Grooming Problem Research Articles

Dynamic multi-hop multipath RMSA and traffic grooming in OFDM-based sliceable elastic optical networks

In elastic optical networks (EON), routing, modulation selection, and spectrum assignment (RMSA) is crucial in provisioning connection requests. Multipath RMSA offers a number of benefits including provisioning of ultra-high bandwidth demands and better utilization of fragmented spectrum resource. By Combining with traffic grooming, multipath RMSA and traffic grooming is able to provide better utilization of network resource in provisioning connection requests. Adding multi-hop routing mechanism to multipath RMSA and traffic grooming increases the flexibility for selecting paths resulting in higher probability of successfully finding routing paths for connection requests. Dynamic multipath RMSA problem in EON has been investigated extensively in the literature. Dynamic multi-hop multipath RMSA and traffic grooming problem in EON is far from been well studied. This paper proposes an algorithm for the dynamic multi-hop multipath RMSA and traffic grooming problem in OFDM-based elastic optical networks with sliceable bandwidth-variable transponders. Performance of the proposed algorithm is studied via simulation. Our simulation results show that the proposed algorithm yields lower bandwidth blocking ratio than an existing algorithm.

Provision of Energy- and Wavelength-Efficient Traffic Grooming for Sparse WDM-Enabled Distributed Satellite Cluster Networks

Sparse wavelength division multiplex (WDM) enabled distributed satellite cluster networks (DSCNs) have emerged as a promising architecture to accommodate future extensive applications. Networking of the DSCNs will face the challenges of explosively increasing traffic requests, the limited number of wavelengths, and restricted energy provisioning. To address these issues, a novel approach, the two-phase traffic grooming based on the matching algorithm (TPTG_MA), is proposed in this paper. To analyze resource utilization, energy- and wavelength- minimized models are established. After that, we develop the MA to tackle the traffic grooming problem in two phases, including the first phase for traffic aggregation and sub-wavelength assignment (TAASA) and the second phase for sub-wavelength grooming (SG). To evaluate the performance of the proposed TPTG_MA, the direct lightpath grooming (DLG) heuristic and the genetic algorithm (GA) are simulated for comparison. The results demonstrate that the TPTG_MA and DLG_GA outperform TPTG and DLG in the average wavelength utilization ratio (AWUR), the energy consumption saving (ESC), and the blocking probability. Compared with the DLG_GA, the TPTG_MA achieves at most 18% and 23% higher AWUR in the 12-node and 22-node topologies, respectively. In addition, the TPTG_MA can actualize at most 10% ECS improvement over the DLG_GA. At last, the influence of the network size, the number of wavelengths, and the number of hops are discussed.

The Traffic Grooming Problem in Optical Networks with Respect to ADMs and OADMs: Complexity and Approximation

All-optical networks transmit messages along lightpaths in which the signal is transmitted using the same wavelength in all the relevant links. We consider the problem of switching cost minimization in these networks. Specifically, the input to the problem under consideration is an optical network modeled by a graph G, a set of lightpaths modeled by paths on G, and an integer g termed the grooming factor. One has to assign a wavelength (modeled by a color) to every lightpath, so that every edge of the graph is used by at most g paths of the same color. A lightpath operating at some wavelength λ uses one Add/Drop multiplexer (ADM) at both endpoints and one Optical Add/Drop multiplexer (OADM) at every intermediate node, all operating at a wavelength of λ. Two lightpaths, both operating at the same wavelength λ, share the ADMs and OADMs in their common nodes. Therefore, the total switching cost due to the usage of ADMs and OADMs depends on the wavelength assignment. We consider networks of ring and path topology and a cost function that is a convex combination α·|OADMs|+(1−α)|ADMs| of the number of ADMs and the number of OADMs deployed in the network. We showed that the problem of minimizing this cost function is NP-complete for every convex combination, even in a path topology network with g=2. On the positive side, we present a polynomial-time approximation algorithm for the problem.

