WDM Mesh Networks Research Articles

Physical layer impairment-aware shared path protection in wavelength-routed optical networks

In this paper, physical layer impairment (PLI)-aware shared path protection (SPP) scheme for single-link failures in transparent optical WDM mesh networks is considered. We propose PLI-aware integer linear programming (ILP) and heuristic algorithm for both SPP and dedicated-path protection (DPP) schemes. The objectives are to maximize the network resource utilization and minimize the quality of transmission (QoT) blocking probability, restoration time, and computational time. Both the ILP and the heuristic algorithm are evaluated, and their performance is compared. The heuristic algorithm is evaluated with extensive simulations over different network topologies. The solution obtained from the PLI-unaware SPP and DPP serves as the base line to evaluate the performance of our heuristic algorithm. The simulation result shows that the proposed algorithm is efficient and improves the QoT-blocking probability significantly. It achieves $$100\%$$ restorability and improves the network utilization up to $$73\%$$ . The result also shows an improvement in computational time.

A novel auxiliary graph model for effective dynamic traffic grooming in light-trail optical WDM mesh networks

A light trail is a unidirectional bus from a convener node to an end node. The main advantage of a light trail over a light path is that the communication channel of a light trail can be accessed by intermediate nodes providing more flexibility for traffic grooming. Several auxiliary graph models have been developed in the literature for traffic grooming in light-trail optical WDM mesh networks. These auxiliary graph models have one or more drawbacks that do not fully reflect the characteristics of a light trail. This paper develops a novel auxiliary graph model that has none of the drawbacks and is able to reflect all characteristics of a light trail. Based on the auxiliary graph model, two effective dynamic traffic grooming algorithms are proposed. The proposed dynamic traffic grooming algorithms are shown to yield low request blocking ratio.

Wavelength Assignment Vs. Wavelength Converter Placement in Wavelength-Routed Optical WDM Networks

In this paper, we deal with the wavelength assignment and the converter placement problem in wavelength-routed optical WDM Mesh networks. Our objective is to try to assign wavelengths in an efficient manner with/without wavelength conversion to get a very low blocking probability and optimize the performance of the overall network. Thus, we implement and compare the performance of two proposed algorithms namely DWA “Dynamic Wavelength Assignment” and SWA “Static Wavelength Assignment” with well-known algorithms. We first present a literature review about previously proposed approaches, and then we introduce and evaluate our implemented approaches. We also discuss the wavelength converter placement problem in mesh networks. We finally corroborate our theoretical findings through extensive simulations.

Quasi-Passive Reconfigurable Node for 5G Mobile Optical Backhaul Networks

A novel multi-dimensional quasi-passive reconfigurable (MD-QPAR) node for 5G mobile backhaul optical WDM mesh networks is proposed in this paper. The proposed MD-QPAR is capable of providing dynamic power and wavelength allocations for signals from any input port(s) to any output port(s). Each input/output port is connected to one possible direction or the local wireless nodes, and hence, the data rate, flexibility, robustness, and reliability requirements in 5G backhaul networks can be satisfied. In addition, the MD-QPAR is “quasi-passive,” where it only consumes power during network reconfigurations and there is no power consumption during steady-state operations, to enable high energy efficiency. Three possible MD-QPAR structures are proposed and studied. Simulations under the optical Flow traffic assumption are carried out and the signal blocking probability and the scalability are investigated. Proof-of-concept experiments are also undertaken and the MD-QPAR with Structure II is demonstrated. Results show that dynamic power and wavelength distributions from any input port(s) to any output port(s) can be realized, and the power penalty due to the MD-QPAR is limited to <0.5 dB.

An offline scheme for reducing cost of protection in all-optical WDM mesh networks with fast recovery

ABSTRACTIn Optical WDM networks, a single fiber carries enormous amount of data and consequently designing schemes to prevent the user traffic from disruption and techniques to recover from failures still remains an important area of research. In this paper we address the problem of protecting all-optical WDM mesh networks from single link failure. We propose an offline protection scheme that is not only cost-efficient in terms of network resource consumption but can also provide quick recovery from a link failure. In our scheme, backup paths are combined to reduce cost of protection and to facilitate fast recovery from a failure. We address a critical issue related to selection of backup paths to be combined, which was not addressed earlier. Instead of choosing backup paths for connection requests arbitrary as done in an existing scheme, our scheme is designed to select backup paths in a way that they are suitable for combination and can maximize resource saving as well. We first provide an Integer Linear Program for the problem, and then propose a heuristic eStreams that can provide near optimal solution in polynomial time. Performance comparisons with some well-known schemes show that our protection scheme is definitely an improvement in terms resource conservation while ensuring fast recovery from a link failure.The figure shows how a primary (working) path is protected with the help of a link-disjoint backup path in WDM optical networks. A primary path is used to carry traffic under normal fault free condition. In the event of a link fault (fiber-cut) the traffic is switched over to the backup path.

