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New paradigms are being proposed to cope with the increasing traffic demand in the access networks. One alternative is to leverage cost-efficient VCSEL-based Sliceable Bandwidth Variable Transceivers (S-BVTs) near the edge. In this work, we investigate the adoption of optical S-BVTs for the transport of cellular traffic. A dynamic and decentralized orchestration algorithm is proposed to achieve an optimal user association and resource allocation of the access network’s resources while considering the load-balancing and availability of the underlying optical infrastructure. Two association and resource allocation techniques are explored in a two-tier heterogeneous network featuring different radio access technologies. The results show that the decentralized solution outperforms the coverage mapsbased association and exhibits load balancing capabilities without the need of a centralized coordination, which can be leveraged by the S-BVT’s adaptive capabilities., Grant numbers : Go2Edge - Engineering Future Edge Computing Networks, Systems and Services project.

To deal with the challenging requirements of metropolitan area networks (MANs), it is essential to design cost-effective systems that can support high capacity and dynamic adaptation, as well as a synergy of programmability and efficient photonic technologies. This becomes crucial for very large MANs that support 5G, where multihop connections will need to be dynamically established at target capacities beyond Tb/s. Programmability, automation, and modularity of network elements are key desired features. In this work, a modular photonic system, programmable via a software-defined networking platform, designed for dynamic 5G-supportive MANs, is described and analyzed. We consider modular sliceable bandwidth/bit rate variable transceivers (S-BVTs) based on vertical-cavity surface-emitting laser (VCSEL) technology and dense photonic integration. The proposed system and its programmability are experimentally assessed using a VCSEL with 10 GHz bandwidth. The experiments are performed over connections as long as six-hop and 160 km, from low-level aggregation nodes to metro-core nodes, thereby enabling IP off-loading. Furthermore, a numerical model is derived to estimate the performance when adopting higher bandwidth VCSELs ( ≥ 18 G H z ) and integrated coherent receivers, as targeted in the proposed system. The analysis is performed for both 50 GHz and 25 GHz granularities. In the former case, 50 Gb/s capacity per flow can be supported over the targeted connections, for optical signal-to-noise ratio values above 26 dB. When the granularity is 25 GHz, the filter narrowing effect severely impacts the performance. Nevertheless, 1.2 Tb/s capacity (scalable to higher values if spectral/spatial dimensions are exploited) can be achieved when configuring the S-BVT to enable 40 VCSEL flows. This confirms that the system is promising to support Tb/s connections in future agile MANs.

Simulation experiments prove the suitability of VCSEL-based S-BVTs to enable IP off-loading in large MAN topologies. Multi-Tb/s capacity is demonstrated in a real MAN for all primary and secondary multi-level direct paths., NO ACKNOWLEDGEMENTS

We validate the deployment of isolated transport network slices in IP over DWDM network. To this end, an isolated transport network slice is deployed using multi-layer isolation mechanisms based on OpenConfig and ONF Transport API., Grant numbers :AURORAS - Autonomic and disaggregated optical networks leveraging edge computing and photonic technologies (RTI2018-099178-B-I00) and TeraFlow - TeraFlow – Secured autonomic traffic management for a Tera of SDN flows ( 101015857) projects.

Dense metropolitan areas are responsible for the majority of the traffic growth in telecom operators. The focus of the EU H2020 PASSION project is to develop new photonic technologies for supporting agile metro networks and enabling capacities of Tb/ s per channel to deal with such traffic increment, with a particular focus on two components (1) the Sliceable Bandwidth Variable Transceivers (S-BVT) and (2) Pb/s optical switches. This paper analyses two strategies from the perspective of computation resource consumption: overflow over a paired same-level DC and overflow over a centralized site. We present a methodology to compare both schemes and prove that a proper distribution of computing resources in the centralized overflow together with S-BVT highspeed transmission can outperform the costs of a distributed strategy, requiring fewer processors and much smaller DCs.

