On the importance of time-synchronized operations in software-defined electronic and optical networks

The utilization of time-synchronized operations (TSO) is gaining interest in the research community on Software-Defined Networking (SDN). This paper discusses TSO applicability in electronic packet and optical networks. In electronic packet networks, the TSO approach has been shown to improve network performance, thanks to timed network updates. In optical networks, this approach enables novel security applications and permits to reduce lightpath disruption time. We finally discuss TSO further potentialities and requirements regarding clock availability in network elements

Emulating software-defined disaggregated optical networks in a containerized framework

Telecom operators’ infrastructure is undergoing high pressure to keep the pace with the traffic demand generated by the societal need of remote communications, bandwidth-hungry applications, and the fulfilment of 5G requirements. Software-defined networking (SDN) entered in scene decoupling the data-plane forwarding actions from the control-plane decisions, hence boosting network programmability and innovation. Optical networks are also capitalizing on SDN benefits jointly with a disaggregation trend that holds the promise of overcoming traditional vendor-locked island limitations. In this work, we present our framework for disaggregated optical networks that leverages on SDN and container-based management for a realistic emulation of deployment scenarios. Our proposal relies on Kubernetes for the containers’ control and management, while employing the NETCONF protocol for the interaction with the light-weight software entities, i.e., agents, which govern the emulated optical devices. Remarkably, our agents’ structure relies on components that offer high versatility for accommodating the wide variety of components and systems in the optical domain. We showcase our proposal with the emulation of an 18-node European topology employing Cassini-compliant optical models, i.e., a state-of-the-art optical transponder proposed in the Telecom Infrastructure Project. The combination of our versatile framework based on containerized entities, the automatic creation of agents and the optical-layer characteristics represents a novel approach suitable for operationally complex carrier-grade transport infrastructure with SDN-based disaggregated optical systems.This research was funded Spanish Government: ONOFRE-2 project under Grant TEC2017-84423-C3-2-P (MINECO/AEI/FEDER, UE) and the Go2Edge project under Grant RED2018-102585-T; and by the European Commission: METRO-HAUL project (G.A. 761727)

Optical Interconnections based on Microring Resonators

Projecte fet en col.laboració amb la Facoltà di Ingegneria dell’Informazione. Politecinco de TorinoThe aim of this thesis is to present and analyse optical interconnection architectures based on microring resonators. The trend of meeting large bandwidth and strict latency requirements in both global on-chip and off-chip communication face critical challenges in maintaining a sustainable performance-per-watt. Optical technologies support the immense bandwidth allowed by wavelength division multiplexed (WDM) while could offer a significant power saving switching capabilities. Microring resonators have received considerable attention as promising technologies for realizing photonic integrated circuits. Their small footprint and their capacity for processing high-bandwidth WDM data can lead these devices become the key elements for the switch nodes in next-generation telecommunication networks. This thesis firstly describes the basic principles of operation of a microring resonator defining 1x2 basic switching element (1B-SE). Then, the 2x2 basic SE (2B-SE) based on two 1B-SEs jointly controlled and the new 2x2 mirrored SE (2M-SE) are characterised as atomic building elements for interconnection architectures. The severe asymmetric behaviour presented by those SEs could limit the scalability of classical optical switching fabrics and we aim at balancing the complexity and optical signal level. In a second stage, the well-known switching theory is revised in order to classify the interconnection architectures according to their characteristics when using that SEs as building element. It is applied an exhaustive procedure to obtain the performance of classical Crossbar and Benes structures and of the newly proposed Mirroring and HBC structures. Thereafter, using as a starting point for each analysed structure the characterisation previously obtained, the scalability response of larger switching fabrics is explored. Then we define a construction rule for the new proposed architectures of which we assess the complexity in terms of used microring

On Provisioning Strategies in Translucent Elastic Optical Networks with Flexible Regeneration and Superchannel Transmission

Elastic Optical Networks (EONs) can increase the efficiency of already deployed optical fibers thanks to transponders that adjust the modulation format, baud-rate and number of optical carriers to achieve the desired transmission rate, bandwidth and reach. Due to the high cost of these transponders, transparent end-to-end lightpaths are usually desired, which can require a large amount of spectrum as they are provisioned over long distances. In this paper, we consider the case of translucent lightpaths, which make use of flexible regeneration schemes to reduce the amount of required spectrum. We analyze the trade-off between the spectrum usage and the number of transponder devices. In particular, we propose a proactive approach to provision EONs that considers the spectrum availability. Thus, it is possible to explore the referred trade-off with a load- incremental perspective, which may be relevant for network operators. Results show how the proposed approach can increase the supported capacity in the network at the cost of additional transponder devices

Architecture on Demand Design for High-Capacity Optical SDM/TDM/FDM Switching

Reconfigurable optical add/drop multiplexers (ROADMs) are key elements in operators' backbone networks. The breakthrough node concept of architecture on demand (AoD) permits us to design optical nodes with higher flexibility with respect to ROADMs. In this work, we present a five-step algorithm for designing AoD instances according to some given traffic requests, which are able to support subwavelength time switching up to wavelength/superchannel/fiber switching. We evaluate AoD performancein terms of power consumption and number of backplane optical cross-connections. Furthermore, we discuss trade-offs involved in the migration from a fixed to a flexible grid with regard to the optical node size, capacity, and power consumption. We compare several ROADM architectures proposed in the literature with AoD in terms of power consumption and cost. We also study different technologies for enhancing the scalability of AoD. Results show that AoD can bring significant power savings compared to other architectures while offering a throughput of hundreds of terabits per second