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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.
Improved approaches for costeffective traffic grooming in WDM ring networks: ILP formulations and singlehop and multihop connections
 JOURNAL OF LIGHTWAVE TECHNOLOGY
, 2001
"... Abstract—Traffic grooming is the term used to describe how different traffic streams are packed into higher speed streams. In a synchronous optical network–wavelength division multiplexing (SONET–WDM) ring network, each wavelength can carry several lowerrate traffic streams in time division (TDM) f ..."
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Cited by 56 (6 self)
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Abstract—Traffic grooming is the term used to describe how different traffic streams are packed into higher speed streams. In a synchronous optical network–wavelength division multiplexing (SONET–WDM) ring network, each wavelength can carry several lowerrate traffic streams in time division (TDM) fashion. The traffic demand, which is an integer multiple of the timeslot capacity, between any two nodes is established on several TDM virtual connections. A virtual connection needs to be added and dropped only at the two end nodes of the connection; as a result, the electronic add–drop multiplexers (ADMs) at intermediate nodes (if there are any) will electronically bypass this timeslot. Instead of having an ADM on every wavelength at every node, it may be possible to have some nodes on some wavelength where no add–drop is needed on any timeslot; thus, the total number of ADMs in the network (and, hence, the network cost) can be
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.
Dynamic Traffic Grooming in WDM Mesh Networks Using a Novel Graph Model
"... As our fiberoptic backbone networks migrate from interconnected SONET rings to arbitrary mesh topology, traffic grooming on WDM mesh networks becomes an extremely important research problem. (Traffic grooming refers to the problem of efficiently packing a set of lowspeed connection requests onto h ..."
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Cited by 39 (3 self)
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As our fiberoptic backbone networks migrate from interconnected SONET rings to arbitrary mesh topology, traffic grooming on WDM mesh networks becomes an extremely important research problem. (Traffic grooming refers to the problem of efficiently packing a set of lowspeed connection requests onto highcapacity channels.) To address this problem, we employ a new, generic graph model for dynamic traffic grooming in WDM mesh networks, where connections arrive one at a time and hold for random time durations. The novelty of this model is that, by only manipulating the edges of an auxiliary graph created by the model and the weights of these edges, the 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 a dynamic trafficgrooming algorithm which employs the simple shortestpath computation method to solve the trafficgrooming problem. Different grooming policies can be implemented by different weight functions assigned to the edges in the auxiliary graph. We propose four fixed grooming policies, whose performance is compared in various network scenarios. We also develop an Adaptive Grooming Policy (AGP), in which the weights of the edges are dynamically adjusted according to the current network state, and our results show that it outperforms the fixed grooming policies.
Traffic Grooming in Unidirectional WDM Ring Networks Using Design Theory
 IN IEEE ICC
, 2003
"... We address the problem of traffic grooming in WDM rings with alltoall uniform unitary traffic. We want to minimize the total number of SONET adddrop multiplexers (ADMs) required. We show that this problem corresponds to a partition of the edges of the complete graph into subgraphs, where each s ..."
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Cited by 35 (9 self)
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We address the problem of traffic grooming in WDM rings with alltoall uniform unitary traffic. We want to minimize the total number of SONET adddrop multiplexers (ADMs) required. We show that this problem corresponds to a partition of the edges of the complete graph into subgraphs, where each subgraph has at most C edges (where C is the grooming ratio) and where the total number of vertices has to be minimized. Using tools of graph and design theory, we optimally solve the problem for practical values and infinite congruence classes of values for a given C, and thus improve and unify all the preceding results. We disprove a conjecture of [7] saying that the minimum number of ADMs cannot be achieved with the minimum number of wavelengths, and also another conjecture of [17].
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.
Metropolitan Area PacketSwitched WDM Networks: A Survey on Ring Systems
, 2004
"... We provide a comprehensive survey of packetswitched ring metro WDM networks. ..."
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Cited by 19 (6 self)
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We provide a comprehensive survey of packetswitched ring metro WDM networks.
Traffic Grooming on the Path
"... In a WDM network, routing a request consists in assigning it a route in the physical network and a wavelength. If each request uses at most 1/C of the bandwidth of the wavelength, we will say that the grooming factor is C. That means that on a given edge of the network we can groom (group) at most C ..."
