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44
Multicast Routing and Its QoS Extension: Problems, Algorithms, and Protocols
 IEEE Network
, 2000
"... Multicast services have been increasingly used in large scale continuous media applications. The qualityofservice (QoS) requirements of these continuous media applications prompt the necessity for QoSdriven, constraintbased multicast routing. This article provides a comprehensive overview of exi ..."
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Multicast services have been increasingly used in large scale continuous media applications. The qualityofservice (QoS) requirements of these continuous media applications prompt the necessity for QoSdriven, constraintbased multicast routing. This article provides a comprehensive overview of existing multicast routing algorithms, protocols, and their QoS extension. In particular, we classify multicast routing problems according to their optimization functions and performance constraints, present basic routing algorithms in each problem class, and discuss their strengths and weakness. We also categorize existing multicast routing protocols, outline the issues and challenges in providing QoS in multicast routing, and point out possible future research directions.
An Efficient Partitioning Algorithm for Distributed Virtual Environment Systems
 IEEE TRANS. PARALLEL AND DISTRIBUTED SYSTEMS
, 2002
"... Distributed virtual environment (DVE) systems model and simulate the activities of thousands of entities interacting in a virtual world over a wide area network. Possible applications for DVE systems are multiplayer video games, military and industrial trainings, and collaborative engineering. In ge ..."
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Cited by 72 (0 self)
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Distributed virtual environment (DVE) systems model and simulate the activities of thousands of entities interacting in a virtual world over a wide area network. Possible applications for DVE systems are multiplayer video games, military and industrial trainings, and collaborative engineering. In general, a DVE system is composed of many servers and each server is responsible to manage multiple clients who want to participate in the virtual world. Each server receives updates from different clients (such as the current position and orientation of each client) and then delivers this information to other clients in the virtual world. The server also needs to perform other tasks, such as object collision detection and synchronization control. A large scale DVE system needs to support many clients and this imposes a heavy requirement on networking resources and computational resources. Therefore, how to meet the growing requirement of bandwidth and computational resources is one of the major challenges in designing a scalable and costeffective DVE system. In this paper, we propose an efficient partitioning algorithm that addresses the scalability issue of designing a large scale DVE system. The main idea is to dynamically divide the virtual world into different partitions and then efficiently assign these partitions to different servers. This way, each server will process approximately the same amount of workload. Another objective of the partitioning algorithm is to reduce the servertoserver communication overhead. The theoretical foundation of our dynamic partitioning algorithm is based on the linear optimization principle. We also illustrate how one can parallelize the proposed partitioning algorithm so that it can efficiently partition a very large scale DVE system. Lastly, experiments are carried out to illustrate the effectiveness of the proposed partitioning algorithm under various settings of the virtual world.
Optimal Partition of QoS Requirements on Unicast Paths and Multicast Trees
 IEEE/ACM Transactions on Networking
, 1998
"... We investigate the problem of optimal resource allocation for endtoend QoS requirements on unicast paths and multicast trees. Specifically, we consider a framework in which resource allocation is based on local QoS requirements at each network link, and associated with each link is a cost function ..."
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Cited by 49 (6 self)
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We investigate the problem of optimal resource allocation for endtoend QoS requirements on unicast paths and multicast trees. Specifically, we consider a framework in which resource allocation is based on local QoS requirements at each network link, and associated with each link is a cost function that increases with the severity of the QoS requirement. Accordingly, the problem that we address is how to partition an endtoend QoS requirement into local requirements, such that the overall cost is minimized. We establish efficient (polynomial) solutions for both unicast and multicast connections. These results provide the required foundations for the corresponding QoS routing schemes, which identify either paths or trees that lead to minimal overall cost. In addition, we show that our framework provides better tools for coping with other fundamental multicast problems, such as dynamic tree maintenance. Keywords  QoS, QoSdependent costs, Multicast, Routing, Broadband ne...
Efficient Admission Control for EDF Schedulers
 PROCEEDINGS OF INFORCOM'97
, 1997
"... In this paper we present algorithms for flow admission control at an EDF link scheduler when the flows are characterized by peak rate, average rate and burst size. We show that the algorithms have very low computational complexity and are easily applicable in practice. The complexity can be further ..."
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Cited by 46 (1 self)
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In this paper we present algorithms for flow admission control at an EDF link scheduler when the flows are characterized by peak rate, average rate and burst size. We show that the algorithms have very low computational complexity and are easily applicable in practice. The complexity can be further decreased by introducing the notion of flex classes. We evaluate the penalty in efficiency that the classes incur to the EDF scheduler. We find that this efficiency degradation can be made arbitrarily small and is acceptable even for a small number of classes.
Efficient admission control of piecewise linear traffic envelopes at EDF schedulers
 IEEE/ACM Transactions on Networking
, 1998
"... Abstract—In this paper, we present algorithms for flow admission control at an earliest deadline first link scheduler when the flows are characterized by piecewise linear traffic envelopes. We show that the algorithms have very low computational complexity and, thus, practical applicability. The co ..."
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Cited by 26 (2 self)
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Abstract—In this paper, we present algorithms for flow admission control at an earliest deadline first link scheduler when the flows are characterized by piecewise linear traffic envelopes. We show that the algorithms have very low computational complexity and, thus, practical applicability. The complexity can be further decreased by introducing the notion of discretized admission control. Through discretization, the range of positions for the end points of linear segments of the traffic envelopes is restricted to a finite set. Simulation experiments show that discretized admission control can lend to two orders of magnitude decrease in the amount of computation needed to make admission control decisions over that incurred when using exact (nondiscrete) admission control, with the additional benefit that this amount of computation no longer depends on the number of flows. We examine the relative performance degradation (in terms of the number of flows admitted) incurred by the discretization and find that it is small. Index Terms—Admission control algorithms, earliest deadline first, piecewise linear traffic envelope, quality of service. I.