Upcoming metro networks are required to transport huge and highly dynamic data traffic whilst resulting cost and power efficient. Thus, novel metro network architectures are being investigated to increase the transport capacity (e.g., leveraging dense photonic integrated technologies), and provide effective SDN-based network programmability. The EU-H2020 PASSION project targets such a metro network design exploiting: i) programmable, modular, cost-efficient and low-power sliceable bandwidth variable transceivers (S-BVTs) formed by a pool of vertical cavity surface emitting lasers (VCSEL) and Coherent Receivers (CO-Rx); ii) hierarchical switching nodes in a flexi-grid network to attain all-optical transport and aggregation. The SDN-based control functions considers the features of the adopted PASSION transport layer. First, we detail the defined interfaces (APIs) for the automatic transport network programmability. Such (RESTful-based) interfaces are validated within the ADRENALINE testbed. Next, upon dynamic connection requests with heterogenous data rate demands, an on-line Routing and Spectrum Assignment (RSA) algorithm based on a modified K shortest path (K-SP) is proposed. To accommodate a connection request, a set of optical flows having their own S-BVT VCSEL and CO-Rx devices at the endpoints and path's frequency slots are selected and configured. Each optical flow is subject to the spectral continuity and contiguity constraints. The performance of the RSA algorithm for several traffic loads is experimentally evaluated through different figures of merit (e.g., blocked bandwidth ratio, average used of S-BVT devices, etc.) and diverse RSA's K-SP settings.

An SDN-enabled photonic system adopting VCSEL technology is experimentally analyzed targeting dynamic 5G-supportive MAN. Direct and coherent detection modules are compared and programmability assessed over up to 6-hop 160km HL4-HL2/1 connection including 25km 19-core MCF., Grant numbers : AURORAS - Autonomic and disaggregated optical networks leveraging edge computing and photonic technologies ( RTI2018-099178-B-I00). © 2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.

This article provides insight on two of the most relevant applications driving the design of the future MAN: the implementation of 5G by means of C-RAN (Cloud - Radio Area Network) and the deployment of edge computing. The work addresses important questions such as the target latency budget for future MANs, the target bandwidth requirements for 2020-2030 induced by 5G midhaul and fronthaul traffic, and describes how optical and electronics layers can co-operate to meet the QoS targets of C-RAN and edge computing traffic. In the process, we identify the key architectural elements to meet the challenges of these applications in a cost-effective way.

Network softwarization will permit the dynamic configuration of the transport infrastructure, in order to facilitate the adaptation needed for future advanced services. However, the promise of full flexibility can only be achieved through proper levels of abstraction and by means of normalized interfaces and service and device models. This paper presents the SDN architecture that is being defined by Telef\'onica for the management and control of its transport networks, including a variety of technologies such as IP, optics and microwave radio links, pursuing a standard-based approach for an effective and future-proof introduction of softwarized operations., Comment: IEEE Conference on Standards for Communications and Networking (CSCN)

An SDN-enabled modular photonic system architecture, including VCSEL-based bandwidth/bitrate variable transceivers, for multi-terabit capacity transmission and agile spectrum/space switching in optical metro networks is presented, providing the proposed technological solutions, programmability aspects and preliminary assessment.

A scalable cost-effective solution for high service availability featuring low latency is required for CDN caching. Recently, a field of study is that MAN data centers, within the latency budget, act as a backup for other local data centers of lesser reliability. Given the low latency target of caching, the optical layer is the preferred option to interconnect caches. However, carrying the backup traffic from one data center (DC) to another with a permanent optical circuit based on Fixed Transceivers (FT) features low utilization and no statistical multiplexing gain on the path, which makes the backup network resources costly. In this paper we compare several approaches to implement this scenario with dynamic circuits, considering both inter-cache and backup traffic with FTs featuring both permanent and switched optical circuits, and with the Tb/s sliceable bandwidth-variable transceivers (S-BVT) developed in the EU project PASSION. As we show, S-BVTs can be key devices to improve backup-network scalability in terms of IT resources and transceivers, thanks to their capability to adapt to the actual traffic demand and to obtain multiplexing gains at the optical layer.

