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.

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A novel generic graph model for traffic grooming in heterogeneous WDM mesh networks

Since the energy crisis and environmental protection are gaining increasing concerns in recent years, new research topics to devise technological solutions for energy conservation are being investigated in many scientific disciplines. Specifically, due to the rapid growth of energy consumption in ICT (Information and Communication Technologies), lot of attention is being devoted towards "green" ICT solutions. In this paper, we provide a comprehensive survey of the most relevant research activities for minimizing energy consumption in telecom networks, with a specific emphasis on those employing optical technologies. We investigate the energy-minimization opportunities enabled by optical technologies and classify the existing approaches over different network domains, namely core, metro, and access networks. A section is also devoted to describe energy-efficient solutions for some of today's important applications using optical network technology, e.g., grid computing and data centers. We provide an overview of the ongoing standardization efforts in this area. This work presents a comprehensive and timely survey on a growing field of research, as it covers most aspects of energy consumption in optical telecom networks. We aim at providing a comprehensive reference for the growing base of researchers who will work on energy efficiency of telecom networks in the upcoming years.

Energy Efficiency in Telecom Optical Networks

The emerging software defined networking (SDN) paradigm separates the data plane from the control plane and centralizes network control in an SDN controller. Applications interact with controllers to implement network services, such as network transport with quality of service. SDN facilitates the virtualization of network functions so that multiple virtual networks can operate over a given installed physical network infrastructure. Due to the specific characteristics of optical (photonic) communication components and the high optical transmission capacities, SDN-based optical networking poses particular challenges, but holds also great potential. In this article, we comprehensively survey studies that examine the SDN paradigm in optical networks; in brief, we survey the area of software defined optical networks (SDONs). We mainly organize the SDON studies into studies focused on the infrastructure layer, the control layer, and the application layer. Moreover, we cover SDON studies focused on network virtualization, as well as SDON studies focused on the orchestration of multilayer and multidomain networking. Based on the survey, we identify open challenges for SDONs and outline future directions.

Software Defined Optical Networks (SDONs): A Comprehensive Survey

A method of processing capacity information is disclosed. The capacity information relates to data capacity in a data network in which a consumer circuit is carried on, and consumes bandwidth made available by, a bearer circuit. The method comprises storing, in a network information database, an entity representing the bearer circuit, and associating capacity information with the bearer circuit entity specifying a first bandwidth quantity defining a quantity of bandwidth made available by the bearer circuit. Also stored is an entity representing the consumer circuit, and capacity information is associated with the consumer circuit entity specifying a second bandwidth quantity defining a quantity of bandwidth allocated to the consumer circuit. The consumer capacity information is then associated with the bearer capacity information in the database to indicate that the second bandwidth quantity allocated to the consumer circuit is to be consumed from the first bandwidth quantity made available by the bearer circuit. The resulting capacity model can be used to support service provisioning, service assurance and SLA management, network engineering and network planning processes.

Capacity management for data networks

Power-awareness in networking attracts more attention as the trends in the energy consumption of the Internet raise growing concerns about the environmental impacts and sustainability of the network expansion. Building energy efficient equipment is definitely an integral part of the solution. However, such a strategy should be complemented with appropriate network protocols and routing methods to achieve maximum performance. In this paper, total power consumption of an optical WDM network is modeled in terms of the power consumed by individual lightpaths. The proposed model is then used to develop an ILP (Integer Linear Programming) formulation of the grooming problem. The exact solution of the formulation on a small network indicates that significant energy savings can be achieved with power efficient grooming.

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Power Efficient Traffic Grooming in Optical WDM Networks

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.

Dynamic traffic grooming in WDM mesh networks using a novel graph model

In this article we investigate the problem of efficiently provisioning connections of different bandwidth granularities in a heterogeneous WDM mesh network through dynamic traffic grooming schemes under traffic engineering principles Due to the huge amount of traffic a WDM backbone network can support and the large geographic area it can cover, constructing and upgrading such an optical WDM network can be costly Hence, it is extremely important for network operators to apply traffic engineering strategies to cost-effectively support different bandwidth granularity services using only the appropriate amount of network resources This requires an optical WDM network to have multigranularity switching capability, and such a network tends to be a multivendor heterogeneous network However, WDM network heterogeneity increases the difficulty and challenge of efficient traffic provisioning In this article we present different TE issues that need to be carefully considered in such an optical WDM network, and propose possible solutions and extensions for the generalized multiprotocol label switching optical network control plane We extend an existing generic graph model to perform efficient traffic grooming and achieve different TE objectives through simple shortest path computation algorithms We show that our approach is very practical and very suitable for traffic engineering in a heterogeneous multigranularity optical WDM mesh network

Traffic engineering in multigranularity heterogeneous optical WDM mesh networks through dynamic traffic grooming

Traffic Grooming in Optical WDM Mesh Networks captures the state-of-the-art in the design and analysis of network architectures, protocols, and algorithms for implementing efficient traffic grooming in optical WDM mesh networks. Key topics include: - Static traffic grooming - Dynamic traffic grooming - Grooming models and policies - Grooming node architectures - Design of grooming network - Traffic grooming in next-generation SONET/SDH networks The authors investigate traffic-grooming problems in optical WDM mesh networks from various aspects. They cover static and dynamic traffic grooming, as well as grooming policies for both environments. A fundamental graph model for traffic-grooming networks is proposed. A variety of grooming-node architectures are examined and their performances compared. Design of traffic-grooming networks using different node architectures is explored, and traffic grooming in next-generation SONET/SDH networks is presented.

Traffic Grooming in Optical WDM Mesh Networks

We investigate the survivable traffic-grooming problem for optical mesh networks employing wavelength-division multiplexing (WDM) and dedicated protection. We consider the dynamic-provisioning environment in which a connection arrives at random, holds for a random amount of time, and then departs. A typical connection request may require bandwidth less than that of a wavelength, and it may also require protection from network failures, typically fiber cuts. On the basis of generic grooming-node architecture, we propose two approaches--protection-at-lightpath (PAL) level and protection-at-connection (PAC) level--for grooming a connection request. Here we investigate dedicated protection. In a companion paper [IEEE J. Sel. Areas Commun. 21, 1367 (2003)], we investigate shared protection, which leads to a substantially different treatment. For dedicated protection, we prove that the problem of provisioning a connection under PAC is NP-complete, propose effective heuristics for both schemes, and define comprehensive performance metrics to compare PAL with PAC with respect to wavelength or grooming-port efficiency. Our findings are as follows. Under today's typical connection-bandwidth distribution in which lower-bandwidth connections outnumber higher-bandwidth connections, PAC outperforms PAL (in terms of bandwidth-blocking ratio, lightpath use, and wavelength use) if the number of grooming ports is large; however, PAL outperforms PAC (in terms of bandwidth-blocking ratio and grooming-port use) when the number of grooming ports is moderate or small.

Hongyue Zhu

Papers

A novel generic graph model for traffic grooming in heterogeneous WDM mesh networks

Dynamic traffic grooming in WDM mesh networks using a novel graph model

Traffic engineering in multigranularity heterogeneous optical WDM mesh networks through dynamic traffic grooming

Traffic Grooming in Optical WDM Mesh Networks

Traffic grooming for survivable WDM networks: dedicated protection [Invited]