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CEDAR: a CoreExtraction Distributed Ad hoc Routing Algorithm
 IEEE Journal on Selected Areas in Communications
, 1999
"... Absiract—CEDARis an algorithm for QoS routing in ad hoc network environments. It has three key components: (a) the establishment and maintenance of a setforganizing routing infrastructure catted the core for performing route computations, (b) the propagation of the linkstate of stable highbandw ..."
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Cited by 397 (10 self)
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Absiract—CEDARis an algorithm for QoS routing in ad hoc network environments. It has three key components: (a) the establishment and maintenance of a setforganizing routing infrastructure catted the core for performing route computations, (b) the propagation of the linkstate of stable highbandwidth links in the core through increase/decrease waves, and (c)a QoS ra,ute computation algorithm that is exeeuted at the core nodes using onty locally available state. Our preliminary performance evaluation shows that CEDAR is a robust and adaptive QoS routing algorithm that reacts effectively to the dynamics of the network white stitl approximating linkstate performance for stable networks. Keywords—Ad hoc routing, QoS routing I.
An Overview of QualityofService Routing for the Next Generation HighSpeed Networks: Problems and Solutions
"... The upcoming Gbps highspeed networks are expected to support a wide range of communicationintensive, realtime multimedia applications. The requirement for timely delivery of digitized audiovisual information raises new challenges for the next generation integratedservice broadband networks. On ..."
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Cited by 223 (21 self)
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The upcoming Gbps highspeed networks are expected to support a wide range of communicationintensive, realtime multimedia applications. The requirement for timely delivery of digitized audiovisual information raises new challenges for the next generation integratedservice broadband networks. One of the key issues is the QualityofService (QoS) routing. It selects network routes with sufficient resources for the requested QoS parameters. The goal of routing solutions is twofold: (1) satisfying the QoS requirements for every admitted connection and (2) achieving the global efficiency in resource utilization. Many unicast/multicast QoS routing algorithms were published recently, and they work with a variety of QoS requirements and resource constraints. Overall, they can be partitioned into three broad classes: (1) source routing, (2) distributed routing and (3) hierarchical routing algorithms. In this paper we give an overview of the QoS routing problem as well as the existing solutions. We present the strengths and the weaknesses of different routing strategies and outline the challenges. We also discuss the basic algorithms in each class, classify and compare them, and point out possible future directions in the QoS routing area.
QoS Routing Mechanisms and OSPF Extensions
 In Proceedings of the 2nd IEEE Global Internet MiniConference
, 1997
"... Status of this Memo ..."
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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Cited by 80 (0 self)
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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.
A Simple Efficient Approximation Scheme for the Restricted Shortest Path Problem
 Operations Research Letters
, 1999
"... In this short paper we give a very simple fully polynomial approximation scheme for the restricted shortest path problem. The complexity of this fflapproximation scheme is O(jEjn(loglog n + 1=ffl)), which improves Hassin's original result [Has92] by a factor of n. Furthermore, this complex ..."
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Cited by 73 (2 self)
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In this short paper we give a very simple fully polynomial approximation scheme for the restricted shortest path problem. The complexity of this fflapproximation scheme is O(jEjn(loglog n + 1=ffl)), which improves Hassin's original result [Has92] by a factor of n. Furthermore, this complexity bound is valid for any graph, regardless of the cost values. This generalizes Hassin's results which apply only to acyclic graphs. Our algorithm is based on Hassin's original result [Has92] with two improvements. First we modify Hassin's result and achieve time complexity of O(jEjn(log log(UB=LB) + 1=ffl)), where UB and LB are upper and lower bounds for the problem. This modified version can be applied to general graphs with any cost values. Then we combine it with our second contribution, which shows how to find an upper and a lower bound such that UB=LB n, to obtain the claimed result. 1
Distributed QoS Routing with Imprecise State Information
"... The goal of QualityofService (QoS) routing is to find a network path which has sufficient resources to satisfy certain constraints on metrics such as delay and bandwidth. The state information maintained at every node is often imprecise in a dynamic network because of nonnegligible propagation d ..."
