Software-defined Operations.

The information and communications technologies (ICT) industry made significant steps towards higher efficiency through automation over the last decade. Still, carrier network operations are catching up with other ICT sectors. In this Special Issue, we use the term software-defined operations to refer to approaches that aim to further simplify and automate the daily ICT infrastructure run time and at the same time increasing reliability and enhancing visibility into the state of the system. While traditional observability methods focused on metrics such as delay, loss, or CPU utilization, enhancing the visibility includes exposing internal telemetry data such as buffer occupancy for switch chips and cache miss ratios for multi-core processors, as well as allowing to define aggregate metrics in software and computing them at data plane speeds. Looking back at the evolution of other industries, we could draw some parallels between current telecom operations and the state of vehicle manufacturing at the beginning of the 1970s when Japanese vendors introduced robots and production automation at a large scale. That step advance transformed the automobile industry as a whole and led to more reliable and safer cars. We believe that the ICT industries are headed towards a similar wave of transformation, and the development and adoption software-defined operations will play a central role in this process. Software-defined operations is part of the evolution that started with software-defined networking (SDN), a set of technologies that increased the degrees of flexibility and automation in the management and control planes of the network as discussed in RFC 7426. Control protocols such as OpenFlow and the domain-specific languages associated with configuration management tools such as Chef, Puppet, and Ansible are typical representatives of this approach. Different solutions have emerged using said tools and associated concepts to further optimize the infrastructure and increase the user friendliness towards developers and operations personnel. Software-defined operations are a stepping stone towards autonomic infrastructure, enabling operations personnel to elevate from mundane hands-on configuration tasks to an interaction driven by higher-layer management and control plane abstractions. This is a shift change compared with the myriad of variables and commands that need to be dealt with in daily routines and are currently part of various certification curricula for operations personnel. Using another automobile metaphor, think of competitive motorsports that have also changed much over the last decades. Yet higher-level abstractions (e.g., pressing buttons instead of manually shifting gears) did not eliminate drivers from Formula 1 teams—they just equipped them with more powerful knobs and levers that allowed them to focus on the situation on the track while driving at significantly higher speeds with greater safety. The road towards software-defined operations needs to overcome a series of challenges. Some of them are presented in a document discussed in the Network Function Virtualization Research Group (NFV RG) at the Internet Research Task Force (IRTF). 1 Some prominent challenges include trade-offs in terms of consistency, availability and partitioning (CAP) and observability methods that allow for transparent and programmable specification of compromises between accuracy and the overhead incurred by the infrastructure when measuring values of a certain key performance indicator (KPI). Verification methods adapted to the rapid cycles of resource scale up/down imposed by varying utilization patterns and operator policies were also identified as essential for software-defined operations based on recent research outcomes. 2 This Special Issue focuses on research results that potentially have wide applicability and relevance to simplifying operations in large-scale software-defined infrastructures. Through 2014–2016, the world experienced a significant number of natural disasters that disrupted deployed telecommunication infrastructure: earthquakes, hurricanes, and widespread forest fires. This Special Issue opens with the paper by Ying et al. entitled ‘Prediction Based Survivable Virtual Network Mapping against Disaster Failures’ that timely proposes a solution to optimize virtual network embedding to provide increased survivability in case of disasters. In contrast with the earlier literature, the authors assume that several nodes or links of the substrate network are affected by the disaster. They implement and evaluate two algorithms that attempt to minimize the loss of capacity under these constraints. In the second paper on software-defined operations, entitled ‘ReversePTP: A Clock Synchronization Scheme for Software Defined Networks’, Mizrahi et al. propose a clock synchronization scheme that takes advantage of the split architecture of OpenFlow networks to provide clock synchronization with an accuracy that matches that of the conventional clock synchronization protocol. Furthermore, as a significant part of the method is implemented in the network controller, it simplifies operations so that updates could be deployed faster and with less effort. Clock synchronization is an important enabler for automating operations, allowing the implementation of measurement capabilities and coordinated triggering of changes. The authors note that while the example implementation targets OpenFlow networks, other control protocols that implement a split control/data plane architecture could benefit from their results in environment such as industrial automation or power grid systems. Xuxia et al. in their paper entitled ‘FlowVisor-based cost-aware VN embedding in OpenFlow networks’ revisit the cost-aware network embedding problem and propose two efficient solutions. In terms of software-defined operations, these methods add clarity and transparency on the trade-offs that operators need to make when taking important network planning decisions. Their findings demonstrate the feasibility of delegating such decisions to an automated system while understanding the results and keeping control over the high-level parameters that steer run-time aspects. Finally, the Special Issue contains the paper entitled ‘A Flexible Information Service for Management of Virtualized Software-Defined Infrastructures’ by Mamatas et al. who develop and evaluate a solution for managing data generated by entities in a virtualized software-defined infrastructure. Designed as a flexible information service, the proposed solution was evaluated for scenarios that reflect two key properties: adaptability to new conditions and flexibility with respect to requirements for management data. We would like to express our appreciation to all authors who submitted their work in the journal's peer-review process, as well as the reviewers for their efforts to provide highly qualified reviews. Moreover, the editors would like to extend their gratitude to the editorial board of IJNM and, in particular, to James Won-Ki Hong and Filip De Turck for the great opportunity to serve as Guest Editors for this Special Issue on software-defined operations and for the prompt support during the submission and evaluation processes provided by Yoonseon Han. We acknowledge that part of the work of the editors has received funding from the European Union Seventh Framework Programme FP7/2007-2013 in the framework of the UNIFY project under grant agreement no. 619609.