Virtualization of elastic optical networks and regenerators with traffic grooming

An elastic optical network (EON) plays an important role in transport technology for virtualization of networks. A key aspect of EONs is to establish lightpaths (virtual links) with exactly the amount of spectrum that is needed and with the possibility of grooming, the process of grouping many small traffic flows into larger units, creating a super-lightpath. Grooming eliminates the need for many guard bands between lightpaths and also saves transceivers; however, it often leads to the need to perform optical–electrical–optical conversions to multiple-data-rate optical signals at intermediate nodes. The aim of this paper is to provide a mixed-integer linear programming (MILP) formulation, as well as heuristic and meta-heuristic approaches, for the design of multiple virtual optical networks (VONs) in an elastic optical substrate network with bandwidth-variable lightpaths, modulation format constraints, and virtual elastic regenerator placement. Traffic grooming is allowed inside each VON, and a distance-adaptive modulation format technique is employed to guarantee efficiency in terms of bandwidth for a physical substrate, subject to several virtual topologies. A reduced MILP formulation without grooming capability is also proposed for comparison. The complete MILP formulation jointly solves the virtual topology design, regenerator placement, and grooming problems, as well as the routing, modulation, and spectrum assignment (RMSA) problem. The reduced MILP formulation, heuristics, and meta-heuristic, on the other hand, separate the virtual topology design problem from the RMSA problem. It is shown that the grooming approach can provide good results, since it solves the problem for a complete design when compared to the approach without grooming. Furthermore, heuristic solutions for large networks are proposed, which present good performance (in terms of saving spectrum) for the design with large instances.

A metaheuristic approach for source traffic grooming in elastic optical networks

AbstractThe increasing demands for higher spectrum efficiency have made elastic optical networks (EON) to be an interesting area for the research community. The possibility that some network parameters are changed according to different types of services allows that optical paths can be established using just enough spectrum as needed. Since individual optical paths have to be separated by guard bands, a large part of the available spectrum is wasted. The efficient utilization of available network capacity is among network operators' major concerns and therefore, traffic engineering techniques that provide additional capacity on the existing infrastructure are of the interest. As such, the traffic grooming technique has been analyzed in this article. By applying the grooming technique, the basic problem in EONs, namely routing and spectrum allocation is extended and made more complex, especially in the case of realistic networks. Compared to electrical traffic grooming applied in traditional wavelength division multiplexing networks, traffic grooming directly at the optical layer is an attractive option for EON because it provides the opportunity to groom several same source connections into one transmitter and in such a way eliminating the guard bands. In this article, we solve the grooming problem in EON with static traffic demands using the bee colony optimization metaheuristic approach. The objective is to serve all traffic demands such that spectrum savings are maximized and total spectrum usage is minimized. The results indicate considerable spectrum savings compared to the scenario without grooming and a significant improvement considering some referenced grooming algorithms.

Efficient Integration of Logical Topology Design and Survivable Traffic Grooming for Throughput Enhancement in WDM Optical Networks

Optical networks that employ traffic grooming, merge several low-speed traffic streams onto a high-speed lightpath. A fiber cut (or a link failure) in such networks can disrupt a large number of lightpaths and can cause a huge amount of data loss. Designing survivability schemes to make the network withstand a link failure is thus vital. In this paper we address the problem of survivable traffic grooming in a static scenario. In a static scenario the primary objective is to maximize throughput with the available network resources. Since the problem is NP-Complete, we propose an efficient heuristic TATG (Throughput Aware Traffic Grooming) for the problem. TATG employs an efficient approach of integrating logical topology design and survivable traffic grooming with heuristics at sub-problem level. Our approach ensures that the logical topology carrying the traffic always stay connected in the event of a link failure. Time complexity analysis shows that our heuristic runs in polynomial time. We study two separate forms of survivability in heuristics TATG-SC (TATG -Survivability at Connection) and TATG-SL (TATG-Survivability at Lightpath) with three categories of traffic demand. Performance comparison with a well known heuristic shows that the proposed approach provides much better throughput performance when resources are scarce. The average percentage decrease in request blocking over all experiments obtained using TATG-SC and TATG-SL is 54.87% and 59.57% respectively.

