Lluis Gifre

Experimental assessment of in-operation spectrum defragmentation

Dynamic operation of flexgrid networks might cause optical spectrum to be divided into fragments, which makes it difficult finding contiguous spectrum of the required width for incoming connection requests, leading thus to an increased blocking probability. To alleviate to some extent that spectrum fragmentation, the central frequency of already established connections can be shifted to create wider contiguous spectrum fragments to be allocated to incoming connections; this procedure is called spectrum defragmentation. In this paper, we propose using the so called applications based network operations (ABNO) architecture, currently under standardization in the IETF, to deal with the defragmentation use case while the network is in operation. A workflow involving several elements in the ABNO architecture is proposed and experimentally assessed in a distributed test bed connecting facilities in three major European cities.

Experimental Assessment of ABNO-Driven Multicast Connectivity in Flexgrid Networks

The increasing demand of internet services is pushing cloud services providers to increase the capacity of their data centers (DC) and create DC federations, where two or more cloud providers interconnect their infrastructures. As a result of the huge capacity required for the inter-DC network, the flexgrid optical technology can be used. In such scenario, applications can run in DCs placed in geographically distant locations, and hence, multicast-based communication services among their components are required. In this paper, we study two different approaches to provide multicast services in multilayer scenarios assuming that the optical network is based on the flexgrid technology: 1) establishing a point-to-multipoint optical connection (light-tree) for each multicast request, and 2) using a multipurpose virtual network topology (VNT) to serve both unicast and multicast connectivity requests. When that VNT is not able to serve an incoming request as a result of lack of capacity, it is reconfigured to add more resources. A control plane architecture based on the applications-based network operations (ABNO) one, currently being standardized by the IETF, is presented; workflows are proposed and PCEP extensions are studied for the considered approaches. The experimental validation is carried-out on a testbed setup connecting Telefonica, CNIT, and UPC premises.

Experimental Demonstration of Multivendor and Multidomain EON With Data and Control Interoperability Over a Pan-European Test Bed

The operation of multidomain and multivendor EONs can be achieved by interoperable sliceable bandwidth variable transponders (S-BVTs), a GMPLS/BGP-LS-based control plane, and a planning tool. The control plane is extended to include the control of S-BVTs and elastic cross connects, which combine a large port-count fiber-switch (optical backplane) and bandwidth-variable wavelength-selective switches, enabling the end-to-end provisioning and recovery of network services. A multipartner testbed is built to demonstrate and validate the proposed end-to-end architecture. Interoperability among S-BVTs is experimentally tested between different implementations. In this case, transponders are configured using the proposed control plane. The achieved performance with hard-decision and soft-decision FECs using only the information distributed by the control plane is measured against the performance of the single-vendor implementation, where proprietary information is used, demonstrating error-free transmission up to 300 km.

Experimental assessment of a high performance back-end PCE for Flexgrid optical network re-optimization

A specialized high performance Graphics Processing Unit (GPU)-based back-end Path Computation Element (PCE) to compute re-optimization in Flexgrid networks is presented. Experimental results show 6× speedups compared to single centralized PCE.

Virtual Network Topology Adaptability Based on Data Analytics for Traffic Prediction

The introduction of new services requiring large and dynamic bitrate connectivity can cause changes in the direction of the traffic in metro and even core network segments throughout the day. This leads to large overprovisioning in statically managed virtual network topologies (VNTs), which are designed to cope with the traffic forecast. To reduce expenses while ensuring the required grade of service, in this paper we propose a VNT reconfiguration approach based on data analytics for traffic prediction (VENTURE). It regularly reconfigures the VNT based on the predicted traffic, thus adapting the topology to both the current and the predicted traffic volume and direction. A machine learning algorithm based on an artificial neural network is used to provide robust and adaptive traffic models. The reconfiguration problem that takes as its input the traffic prediction is modeled mathematically, and a heuristic is proposed to solve it in practical times. To support VENTURE, we propose an architecture that allows collecting and storing data from monitoring at the routers and that is used to train predictive models for every origin-destination pair. Exhaustive simulation results of the algorithm, together with the experimental assessment of the proposed architecture, are finally presented.

