Getting routers out of the core: Building an optical wide area network with "multipaths"

We propose an all-optical networking solution for a wide area network (WAN) based on the notion of multipoint-to-multipoint lightpaths that, for short, we call "multipaths". A multipath concentrates the traffic of a group of source nodes on a wavelength channel using an adapted MAC protocol and multicasts this traffic to a group of destination nodes that extract their own data from the confluent stream. The proposed network can be built using existing components and appears less complex and more efficient in terms of energy consumption than alternatives like OPS and OBS. The paper presents the multipath architecture and compares its energy consumption to that of a classical router-based ISP network. A flow-aware dynamic bandwidth allocation algorithm is proposed and shown to have excellent performance in terms of throughput and delay

Research challenges on energy-efficient networking design

The networking research community has started looking into key questions on energy efficiency of communication networks. The European Commission activated under the FP7 the TREND Network of Excellence with the goal of establishing the integration of the EU research community in green networking with a long perspective to consolidate the European leadership in the field. TREND integrates the activities of major European players in networking, including manufacturers, operators, research centers, to quantitatively assess the energy demand of current and future telecom infrastructures, and to design energy-efficient, scalable and sustainable future networks. This paper describes the main results of the TREND research community and concludes with a roadmap describing the next steps for standardization, regulation agencies and research in both academia and industry.The research leading to these results has received funding from the EU 7th Framework Programme (FP7/2007–2013) under Grant Agreement No. 257740 (NoE TREND)

Optical Power Control to Efficiently Handle Flex-Grid Spectrum Gain over Existing Fixed-Grid Network Infrastructures

International audienceThe exponential traffic growth in optical networks has triggered the evolution from Fixed-Grid to Flex-Grid technology. This evolution allows better spectral efficiency and spectrum usage over current networks in order to facilitate dynamic and huge traffic demands. The integration of Flex-Grid technology increases the number of optical channels established over optical links, leading, however, to an increase in amplification power and possibly saturating optical amplifiers. In this work, we propose a power adaptation process that takes advantage of link optical signal to noise ratio (OSNR) margins to allow network operators to support this power increase while maintaining the use of legacy amplifiers. Results show that controlling channel optical power benefits from the Flex-Grid in terms of spectrum and capacity gain using in-place amplifier infrastructure

GNPy experimental validation on flex-grid, flex-rate WDM optical transport scenarios

We demonstrate accurate GSNR predictions for a flex-grid and flex-rate experimental transmission using an enhanced implementation of the open-source GNPy library for a 1600 km OLS, involving QPSK, 8-QAM and 16-QAM modulation formats

Dynamic bandwidth allocation for all-optical wide-area networks

International audienceNous proposons une architecture pour un réseau WAN tout-optique basée sur la notion de connexions optiques multipoint à multipoint, que nous appelons multipaths. L'ensemble des noeuds d'accès est partitionné en groupements pour l'émission et la réception. Une (ou plusieurs) longueur d'onde est allouée à chaque paire groupement-source groupement-destination. Les noeuds d'un même groupement-source se partagent la capacité de cette longuer d'onde selon un protocole MAC adapté. Les données transmises sur une longueur d'onde sont diffusées à tous les noeuds du groupement-destination, et chaque récepteur extrait alors les données qui lui sont destinées à partir du flux reçu. Le réseau que nous proposons ne nécessite que des composants existants et se compare favorablement en termes de complexité et d'efficacité énergétique à des solutions alternatives comme la commutation optique par paquet (Optical Packet Switching - OPS) ou la commutation optique par rafale (Optical Burst Switching - OBS). Nous présentons d'abord l'architecture multipath et comparons sa consommation d'énergie celle d'un réseau classique à base de routeurs. Nous proposons ensuite un algorithme d'allocation dynamique de la bande passante. Nous évaluons la performance de l'algorithme proposé à l'aide de simulations et nous montrons que notre solution permet d'atteindre d'excellentes performances en terme de délai et temps de réponse

