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While elastic optical network technologies have emerged as promising solutions for future ultra-high-speed optical transmission, the unavoidable spectral fragmentation problem that appears in such networks significantly degrades their performance. In light of this, spectral defragmentation technologies have been introduced in elastic optical networks, aiming to increase the spectrum utilisation. During the defragmentation operation, the available fragmented spectrum bands are consolidated by reallocating existing connections, either re-routing them along alternative routes and/or re-tuning them onto different spectrum portions. Obviously, spectral defragmentation increases network complexity and cost. Therefore, it is highly desirable to limit its application as much as possible, while keeping network performance within acceptable margins. In this paper, we focus on analyzing the correlation between the optimal (i.e. minimum) spectrum defragmentation periodicity in the network with the granularity of the supported traffic. For this purpose, we initially introduce a novel algorithm for efficient spectrum defragmentation. The proposed algorithm aims to consolidate the available fibre spectrum as much as possible, while limiting the number of reallocated active connections. Then, supported on extensive simulation results, we show how spectral defragmentation periodicity can be effectively configured by having knowledge of the offered traffic granularity. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Network virtualization opens the door to novel infrastructure services offering connectivity and node manageability. In this letter, we focus on the cost-efficient embedding of on-demand virtual optical network requests for interconnecting geographically distributed data centers. We present a mixed integer linear programming formulation that introduces flexibility in the virtual-physical node mapping to optimize the usage of the underlying physical resources. Illustrative results show that flexibility in the node mapping can reduce the number of add-drop ports required to serve the offered demands by 40%. [ABSTRACT FROM AUTHOR]

Automatic resource discovery plays a significant role in next-generation optical networks, where nodes can maintain a large number of input/output ports (fibers, wavelengths, time slots, etc.). This automation avoids long and tedious manual node configurations and minimizes resource misconfiguration probability, which can result in high cost savings for network operators. The generalized multiprotocol label sswitching (GMPLS) Link Management Protocol (LMP) has been defined to provide such functionalities. However, it requires optical nodes to transmit in-band information, thus requesting link termination on each incoming port. This issue, in transparent optical networks, implies additional hardware, high complexities, or even signal losses. This article proposes and evaluates novel extensions to standard LMP that cope with the discovery of all-optical transport planes. In addition, playing a crucial role in ASON/GMPLS networks, this article also generically covers the automatic discovery of the control plane. [ABSTRACT FROM AUTHOR]

The use of optical technologies in modern network scenarios has increased in the last decade, mostly due to their support in crucial networking topics (ie, bandwidth and scalability). In parallel, these scenarios have also experienced the emergence of a new paradigm recognized as software‐defined networking (SDN), which bases on the decoupling of forwarding and control functions, with aims to provide a more efficient way to manage network resources compared to legacy networking architectures. As both SDN and optical technologies are constantly being introduced in different networking scenarios (eg, data centers, metro, and access networks), their coexistence becomes a must. In this matter, it is important to notice that SDN was initially designed for electronic‐based networks; hence, its support for optical technologies is still at an early stage. Consequently, integration of both solutions still requires research efforts by the community. In this paper, we present a mechanism to address topology discovery in wavelength‐switching optical transport networks (OTNs). In particular, we discuss the importance of the topology discovery function and analyse the proposed mechanism, which bases itself on the use of wavelength‐specific signaling tones as link‐binding data to provide preservice parallel link discovery in OTNs. Furthermore, we validate the method experimentally against an emulated OTN testbed with two different setups and compare the results to our previous work on this subject, achieving substantial reductions in the total topology discovery time. In this paper, we present a mechanism to address topology discovery in Optical Transport Networks (OTNs). We discuss the importance of the topology discovery function and analyse the proposed mechanism, which bases on the use of wavelength‐specific signaling tones as link‐binding data to provide parallel link discovery in OTNs. Furthermore, we validate the method experimentally against an emulated OTN testbed and compare the results to our previous work on this subject, achieving substantial reductions in the total topology discovery time. [ABSTRACT FROM AUTHOR]