Dynamic multicast traffic grooming in light-trail WDM optical mesh networks

A light trail in a WDM optical network is an optical communication channel that allows intermediate nodes to access the channel providing the flexibility for multiplexing traffic of multiple connections into the optical communication channel at intermediate nodes. The technique of multiplexing traffic of multiple connections into a single communication channel is known as traffic grooming. This paper studies the problem of dynamic multicast traffic grooming that deals with dynamically arriving and departing multicast connections in light-trail WDM optical networks. Our objective is to reduce blocking ratio. This paper proposes an auxiliary graph model for light-trail WDM optical networks that can be used for routing and traffic grooming purposes. Based on the auxiliary graph model, two dynamic multicast traffic grooming algorithms are studied. Compared with existing algorithms in the literature, the two algorithms yield significantly better performance.

Waiting Probability Based Traffic Grooming In Optical Networks

In this paper, we have proposed an efficient traffic grooming model for optical networks. This model has low complexity and it can be easily implemented for traffic grooming problems. It is used to calculate the waiting probability of computer networks and then traffic grooming problems are addressed based on the calculated waiting probability. Waiting probability is always a major parameter during the analysis of network performance because it provides an estimate for the waiting of calls in the transmission route. This model can also be used to calculate some other key network parameters such as number of server required, ideal route length, number of free wavelengths required etc. based on a fixed value of waiting probability. This model can be applied on different network topologies for traffic grooming with equal efficiency.

Grooming Telecommunications Network: Optimization Replicas and Techniques

The rapid expansion of the use of internet in the last decade has been made feasible largely by optical networks with high bandwidth and consistency. This paper explores the meaning of grooming, the methodological context in which it can be applied. An innovative nomenclature incarcerates useful aspects of grooming problems and is used to review publications on traffic-engineering and optimization problem class. The paper proposed an efficient traffic grooming model for all optical networks. The model has low complexity and it can be easily implemented for traffic grooming problems.

A matheuristic for a telecommunication network design problem with traffic grooming

This paper addresses a network design and traffic grooming problem arising in optical telecommunication networks that are based on wavelength division multiplexing. Given a set of nodes and a set of traffic demands between these nodes, the network design and traffic grooming problem (NDGP) consists of installing a minimum number of lightpaths between the nodes and of routing the demand on the lightpaths while respecting capacity constraints. We introduce a new mathematical formulation of the NDGP as well as a hybrid algorithm capable of finding high quality solutions in short computing times. The proposed algorithm uses linear and mixed integer programming as slave methods and embeds them within a tabu search procedure. Computational results and comparisons with an existing method from the literature show the effectiveness of the proposed algorithm. Further analyses also show the efficiency of the neighborhood structure and of its evaluation technique.

GPU Neural Mutli Objective Solver for Optical Burst Grooming

Transparent Optical Networks has been known as a potential solution for high speed flexible optical backbone networks since a long time ago. However, many scientific challenges remain to be overcome such as the problem of Optical Burst Grooming (OBG) with several conflicting objectives and constraints.OBG is a fundamental problem in the engineering, control, and management of optical traffic networks, and arises in most network design applications, including optical burst routing, survivability design, and traffic scheduling. The traffic grooming problem is to coalesce several high and low speed sub bursts close in time together to form a larger burst that will be switched as one unit.In this paper, we first formulate OBG as a Multi Objective Integer Linear Programming (MO-ILP) optimization problem. Then we propose to use a parallel and hierarchical solver based on Artificial Neural Networks (ANN) with Graphics Processing Unit (GPU) parallel implementation using Compute Unified Device Architecture (CUDA). The processing time remains fixed regardless of the input size and the number of optical constraints and conflicting objectives.Our OBG solver benefits of the joint use of advanced ILP-MO optimization methods, ANN large-scale inherent parallelism and CUDA-GPU High-Performance Computing (HPC) architecture. Through a comprehensive simulation study, we show that, our proposed grooming approach can significantly improve the optical traffic performance, resulting in less contention and low burst lost probability.

