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156
A novel generic graph model for traffic grooming in heterogeneous WDM mesh networks
 IEEE/ACM TRANSACTIONS ON NETWORKING
, 2003
"... As the operation of our fiberoptic backbone networks migrates from interconnected SONET rings to arbitrary mesh topology, traffic grooming on wavelengthdivision multiplexing (WDM) mesh networks becomes an extremely important research problem. To address this problem, we propose a new generic graph ..."
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Cited by 64 (6 self)
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As the operation of our fiberoptic backbone networks migrates from interconnected SONET rings to arbitrary mesh topology, traffic grooming on wavelengthdivision multiplexing (WDM) mesh networks becomes an extremely important research problem. To address this problem, we propose a new generic graph model for traffic grooming in heterogeneous WDM mesh networks. The novelty of our model is that, by only manipulating the edges of the auxiliary graph created by our model and the weights of these edges, our model can achieve various objectives using different grooming policies, while taking into account various constraints such as transceivers, wavelengths, wavelengthconversion capabilities, and grooming capabilities. Based on the auxiliary graph, we develop an integrated trafficgrooming algorithm (IGABAG) and an integrated grooming procedure (INGPROC) which jointly solve several trafficgrooming subproblems by simply applying the shortestpath computation method. Different grooming policies can be represented by different weightassignment functions, and the performance of these grooming policies are compared under both nonblocking scenario and blocking scenario. The IGABAG can be applied to both static and dynamic traffic grooming. In static grooming, the trafficselection scheme is key to achieving good network performance. We propose several trafficselection schemes based on this model and we evaluate their performance for different network topologies.
Traffic Grooming in Path, Star, and Tree Networks: Complexity Bounds and Algorithms
, 2004
"... We consider the problem of traffic grooming in WDM path, star, and tree networks. Traffic grooming is a variant of the wellknown logical topology design, and is concerned with the development of techniques for combining low speed traffic components onto high speed channels in order to minimize netw ..."
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Cited by 40 (12 self)
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We consider the problem of traffic grooming in WDM path, star, and tree networks. Traffic grooming is a variant of the wellknown logical topology design, and is concerned with the development of techniques for combining low speed traffic components onto high speed channels in order to minimize network cost. Our contribution is twofold. In the first part of the paper we present a wealth of results which settle the complexity of traffic grooming in path and star networks, by proving that a number of variants of the problem are computationally intractable. Since routing and wavelength assignment in these two topologies is trivial, these results demonstrate that traffic grooming is itself an inherently difficult problem. Our results have implications for ring and other more general topologies, which we explore. In the second part, we design practical grooming algorithms with provable properties. Specifically, for all three topologies, we obtain a series of lower and upper bounds which are increasingly tighter but have considerably higher computational requirements; the series of upper bounds forms an algorithm for the traffic grooming problem with strong performance guarantees. We also present corresponding heuristics with good performance. Our work is a first step towards a formal and systematic approach to the grooming problem in general topologies that builds upon results and algorithms for more elementary networks.
Traffic Grooming, Routing, and Wavelength Assignment in Optical WDM Mesh Networks
 Proceedings of the IEEE INFOCOM 2004
, 2004
"... In this paper, we consider the traffic grooming, routing, and wavelength assignment (GRWA) problem for optical mesh networks. In most previous studies on optical mesh networks, traffic demands are usually assumed to be wavelength demands, in which case no traffic grooming is needed. In practice, opt ..."
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Cited by 35 (0 self)
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In this paper, we consider the traffic grooming, routing, and wavelength assignment (GRWA) problem for optical mesh networks. In most previous studies on optical mesh networks, traffic demands are usually assumed to be wavelength demands, in which case no traffic grooming is needed. In practice, optical networks are typically required to carry a large number of lower rate (subwavelength) traffic demands. Hence, the issue of traffic grooming becomes very important since it can significantly impact the overall network cost. In our study, we consider traffic grooming in combination with traffic routing and wavelength assignment. Our objective is to minimize the total number of transponders required in the network. We first formulate the GRWA problem as an integer linear programming (ILP) problem. Unfortunately, for large networks it is computationally infeasible to solve the ILP problem. Therefore, we propose a decomposition method that divides the GRWA problem into two smaller problems: the traffic grooming and routing problem and the wavelength assignment problem, which can then be solved much more efficiently. In general, the decomposition method only produces an approximate solution for the GRWA problem. However, we also provide some sufficient condition under which the decomposition method gives an optimal solution. Finally, some numerical results are provided to demonstrate the efficiency of our method.