An online cost-efficient protection scheme for quick recovery in all-optical WDM mesh networks

Since a single fiber carries a huge amount of data in optical WDM networks, a fiber cut even for a brief period is a very serious event. Designing schemes to prevent disruption of user traffic and recovery techniques from failures is thus an important area of research. Since a single fiber cut is the most common type of fault, in this paper we address the problem of protecting all-optical WDM mesh networks from single link failure. Our proposed online protection scheme is an improvement over an existing approach and is not only cost-efficient in terms of network resource consumption but can also provide quick recovery from a link failure. We first provide an ILP formulation for the problem and then propose a heuristic solution iStreams that can provide near-optimal solution in polynomial time. Performance comparisons with some well-known schemes of protection show that our heuristic algorithm can be a better choice for conserving resource while providing quick recovery from a link failure.

Energy-efficient virtual topology design in IP over WDM mesh networks

Energy efficiency has been well recognized as an important objective in design of IP over WDM mesh networks. While previous works always focus on energy minimization through green routing and resource provisioning, the comprehensive performances of the two-layer network cannot be guaranteed. This would be not good for realization of energy-efficient networking methods.In this paper, we first study the problem of getting a good tradeoff between the three-part network comprehensive performances: energy efficiency, resource efficiency and cross-layer survivability efficiency for IP over WDM mesh networks under the static traffic demand. We present the virtual-link energy model for two-layer networks. The energy model is computed from the power consumption value of commercial network devices. Based on the energy-aware two-layer auxiliary graph, we propose a new Energy-Efficient Virtual Topology Design (E2VTD) scheme. The novelty of our proposed E2VTD scheme is mainly twofold as following: the first is the energy-efficient virtual link direct mapping and rerouting and the second is the cross-layer survivability improvement for energy-efficient virtual topology. We use extensive simulations to demonstrate the efficiency of our proposed E2VTD scheme. It is shown that the network comprehensive performances are significantly improved for two-layer networks. Compared with the previous algorithms, network energy consumption is reduced by about 39.8%, network resource is reduced by about 28.2%, and cross-layer topology survivability can be enhanced by about 35.7% in average.

Numerical analysis on delay time and wavelength increase of inverse multiplexing using parallel routes in upgrade scenario of optical path networks

Optical inverse multiplexing is a promising technology for high-rate data transmission and rapidly increased demand for capacity. To realize this technology, a key issue is the buffering to alleviate the delay among parallel routes. As described in this paper, delay time characteristics and wavelength increase of optical inverse multiplexing using optical parallel routes in WDM mesh networks are evaluated quantitatively for rapid capacity demand, comparison with the case of whether the existing route is still used or not.

Resource efficient multicast traffic grooming in WDM mesh networks

In this paper, we have considered an optimal design and provisioning of WDM networks for the grooming of sub-wavelengths traffic requests. As higher layer electronic ports, such as transceivers and optical splitters are dominant cost factors of an optical network, it is essential to reduce their numbers of use while grooming the multicast traffic requests into high bandwidth light-trees. This paper provides an optimal cost design of WDM networks with multicast traffic grooming under static traffic demand. We develop a unified framework for the optimal provisioning of different practical scenarios of multicast traffic grooming in a static traffic scenario. In this study, we design an Integer linear Programming (ILP) formulation for multicast traffic grooming to minimize the cost associated with the higher layer electronic ports such as transceivers, splitters and wavelengths, and simultaneously maximize the bandwidth utilization of the network. We propose a heuristic algorithm called Efficient Light-Tree based Multicast Traffic Grooming (ELT-MTG) algorithm to achieve scalability in large size optical networks. Simulations are conducted on several standard well-known WDM mesh networks to study the design cost (based on number of transceivers, optical splitters and wavelengths) used in the networks. The result, thus obtained by comparison, helped us to conclude that the proposed approach ELT-MTG gives better performance than well-known existing logical-first sequential routing with single-hop grooming (LFSEQSH) and logical-first sequential routing with multi-hop grooming (LFSEQMH) algorithms in a static traffic environment.