A Cross-layer Traffic Grooming Algorithm in Joint Optimization of the IP over Elastic Optical Network

Abstract To fully utilize the existing optical network resource, the dynamic traffic grooming technology, which could efficiently multiplex many low-speed services arriving dynamically onto high-capacity optical channels, has been studied extensively and used widely. In this article, the problem of dynamic traffic grooming in joint optimization of IP over elastic optical network (EON) is studied. This problem consists of three sub-problems at two layers: the routing problem at the IP-layer (IPR), the routing, modulation level (RML), and the spectrum allocation (SA) problems at the optical layers. We proposed a novel topology-integration and adaptive-modulation based in cross-layer routing spectrum allocation (CL-RSA) algorithm, which follows a multi-cost approach that solves the IPR, the RML, and the SA problems jointly. The most important features of the proposed algorithm are merging physical topology with virtual topology and using the minimum-weight preferred method for route selection. Meanwhile, the effect of physical-layer impairments (PLI) on signal transmission is considered. In addition, the adaptive modulation scheme is used to allocate the spectrum resource. The simulation results show that the algorithm can effectively improve the spectrum resource utilization and reduce the network blocking probability compared to other algorithms in various network conditions, especially in the high load condition effectively.

An auxiliary graph based dynamic traffic grooming algorithm in spatial division multiplexing enabled elastic optical networks with multi-core fibers

Abstract A proper traffic grooming strategy in dynamic optical networks can improve the utilization of bandwidth resources. An auxiliary graph (AG) is designed to solve the traffic grooming problem under a dynamic traffic scenario in spatial division multiplexing enabled elastic optical networks (SDM-EON) with multi-core fibers. Five traffic grooming policies achieved by adjusting the edge weights of an AG are proposed and evaluated through simulation: maximal electrical grooming (MEG), maximal optical grooming (MOG), maximal SDM grooming (MSG), minimize virtual hops (MVH), and minimize physical hops (MPH). Numeric results show that each traffic grooming policy has its own features. Among different traffic grooming policies, an MPH policy can achieve the lowest bandwidth blocking ratio, MEG can save the most transponders, and MSG can obtain the fewest cores for each request.

Hybrid graph-based multicast traffic grooming in metro networks with quality-of-transmission considerations

This paper investigates the problem of multicast traffic grooming in optical networks utilizing a novel grooming approach that is based on the routing/grooming of multicast calls on hybrid graphs (HGs). HGs are constructed dynamically upon the arrival of each multicast call, in such a way that they consist of both the available physical links and the logical links with available capacity. Several schemes were developed for the construction of the HGs, namely the minimum free capacity light-tree first, the maximum free capacity light-tree first, the maximum overlapping light-tree first, the least-used light-tree first, and the most-used light-tree first scheme. Also, a novel hybrid Steiner tree heuristic for routing/grooming on the HGs is presented. The proposed grooming approach exhibits improved performance in terms of blocking probability compared to existing multicast grooming approaches that route/groom multicast calls by considering physical and logical links separately. Furthermore, the physical layer impairments were also considered during the provisioning phase of the newly established light-trees on the HG, in which case the proposed schemes also exhibit improved performance compared to other grooming approaches.

Cost Efficient Grooming Based on p-Cycle Protection in Elastic Optical Networks

The pre-configured protection cycle, known as p-cycle, is an efficient method, which may overcome long restoration time and complicated protection switching procedure comparing with other schemes. Meanwhile, traffic grooming enabled by sliceable transponders can reduce power consumption and obtain higher spectrum efficiency. In this paper, we study survivable grooming problem based on p-cycle protection in Elastic Optical Networks (EONs). We develop a heuristic algorithm called Shared p-Cycle Grooming Protection (SCGP) to get enough protection and less resources consumption. Numerical simulation results show that the proposed SCGP scheme achieves better performances than the traditional p-Cycle Protection (CP) schemes without grooming.

GRASP for traffic grooming and routing with simple path constraints in WDM mesh networks

This paper studies the traffic grooming and routing problem with simple path constraint (denoted as GR) in WDM mesh networks. To the best of our knowledge, the simple path constraint has not been studied in previous literature. However, this non-trivial constraint is essential in practice and it makes the traffic grooming and routing problem become much more challenging due to the introduction of quadratic constraints. By giving the mathematical formulation of the GR problem, we propose a greedy randomized adaptive search procedure (GRASP) for solving the GR problem, and introduce a mechanism to tackle the interaction between the grooming problem and the routing problem. To test the performance of the proposed GRASP algorithm, we apply it to tackle three sets of totally 38 instances generated according to real-world scenarios. Computational results show the efficacy of the GRASP algorithm in terms of both solution quality and search efficiency by comparison with public software LocalSolver and the lower bounds obtained by CPLEX.