We model via YANG an adaptive, modular and programmable VCSEL-based S-BVT for optical flexi-grid metro networks. Discussion and experimental validation of the PCECC T-SDN controller interfaces for automatic provisioning of flexi-grid connections are provided., Grant numbers : DESTELLO - Dynamic flexible orchestration of data centers and programmable elastic optical networks and systems (TEC2015-69256-R). © 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.

The need of introducing interoperability in the transport network segment has motivated the emergence of several open initiatives and standardization efforts for the development of different interfaces to allow Software Defined Network (SDN) controllers manage and control the network devices. Optical disaggregation in particular aims the introduction of standard device-level interfaces in the optical terminals and line-systems to ‘open’ them from vendor lock-in situations, allowing an interoperable ecosystem in the optical network's transport segment. In this article, it is firstly presented the Software Defined Transport Network (SDTN) architecture, as the control and management framework to build a L0-L3 multi-layer, multi-technology transport network, enabling end-to-end network service delivery. Later, we introduce the partially disaggregated network architecture proposed, including the technical assessment of the topology discovery and resilience service provisioning use cases, by providing a low-level description of the information models employed and the translation between models. To conclude, a proof-of-concept of multi-layer service provisioning over resilient disaggregated multi-vendor testbed is presented, including the results obtained in the experimental demonstration presented in last 2019 Optical Fiber Conference (OFC).

Flexgrid technology has recently been presented as the most promising option for upgrading the currently operating fixed grid optical networks and extending their capacity to be able to deal with the massive traffic volumes forecast for the next decade. Although the current traffic is successfully supported on fixed grid networks, flexgrid technology brings features that are not offered by the fixed grid networks, such as transporting optical connections with a capacity beyond 100 Gb/s and elasticity against time-varying traffic. In light of this, a gradual fixed grid to flexgrid migration is generally accepted in order to add these useful features to the network. In this article, we study the migration process where flexgrid is deployed in the network progressively, and review the main drivers and open issues induced by its deployment.

We validate the Transport API interoperability with a hierarchical orchestration layer. The demonstration shows the end-to-end provision of connections based on the topology and connectivity services of the Transport API.

Operators are challenged by the new cloud services, which can modify current traffic pattern. This talk presents the Telefonica I+D view on the evolution towards a transport network ready to support cloud services. It explains the reasons why current transport networks are not efficiently design for a cloud environment and it describes the architecture for a cloud-ready network. To show the feasibility of such cloud-ready network, experimental validations are presented to show the concepts of a cloud-ready transport network.

A common Transport API is proposed for joint cloud/network orchestration, allowing interworking of heterogeneous control planes to provide provisioning/recovery of QoS-aware E2E services. We present its first demonstration in a multi-partner testbed including data-plane monitoring.

The operation of multi-domain and multi-vendor EONscan be achieved by interoperable Sliceable Bandwidth Variable Transponders, a GMPLS/ BGP-LS -based control plane and a planning tool. This paper reports the first full demonstration and validation this end-to-end architecture

This paper presents the challenges and purpose of building the Traffic Engineering Database (TED) to facilitate Software Defined control of an Elastic Optical Network (EON). It explains how a standardized protocol and data model can facilitate this and describes a YANG model that has been developed to represent the TED including the representation of nodes, transponders, links, and available media channels available. This model also represents the established connections (Label Switched Paths - LSPs) between endpoints.

The Control Orchestration Protocol (COP) abstracts a common set of control plane functions used by an various SDN controllers, allowing the interworking of heterogeneous control plane paradigms (i.e., OpenFlow, GMPLS/PCE). COP has been defined using YANG model language and can be transported using RESTconf, which is being incorporated by industry. COP has been defined in the scope of STRAUSS due to the need for an overarching control plane protocol for network orchestration. In this paper, several research projects describe how the COP could fit in their architecture and propose a use case for COP usage. The proposed COP use cases cover the following research projects: STRAUSS, IDEALIST, DISCUS, COMBO, INSPACE.