Fault Tolerant System for Sparse Traffic Grooming in Optical WDM Mesh Networks Using Combiner Queue

Queuing theory is an important concept in current internet technology. As the requirement of bandwidth goes on increasing it is necessary to use optical communication for transfer of data. Optical communication at backbone network requires various devices for traffic grooming. The cost of these devices is very high which leads to increase in the cost of network. One of the solutions to this problem is to have sparse traffic grooming in optical WDM mesh network. Sparse traffic grooming allows only few nodes in the network as grooming node (G-node). These G-nodes has the grooming capability and other nodes are simple nodes where traffic grooming is not possible. The grooming nodes are the special nodes which has high cost. The possibility of faults at such a node, or link failure is high. Resolving such faults and providing efficient network is very important. So we have importance of such survivable sparse traffic grooming network. Queuing theory helps to improve the result of network and groom the traffic in the network. The paper focuses on the improvement in performance of the backbone network and reduction in blocking probability. To achieve the goals of the work we have simulated the model. The main contribution is to use survivability on the sparse grooming network and use of combiner queues at each node. It has observed that Combiner queuing alone does the job of minimizing blocking probability and balancing the load over the network. The model is not only cost effective but also increases the performance of network and minimizes the call blocking probability

Optimal nonuniform wavebanding in WDM mesh networks

Grouping together a set of consecutive wavelengths in a WDM network and switching them together as a single waveband could achieve savings in switching costs of an optical cross-connect. This technique is known as waveband switching. While previous work has focused on either uniform band sizes or nonuniform band sizes considering a single node or ring networks, in this paper we focus on optimizing the number of wavebands and their sizes for mesh topologies. We formulate a problem of optimizing the number of wavebands in a mesh network for a given set of lightpaths. The objective of the band minimization problem is to minimize the number of nonuniform wavebands in the network while satisfying the traffic requests. We formulate an integer linear program and propose efficient heuristics. Simulation results are presented to demonstrate the effectiveness of the proposed approaches under static traffic case. Our results show that the number of switching elements can be reduced by a large amount using waveband switching compared to wavelength switching. We also apply the proposed waveband strategy to the dynamic stochastic traffic case and evaluate the network performance in terms of blocking probability through numerical simulations.

Design of efficient node p-cycles in WDM mesh networks

p-cycles have been extensively studied under a single link failure scenario. Even though not as common, single node failures may occur as well, and the resulting consequences can be devastating. Failure-Independent Path-Protecting (FIPP) p-cycles provide end-to-end path protection, and thereby protection against node failures, assuming that precautions are taken.In this paper, we propose enhanced p-cycles, called node p-cycles, different from the FIPP p-cycle scheme, which can guarantee 100% protection against any single node failure. We design a scalable optimization model, which relies on a column generation formulation, in order to design the enhanced node p-cycles.Extensive comparative experiments have been conducted after designing a column generation framework for all compared protection schemes, in order to guarantee scalable models for each of them. Experiments include the (link) p-cycles, the node p-cycles of Onguetou and Grover (2009) [16], our enhanced node p-cycles and the FIPP p-cycles. We show that node p-cycles offering node and link protection only require slightly more spare capacity than link p-cycles, while requiring sometimes less, sometimes more spare capacity than FIPP p-cycles. For the comparison with the work of Grover and Onguetou (2009) [2], results show that our new node p-cycle scheme clearly outperforms their design in terms of capacity efficiency.

Multicast protection and grooming scheme in survivable WDM optical networks

Network survivability is an important factor in the design of WDM optical networks. In dynamic provisioning context, a typical connection request may require bandwidth less than a wavelength channel capacity and it may also require protection from network failure, typically fiber cuts. In this paper, we investigate the multicast traffic protection with grooming in WDM mesh network under single link failure and propose a novel multicast protection algorithm called shared segment protection with grooming (SSPG) that constructs the primary or working light-tree and corresponding link disjoint backup light-tree for each dynamic multicast connection request. In this approach, a backup segment can efficiently share the wavelength channel capacity of its working segments and simultaneously use the common network resources at the backup light-tree. In order to efficiently utilize the network resources (such as wavelength, transceivers, optical splitters and wavelength channels), the sub-wavelength demands are groomed to protect multicast requests against single link failure. The main objective of this work is to minimize the blocking probability of client calls or bandwidth blocking probability of a dynamically changing multicast request of WDM optical networks and efficiently utilize the network resources, respectively. The performances of various algorithms are evaluated based on extensive simulations to study dynamic provisioning of survivable multicast sessions in standard WDM mesh networks. The simulation results reveal that the proposed SSPG produces better performance in terms of blocking probability (in terms of requests), bandwidth blocking probability (in terms of bandwidth capacity), wavelength channel utilization and cost which is associated with the network resources such as transceivers, splitters and wavelengths than existing standard link shared protection with grooming (LSPG) and path-pair shared protection with grooming (PSPG) algorithms.