A Comprehensive Study on Nextgeneration Optical Grooming Switches
 IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS
, 2003
"... This paper investigates the characteristics and performance of different optical grooming switches, i.e., optical crossconnects (OXCs) capable of traffic grooming, under a dynamic traffic environment. We present four optical groomingOXC architectures, namely, singlehop grooming OXC, multihop par ..."
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Cited by 35 (5 self)
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This paper investigates the characteristics and performance of different optical grooming switches, i.e., optical crossconnects (OXCs) capable of traffic grooming, under a dynamic traffic environment. We present four optical groomingOXC architectures, namely, singlehop grooming OXC, multihop partialgrooming OXC, multihop fullgrooming OXC, and lighttreebased sourcenode grooming OXC. After exploring their grooming capabilities, we propose three grooming schemes and two corresponding algorithms, grooming using auxiliary graph and grooming using lighttree. Through the algorithms, we evaluate the performance of different optical grooming OXCs in a dynamic traffic environment under different connection bandwidthgranularity distributions. Our investigation uncovers the following results: 1) the multihop fullgrooming OXC can achieve the best network performance, but it may encounter cost and scalability constraints; 2) by using significantly less lowgranularity electronic processing and intelligent trafficgrooming algorithms, the multihop partialgrooming OXC shows reasonable network performance and, hence, can be viewed as a costeffective alternative when a network node does not require fullgrooming capability; 3) the singlehop grooming OXC may cause a large amount of capacity waste and lead to poor network performance; and 4) through its multicast capability, a lighttreebased sourcenode grooming OXC can significantly outperform the performance of a singlehop grooming OXC in terms of network throughput and network resource efficiency. From our results, we also observe that the connection bandwidthgranularity distribution has a large impact on network throughput and network resource efficiency and, therefore, should be carefully considered for network design and traffic provisioning.
On hierarchical traffic grooming in WDM networks
 IEEE/ACM Transactions on Networking
, 2008
"... Abstract—The traffic grooming problem is of high practical importance in emerging widearea wavelength division multiplexing (WDM) optical networks, yet it is intractable for any but trivial network topologies. In this work, we present an effective and efficient hierarchical traffic grooming framewo ..."
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Cited by 26 (9 self)
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Abstract—The traffic grooming problem is of high practical importance in emerging widearea wavelength division multiplexing (WDM) optical networks, yet it is intractable for any but trivial network topologies. In this work, we present an effective and efficient hierarchical traffic grooming framework for WDM networks of general topology, with the objective of minimizing the total number of electronic ports. At the first level of hierarchy, we decompose the network into clusters and designate one node in each cluster as the hub for grooming traffic. At the second level, the hubs form another cluster for grooming intercluster traffic. We view each (firstor secondlevel) cluster as a virtual star, and we present an efficient nearoptimal algorithm for determining the logical topology of lightpaths to carry the traffic within each cluster. Routing and wavelength assignment is then performed directly on the underlying physical topology. We demonstrate the effectiveness of our approach by applying it to two networks of realistic size, a 32node, 53link topology and a 47node, 96link network. Comparisons to lower bounds indicate that hierarchical grooming is efficient in its use of the network resources of interest, namely, electronic ports and wavelengths. In addition to scaling to large network sizes, our hierarchical approach also facilitates the control and management of multigranular networks. Index Terms—Hierarchical traffic grooming, Kcenter, optical networks, wavelength division multiplexing (WDM).
Traffic Grooming for Survivable WDM Networks  Shared Protection
 IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS
, 2003
"... This paper investigates the survivable trafficgrooming problem for optical mesh networks employing wavelengthdivision multiplexing (WDM). In the dynamicprovisioning context, a typical connection request may require bandwidth less than that of a wavelength channel, and it may also require protect ..."
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Cited by 22 (3 self)
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This paper investigates the survivable trafficgrooming problem for optical mesh networks employing wavelengthdivision multiplexing (WDM). In the dynamicprovisioning context, a typical connection request may require bandwidth less than that of a wavelength channel, and it may also require protection from network failures, typically fiber cuts. Based on a generic groomingnode architecture, we propose three approaches—protectionatlightpath (PAL) level, mixed protectionatconnection (MPAC) level, and separate protectionatconnection (SPAC) level—for grooming a connection request with shared protection. In sharedmesh protection, backup paths can share resources as long as their corresponding working paths are unlikely to fail simultaneously. These three schemes explore different ways of backup sharing, and they trade off between wavelengths and grooming ports. Since the existence version of the problem for provisioning one connection request with shared protection is N Pcomplete, we propose effective heuristics. Our findings are as follows. Under today’s typical connectionbandwidth distribution where lower bandwidth connections outnumber higher bandwidth connections, 1) it is beneficial to groom working paths and backup paths separately, as in PAL and SPAC; 2) separately protecting each individual connection—i.e., SPAC—yields the best performance when the number of grooming ports is sufficient; and 3) protecting each specific lightpath—i.e., PAL—achieves the best performance when the number of grooming ports is moderate or small.