In recent years, significant work has been completed on traffic engineering enhancements to the generalized multiprotocol label switching protocol suite (E. Mannie Oct 2004) (D. Katz et al., Sept. 2003) (K. Kompella et al., Oct 2003). As a next step, reproducing the current trend of switching layers' integration happening in the data plane, network control is foreseen to go beyond the traditional per layer approach and tend toward an integrated model (K. Shimoto et al., Oct 2004) (E. Dotaro et al., Dec. 2004). In these multilayer environments, a single GMPLS control plane drives various distinct switching layers at the same time and as a coherent whole, taking benefit from the "common" property of GMPLS. Beyond this application of supporting network control across different technologies, in this article we catalog the unified traffic engineering paradigms, discuss their applicability, and present their enforcement techniques. Furthermore, we show that the common GMPLS concept has the advantage of low operational complexity, and enables unified TE capabilities such as efficient network resource usage and rapid service provisioning.

Simple and cost-effective DMT transmission in combination with shared coherent detection is proposed for evolutionary flexgrid metro/regional networks. Network testbed experiments show successful 10Gb/s connections from MTUs to the sliceable transceiver at the virtual BRAS farm, covering up to 150km.

SDN brings automation to network operation and abstracts the complexity of optical networks. An orchestration layer is required to support multivendor interoperability scenarios. This work demonstrates that an ABNO architecture enables SDN controlled domain interoperability.

We numerically analyze a flexgrid metro network scenario identifying the requirements for BRAS centralization. A cost-effective S-BVT architecture based on MB-OFDM and DD with DSPenabled software-defined flexible/adaptive capabilities is proposed and experimentally evaluated for supporting multiple 10Gb/s connections. Introduction Flexgrid technologies have been studied for core scenarios. However, due to the high bandwidth pressure in metro area networks (MAN), flexgrid technologies can also find application in that network segment to improve spectrum and network efficiency and reduce CapEx investment. Lately, main European network operators have been expanding their photonic mesh to the regional networks. A high capacity photonic regional network motivates the centralization of the Broadband Remote Access Servers (BRASes) that were distributed and placed at lower aggregation levels close to the users. Centralization in this scenario means the creation of a conveniently dimensioned pool of BRASes co-located in a transit router. For this metro scenario, using technologies for core networks is overkill, since the requirements are substantially different. Thus, a more costeffective solution is required. A Sliceable Bandwidth Variable Transceiver (S-BVT) is able to concurrently serve multiple destinations through individual control of its carriers. This feature is well aligned with the requirements for the BRASes centralization. In a previous work, we proposed a cost-effective OFDM-based SBVT solution using real-valued processing, double sideband modulation and direct detection (DD). For BRAS centralization in a regional network, the S-BVT must be both cost-effective and robust against transmission impairments, in order to support multiple low bit rate connections over regional optical paths of hundreds of km. In this paper, we evaluate the applicability of flexgrid technologies in this evolutionary regional/MAN network scenario, proposing an improved S-BVT architecture based on multiband OFDM (MB-OFDM) and DD. We first analyze a representative network scenario considering a regional domain of the TID Spanish network, to obtain realistic requirements. Then we numerically assess the performance of the proposed S-BVT building block according to those. Furthermore, we experimentally validate our solution within the 4node ADRENALINE photonic mesh network. Network scenario and S-BVT architecture The network scenario consists of a flexgrid metro network, and in particular region-A of TID network, containing 30 optical nodes (Fig.1). The network has to support traffic generated by several Multi-Tenant Unit (MTU) switches that communicate with the centralized pool of BRASes. Actually, for protection purposes, there are 2 centralized BRAS pools and each MTU switch is connected to both of them via two different ingress nodes and node-disjoint lightpaths, as shown in Fig.1. It is assumed that the traffic demand per each MTU (aggregating traffic from lower level OLTs) is 10Gb/s and that traffic at the BRAS nodes is served by S-BVTs. The cost-effective software-defined S-BVT is based on digitally processed MB-OFDM, also referred to as subcarrier multiplexing. It is able to serve NxM MTUs. The array of modulators generates N slices that can be directed towards different destinations nodes. Each MB-OFDM BVT (S-BVT building block) serves M MTUs with a single optoelectronic front-end by using only one laser source and simple/cost-effective DD. The number (M) of MTUs per MB-OFDM slice (corresponding to a single optical carrier n) is limited by the bandwidth of digital-to-analog converter (DAC) and optoelectronic components (we consider 10GHz bandwidth devices). Combining DD with single sideband (SSB) modulation, longer elastic optical paths can be supported, thanks to the enhanced robustness to chromatic dispersion (CD). This requires a guard band (BG) and an optical filter at the transmitter (BVTx). The worst optical path to be covered is calculated for the regional topology and traffic at hand. As shown in Fig 1, the MTU channels can be formed by a variable number (L M) of sub-bands (BSk) at variable rate, enabling distance-adaptive transmission. Fig. 1: Network scenario (top left); TID region-A topology and ADRENALINE photonic mesh network (bottom left), dotted and dashed lines indicate 2-hop paths of 85km (path1) and 185km (path2); S-BVT architecture based on MB-OFDM (on the right). The transceiver digital signal processing (DSP) supports multiple m-QAM formats. By considering narrow sub-bands, the flexibility and spectral efficiency can be enhanced (reducing BG), and the DSP requirements relaxed. Furthermore, the mixing between optical carrier and OFDM signal can also be reduced by properly adjusting the MZM biasing point. For a software-defined OFDM band tuning over the spectrum, the radio frequency (RF) mixing is performed in the digital domain, resulting in a cost-effective solution (no additional hardware).

