A Review of Traffic Grooming in WDM Optical Networks: Architectures and Challenges
01 Jan 2002-
TL;DR: Various network and node architectures for different traffic -grooming scenarios are compared and discussed and it is expected that there will be much more interest on the mesh topology suitable for long-haul, widearea networks.
Abstract: The transmission capacity of a link in today’s optical networks has increased significantly due to wavelength-division multiplexing (WDM) technology. The network performance is now mainly limited by the processing capability of the network elements, which are mainly electronic. By efficiently grooming low-speed traffic streams onto high-capacity optical channels, it is possible to minimize this electronic processing and eventually increase the network performance. Traffic grooming is an emerging topic that has been gaining more research and commercial attention. Most previous research on traffic grooming is mainly based on the ring network topology. It is expected that there will be much more interest on the mesh topology suitable for long-haul, widearea networks. This paper reviews most of the recent research work on traffic grooming in WDM ring and mesh networks. Various network and node architectures for different traffic -grooming scenarios are compared and discussed. * This work has been supported by the National Science Foundation (NSF) under Grant Nos. NCR-9508239 andANI-9805286, and by Sprint Advanced Technology Laboratories (ATL).
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TL;DR: A tutorial that covers the key aspects of elastic optical networks, and explores the experimental demonstrations that have tested the functionality of the elastic optical network, along with the research challenges and open issues posed by flexible networks.
Abstract: Flexgrid technology is now considered to be a promising solution for future high-speed network design. In this context, we need a tutorial that covers the key aspects of elastic optical networks. This tutorial paper starts with a brief introduction of the elastic optical network and its unique characteristics. The paper then moves to the architecture of the elastic optical network and its operation principle. To complete the discussion of network architecture, this paper focuses on the different node architectures, and compares their performance in terms of scalability and flexibility. Thereafter, this paper reviews and classifies routing and spectrum allocation (RSA) approaches including their pros and cons. Furthermore, various aspects, namely, fragmentation, modulation, quality-of-transmission, traffic grooming, survivability, energy saving, and networking cost related to RSA, are presented. Finally, the paper explores the experimental demonstrations that have tested the functionality of the elastic optical network, and follows that with the research challenges and open issues posed by flexible networks.
547 citations
TL;DR: A new generic graph model for traffic grooming in heterogeneous WDM mesh networks, based on the auxiliary graph, is proposed which can achieve various objectives using different grooming policies, while taking into account various constraints such as transceivers, wavelengths, wavelength-conversion capabilities, and grooming capabilities.
Abstract: As the operation of our fiber-optic backbone networks migrates from interconnected SONET rings to arbitrary mesh topology, traffic grooming on wavelength-division 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, wavelength-conversion capabilities, and grooming capabilities. Based on the auxiliary graph, we develop an integrated traffic-grooming algorithm (IGABAG) and an integrated grooming procedure (INGPROC) which jointly solve several traffic-grooming subproblems by simply applying the shortest-path computation method. Different grooming policies can be represented by different weight-assignment 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 traffic-selection scheme is key to achieving good network performance. We propose several traffic-selection schemes based on this model and we evaluate their performance for different network topologies.
355 citations
Cites background from "A Review of Traffic Grooming in WDM..."
...…Traffic Grooming in Heterogeneous WDM Mesh Networks Hongyue Zhu, Student Member, IEEE, Hui Zang, Member, IEEE, Keyao Zhu, Student Member, IEEE, and Biswanath Mukherjee, Member, IEEE Abstract As the operation of our fiber-optic backbone networks migrates from interconnected SONET rings to…...
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TL;DR: This work investigates the survivable traffic-grooming problem for optical mesh networks employing wavelength-division multiplexing (WDM), and proposes effective heuristics for grooming a connection request with shared protection.