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Cited by 14 (6 self)
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In a WDM network, routing a request consists in assigning it a route in the physical network and a wavelength. If each request uses at most 1/C of the bandwidth of the wavelength, we will say that the grooming factor is C. That means that on a given edge of the network we can groom (group) at most C requests on the same wavelength. With this constraint the objective can be either to minimize the number of wavelengths (related to the transmission cost) or minimize the number of Add Drop Multiplexers (shortly ADM) used in the network (related to the cost of the nodes). We consider here the case where the network is a path on N nodes, PN. Thus the routing is unique. For a given grooming factor C minimizing the number of wavelengths is an easy problem, well known and related to the load problem. But minimizing the number of ADM’s is NPcomplete for a general set of requests and no results are known. Here we show how to model the problem as a graph partition problem and using tools of design theory we completely solve the case where C = 2 and where we have a static uniform alltoall traffic (one request for each pair of vertices).
Hardness and approximation of traffic grooming
 IN THE 18TH INTERNATIONAL SYMPOSIUM ON ALGORITHMS AND COMPUTATION (ISAAC 2007
, 2007
"... Traffic grooming is a central problem in optical networks. It refers to pack low rate signals into higher speed streams, in order to improve bandwidth utilization and reduce network cost. In WDM networks, the most accepted criterion is to minimize the number of electronic terminations, namely the n ..."
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Cited by 12 (1 self)
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Traffic grooming is a central problem in optical networks. It refers to pack low rate signals into higher speed streams, in order to improve bandwidth utilization and reduce network cost. In WDM networks, the most accepted criterion is to minimize the number of electronic terminations, namely the number of SONET AddDrop Multiplexers (ADMs). In this article we focus on ring and path topologies. On the one hand, we provide the first inapproximability result for Traffic Grooming for fixed values of the grooming factor g, answering affirmatively the conjecture of Chow and Lin (Networks, 44:194202, 2004). More precisely, we prove that Ring Traffic Grooming for fixed g ≥ 1 and Path Traffic Grooming for fixed g ≥ 2 are APXcomplete. That is, they do not accept a PTAS unless P = NP. Both results rely on the fact that finding the maximum number of edgedisjoint triangles in a graph (and more generally cycles of length 2g + 1 in a graph of girth 2g + 1) is APXcomplete. On the other hand
Design of a MetaMesh of Chain Subnetworks: Enhancing the Attractiveness of MeshRestorable WDM Networking on Low Connectivity Graphs
 IEEE Journal On Selected Areas In Communications
, 2002
"... Abstract—We have developed a design refinement to increase the capacity efficiency of spanrestorable mesh networks on sparse facility graphs. The new approach views the network as a “metamesh of chain subnetworks. ” This makes the prospect of WDM mesh networking more economically viable than with ..."
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Cited by 10 (3 self)
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Abstract—We have developed a design refinement to increase the capacity efficiency of spanrestorable mesh networks on sparse facility graphs. The new approach views the network as a “metamesh of chain subnetworks. ” This makes the prospect of WDM mesh networking more economically viable than with previous meshbased designs where the average nodal degree is low. The metamesh graph is a homeomorphism of the complete network in which edges are either direct spans or chains of degree2 nodes. The main advantage is that loopbacktype spare capacity is provided only for the working demands that originate or terminate in a chain and not for the entire flow that crosses a chain. The transiting (“express”) flows are entirely meshprotected within the metamesh graph which is of higher average degree and hence efficiency for mesh restoration than the network as a whole. Nodal equipment savings also arise from the grooming of express lightpaths onto the logical chainbypass span. Only the metamesh nodes need optical crossconnect functionality. Other sites use OADMs and/or glassthroughs. The resultant designs comprise a special class of restorable network that is intermediate between pure span restoration and path restoration. Most of the efficiency of path restoration is achieved, but with a span restoration mechanism which is more localized and potentially faster and simpler than path restoration. The concept lends itself to implementation with OADMs having a passive waveband passthrough feature to support the logical chain bypass spans for express lightpaths. Index Terms—Logical topology design, network architecture, network management, network planning and optimization, protection and restoration, reconfiguration, transport networks. I.