In this paper, we describe the validation of GNPy. GNPy is an open source application that approaches the optical layer according to a disaggregated paradigm, and its core engine is a quality-of-transmission estimator for coherent wavelength division multiplexed optical networks. This software is versatile. It can be used to prepare a request for proposal/request for quotation, as an engine of a what-if analysis on the physical layer, to optimize the network configuration to maximize the channel capacity, and to investigate the capacity and performance of a deployed network. We validate GNPy by feeding it with data from the network controller and comparing the results to experimental measurements on mixed-fiber, Raman-amplified, multivendor scenarios over the full C-band. We then test transmission distances from 400 up to 4000 km, polarization-multiplexed (PM) quadrature phase shift keying, the PM-8 quadrature amplitude modulation (QAM) and PM-16QAM formats, erbium-doped fiber amplifier (EDFA) and mixed Raman–EDFA amplification, and different power levels. We show excellent accuracy in predicting both the optical signal-to-noise ratio and the generalized signal-to-noise ratio (GSNR), within 1 dB accuracy for more than 90% of the 500 experimental samples. We also demonstrate the ability to estimate the transmitted power maximizing the GSNR within 0.5 dB of accuracy.
In this paper, quality of transmission (QoT)-aware lightpath provisioning schemes for transparent optical networks are proposed and assessed. The main idea is to overcome lightpath blocking due to excessive physical impairments (i.e., unacceptable QoT) by means of successive lightpath set up attempts performed by generalized multiprotocol label switching (GMPLS) signaling protocol along alternate routes. The schemes are enabled by the introduction into current GMPLS signaling protocol [i.e., resource reservation protocol with traffic engineering (RSVP-TE)] of extensions which encompass the QoT parameters that characterize the optical layer. Differently from previous approaches, the proposed GMPLS-based schemes are still distributed but they do not imply the introduction of additional extensions into the routing protocol (e.g., OSPF-TE). The QoT-aware provisioning schemes are first validated by simulations\ud performed on a WDM mesh network. Results show that only few successive set up attempts are required to complete the lightpath establishment. In addition, an experimental demonstration where the proposed RSVP-TE extensions are implemented in the control plane of a transparent metro network is reported showing that impairment-aware lightpath provisioning is achieved on a time scale of few milliseconds
We examine how datarate-adaptive transceivers can be used to follow the pronounced variations in requested bandwidth in core networks and therefore allow significant energy savings compared to static networks configured to support the peak traffic all the times. We investigate two schemes for datarate adaptation in optical transceivers: modulation-format adaptation and symbol-rate adaptation, and show how they yield comparable energy savings but through very different mechanisms. We quantify these energy savings with respect to static networks for the case of a European backbone network and find potential for up to 30% of savings when the two schemes are combined.
We tackle the problem of reducing power consumption in IP-over-WDM networks, targeting the power-aware logical topology design (LTD). Unlike the previous work in the literature, our solution reduces the power consumption with consideration of the cost (in terms of reconfigured traffic) incurred when the network is reconfigured. We first formulate the LTD with reconfiguration costs as an optimization problem. Then, we present three heuristics to effectively solve it. We compare our algorithms over an extensive set of networks and scenarios. Results indicate that our algorithms are effective in reducing power consumption while limiting the amount of traffic that is reconfigured. Moreover, we show that the input parameters are intuitive and easy to set, which makes our algorithms more practical.
Energy saving in telecommunications networks has become a well established topic in the research community. We look at the electrical and optical layers of IP-over-WDM networks, and present a list of evaluation criteria for the Energy-Aware Adaptive Routing Solutions (EA-ARSs) from the perspective of a network operator. Furthermore, we briefly explain the EA-ARSs originating from European Union's TREND, the FP7 Network of Excellence, show saving of energy consumed by Line Cards (LCs) on a reference scenario, and use the evaluation criteria to identify the next steps toward introduction of the EA-ARSs into real operation.
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