Optimal multicasting of multiple lighttrees of different bandwidth granularities in a wdm mesh network with sparse splitting capabilities
 Networking, IEEE/ACM Transactions on
, 2006
"... Abstract—With the advent of nextgeneration, bandwidthintensive multimedia applications such as HDTV, interactive distance learning, and movie broadcasts from studios, it is becoming imperative to exploit the enormous bandwidth promised by the rapidly growing wavelengthdivisionmultiplexing (WDM ..."
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Cited by 13 (0 self)
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Abstract—With the advent of nextgeneration, bandwidthintensive multimedia applications such as HDTV, interactive distance learning, and movie broadcasts from studios, it is becoming imperative to exploit the enormous bandwidth promised by the rapidly growing wavelengthdivisionmultiplexing (WDM) technology. These applications require multicasting of information from a source to several destination nodes which should be performed judiciously to conserve expensive network resources. In this study, we investigate two switch architectures to support multicasting in a WDM network: one using an opaque (opticalelectronicoptical approach and the other using a transparent (alloptical) approach. For both these switch architectures, we present mathematical formulations for routing and wavelength assignment of several lighttreebased multicast sessions on a given network topology at a globally optimal cost. We expand our work to also accommo
Fast Exact ILP Decompositions for Ring RWA
, 2010
"... WDM rings are now capable of supporting more than 100 wavelengths over a single fiber. Conventional link and path formulations for the RWA problem are inefficient due to the inherent symmetry in wavelength assignment and the fact that the problem size increases fast with the number of wavelengths. ..."
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Cited by 11 (9 self)
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WDM rings are now capable of supporting more than 100 wavelengths over a single fiber. Conventional link and path formulations for the RWA problem are inefficient due to the inherent symmetry in wavelength assignment and the fact that the problem size increases fast with the number of wavelengths. Although a formulation based on maximal independent sets (MIS) does not have these drawbacks, it suffers from the exponential growth in the number of variables with the increasing network size. We develop a new ILP formulation based on the key idea of partitioning the path set and representing the maximal independent sets in the original network using the independent sets calculated in each of these partitions. This exact decomposition trades off the number of variables with the number of constraints and, as a result, achieves a much better scalability in terms of network dimension. Numerical results on ring networks of various sizes demonstrate that this new ILP decomposition achieves several orders of magnitude decrease in running time compared to existing formulations. Our main contribution is a novel and extremely fast technique to obtain, in a few seconds using commodity CPUs, optimal solutions to instances of maximum size SONET rings with any number of wavelengths; such instances cannot be tackled with classical formulations without vast investments in computational resources and time.
An introduction to queueing theory and stochastic teletraffic models. [online]. Available: http://www.ee.unimelb.edu.au/staff/mzu/classnotes.pdf
, 2007
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Research problems in dynamic traffic grooming in optical networks
 In Proc. 1st Int. Workshop on Traffic Grooming
"... Traffic grooming has recently emerged as an important area in wide area wavelengthrouted optical networks research. This research area addresses the problem of multiplexing lower rate traffic demands into wavelength channels of high bandwidth, so as to reduce network equipment cost by maximizing ..."
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Cited by 10 (1 self)
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Traffic grooming has recently emerged as an important area in wide area wavelengthrouted optical networks research. This research area addresses the problem of multiplexing lower rate traffic demands into wavelength channels of high bandwidth, so as to reduce network equipment cost by maximizing the optical (wavelength) routing and minimizing electronic routing. Recently, there have been efforts to extend studies of this kind to cases of dynamic traffic. However, this area is still comparatively new, and most of the proposed approaches ignore the optical routing maximization aspect in favor of simply considering blocking probability. In this position paper, we describe a range of problems that we consider appropriate for consideration under the umbrella of dynamic grooming, and show what the various dimensions are along which various flavors of this class of problems may be found. We provide some sample formulations describing some of these problems precisely. 1