On the Legacy Amplifier Limitation in Flexgrid Optical Networks

International audienceFlexgrid technology is an interesting solution to improve network capacity. However, for a given spectral band, it gives rise to the increase of the number of channels, requiring more amplification power in respect with the conventional fixed grid technology. In this work, we demonstrate that re-engineering the link margins allows supporting this increase while keeping in use legacy amplifier

Energy Efficient Content Distribution in an ISP Network

International audienceWe study the problem of reducing power consump- tion in an Internet Service Provider (ISP) network by designing the content distribution infrastructure managed by the operator. We propose an algorithm to optimally decide where to cache the content inside the ISP network. We evaluate our solution over two case studies driven by operators feedback. Results show that the energy-efficient design of the content infrastructure brings substantial savings, both in terms of energy and in terms of bandwidth required at the peering point of the operator. Moreover, we study the impact of the content characteristics and the power consumption models. Finally, we derive some insights for the design of future energy-aware networks

Assessment on the in-field lightpath QoT computation including connector loss uncertainties

Reliable and conservative computation of the quality of transmission (QoT) of transparent lightpaths (LPs) is a crucial need for software-defined control and management of the wavelength division multiplexing optical transport. The LP QoT is summarized by the generalized SNR (GSNR) that can be computed by a QoT estimator (QoT-E). Within the context of network automation, the QoT-E must rely only on data from the network controller or provided by network elements through common control protocols and data structures. Therefore, given the theoretical accuracy of the QoT-E, the in-field accuracy in the GSNR computation is also determined by the level of knowledge of input parameters. Among these, a fundamental value is the connector loss at the input of each fiber span, which defines the actual power levels triggering the nonlinear effects in the fiber, and so defining the amount of nonlinear interference and spectra tilt due to the stimulated Raman scattering introduced by the fiber span. This value cannot be easily measured and may vary in time because of equipment update or maintenance. In this paper, we consider a lab measurement campaign in which the GSNR has been computed by means of the open source project Gaussian noise model in Python (GNPy) and analyze the computation error distribution. We show how the assumption on the value for the connector loss modifies the GSNR computation error and how the GSNR computation is more conservative while accurate at the lower values for the connector loss. Using the outcome of the measurement campaign carried out in the laboratory, we present results on the error of GSNR computation in a production network, specifically, over two paths of the Microsoft core network. Using GNPy with the assumption of a connector loss of 0.25 dB as derived from the measurement campaign carried out in the laboratory, and using the physical layer description from the network controller, we show that GNPy is not conservative by overestimating the GSNR in only 5% of cases, while in conservative predictions, the underestimation error exceeds 1 dB only for a few outliers. (C) 2020 Optical Society of Americ

Software-Based Burst Mode Reception Implementation for Time-domain Wavelength Interleaved Networks

International audienceWe demonstrate burst mode functionality on a continuous commercial receiver piloted by real-time control plane in an end-to-end sub-wavelength switching test-bed. The results show the receiver can maintain its continuous performance with marginal penalty regardless of data burst absence duration. Introduction Switching sub-wavelength entities inside the big pipes channels appears as a promising solution for the operator that has to build a network with an efficient filling and different services. Access to the sub-wavelength granularity directly at the optical layer is an alternative to electrical solution to reduce cost and power consumption by saving on electrical transit and electrical-to-optical and optical-to-electrical conversions. Amongst the various Sub-Lambda Photonically Switched Network (SLPSN) solutions, Time-domain Wavelength Interleaved Networking (TWIN) is an interesting solution since it provides optically transparent sub-wavelength grooming at intermediate/core nodes, while the intelligence and processing power remains at control plane and the edge node

Experimental Validation of an Open Source Quality of Transmission Estimator for Open Optical Networks

We test the QoT-E of the GNPy library fed by data from the network controller against experimental measurements on mixed-fiber, Raman-amplified, multi-vendor scenarios on the full C-band: an excellent accuracy within 1 dB is shown