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Cited by 65 (7 self)
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The goal of QualityofService (QoS) routing is to find a network path which has sufficient resources to satisfy certain constraints on metrics such as delay and bandwidth. The state information maintained at every node is often imprecise in a dynamic network because of nonnegligible propagation delay of state messages, periodic updates due to overhead concern, and hierarchical state aggregation. The information imprecision makes QoS routing difficult. The traditional shortestpath routing algorithm does not provide satisfactory performance when the state information is imprecise, and the flooding algorithm has an excessively high overhead. We propose a distributed routing scheme, called ticketbased probing, which searches multiple paths in parallel for a qualified one. The scheme is based on a realistic imprecision state model. The number of paths searched is determined in a flexible way, which allows the dynamic tradeoff between the overhead and the routing performance. The proposed routing algorithms collectively utilize the state information of the intermediate nodes to guide the routing messages along the most appropriate paths, so that the success probability is maximized with limited overhead. The algorithms consider not only the QoS requirement but also the optimality of the routing path. Lowcost paths are given preference in order to improve the overall network performance.
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 50 (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...
Lagrange Relaxation Based Method for the QoS Routing Problem
, 2001
"... In this paper a practically efficient QoS routing method is presented, which provides a solution to the delay constrained least cost routing problem. The algorithm uses the concept of aggregated costs and provides an efficient method to find the optimal multiplier based on Lagrange relaxation. This ..."
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Cited by 47 (0 self)
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In this paper a practically efficient QoS routing method is presented, which provides a solution to the delay constrained least cost routing problem. The algorithm uses the concept of aggregated costs and provides an efficient method to find the optimal multiplier based on Lagrange relaxation. This method is proven to be polynomial and it is also efficient in practice. The benefit of this method is that it also gives a lower bound on the theoretical optimal solution along with the result. The difference between the lower bound and the cost of the found path is very small proving the good quality of the result. Moreover, by further relaxing the optimality of paths, an easy way is provided to control the tradeoff between the running time of the algorithm and the quality of the found paths. We present a comprehensive numerical evaluation of the algorithm, by comparing it to a wide range of QoS routing algorithms proposed in the literature. It is shown that the performance of the proposed polynomial time algorithm is close to the optimal solution computed by an exponential algorithm. KeywordsQoS routing, delay, optimization, Lagrange relaxation I.
A*Prune: An algorithm for finding K shortest paths subject to multiple constraints
 In 20th Annual Joint Conference of the IEEE Computer and Communications Societies
, 2001
"... Abstract—We present a new algorithm, A*Prune, to list (in order of increasing length) the first K MultipleConstrainedShortestPath (KMCSP) between a given pair of nodes in a digraph in which each arc is associated with multiple QualityofService (QoS) metrics. The algorithm constructs paths start ..."
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Abstract—We present a new algorithm, A*Prune, to list (in order of increasing length) the first K MultipleConstrainedShortestPath (KMCSP) between a given pair of nodes in a digraph in which each arc is associated with multiple QualityofService (QoS) metrics. The algorithm constructs paths starting at the source and going towards the destination. But, at each iteration, the algorithm gets rid of all paths that are guaranteed to violate the constraints, thereby keeping only those partial paths that have the potential to be turned into feasible paths, from which the optimal paths are drawn. The choice of which path to be extended first and which path can be pruned depend upon a projected path cost function, which is obtained by adding the cost already incurred to get to an intermediate node to an admissible cost to go the remaining distance to the destination. The Dijkstra’s shortest path algorithm is a good choice to give a good admissible cost. Experimental results show that A*Prune is comparable to the current best knownapproximate algorithms for most of randomly generated graphs. BA*Prune, which combines the A*Prune with any known polynomial timeapproximate algorithms to give either optimal orapproximate solutions to the KMCSP problem, is also presented. Keywords—shortest paths, constraint based routing, QoS routing, multiple constrained path selection, Dijkstra algorithm, NP complete. I.
Search Space Reduction in QoS Routing
 In Proceedings of the 19th International Conference on Distributed Computing Systems
, 2001
"... To provide realtime service or engineer constrainedbased paths, networks require the underlying routing algorithm to be able to find lowcost paths that satisfy given QualityofService (QoS) constraints. However, the problem of constrained... ..."
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Cited by 37 (3 self)
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To provide realtime service or engineer constrainedbased paths, networks require the underlying routing algorithm to be able to find lowcost paths that satisfy given QualityofService (QoS) constraints. However, the problem of constrained...