Metro and carrier-grade Ethernet networks, as well as industrial area networks and specific local area networks (LANs), have to guarantee fast resiliency upon network failure. However, the current OpenFlow architecture, originally designed for LANs, does not include effective mechanisms for fast resiliency. In this paper, the OpenFlow architecture is enhanced to support segment protection in Ethernet-based networks. Novel mechanisms have been specifically introduced to maintain working and backup flows at different priorities and to guarantee effective network resource utilization when the failed link is recovered. Emulation and experimental demonstration implementation results show that the proposed architecture avoids both the utilization of a full-state controller and the intervention of the controller upon failure, thus guaranteeing a recovery time only due to the failure detection time, i.e., a few tens of milliseconds within the considered scenario.

Abstract-Network slices combine resource virtualization with the isolation level required by future 5G applications. In addition, the use of monitoring and data analytics help to maintain the required network performance, while reducing total cost of ownership. In this paper, an architecture to enable autonomic slice networking is presented. Extended nodes make local decisions close to network devices, whereas centralized domain systems collate and export metered data transparently to customer controllers, all of them leveraging customizable and isolated data analytics processes. Discovered knowledge can be applied for both proactive and reactive network slice reconfiguration, triggered either by service providers or customers, thanks to the interaction with state-of-the-art software-defined networking controllers and planning tools. The architecture is experimentally demonstrated by means of a complex use case for a multi-domain multilayer MPLS-overoptical network. In particular, the use case consists of the following Observe-Analyze-Act loops: i) proactive network slice rerouting after BER degradation detection in a lightpath supporting a virtual link (vlink); ii) reactive core network restoration after optical link failure; and iii) reactive network slice rerouting after the degraded lightpath is restored. The proposed architecture is experimentally validated on a distributed testbed connecting premises in UPC (Spain) and CNIT (Italy).

Accurate real-time availability of transmission parameters at the network controller has the potential to significantly improve the efficiency of control and management operations, particularly in the case of soft failures where detection and localization procedures are typically affected by the long monitoring time intervals usually adopted in current Elastic Optical Networks (EONs). In this paper, we report on the design, implementation and experimental demonstration of a telemetry service exploiting the gRPC protocol to enable on-demand streaming of real-time monitoring parameters, dynamically retrieved from a configurable set of network devices. The telemetry service is efficiently introduced for Software Defined Networking in EONs, also accounting for disaggregated network elements through standard YANG-defined network models. The implemented telemetry service is experimentally validated for partial and fully disaggregated architectures over networking scenarios where soft failures not addressable through traditional monitoring solutions are successfully detected and localized. Moreover, detailed performance evaluation is conducted varying the number of subscribed network elements, the type of communication (e.g., compressed vs. uncompressed, bundled vs. unbundled), showing remarkable scalability performance particularly in the case of compressed and bundled telemetry configurations.

Segment Routing (SR) technology has been recently proposed to enforce effective routing strategies without relying on signaling protocols. So far, the SR technology has received limited attention within the scientific community. In this paper, two SR implementations are presented and successfully demonstrated in two different network testbeds. The first implementation focuses on a Software Defined Networking (SDN) scenario where nodes consist of OpenFlow switches and the SR Controller is a specifically designed enhanced version of an OpenFlow Controller. The second implementation includes a novel PCE scenario where nodes consist of commercially available IP/MPLS routers and the SR Controller is a new extended version of a PCE solution. Both implementations have been successfully applied to demonstrate dynamic traffic rerouting. In particular, by enforcing different segment list configurations at the ingress node, rerouting is effectively achieved with no packet loss and without requiring the use of signaling protocols. Effective scalability performance is achieved in both proposed implementations, under different segment list conditions.

Disaggregation at the optical layer is expected to bring benefits to network operators by enriching the offering of available solutions and enabling the deployment of optical nodes that better fit their needs. In this paper, we assume a partially disaggregated model with transponder nodes for transmission and ROADMs for switching, where each optical node is conceived as a whitebox consisting of a set of optical devices and a local node controller that exposes a single interface to the SDN controller. An architecture to provide autonomic networking is proposed, including the SDN controller and supporting monitoring and data analytics (MDA) capabilities; YANG data models and software interfaces have been specifically tailored to deal with the level of disaggregation desired. To demonstrate the concept of autonomic networking, use cases for provisioning and self-tuning based on the monitoring of optical spectrum have been proposed and experimentaly assessed in a distributed test-bed connecting laboratories in Spain and Italy.

Use of disaggregated equipment in optical transport networks is emerging as an attractive solution to bring flexibility and break vendor lock-in dependencies. The disaggregation process requires standard protocols and interfaces between the control plane and network equipment. NETCONF has been selected as the standard protocol and multiple initiatives are currently working on the definition of standard models for each type of data plane devices. Different levels of disaggregation of the data plane are under evaluation, and it is still not clear up to which level it will be useful to disaggregate the data plane. The disaggregation of optical networks yielded the development of several SDN-based controllers providing an environment for creating and deploying networking application on optical networks. Among them, the ONOS controller features the most active community with the recent establishment of the ODTN working group, specifically focused on the introduction of required functionality to control and monitor disaggregated transport networks. This paper reports on the state-of-art, potentials and limitations of the ONOS controller applied to disaggregated optical networks with specific focus on the ongoing activities within the ODTN working group. Then, the paper describes a set of experiments performed on a setup including both emulated and real optical devices controlled with ONOS. The performed experiments consider both the establishment of a connectivity service and the recovery of the connectivity in case of failure on the data plane.

Segment routing is an emerging traffic engineering technique relying on MPLS label stacking to steer traffic using the source routing paradigm. Traffic flows are enforced through a given path by applying a specifically designed stack of labels (i.e., the segment list). Each packet is then forwarded along the shortest path toward the network element represented by the top label. Unlike traditional MPLS networks, segment routing maintains per-flow state only at the ingress node, no signaling protocol is required to establish new flows neither to change the routing of active flows. Thus, control plane scalability is greatly improved. Several segment routing use cases have been recently proposed. As an example, it can be effectively used to dynamically steer traffic flows on paths characterized by low latency values. However, it may also suffer from some potential issues. Indeed, deployed MPLS equipment typically supports a limited number of stacked labels. Therefore, it is important to define the proper procedures to minimize the required segment list depth. This work is focused on two relevant segment routing use cases: dynamic traffic recovery and traffic engineering in multi-domain networks. Indeed, in both use cases, the utilization of segment routing can significantly simplify the network operation with respect to traditional IP/MPLS procedures. Original schemes are proposed in this paper and evaluated including a simulative analysis of the depth of the required segment lists. Moreover, an experimental demonstration is performed in a multi-layer testbed exploiting an SDN-based implementation of segment routing.

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