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A Survey of Combinatorial Optimization Problems in Multicast Routing
, 2003
"... In multicasting routing, the main objective is to send data from one or more source to multiple destinations, while at the same time minimizing the usage of resources. Examples of resources which can be minimized include bandwidth, time and connection costs. In this paper we survey applications of c ..."
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Cited by 40 (1 self)
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In multicasting routing, the main objective is to send data from one or more source to multiple destinations, while at the same time minimizing the usage of resources. Examples of resources which can be minimized include bandwidth, time and connection costs. In this paper we survey applications of combinatorial optimization to multicast routing. We discuss the most important problems considered in this area, as well as their models. Algorithms for each of the main problems are also presented.
Applicability of group communication for increased scalability in MMOGs
 In NetGames
, 2006
"... Massive multiplayer online games (MMOGs) are today the driving factor for the development of distributed interactive applications, and they are increasing in size and complexity. Even a small MMOG supports thousands of players, the biggest support hundreds of thousands of concurrent players. Since t ..."
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Cited by 9 (6 self)
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Massive multiplayer online games (MMOGs) are today the driving factor for the development of distributed interactive applications, and they are increasing in size and complexity. Even a small MMOG supports thousands of players, the biggest support hundreds of thousands of concurrent players. Since they are typically built as strict clientserver systems, they suffer from the inherent scalability problem of the architecture. Computing power and bandwidth limitations close to the server limit the possible number of players. Also, the latency of communication between players through the server will be higher than using direct communication. In the paper, we address these issues and investigate improvement options. A typical MMOG consists of a virtual world with a concept of time and space that is similar to the real world. In it, players are represented by avatars. Only subsets of these avatars interact with each other at any given time. This allows us to divide them into groups, and communication among group members becomes a multiparty communication problem. Thus, to reduce resource consumption, we compare the performance of several algorithms for group communication with the current central server approach. We use overlay multicast as the means of providing group communication, and research algorithms for creating shortest path trees, spanning trees, delaybounded spanning trees and, more specific, applying Steiner tree heuristics. Our experimental results indicate that different approaches are useful to reduce resource consumption while achieving a good perceived quality under varying conditions, such as frequent changes in group membership and the demand for low latency. 1.
OPTIMIZATION PROBLEMS IN MULTICAST TREE CONSTRUCTION
, 2005
"... Multicasting is a technique for data routing in networks that allows multiple destinations to be addressed simultaneously. The implementation of multicasting requires, however, the solution of difficult combinatorial optimization problems. In this chapter, we discuss combinatorial issues occurring ..."
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Cited by 6 (2 self)
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Multicasting is a technique for data routing in networks that allows multiple destinations to be addressed simultaneously. The implementation of multicasting requires, however, the solution of difficult combinatorial optimization problems. In this chapter, we discuss combinatorial issues occurring in the implementation of multicast routing, including multicast tree construction, minimization of the total message delay, centerbased routing, and multicast message packing. Optimization methods for these problems are discussed and the corresponding literature reviewed. Mathematical programming as well as graph models for these problems are discussed.
Construction Algorithms and Approximation Bounds for the Streaming Cache Placement Problem in Multicast Networks
, 2004
"... We study a problem in the area of multicast networks, called the Streaming Cache Placement Problem (SCPP). In the SCPP one wants to determine the minimum number of multicast routers needed to deliver content to a specified number of destinations, subject to predetermined link capacities. The SCP ..."
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Cited by 4 (1 self)
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We study a problem in the area of multicast networks, called the Streaming Cache Placement Problem (SCPP). In the SCPP one wants to determine the minimum number of multicast routers needed to deliver content to a specified number of destinations, subject to predetermined link capacities. The SCPP is known to be NPhard [1] and also MAX SNP hard [2]. We improve the approximation results for this problem, using a reduction from Set Cover. In particular, given k destinations, we show that the SCPP cannot have a O(log log k #) approximation algorithm, for a very small #, unless NP can be solved in subexponential time. We also propose construction algorithms for the SCPP, based on two general techniques: adding destinations to a partial solution, and reducing the number of infeasible nodes in an initial solution. We report the results of computational experiments based on these two algorithms and its variations.
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"... ngro unlogy, pc ult h h ast m, w od i me 30 ptim rvices oint co by the ommun Interne t com ode) a needs to be transported through a link, and it can be shared by multiple destination nodes. In multicast transmissions, the choice of a multicast route has several significant impacts both on the prot ..."
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ngro unlogy, pc ult h h ast m, w od i me 30 ptim rvices oint co by the ommun Interne t com ode) a needs to be transported through a link, and it can be shared by multiple destination nodes. In multicast transmissions, the choice of a multicast route has several significant impacts both on the protocol performance and on the network utilization. There are two proposals to build a multicast route: a treebased approach and a ringbased approach. When there are multiple multicast sessions to be set up, sequentially choosing the optimal multicast routing tree for each session may not lead to a globally optimal solution. The set of multicast routing trees should be selected simultaneously, and the problem is referred to as the multicast route packing problem (MRP) [10,11,14,16]. The two following objectives have been considered for MRP: (1) to minimize the maximum utilization or congestion [3,10], and (2) to minimize the total installation cost [11,14,16]. In the first