Optimal Partition of QoS Requirements with Discrete Cost Functions
, 2000
"... The future Internet is expected to support applications with quality of service (QoS) requirements. For this end several mechanisms are suggested in the IETF to support signaling, the most promising among them is DiffServ. An important problem in this framework is how to partition the QoS requiremen ..."
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Cited by 24 (2 self)
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The future Internet is expected to support applications with quality of service (QoS) requirements. For this end several mechanisms are suggested in the IETF to support signaling, the most promising among them is DiffServ. An important problem in this framework is how to partition the QoS requirements of an application along a selected path. The problem which is in general NP complete, was solved for continuous convex cost functions by Lorenz and Orda. This work concentrates on discrete cost functions, and presents efficient exact and approximated solutions for various conditions of the problem. We also show that the more complex problem of QoS sensitive routing with discrete cost functions is hard, but has a fully polynomial approximation scheme. I. INTRODUCTION The future networks are expected to support applications with quality of service (QoS) requirements. For this end, mechanisms are required to support signaling for connection establishment that include QoS routing and resource...
A Fast Multicast Routing Algorithm for DelaySensitive Applications
, 1997
"... : We propose a heuristic algorithm for delayconstrained minimum cost multicast routing in the packetswitched networks. The algorithm is computationally efficient since, unlike previous heuristics, it does not rely on any enumerative step that generates a set of delaybounded paths between a pair of ..."
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Cited by 21 (0 self)
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: We propose a heuristic algorithm for delayconstrained minimum cost multicast routing in the packetswitched networks. The algorithm is computationally efficient since, unlike previous heuristics, it does not rely on any enumerative step that generates a set of delaybounded paths between a pair of nodes and chooses a minimum cost path. An extensive computational experiment is done on wide varieties of instances including relatively large and dense networks. For small and sparse networks, the algorithm can find nearoptimal multicast trees. Even when the network size grows, the quality of multicast tree does not seem to deteriorate while the computation time remains quite moderate. 1 Introduction Multicast is a communication in which message streams generated by a single node (source) are concurrently distributed to more than one nodes (destinations). If the routing goal is to optimize the total cost defined by a single cost parameter (e.g. bandwidth cost) assigned on each edge, the ...
Efficient QoS partition and routing of unicast and multicast
 in Proc. of IWQoS 2000
, 2000
"... Abstract—In this paper, we study problems related to supporting unicast and multicast connections with quality of service (QoS) requirements. We investigate the problem of optimal routing and resource allocation in the context of performance dependent costs. In this context, each network element can ..."
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Cited by 21 (3 self)
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Abstract—In this paper, we study problems related to supporting unicast and multicast connections with quality of service (QoS) requirements. We investigate the problem of optimal routing and resource allocation in the context of performance dependent costs. In this context, each network element can offer several QoS guarantees, each associated with a different cost. This is a natural extension to the commonly used bicriteria model, where each link is associated with a single delay and a single cost. This framework is simple yet strong enough to model many practical interesting networking problems. An important problems in this framework is finding a good path for a connection that minimizes the cost while retaining the endtoend delay requirement. Once such a path (or a tree, in the multicast case) is found, one needs to partition the endtoend QoS requirements among the links of the path (tree). We consider the case of general integer cost functions (where delays and cost are integers). As the related problem is NP complete, we concentrate on finding efficientapproximation solutions. We improve on recent previous results by Ergün et al. Lorenz and Orda, and Raz and Shavitt, both in terms of generality as well as in terms of complexity of the solution. In particular, we present novel approximation techniques that yield the best known complexity for the unicast QoS routing problem, and the first approximation algorithm for the QoS partition problem on trees, both for the centralized and distributed cases. Index Terms—Approximation, multicast, QoSdependent costs, QoS, resource allocation, routing.
QoS Routing with PerformanceDependent Costs
, 2000
"... We study a network model in which each network link is associated with a set of delays and costs. These costs are a function of the delays and reflect the prices paid in return for delay guarantees. Such a cost structure can model a setting in which the service provider provides multiple service cla ..."
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Cited by 19 (0 self)
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We study a network model in which each network link is associated with a set of delays and costs. These costs are a function of the delays and reflect the prices paid in return for delay guarantees. Such a cost structure can model a setting in which the service provider provides multiple service classes with a different price and delay guarantee for each class. We are given a source node s, a sink node t, and an endtoend delay constraint D. Our aim is to choose an st path and determine a set of per link delay guarantees along this path so as to satisfy the constraint D while minimizing the total cost incurred. In the case where the st path is known, we aim to optimally partition the endtoend delay constraint into link constraints along the path. We present approximation algorithms for both problems, since they are known to be NPhard. Our algorithms guarantee to produce solutions that are within a factor 1 + " of the optimal, where " is a parameter of our choice. The running ti...
Smart: A ManyToMany Multicast Protocol For ATM
, 1996
"... We present a protocol for controlling a shared ATM multicast tree supporting manytomany communication. The protocol supports one or several ATM VCCs of the manytomany type. The number of VCCs is independent of the number of endpoints. The protocol guarantees that there is no interleaving on any ..."
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Cited by 12 (0 self)
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We present a protocol for controlling a shared ATM multicast tree supporting manytomany communication. The protocol supports one or several ATM VCCs of the manytomany type. The number of VCCs is independent of the number of endpoints. The protocol guarantees that there is no interleaving on any VCC of the tree. The protocol also guarantees that the traffic contract associated with the VCCs is respected, thus making it possible to use ordinary VCCs of the CBR, VBR or UBR class. No resequencing server is required, and all cell forwarding is performed at the ATM layer. We describe the protocol both informally and formally.