CORDIS - EU research results

Optical peRformanCe monitoring enabling dynamic networks using a Holistic cross-layEr, Self-configurable Truly flexible appRoAch

Periodic Reporting for period 2 - ORCHESTRA (Optical peRformanCe monitoring enabling dynamic networks using a Holistic cross-layEr, Self-configurable Truly flexible appRoAch)

Reporting period: 2016-08-01 to 2018-01-31

ORCHESTRA EU Horizon 2020 project developed a hierarchical and integrated performance monitoring, optimization, and control architecture for next generation optical networks. The optical network, as any system, has to be observable before being controllable and subject to optimization. In ORCHESTRA monitoring data is collected from coherent optical transceivers which are deployed today in optical networks and can be extended to serve as software-defined optical performance monitors (soft-OPM). To achieve this, state-of-the-art and novel digital signal processing (DSP) algorithms for multi-impairment monitoring were developed and combined with a novel hierarchical monitoring plane that handles monitoring information in an efficient and scalable manner. By using and correlating monitoring information, ORCHESTRA’s control and management plane learns and then optimizes the network. ORCHESTRA provisions lightpaths with low margins and continuously re-optimizes the network to maintain high efficiency, improve the reliability, and simplify maintenance and operation procedures.

Fig. ORCHESTRA observe-decide-act control cycle.

To achieve its ambitious mission, ORCHESTRA set the following objectives:
1. Develop an advanced DSP physical-layer multi-impairment monitoring algorithm suite
2. Develop a holistic approach to Quality of Transmission (QoT) determination for new or adapted lightpaths, using information from distributed software-defined optical performance monitors (soft-OPMs) and advanced correlation algorithms
3. Develop a hierarchical control and monitoring infrastructure providing active and passive monitoring capabilities and rapid network adaptation
4. Develop dynamic optimization procedures for fault management and network re-optimization yielding unprecedented network efficiency
5. Lower the barriers of resource sharing among operators’ domains through the efficient monitoring of alien lightpaths and accurate physical layer SLAs
6. Demonstrate dynamic and highly efficient flexible network operation enabled by soft-OPMs
The future of optical networks is coherent and elastic: operators are deploying an all-coherent, multi-format network, leveraging DSP for modulation/demodulation and for mitigating several physical impairments. ORCHESTRA exploited these evolving trends by developing advanced DSP algorithms that extend existing optical transceivers and use them as soft-OPMs. In addition to typical monitored parameters, ORCHESTRA measures optical signal to noise ratio (OSNR) and filtering effects. A key difference is that, currently, monitoring is used by humans for troubleshooting, while ORCHESTRA uses it to automate network operation and optimization.

A soft-OPM at a receiver provides aggregate measures over a multi-link path. The ORCHESTRA optimization engine analyzes information from multiple soft-OPMs and other monitors (e.g. power monitors) and correlates that with routing information, to provide a variety of advanced capabilities, such as: accurate quality of transmission (QoT) estimation; anticipation, as well as detection and recovery from hard (total link) and soft (QoT degradation) failures.

ORCHESTRA developed a hierarchical control and monitoring infrastructure, extending the emerging ABNO architecture, enabling effective distributed processing of monitored information and fault management, avoiding bottlenecks in traditional centralized control. We developed a new resilience scheme, namely pre-programming, which, in contrast to typical centralized resilience, can be applied locally at the transceiver agents to achieve high re-action speed. NETCONF with appropriate YANG models was used for both monitoring and control functionalities.

ORCHESTRA relies on the feedback from soft-OPMs and developed a planning algorithm to provision lightpaths with reduced margins and operational algorithms to regulate the margins and maintain the efficiency high to continuously re-optimize the network.

Five use cases that harvest the benefits of ORCHESTRA were identified:
• Lightpaths provisioning with reduced margins
• Dynamic network adaptation
• Hard/soft-failure localization and handling
• Optimization during upgrade and maintenance tasks
• Alien lightpaths support

Overall, ORCHESTRA met all its objectives and completed successfully. Detailed technoeconomic studies quantified the benefits of ORCHESTRA when provisioning lightpaths with reduced margins. The added flexibility, the continuously optimized operation and the increased availability of ORCHESTRA network were demonstrated in joint lab experiments in Pisa (SSSA), Paris (NBL) and a field trial in Torino (TIM).

The outcomes of ORCHESTRA led to numerous publications in high impact journals and conferences. Solid progress was made in interactions with IETF and ITU standardization bodies, while the invention of pre-programming was patented.

The project objectives remain relevant and in-line with the partners’ roadmaps as well as with the work programme expected impacts. This is confirmed by the observed increased interest from major optical vendors, telecom operators, and the research community in the directions explored in ORCHESTRA.
Monitoring and Dynamic Network Architecture
ORCHESTRA harvests the monitoring capabilities already present in optical networks, collecting monitoring data from the DSP of coherent transceivers, which are extended to serve as soft-OPM. The use of coherent transceivers as monitors is an improvement over existing management suites, which rely on hardware power monitors. Monitoring is currently used by humans for troubleshooting while ORCHESTRA uses it for automation and optimization.

Software-Defined Optical Performance Monitoring Algorithm Suite
ORCHESTRA developed a flexible transceiver and a fully functional DSP mod/demodulation suite for up to DP-64-QAM formats on top of which we developed a performance monitoring suite. In additional to typical DSP measurements, we developed novel algorithms for filtering effects.

Multiple-Rx Correlation and Optimization Algorithms
Estimating the QoT is required when planning, upgrading, or operating an optical network. Since it is hard to obtain accurate physical parameters and to account for equipment ageing and increased interference, high margins are typically used. ORCHESTRA uses monitoring information that is correlated with routing information, to obtain accurate QoT estimates. Also, lightpaths establishment algorithms (RSA) typically neglect the physical layer or use high margins. We developed an algorithm that takes into account the actual physical performance to provision lightpaths with actual (just enough) margins, and an adaptation toolkit that adapts lightpaths, regulating the margins and operating the network efficiently.

Control and Monitoring Plane and OAM Handler
Recently, several advances were achieved in the data and control planes for optical networks, but the management plane is lagging behind. ORCHESTRA proposed a generic architecture of the OAM Handler and monitoring entities and databases to enable cross-layer optimization. It developed a hierarchical management plane to provide high scalability. ORCHESTRA control and management components, based on new YANG models, are very relevant with the emerging trend of white boxes. Finally, ORCHESTRA innovated a control paradigm named pre-programming which instructs devices to self-reconfigure when events (e.g. physical layer changes) occur.
Fig. 1. ORCHESTRA observe-decide-act dynamic control cycle.