Emerging cloud applications such as real-time data backup, remote desktop, server clustering, etc. require not only more traffic being delivered between datacenters, but also dedicated and application-specific virtual optical network (VON) services to support each application's QoS and SLA level. On the other hand, another requirement is to support end-to-end network service provisioning across multiple VONs comprising different transport (e.g. Flexi-grid DWDM OCS, OPS, etc) and control plane technologies (e.g., centralized OpenFlow or distributed GMPLS). This paper presents the preliminary architecture of the network virtualization, control and orchestration layers proposed in the STRAUSS project.

Optical networks and Internet Protocol/Multi-Protocol Label Switching (IP/MPLS) based networks have been traditionally designed and operated by separate departments of network operators. Likewise, both layers have always represented different business areas for system providers, which maintain different product lines for each of them. However, network operators have an IP/MPLS over WDM architecture. The main drivers for this unique transport network are the cost savings achieved by simplifying the network infrastructure. Thanks to the advent of reconfigurable optical equipment and a multi-layer control plane, 1+1 node protection at the IP layer in each location is no longer required. This work compares two resilience strategies on multi-layer network dimensioning: dual-plane protection and a multi-layer shared backup router (MLSBR). Based on the results of this paper, a MLSBR provides a significant reduction (up to 24%) on the required IP equipment in comparison with the IP protection approach.

ABNO architecture is proposed in IETF as a framework which enables network automation and programmability thanks to the utilization of standard protocols and components. This work not only justifies the architecture but also presents the first experimental demonstration.

Metro and core networks have been traditionally designed and managed by different departments within network operators. Moreover, even in the cases where both metro and core networks are based on the same technology, e.g. MPLS, services need to be provided separately per domain. This historic separation is now being questioned in light of the potential cost efficiency and lower time-to-market that an end-to-end service provisioning could bring, especially in a cloud ready context, where the traffic demands are less predictable and fast provisioning is needed. This paper presents the drivers, enablers and challenges for an end-to-end service provisioning, in which a multi-layer IP/MPLS over WDM core and MPLS based metro networks are coordinated to support dynamic service provisioning. The feasibility of the end-to-end service provisioning is demonstrated in an experimental activity using commercial IP/MPLS routers, optical nodes and a network controller triggering control plane mechanisms.

