As optical networks are evolving from traditional opaque networks toward future transparent networks, physical impairments from transmission and switching have become the significant transparent reach limitation for signals. To overcome physical impairments, sparsely deploying optical-electrical-optical regenerators in transparent networks is currently the most economic and reliable solution, namely translucent networks. We study the impairment aware protection issues and propose an impairment aware sharing constraint relaxed path protection (ISRPP) scheme for single-link failures in translucent optical networks. By relaxing the traditional sharing constraint in a limited degree, ISRPP effectively enhances the resource utilization on both wavelengths and regenerators, which contributes to improve the performance of connection blocking probability. Simulation results show that ISRPP can obtain notable resource efficiency and achieve satisfactory tradeoff between blocking probability and vulnerability ratio with respect to its counterpart.
We propose a Mixed Sharing Auxiliary Graph (MSAG) for dynamic traffic grooming in heterogeneous WDM mesh
networks. Based on MSAG model, a novel heuristic named BLSW-ILMS (Backup LSP Shared Working Lightpath with
Inter-layer Mixed Sharing) is proposed. Simulation results show that the proposed algorithm can efficiently decrease the
blocking probability.
In this paper, we focus on the survivable traffic grooming problem under SRLG (Shared Risk Link Groups)
constraints in WDM mesh networks. Our objective is to minimize the total network resource for a given traffic
demands metric. An efficient simplified ILP (Integer Linear Programming) mathematical formulation is presented.
Considering the computational complexity of ILP, a fast heuristic algorithm named Cross Layer Information
Routing & Multi-Layer Traffic Grooming (CLIR-MLTG) is proposed and evaluated. We compare our simplified
ILP model with the regular ILP model, and the CLIR-MLTG algorithm is also compared both with our simplified
model and a heuristic algorithm named SSR in the literature [1]. Finally, we demonstrate in numerical results that our
simplified ILP model obtains optimal performance and costs much less time compared to the regular ILP model, and
the CLIR-MLTG algorithm outperforms the SSR scheme and it obtains similar performance compared to the ILP
model.
In this paper, we propose a heuristic algorithm for solving node inclusion routing problem with additive constraints for the first time. The node inclusion routing problem is significant while a demand need to by-pass several domains and some boundary routers are assigned to be appeared in the route. The integer linear programming model is presented. Two other heuristic algorithms are evaluated. The results show that our heuristic algorithm is more effective with lower trap ratio and very close to the optimal result.
In this paper, we propose a novel multi-modular optimal capacity algorithm for SDH (Synchronous Digital Hierarchy) mesh networks. Our objective is to minimize total capital cost of the SDH mesh networks with modularity. First, the optimization problem is formulated as an integer linear programming (ILP) model. Then considering the time complexity of ILP formulation for large-scale networks, a fast heuristic algorithm named Multi-Modular Optimal Capacity (MMOC) is proposed. Several network models, which serve as test cases, are provided and the numerical results show our heuristic algorithm has low time complexity and good performance (in terms of network cost) near to the ILP results.
This paper focuses on minimizing the capacity of DiffServ/MPLS networks taking into account two widely deployed bandwidth constraint models: the maximum allocation model (MAM) and the Russion doll model (RDM). With the given physical network and traffic demands, by optimizing Label Switched Paths (LSPs) resource allocation, route distribution, our designs aim at minimizing the link capacity of the total network. The optimization problems are formulated as integer linear programming (ILP) models first, and then, since the ILP formulation is not adapted for large-scale network, two novel fast algorithms are proposed. Numerous simulation results for a variety of networks indicate that the performances of our proposed algorithms are close to the optimal results.
In this paper, we propose a novel segment-shared protection algorithm (SSPA) for multi-domain optical mesh
networks. In SSPA, intra-domain links and inter-domain links are protected with segment-backup paths respectively.
The segment-working path is protected with path shared protection in single-domain and the inter-domain link is
protected with shared segment-backup path that it could traverse several domains. The major advantage of SSPA is
its shorter recovery time than previous path protection in multi-domain optical mesh networks. The SSPA resolves
the inter-domain link protection problem successfully. The computer simulation results show that resources
utilization ratio of our proposed SSPA is near to the optimization algorithm that requires the global knowledge of
network topology.
