Optical Connections Magazine Spring 2022


can implement, manage, operate, and evolve these networks faster, and can optimize them more comprehensively, including real-time coordination with the upper layers, such as Layer 3 or the IP layer, by improving machine-to-machine communication. Network automation will further accelerate network operations in these networks. However, there are certain barriers in today’s networks, and according to the ACG report, open application programming interfaces (APIs) and standards are the most important and demanded capabilities. These are typically addressed with an intermediate software layer, the so-called software-defined networking (SDN) controller, which provides a way to abstract physical infrastructure and doesn’t require operators to replace legacy hardware. Implementing SDN control and software is an important step in multi- vendor networks today, and more than 70% of operators see it as extremely important or critical for the near future. Many transport network vendors have implemented standard open APIs on their SDN controllers so that their infrastructure is abstracted and digitalized to the latest standards. Vendors are also enabling native open APIs on their platforms and systems based on standard data models such as YANG to accelerate the adoption of their solutions. Additionally, both vendors and service providers are actively participating in industry initiatives such as Telecom Infra Project (TIP), Open ROADM MSA, Internet Engineering Task Force (IETF), and Open Networking Foundation (ONF) to make sure the implementation complies with standards and to ensure interworking, while network operators ensure their use cases, and their interests are covered. The optical SDN controller typically manages the transponders and line system, and it interfaces directly with the network hardware, transponders, and DWDM line system southbound through proprietary interfaces or OpenConfig or Open ROADM and northbound toward the hierarchical controller through, for example, a T-API interface. In case there are more optical vendors to be managed, each vendor deploys its own SDN controller. As the network has more layers, such as IP, these solution providers also deploy their SDN controllers. The hierarchical controller, also called a multi-layer orchestrator, brings all the technology layers together toward the operations support system or business support system with standardized open APIs such as T-API. With such an infrastructure, operations and management are more unified and simplified. Applications such as network analytics, artificial intelligence, and machine learning can now be implemented faster and more easily, which further improves network operations.

Figure 2: Digitalized and transformed end-to-end transport network

In recent years we have seen that the management and operations software architectures of these multi-layer and multi-vendor networks are converging in terms of reference control architectures. From TIP, IETF, ONF, and Open ROADM we see a similar architecture setup. The most recent evolution in the SDN ecosystem is to evolve toward multi- vendor domain controllers. Instead having an SDN controller from each vendor or solution provider, there is a trend to deploy an optical domain controller that manages all optical network equipment regardless of the vendor. Similarly, there is an IP-domain controller that manages all IP network gear. This evolution requires the network elements and systems to support standard open APIs, with OpenConfig YANG data models gaining preference. Management and operations are now more simplified and unified. However, there is still some work to do in the standardizations to cover all requirements and close all gaps. Nonetheless, these evolutions promise to enable faster onboarding of innovative technologies from any vendor as the operational model stays the same and only adoption is required. The diagram below shows such a simplified architecture that networks are currently converging toward. SUMMARY The network transformation journey continues. Telecommunication transport networks and especially optical transport networks are being transformed from hardware-centric, manual, closed and proprietary with reactive operations, toward proactive, open, programmable, automated, and software-driven

networking. We are getting ready for more programmable, automated, and value- driven next-level networking in the era of 5G and cloud networking. Evolved Networks of tomorrow Hardware-centric Software-driven Traditional Networking

Automated and Self-sustaining


Open and Programable






Christian Uremovic, Director of Solution Marketing, Infinera, serves as an evangelist for Infinera’s overall solutions. Previously roles include Director for Technical Solution Sales at Coriant from 2013 until Coriant’s 2018 acquisition by Infinera, and Solution Sales Management at Tellabs from 2010 to 2013, when Tellabs merged with Coriant. Earlier in his career Christian held system sales engineering and business development roles at Nortel and ADVA Optical. Christian holds a diploma degree (Dipl. Ing.) in Telecommunications from FH Mannheim in Germany.



ISSUE 28 | Q1 2022

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