This paper reports on the first user/application-driven multi-technology optical sub-wavelength network for intra/inter Data-Centre (DC) communications. Two DCs each with distinct sub-wavelength switching technologies, frame based synchronous TSON and packet based asynchronous OPST are interconnected by a WSON inter-DC communication. The intra/inter DC testbed demonstrates ultra-low latency (packet-delay

Orchestration between multiple layers requires a standard architecture to enable such coordination in multi-vendor scenarios. This work proposes an architecture to solve multi-layer orchestration and experimentally validates topology dissemination in a multi-vendor environment.

Current inter-data-center connections are configured as static big fat pipes, which entails large bit rate over-provisioning and thus high operational costs for DC operators. On the other hand, network operators cannot share such connections between customers, because DC traffic varies greatly over time. Those connections are used to perform virtual machine migration and database synchronization among federated DCs, allowing elastic DC operations. To improve resource utilization and save costs, dynamic inter-DC connectivity is currently being targeted from a research point of view and in standardization form. In this article, we show that dynamic connectivity is not enough to guarantee elastic DC operations and might lead to poor performance provided that not enough overprovisioning of network resources is performed. To alleviate it to some extent, we propose using the flexgrid optical technology that enables finer spectrum granularity adaptation and the ability to dynamically increase and decrease the amount of optical resources assigned to connections. DCs can be interconnected through a flexgrid-based network controlled using a centralized software defined network, based on the architecture currently being proposed by the IETF; a cross-stratum orchestrator architecture coordinates DC and network elastically. Illustrative results show that dynamic elastic connectivity provides benefits by reducing the amount of overprovisioned network resources and facilitating elastic DC operations. The research leading to these results has received funding from the European Community’s Seventh Framework Pro- gramme FP7/2007-2013 under grant agreement no. 317999 IDEALIST project. Moreover, it was supported by the Span- ish science ministry through the TEC2011-27310 ELASTIC project.

This paper investigates the most favorable conditions for a full defragmentation procedure when evolving from a fixed to a flexible-grid scenario. Results show that migrating legacy channels to flexible-grid formats can yield up to 50% more capacity for future traffic, provided these legacy channels are also spectrally re-planned.

Multi-layer integration is an important trend in the telecom industry as a cost-efficient alternative. From an incremental CapEx analysis, we aim to quantify the maximum cost savings that could be achieved by such integration.

OBS-based metro-regional networks can be interconnected through WSON networks to offer inter-data center connectivity. This paper validates, in a multi-partner testbed, the application of the H-PCE architecture for path computation in such Multi-layer, Multi-domain networks.

Network operators want to deliver multiple services to the end customers. This leads to the need of efficient transport of data using optical network technologies. OBS is a promising technology for metro networks, where the operator can locate their servers to provide services such as video, backup or PC virtualization. These services are competing for shared network bandwidth when running in parallel. This work develops an FPGA-based access edge node, which operates with multiple QoS applications. This paper describes the architecture of the design as well as the behaviour of the implemented solution.

In this paper the uncertainties and the implied level of risk associated with next-generation network architectures is modelled using Monte Carlo simulation, aimed at understanding network economics evolution. A high number of network parameters - like incremental network deployment, data centre location, network architecture, service mix, traffic growth and subscriber take-up - are modelled. A wide range of values is used for these parameters to gain understanding of their impact on network cost. Such an approach provides insight into the risk level undertaken by operators when building their network infrastructure based on a specific forecast. Thus, the core result of this analysis is that a sub-wavelength optical packet forwarding technology can de-risk network investments by 500% when compared to a next-generation IPoDWDM solution. Second, in a scaled network scenario the sub-wavelength solution also provides 150% capital savings. Finally, on the medium and long term the sub-wavelength approach yields a cost benefit for 99.8% of the configurations, when compared to an IPoDWDM architecture.