We address the problem of routing dynamic connections with differentiated reliability (DiR) requirements in wavelength-division multiplexing (WDM) mesh networks when spare capacity sharing is allowed. The problem is called routing with DiR (ROWD). In order to meet the reliability requirement of each connection request, not only an active path (AP) but also a backup path (BP) or a set of backup segments (BSs) should be derived. We propose two novel heuristics, single-protection-segment-based heuristic (SPBH) and auxiliary-graph-based heuristic (AGBH), for problem ROWD. While SPBH computes a single BS to protect the AP, AGBH computes as many BSs as necessary to protect the AP. Numerical results from extensive simulations demonstrate the good performance of the two algorithms.
It has been widely recognized that survivability is of great importance in survivable mesh WDM networks. Among various survivable schemes proposed in the literature, segment shared protection is reported to have the best performance in terms of making trade offs between spare capacity utilization and restoration time. This paper proposes a novel technique, called backup segment backup cost adjusting (BSBCA), to further reduce the spare capacity consumed for
shared segment protection. To guarantee the BSBCA technique can be used in real networks, we further propose a novel approach to select appropriately the backup segment whose backup cost will be adjusted. Simulation results demonstrate the good performance of the BSBCA technique.
Wavelength conversion and optical buffer are the two most commonly used and most useful contention resolution schemes. This paper presents a comprehensive study of them in a multiwavelength optical burst switching network. Specially, we focus on 1) how does the wavelength conversion degree affect the burst blocking performance? 2) how does the optical buffer affect the burst blocking performance? Different from the studies in literature, we will not only investigate the effect of optical buffer length on the blocking performance, but also we investigate the effect of the granularity, which is defined the length of an FDLs and measured in terms of a delay unit, of optical buffers on the burst blocking performance. 3) how does various combinational schemes can be architected and how they perform.
In this paper, we describe and investigate the protection design for survivable WDM mesh networks, and propose our heuristic shared-path protection algorithm, called dual-link failures protection (DLFP). We also present a backup resources assignment scheme to completely protect the dual-link failures, and suggest a joint selection method, which consider the integrated performance of resource utilization and protection recovery time, to compute an optimal working and backup path pair. The simulation results show that DLFP can not only perform better than previous three-step algorithm (TSA) for dual-link failures but also determine the appropriate tradeoffs between the resource utilization ratio (or blocking ratio) and the protection recovery time.
In this paper, we propose a new shared-path protection approach, called joint routing algorithm (JRA), under shared-risk link group (SRLG) constraints for survivable WDM mesh networks. JRA differs from previous algorithms that are socalled separated routing algorithm (SRA), and can find K path pairs and select an optimal path pair as the result, while SRA can only find a path pair that may be not an optimal routing pair. So, JRA can perform better than SRA. We also study the relationship between the protection switching time and the resource utilization, and suggest a new joint cost function to compute the least-cost path pairs. Under dynamic traffics with different load, the simulation results show that JRA not only has better performances than SRA but also can determine the appropriate tradeoffs between the resource utilization ratio (or blocking ratio) and the protection switching time.
Under the constraints of the number of transceivers per node and wavelength continuity, the fairness issue of connections with different bandwidth granularities in survivable traffic-grooming WDM mesh networks is investigated. An extended wavelength-plane graph (EWG) model and two dynamic grooming path protection algorithms with considering blocking fairness are proposed. Based on dynamic traffic with different load, the performance of our schemes has been evaluated via simulations. The results show that they provide good blocking fairness while at the same time ensure a small increase in the overall traffic blocking probability.
Optical burst switching (OBS) is a switching technology proposed to efficiently support the growing broadband traffic over all optical WDM networks. In this paper, we analyze the blocking performance of an OBS network with limited number wavelength conversion, where only a fraction of input wavelengths can be converted to a set of (but not all) output wavelength. We have derived exact analytical results for the blocking probability for the case of exponentially distributed burst size. Analytical and simulation results indicate that by using wavelength conversion, we can improve the burst blocking performance evidently. These results also indicate that, by using limited number wavelength conversion (for example, the number of wavelengths that can be converted is seven-eighths of the total number of wavelengths), we can achieve almost the same performance as that of using full wavelength conversion.
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