Brokered Orchestration for End-to-End Service Provisioning Across Heterogeneous Multi-Operator (Multi-AS) Optical Networks

This paper proposes a new networking paradigm introducing the broker-plane above the management planes of Autonomous Systems (ASes). The brokers communicate with the manager of each AS to assist coordinate end-to-end resource management and path provisioning across the multi-AS networks involving multiple operators. The broker plane updates the virtual network topology, manages the resource information of inter-AS links and aggregated (abstracted) intra-AS links, and computes end-to-end routing, modulation formats, and spectrum assignment (RMSA). Notwithstanding, due to the different dynamicity of each AS, the probability of finding a multi-AS transparent path fulfilling the spectrum continuity and contiguity constraints might be low. To improve the grade of the inter-domain connectivity service, spectrum converters can be installed in inter-domain nodes or per-AS defragmentation can be performed with a global view. In this paper, we introduce a mechanism where each AS can advertise its internal capabilities, e.g., spectrum conversion, their ability to implement spectrum defragmentation or any other network feature. The Multi-AS RMSA with Defragmentation Capability problem is presented and mathematically modeled. A heuristic algorithm is designed to solve it. The mechanisms workflow is comprehensively tested using simulations. Results show connection blocking reduction as high as 26%, clearly validating the benefits of the proposed mechanism. Finally, its experimental assessment was conducted on a distributed multi-continental testbed.

Big data analytics in support of virtual network topology adaptability

ABNOs OAM Handler is extended with big data analytics capabilities to anticipate traffic changes in volume and direction. Predicted traffic is used as input for VNT re-optimization. Experimental assessment is realized on UPCs SYNERGY testbed.

On-demand incremental capacity planning in optical transport networks

Incremental planning is performed periodically to decide how a backbone optical network has to be updated to serve the forecast traffic during the next planning period. Based on reliable traffic prediction, new equipment is installed and its capacity is ready to be used. Nonetheless, due to the introduction of new services among other reasons, exact prediction is not usually available. This leads to the installation of more capacity than required, thus increasing network expenditures. In this paper, we propose to reduce expenses by incrementing the capacity of the network as soon as it is required to meet the target performance. Hence, performance metrics are monitored and the incremental capacity (INCA) planning problem is solved on-demand when some metrics drop under a threshold. The INCA problem is mathematically modeled and a heuristic algorithm is proposed to solve the problem in practical computation times. Since solving the INCA problem requires access to both operation and inventory databases, an architecture to support on-demand network planning as well as a model for the inventory is proposed. Exhaustive simulation results, together with its experimental assessment, validate the proposed on-demand INCA planning.

iONE: An environment for experimentally assessing in-operation network planning algorithms

Huge amount of algorithmic research is being done in the field of optical networks, including Routing and Spectrum Allocation (RSA), elastic operations, spectrum defragmentation, and other re-optimization algorithms. Frequently, those algorithms are developed and executed on simulated environments, where many assumptions are done about network control and management issues. Those issues are relevant, since they might prevent algorithms to be deployed in real scenarios. To completely validate network-related algorithms, we developed an extensible control and management plane test-bed, named as iONE, for single layer and multilayer flexgrid-based optical networks. iONE is based on the Applications-Based Network Operations (ABNO) architecture currently under standardization by the IETF. iONE enables deploying and assessing the designed algorithms by defining workflows. This paper presents the iONE test-bed architecture, describes its components, and experimentally demonstrates its operation with a specific use-case.

Carrier SDN for flexgrid-based inter-datacenter connectivity

Managing inter-datacenter (DC) connectivity to transport increasing amounts of data and optimize DC performance and costs becomes a challenge not only for DC operators but also for network operators. Current inter-DC connections are configured as static big fat pipes, resulting in large bitrate over-provisioning thus increasing operational costs for DC operators. Furthermore, because of the nature of inter-DC traffic, which highly varies during the time, network operators cannot share such connections with other customers, and network resources may be underutilized. Therefore, an increasing number of studies are being carried out with the aim to address different challenges arising from inter-DC connectivity requirements. This paper summarizes connectivity models and results showing remarkable advantages of considering carrier software defined network (SDN) and elastic operations for managing inter-DC connections.