Multi-Layer High-Speed Network Design in Mobile Backhaul Using Robust Optimization

The multi-layer network design problem and the mobile backhaul problem are both interesting from the perspective of choosing the correct technology and protocol as well as choosing the appropriate node architecture to meet a wide variety of overlay traffic demands. Network operators encounter two variants of the multi-layer/backhaul problem: 1) For a given set of uncertain traffic demands, which set of technologies would minimize the network cost? 2) Would these technology choices be invariant to the changing traffic demands? This problem of technology choice can essentially be abstracted to a switching and grooming problem with the added complexity of unknown traffic demands, which at best may be approximated to some known statistical parameters. To solve this complex switching and grooming problem, our goal is to make use of the theory of robust optimization with the assumption of known boundary conditions on traffic. We present a comprehensive optimization model that considers technology choices in terms of protocols, physical layer parameters, link boundary conditions, and transmission layer constraints. Validated by simulations, our model shows the stand-off conditions between various technologies and how a network operator must take proactive steps to be able to meet requirements of the next-generation networks and services. Our main result showcases network design using two technology alternatives [1) Multi-Protocol Label Switching (MPLS) + Optical Transport Network (OTN) + Reconfigurable Optical Add–Drop Multiplexer (ROADM) and 2) Carrier Ethernet (CE) + OTN + ROADM] and the effect of robustness on these choices. A heuristic is used for comparative purposes as well as to exhaustively model the dynamic case of brownfield networks.

Modified Multiobjective Metaheuristics for Sparse Traffic Grooming in Optical WDM Mesh Networks

Abstract Now days the number of users that use data networks has increased tremendously and this demand will keep on increasing. This has made an increase of bandwidth necessary. Our current data networks are unable to support this growth, so better solution is to use optical data networks, in which the bandwidth is over 50Tbps. Data network provides also provides a huge bandwidth but the maximum speed for an end user is only a few Gbps which is speed of their devices. So if we use wavelength division multiplexing, maximum bandwidth utilization will be done because of simultaneous transmission of data. Traffic grooming problem is a NP-hard problem, so we need to use metaheuristics. DEPT and MOVNS have been proved to provide most optimal solutions. But these were implemented earlier on full grooming network. This paper proposes variants of DEPT and MOVNS using sparse grooming network which will provide better results in terms of throughput and propagation delay.

Bandwidth-ratio-based light-tree selection in dynamic multicast traffic grooming for optical WDM mesh networks

This paper studies the dynamic multicast traffic grooming problem in optical WDM mesh networks. A key step in dynamic multicast traffic grooming is to select a subset of exiting light-trees to support a new multicast request. A number of selection rules have been used in algorithms proposed in the literature. This paper proposes to use the bandwidth usage per multicast destination called bandwidth ratio as the light-tree selection criterion and to employ a light-tree selection rule that chooses the shortest-path tree branch with the smallest bandwidth ratio. Based on the light-tree selection rule, this paper develops an effective dynamic multicast traffic grooming algorithm. A number of performance measures including request blocking ratio, bandwidth utilization factor, unnecessary bandwidth utilization factor, mean number of light-trees per accepted connection request, and computation time are used to compare the proposed algorithm with other algorithms in the literature that employ various light-tree selection rules. Simulation results show that the proposed algorithm is able to make efficient utilization of the bandwidth resource and yield significantly lower request blocking ratio.

Holding-time-aware dynamic traffic grooming algorithms based on multipath routing for WDM optical networks

This paper investigates approaches for the traffic grooming problem that consider connection holding-times and bandwidth availability. Moreover, solutions can indicate the splitting of connections into two or more sub-streams by multipath routing and fine-tuned by traffic grooming to utilize network resources better. Algorithms are proposed and the results of simulations using a variety of realistic scenarios indicate that the proposed algorithms significantly reduce the blocking of connection requests yet promote a fair distribution of the network resources in relation to the state-of-the-art solutions.