Service providers want to simplify their network operations in order to drive efficiencies, but their strategies for managing coherent pluggables vary. Ciena’s Marie Fiala describes the cutting-edge proof-of-concept conducted by Ciena and BT Group Research that validated multi-vendor interoperability for simplified management of coherent pluggables.

There’s been a lot of discussion and activity in the industry about converged IP/optical networks and the approaches for the management of coherent pluggables. In a recent survey conducted by Heavy Reading, operators were split on the best management approach, correlated primarily to their specific technology role.

Figure 1: Findings from “Open, Automated, and Programmable Transport Networks:
2024 Heavy Reading Survey”, September 2024

Surprisingly, 13% of respondents said that no controller is needed for the management of coherent pluggables in routers. This highlights the need for continued dialogue about performance management requirements for coherent optics. Long gone are the days of ‘set and forget’ optical networks. Today’s growing bandwidth demands and business expenditure constraints require fine-tuning of coherent pluggables – as well as transponders – in order to extract the most capacity out of the optical assets that form the critical underlay of internet and cloud applications. Furthermore, correlation of performance metrics, alarms, and power levels from routers, pluggables, and the line system is essential for rapid troubleshooting, fault isolation, and repair.

Exploring this concept further, BT Group’s Research team decided to trial a new management approach: to extend the optical controller scope to manage the coherent pluggables via a direct interface to the routers. This approach eliminates the additional complexities of a separate hierarchical controller which would require time and effort for integration testing, as well as periodic regression testing of multiple third-party controller interfaces whenever software updates were applied. Such a streamlined approach aligned well with Ciena’s advocated position and product capabilities.

“This trial has enabled us to demonstrate the feasibility of integrating coherent pluggables within existing networks to meet required performance needs. With an ambition to simplify our networks to drive efficiencies, technologies like this will be key to enable converged IP and optical networks to be managed effectively” said Andrew Lord, Senior Manager of Optics research at BT.

Figure 2: Management approach adopted in BT Group’s proof-of-concept

Implemented in August, this trial architecture leveraged open industry-accepted OpenConfig data models and NETCONF and gNMI interfaces between Ciena’s Navigator Network Control Suite and a third-party router for management of  Ciena’s WaveLogic 5 Nano coherent pluggables (in a QSFP-DD form factor) in the third-party host router, carried over a Ciena 6500 open line system (OLS).

Coherent pluggable attributes were able to be easily tuned (e.g. power levels, center frequency) to meet required performance needs (e.g. distance, capacity). Moreover, coherent pluggables were able to be seamlessly integrated into operational workflows for topology discovery, visualization, alarm correlation, performance metrics monitoring, and configuration across IP and optical layers. Management of the coherent pluggables was proven to be at parity with transponders including advanced applications such as Problem Analysis to facilitate fast troubleshooting. Additional capabilities are planned to be exercised in the future, such as Liquid Spectrum’s Channel Margin Gauge which provides real-time visibility into the Signal Noise Ratio (SNR) margin for wavelengths, supported by coherent pluggables, to identify whether capacity can be upgraded. This comprehensive level of visibility and functionality from a single point of control – without having to learn yet another tool – saved significant manual effort and time.

Figure 3: Visualization of detailed power level readings along the photonic path between Ciena coherent pluggables in third-party router hosts

Figure 4: Clear fiber fault detection along path between Ciena coherent pluggables in third-party host over Ciena 6500 OLS

This proof-of-concept with Ciena and BT Group sets the stage for future research collaborations in the area of converged network operations. In addition to demonstrating operational simplicity, the work underscored the value of open interfaces between hardware and software network components. This ultimately provides a service provider with flexibility of choice of best-of-breed component vendors, while curtailing operational complexity.