Routing in dynamic OFDM-based optical networks by simultaneous optimization of allocated spectrum and transponder reach is proven beneficial when flexi-grid technology is used regarding blocking performance and spectral efficiency when compared to standard-grid counterpart.

This paper summarises the modelling results obtained with a sub-wavelength optical packet switching technology, called OPST (Optical Packet Switch and Transport), when compared against an IPoDWDM solution. In particular, the impact of data centre location in the network on the network cost is studied for two architectures based on different technologies. Data centre location, routing strategies, service mix, traffic growth and subscriber service take-up is modelled to obtain a broad view about the cost sensitivities in these networks. The main contribution of the paper is to demonstrate that resilience to data centre location and changing traffic patterns enable the sub-wavelength packet optical solution to achieve cost savings of 150% when compared to the IPoDWDM approach. Such flexibility of the packet optical solution also enables 100–300% of power consumption cost reduction and an average 150% savings on rack cabinets for typical configurations.

The impact of the frequency grid on the CAPEX required to deploy a multi-layer IP/MPLS-over-EON is analyzed. Results showing significant savings at the electronic layer motivate the introduction of narrower grids with enhanced BV-WSS.

This paper discusses the requirements and motivations for setting-up and utilizing two different optical fiber test-beds both of a Telecom Operator as well as the UEssex/JANET Aurora field fiber testbed for optical metro networks research within the EU ICT MAINS project. Using both test-beds the MAINS project aims to evaluate its proposed mesh-ring topologies which feature innovative sub-wavelength switching nodes. Different research and technology attributes are considered for evaluation over the research and real commercial environments. The paper illustrates how the first test-bed scenario is designed to experimentally analyze multi-technology interoperability both at the data and control planes and how the second test-bed scenario with the use of a virtual PC application over sub-wavelength switching ring network aims to validate the proposed solutions with real customers and obtain supportive statistics and performance measures.

Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. V. López, J. L. Añamuro, V. Moreno, J. E. L. De Vergara, J. Aracil, C. García, J. P. Fernández-Palacios, and M. Izal, "Implementation of multi-layer techniques using FEDERICA, PASITO and OneLab network infrastructures", in 17th IEEE International Conference on Networks, ICON 2011, p. 89-94, This paper describes an implementation of multilayer techniques using the network infrastructure provided by FEDERICA, PASITO and OneLab projects. FEDERICA project provides a network infrastructure, based on virtualization capabilities in both network and computing resources, which creates custom-made virtual environments. PASITO is a layer- 2 network that connects universities and research centers in Spain. OneLab measurements tools allow carrying out highaccuracy active network measurements. Thanks to FEDERICA and PASITO, we have a multi-layer architecture where the traffic is routed based on the measurements of OneLab equipment. To carry out this experiment, we have developed a Multi-layer Traffic Engineering manager and an implementation of the Path Computation Element Protocol to solve the lack of a control plane in IP oriented networks. This work shows the feasibility of multilayer techniques as a convenient solution for network operators and it validates our Path Computation Element implementation., This work has been partially funded by the Spanish Ministry of Education and Science under project ANFORA (TEC2009-13385), by the Spanish Ministry of Industry, Tourism and Trade under PASITO project, and by the European Union under project OneLab2 (FP7-224263). Authors would like to thank Mauro Campanella (GARR, the project coordinator of FEDERICA) and Miguel Angel Sotos (RedIris) for their support to carry out this work.

This work defines a HiSpeed File Transfer Protocol (FTP) designed for subwave-length metro optical networks. HiSpeed FTP improves TCP throughput, achieves a high rate in 10Gbps links and avoids penalizing transmission of small packets.