Abstract: We investigate the survivable traffic-grooming problem for optical mesh networks employing wavelength-division multiplexing (WDM). In the dynamic provisioning 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 grooming-node architecture, we propose three approaches for grooming a connection request with shared protection: protection-at-lightpath level (PAL); mixed protection-at-connection level (MPAC); separate protection-at-connection level (SPAC). In shared-mesh 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 existing version of the problem for provisioning one connection request with shared protection is NP-complete, we propose effective heuristics. Under today's typical connection-bandwidth distribution where lower bandwidth connections outnumber higher bandwidth connections, we find the following: 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; 3) protecting each specific lightpath, i.e., PAL, achieves the best performance when the number of grooming ports is moderate or small.
171 citations
Cites background from "A Review of Traffic Grooming in WDM..."
...Please see [1] for an extensive review on traffic grooming....
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17 Nov 2002
TL;DR: A new, generic graph model for dynamic traffic grooming in WDM mesh networks is employed and an adaptive grooming policy (AGP) is proposed, and the results show that AGP outperforms the fixed grooming policies.
Abstract: We employ a new, generic graph model for dynamic traffic grooming in WDM mesh networks. 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. Based on the auxiliary graph, we develop a dynamic traffic-grooming algorithm. Different grooming policies can be implemented by different weight functions assigned to the edges in the auxiliary graph. We propose four fixed grooming policies and an adaptive grooming policy (AGP), and our results show that AGP outperforms the fixed grooming policies.
143 citations
Cites background from "A Review of Traffic Grooming in WDM..."
...The work in [6] reviews most of the recent research work on traffic grooming in WDM ring and mesh networks....
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TL;DR: State of the art of the key enabling technologies are demonstrated including hierarchical optical cross-connect switch architectures, hierarchical optical path network design algorithms, a newly developed waveband filter, and waveband conversion technologies.
Abstract: This paper investigates the prospects and challenges of hierarchical optical path networks The merits and issues of introducing higher order optical paths are elucidated State of the art of the key enabling technologies are demonstrated including hierarchical optical cross-connect switch architectures, hierarchical optical path network design algorithms, a newly developed waveband filter, and waveband conversion technologies
94 citations
Cites background from "A Review of Traffic Grooming in WDM..."
...The number of wavelength converters may be limited because of their cost; collision can be reduced by applying effective routing and wavelength assignment algorithms [49]–[52]....
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References
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Book•
01 Jan 1998TL;DR: The second edition of Optical Networks: A Practical Perspective succeeds the first as the authoritative source for information on optical networking technologies and techniques as discussed by the authors, covering componentry and transmission in detail but also emphasizing the practical networking issues that affect organizations as they evaluate, deploy, or develop optical solutions.
Abstract: This fully updated and expanded second edition of Optical Networks: A Practical Perspective succeeds the first as the authoritative source for information on optical networking technologies and techniques. Written by two of the field's most respected individuals, it covers componentry and transmission in detail but also emphasizes the practical networking issues that affect organizations as they evaluate, deploy, or develop optical solutions.
2,282 citations
"A Review of Traffic Grooming in WDM..." refers background in this paper
..., peak electronic speed of a few gigabits per second (Gbps) [1, 2]....
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Book•
01 Jan 1997TL;DR: A comprehensive explanation of the newest developments in optical networks in the MCGRAW-HILL COMPUTER COMMUNICATIONS series.
Abstract: A comprehensive explanation of the newest developments in optical networks in the MCGRAW-HILL COMPUTER COMMUNICATIONS series. Case studies and research projects at AT&T, Fujitsu, and NTT are considered in order to provide the reader with hands-on information which can be applied in practice.
852 citations
"A Review of Traffic Grooming in WDM..." refers background in this paper
..., peak electronic speed of a few gigabits per second (Gbps) [1, 2]....
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TL;DR: The node architecture for a WDM mesh network with traffic-grooming capability, using wavelength-division multiplexer (OADM) to perform the optical bypass at intermediate nodes to improve the network throughput is studied.
