance and the overhead associated with the additional configuration steps that our solution requires. The paper’s contributions are in formulating and evaluating an approach to traffic engineering for existing IP networks that achieves performance levels comparable to that offered when deploying other forwarding technologies such as MPLS.Publication Interactions, Competition and Innovation in a Service-Oriented Internet: An Economic Model(2009-12-21) Zhang, Zhi-Li; Nabipay, Papak; Odlyzko, Andrew; Guérin, Roch AThis paper presents a new economic approach for studying competition and innovation in a complex and highly interactive system of network providers, users, and suppliers of digital goods and services (i.e., service providers). It employs Cournot and Bertrand games to model competition among service providers and network providers, respectively, and develops a novel unified model to capture the interaction and competition among these players in a “service-oriented” Internet. Incentives for service and network innovation are studied in this model.Publication Balancing Performance, Robustness and Flexibility in Routing Systems(2010-01-01) Kwong, Kin-Wah; Guérin, Roch; Shaikh, Anees; Tao, ShuModern networks face the challenging task of handling increasingly diverse traffic that is displaying a growing intolerance to disruptions. This has given rise to many initiatives, and in this paper we focus on multiple topology routing as the primary vehicle for meeting those demands. Specifically, we seek routing solutions capable of not just accommodating different performance goals, but also preserving them in the presence of disruptions. The main challenge is computational, i.e., to identify among the enormous number of possible routing solutions the one that yields the best compromise between performance and robustness. This is where our principal contribution lies, as we expand the definition of critical links -- a key concept in improving the efficiency of routing computation -- and develop a precise methodology to efficiently converge on those solutions. Using this new methodology, we demonstrate that one can compute routing solutions that are both flexible in accommodating different performance requirements and robust in maintaining them in the presence of failures and traffic fluctuations.Publication The Impact of Reprovisioning on the Choice of Shared versus Dedicated Networks(2010-09-20) Sen, Soumya; Yamauchi, Kristin; Guerin, Roch; Hosanagar, KartikAs new network services emerge, questions about service deployment and network choices arise. Although shared networks, such as the Internet, offer many advantages, combining heterogeneous services on the same network need not be the right answer as it comes at the cost of increased complexity. Moreover, deploying new services on dedicated networks is becoming increasingly viable, thanks to virtualization technologies. In this work, we introduce an analytical framework that gives Internet Service Providers the ability to explore the trade-offs between shared and dedicated network infrastructures. The framework accounts for factors such as the presence of demand uncertainty for new services, (dis)economies of scope in deployment and operational costs, and the extent to which new technologies allow dynamic (re)provisioning of resources in response to excess demands. The main contribution is the identification and quantification of dynamic (re)provisioning as a key factor in determining the preferred network infrastructure, i.e. shared or dedicated.Publication Light-Weight Overlay Path Selection in a Peer-to-Peer Environment(2006-04-28) Fei, Teng; Tao, Shu; Gao, Lixin; Guérin, Roch A; Zhang, Zhi-LiLarge-scale peer-to-peer systems span a wide range of Internet locations. Such diversity can be leveraged to build overlay “detours” to circumvent periods of poor performance on the default path. However, identifying which peers are “good” relay choices in support of such detours is challenging, if one is to avoid incurring an overhead that grows with the size of the peer-to-peer system. This paper proposes and investigates the Earliest Branching Rule (EBR) to perform such a selection. EBR builds on the Earliest Diverging Rule (EDR) that selects relay nodes whose AS path diverges from the default path at the earliest possible point, but calls for monitoring a much smaller number of paths. As a result, it has a much lower overhead. The paper explores the performance and overhead of EBR, and compares them to that of EDR. The results demonstrate that EBR succeeds in selecting good relay nodes with minimum control overhead. Hence, providing a practical solution for dynamically building good overlays in large peer-to-peer systems.Publication On the Impact of Policing and Rate Guarantees in Diff-Serv Networks: A Video Streaming Application Perspective(2001-08-01) Ashmawi, Wael; Guérin, Roch A; Wolf, Stephen; Pinson, MargaretOver the past few years, there have been a number of proposals aimed at introducing different levels of service in the Internet. One of the more recent proposals is the Differentiated Services (Diff-Serv) architecture, and in this paper we explore how the policing actions and associated rate guarantees provided by the Expedited Forwarding (EF) translate into perceived benefits for applications that are the presumed users of such enhancements. Specifically, we focus on video streaming applications that arguably have relatively strong service quality requirements, and which should, therefore, stand to benefit from the availability of some form of enhanced service. Our goal is to gain a better understanding of the relation that exists between application level quality measures and the selection of the network level parameters that govern the delivery of the guarantees that an EF based service would provide. Our investigation, which is experimental in nature, relies on a number of standard streaming video servers and clients that have been modified and instrumented to allow quantification of the perceived quality of the received video stream. Quality assessments are performed using a Video Quality Measurement tool based on the ANSI objective quality standard. Measurements were made over both a local Diff-Serv testbed and across the QBone, a QoS enabled segment of the Internet2 infrastructure. The paper reports and analyzes the results of those measurements.