This paper provides an overview of the recent developments in research and the IETF standardization body on using a path computation element in complex telecom networking scenarios such as the multi-layer and multi-domain cases. Implications on the control plane when using such element are addressed as well as the required protocol extensions. The emerging impairment-aware routing and wavelength assignment problem is extensively treated for networks using lightpaths.

This paper evaluates the balance between the cost of multifibres and the cost of wavelength converters in multilayer networks. A novel ILP formulation of the static planning problem is applied.

Three recovery mechanisms are implemented with the end-to-end signaling capabilities The results presenting the network equipment interface requirements and recovery time performance confirm the advantages of cross-layer coordination of the IP/MPLS data client networks served by a GMPLS transport network

Network operators have been facing big changes since IP traffic began overwhelming other kinds of data transport. On the other hand, access networks are continuously improving and it is anticipated that bandwidth demands will exponentially increase within next decade to cope with triple-play service requirements. The first level of aggregation, namely metro access networks, can become the bottleneck if no serious modifications are carried out because they were initially designed for circuit-oriented services such as analogical voice transmission and they can not keep up with bandwidth demands at reasonable Capital Expenditure efforts. In this paper, the authors present a migration roadmap for metro access networks derived from the results of NOBEL, ePhoton/One and FIRM European research projects. To achieve it, Dual Bus Optical Ring Network (DBORN), Resilient Packet Ring (RPR) and Optical Circuit Switched Rings (OCSR) architectures have been analyzed both from the technological and the economic point of view in the short and medium term.

In this paper we evaluate routing strategies for OBS networks taking as a base the MRDV routing protocol. This protocol allows to perform load-based dynamic routing and it also incorporates a hysteresis mechanism to account for sudden load shifts. In this paper, we consider two link metrics: load and blocking probability. The results show that load-based link metrics provide a smoother response of the routing protocol. Thus, a load-based approach for MRDV provides a viable routing protocol for OBS networks.

It is widely acknowledged by operators and market analysts from all parts of the telecommunications industry that bandwidth demand is increasing dramatically, year by year. This traffic growth highly impacts on all network segments and pushes network operators to consider new networking solutions. Flexi-grid technologies enable more flexible use of the spectral resources, increasing the overall network spectral efficiency. However, the currently deployed fixed-grid dense wavelength division multiplexing (DWDM) optical infrastructure might be replaced with new components to enable this technology. This paper first identifies a realistic expectation of modulation formats for the next 10 years and quantifies the possible capacity gains. Second, we study when the capacity will be exhausted using current fixed-grid optical channel assignment, and compare this with a pack of novel evolution strategies toward flexi-grid. Results show that the capacity will be exhausted by 2019 in the Spanish core network, and that by applying the flexi-grid evolutionary model, the network life can be extended up to five years. A shorter-term rationale to migrate to flexi-grid is the availability of cost-effective 400 Gbps and 1 Tbps transmission.

The ever-increasing Internet Protocol (IP) traffic volume has finally brought to light the high inefficiency of current wavelength-routed over rigid-grid optical networks in matching the client layer requirements. Such an issue results in the deployment of large-size, expensive, and power-consuming IP/Multi-Protocol Label Switching (MPLS) layers to perform the required grooming/aggregation functionality. To deal with this problem, the emerging flexgrid technology, allowing for reduced-size frequency grids (usually referred to as frequency slots), has recently attracted much attention among network operators, component and equipment suppliers, and the research community. In this paper, we tackle the multilayer IP/MPLS-over-flexgrid optimization problem. To this end, an integer linear programing formulation and a greedy randomized adaptive search procedure (GRASP) metaheuristic are provided. Using GRASP, we analyze the cost implications that a set of frequency slot widths have on the capital expenditure investments required to deploy such a multilayer network. For the sake of a compelling analysis, exhaustive numerical experiments are carried out considering a set of realistic network topologies, network equipment costs, and traffic instances. Results show that investments in optical equipment capable of operating under slot widths of 12.5 GHz, or even 25 GHz, are more appropriate, given the expected traffic evolution.