Abstract: In wavelength-division multiplexing (WDM) optical networks, the bandwidth request of a traffic stream can be much lower than the capacity of a lightpath. Efficiently grooming low-speed connections onto high-capacity lightpaths will improve the network throughput and reduce the network cost. In WDM/SONET ring networks, it has been shown in the optical network literature that by carefully grooming the low-speed connection and using wavelength-division multiplexer (OADM) to perform the optical bypass at intermediate nodes, electronic ADMs can be saved and network cost will be reduced. In this study, we investigate the traffic-grooming problem in a WDM-based optical mesh topology network. Our objective is to improve the network throughput. We study the node architecture for a WDM mesh network with traffic-grooming capability. A mathematical formulation of the traffic-grooming problem is presented in this study and several fast heuristics are also proposed and evaluated.
675 citations
"A Review of Traffic Grooming in WDM..." refers background in this paper
...Unlike the work in [14], the works in [15, 16] consider a dynamic traffic pattern in a WDM mesh network....
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...The authors in [14] formulate the problem as an ILP....
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...The authors in [14] consider a static traffic matrix set as the network traffic demands....
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...Different network scenarios are considered and compared in [14]....
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...The work in [14] has assumed that every node is a WGXC node, and the grooming capability is constrained by the grooming fabric and transceiver array at every node....
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TL;DR: It is demonstrated that an optimum light-tree-based virtual topology has clear advantages over an optimumLightpath-basedvirtual topology with respect to the above two objectives.
Abstract: We introduce the concept of a light-tree in a wavelength-routed optical network. A light-tree is a point-to-multipoint generalization of a lightpath. A lightpath is a point-to-point all-optical wavelength channel connecting a transmitter at a source node to a receiver at a destination node. Lightpath communication can significantly reduce the number of hops (or lightpaths) a packet has to traverse; and this reduction can, in turn, significantly improve the network's throughput. We extend the lightpath concept by incorporating an optical multicasting capability at the routing nodes in order to increase the logical connectivity of the network and further decrease its hop distance. We refer to such a point-to-multipoint extension as a light-tree. Light-trees can not only provide improved performance for unicast traffic, but they naturally can better support multicast traffic and broadcast traffic. In this study, we shall concentrate on the application and advantages of light-trees to unicast and broadcast traffic. We formulate the light-tree-based virtual topology design problem as an optimization problem with one of two possible objective functions: for a given traffic matrix, (i) minimize the network-wide average packet hop distance, or (ii) minimize the total number of transceivers in the network. We demonstrate that an optimum light-tree-based virtual topology has clear advantages over an optimum lightpath-based virtual topology with respect to the above two objectives.
582 citations
"A Review of Traffic Grooming in WDM..." refers background or methods in this paper
...Optical multicasting using “light-tree” [19] may be a good solution for these requirements....
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...Different multiplexing techniques such as Figure 10: Switch architecture for supporting multicast grooming [19]....
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TL;DR: An overview of the traffic grooming problem is given and some representative work in this area is surveyed, showing that grooming traffic in general mesh networks is an important emerging problem.
Abstract: The emergence of wavelength-division multiplexing technology has led to a tremendous increase In the available transmission capacity in wide area networks. Consequently, these networks may no longer be limited by the transmission bandwidth, but rather by the processing capability of electronic switches, routers, and multiplexers in the network. This realization has led to a new wave of research aimed at overcoming the electronic bottleneck by providing optical bypass at the WDM layer. Traffic grooming can be used as a bypass mechanism by which low-rate circuits are assigned to wavelengths in order to minimize the amount of electronic multiplexing equipment. This topic has received a significant amount of attention in both the research and commercial arenas. We give an overview of the traffic grooming problem and survey some representative work in this area. While most work has focused on grooming in SONET rings, grooming traffic in general mesh networks is an important emerging problem.
357 citations
"A Review of Traffic Grooming in WDM..." refers methods in this paper
...We use an example from [12] to illustrate dynamic traffic grooming for a t-allowable traffic pattern in a SONET/WDM ring....
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