The currently standardized GMPLS protocol suite for packet over optical networks relies on hierarchical instances of signaling sessions. Such sessions have to be established and maintained also in transit nodes, leading to complex and weighty control plane implementations. A novel technology called Segment Routing (SR) has been recently proposed to address these issues. SR relies on the source routing paradigm to provide traffic engineering solutions. In particular, the computed route for a given request is expressed as a segment list applied as an header to data packets at the ingress node. Specific algorithms are then required to perform the path computation and express the computed path through an effective segment list encoding (i.e., label stack), minimizing the segment list depth (SLD) (i.e., the number of labels included in the segment list). So far, no algorithms have been proposed to jointly provide path and segment list computation in SR-based networks. In this study, an efficient segment list encoding algorithm is proposed, guaranteeing optimal path computation and limited SLD in SR-based networks. The algorithm also accounts for equal-cost multiple paths and multiple constraints. The proposed algorithm is successfully applied to different network scenarios, demonstrating its flexibility in several use cases and showing effective performance in terms of segment list depth and introduced packet overhead

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Analogue Radio over Fibre together with subcarrier multiplexing and wavelength division multiplexing is proven to be more cost-efficient when compared to CPRI fronthaul solutions. Furthermore, the results of the allocation of RF channels to better exploit the available modulation bandwidth of commercial transceivers show that the uniformly spaced channel plan is bandwidth efficient but susceptible to interference. The ITU-T G.692 plan results in much higher tolerance to interference but it is more bandwidth consuming. Finally, the proposed 'mind the gap' RF channel plan shows an acceptable compromise between bandwidth consumption and robustness against intermodulation interference.

Segment Routing (SR) is emerging as an innovative traffic engineering technique compatible with traditional MPLS data plane. SR relies on label stacking, without requiring a signaling protocol. This greatly simplifies network operations in transit nodes. However, it may introduce scalability issues at the ingress node and packet overhead. Therefore, specific algorithms are required to efficiently compute the label stack for a given path. This study proposes two algorithms for SR label stack computation of strict routes that guarantee minimum label stack depth. Then, SR scalability performance is investigated. Results show that, in most of the cases, SR uses label stacks composed of few labels and introduces a limited packet overhead. However, relevant scalability issues may arise in specific cases, e.g., large planar topologies.

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Coherent detection and digital signal processing techniques have driven a remarkable development in optical transport technologies, enabling channels at 100 Gb/s to be transmitted over thousands of kilometers. Future optical communications systems will achieve even higher data rates (> Gb/s) through the deployment of superchannels, a designation for subcarrier multiplexing in the optical domain. In addition, a software-defined configuration of modulation format, transmission rate and coding scheme will enable advanced features such as automatic bandwidth provisioning and optimized spectrum allocation. However, compared with the wireless environment, optical systems are still very primitive in terms of intelligence, because their installation and operation require highly skilled manpower. The solution to this problem are adaptive optical transceivers, able to sense the channel conditions and to adapt their operation parameters to extend reach and reduce power consumption. In this paper we review a set of enabling concepts and algorithms of an adaptive optical transceiver, and discuss the challenges for its successful implementation.