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.

Green IP over WDM mesh networks with connection availability guarantee

Energy efficiency has been well recognized as an important objective in IP over WDM mesh networks. In this paper, we study the problem of green IP over WDM mesh networks with connection availability guarantee under static traffic demands. We first present a virtual link power model for the two-layer networks, which is built on the power consumption value of the commercial network devices. Based on the energy-aware two-layer auxiliary graph, we propose a new heuristic algorithm named Availability-Guaranteed Energy-Efficient Design for Two-Layer Optical Networks (AGED_TON). The AGED_TON algorithm first constructs initial energy-efficient virtual topology on which connection requests are carried, and then routes working path and backup path of lightpaths on physical topology. In the procedure of AGED_TON algorithm, connection availability is considered for path calculating to achieve a good tradeoff between connection availability and energy efficiency. Compared with previous green networking algorithms, our proposed AGED_TON algorithm reduces energy consumption significantly and guarantees connection availability at the satisfactory level.

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.

Splitting minimization: a novel approach for multicasting in WDM mesh networks

Multicast routing and wavelength assignment is an important problem in optical fiber networks where dedicated connections are required to be established between a source and multiple number of destinations. To establish such a multicast session, some of the nodes in the network should be capable of splitting an incoming message, in the form of light signal, into multiple outgoing signals. These nodes, also known as multicast capable (MC) nodes, are very costly due to the requirement of signal amplification and difficulty in fabrication. In this paper, we study routing and wavelength assignment problem for multicast communication in WDM mesh network to minimize splitting requirement as well as the delay in communication, which is a major QoS parameter in one-to-many data communication. As the objectives show an opposing behavior, a tread-off solution is often required. Here we have proposed a heuristic based algorithm, which gives an efficient trade-off solution for the problem. On comparison under different network topologies, the proposed algorithm is found to be more efficient than the existing algorithms.

WDM Mesh 네트워크에서 SLA 복구시간을 만족시키는 보호기법

WDM 광 전달망에서 기존의 보호방식은 SLA에 명시된 복구 시간에 대한 고려 없이 모든 연결 요청에 대해 한 쌍의 경로를 설정함으로써, 네트워크 자원의 이용 효율이 감소하고 SLA 위반율이 높아진다. 이를 해결하기 위해 본 논문에서는 예상 보호시간과 SLA에 명시된 복구시간을 비교하여 연결요청을 분류하고, 각 연결 요청 분류에 따른 최적의 망 보호방식 및 백업경로를 설정하는 보호기법을 제안한다. 제안 기법을 실험 망에 적용하여 기존 보호기법보다 높은 자원 효율성 및 낮은 SLA 위반율을 보임을 입증한다. In this paper, we proposed a new protection scheme of the WDM mesh networks that can utilize the network resources efficiently while satisfying with the recovery time defined in the SLA (service level agreement). The protection scheme and the backup path are selected based on the comparison of the expected protection time with the SLA recovery time. The superior performance of the proposed protection scheme was demonstrated by comparing with ones of the existing protection schemes.

A Novel Efficient Design of Survivable WDM Mesh Networks

The design of survivable WDM mesh networksbased on p-cycles has been extensively studied. However,most of studies only deal with a single link failure ratherthan node failure. In this paper, we develop a new scalableand efficient design method for computing node-protectingp-cycles in order to ensure network survivability. Theperformance of our new proposed design method makes anobvious improvement 20% in capacity redundancy overthat of the previous one.The conventional design methods formulate the problemof p-cycle design as an Integer Linear Program (ILP). Tosolve the ILP, the prerequisite is to a priori enumeratedall possible p-cycle candidates. For a large network, theresulting ILP may be intractable as the huge number ofcycles may exist. We propose a new design and solutionmethod based on large scale optimization tools, namelyColumn Generation (CG), where p-cycle candidates aregenerated on-line when needed. The main advantage of ourCG-based method is that no p-cycles are a-priori off-lineenumerated; the generation of the promising set of p-cyclesis embedded in the optimization process.Extensive experiments have been conducted for comparison.Experimental results show that our new proposedmethod outperforms the previous method in terms of capacityefficiency.