Optical transport networks are facing a fundamental transition. Traffic growth, AI workloads and rising expectations around sustainability are all converging at the same time, while networks themselves are becoming increasingly critical to energy systems, public infrastructure, and economic resilience. Meeting these challenges requires more than incremental improvements. It demands a rethink of how optical networks are designed, monitored, and operated from the outset.

This is the motivation behind the CELTIC-NEXT flagship project SUSTAINET, coordinated by Adtran, and its network‑foundations sub‑project SUSTAINET‑advance, which Adtran is also proud to lead.

From connectivity to critical infrastructure

For many years, optical networking was primarily about capacity and reach. Today, it’s become critical infrastructure, supporting energy systems, research networks and essential public services.
SUSTAINET is a flagship European research initiative, bringing together industry, research institutes and universities to address a shared objective: building communication networks that are sustainable, resilient, secure and fit for a digitally sovereign Europe.

The program is structured into three complementary sub-projects, spanning network foundations, advanced services and security, each addressing a different layer of the challenge.

Led by Adtran, SUSTAINET-advance focuses on the network foundations. Its scope spans optical transmission, monitoring, control and automation, with a strong emphasis on how communication networks interact with energy systems. As networks become more tightly coupled with renewable energy sources and critical infrastructure, they need to be able to adapt dynamically, withstand faults and attacks, and operate efficiently under changing conditions.

From the outset, the project has been about practical progress rather than abstract research. The ambition is to develop architectures, algorithms and demonstrators that can be validated in real network environments and ultimately influence how future optical networks are designed and operated.

Adtran’s role as coordinator

As coordinator of SUSTAINET-advance, Adtran is leading a large, multi-country consortium spanning industry partners, research organizations and operators across Europe and beyond. The role is both technical and organizational. It involves aligning national funding priorities and research goals, ensuring interoperability between workstreams, and keeping a clear focus on outcomes that matter to real networks.

Equally important is the level of commitment behind this work. SUSTAINET-advance represents a substantial long-term investment by Adtran in European R&D. Alongside public funding, we’re contributing significant internal resources, engineering expertise and system knowledge. This is tightly connected to our broader optical networking roadmap and our long-held belief that innovation must be built collaboratively and responsibly.

SUSTAINET is building communication networks that are sustainable, secure and fit for a digitally sovereign Europe.

One of the strengths of SUSTAINET-advance is its holistic view of optical networks. Rather than optimizing isolated components, the project looks at how different layers interact and how intelligence can be applied end-to-end.

A central focus is energy-aware networking. As operators integrate more renewable energy and move toward climate-neutral targets, networks must become more adaptive. This includes understanding energy availability, adjusting operation accordingly and avoiding unnecessary overprovisioning while still maintaining performance and reliability.

Another goal is resilience. Optical networks increasingly support critical services, from power grids to research infrastructures. In SUSTAINET-advance, we’re exploring new concepts for fault detection, recovery and continuity of service, ensuring that networks can maintain operation under adverse conditions, whether caused by technical failures, external disruptions or cyber threats.

AI plays an important role, but with a pragmatic mindset. Rather than treating AI as a black box, the project explores trusted, explainable approaches for monitoring, analysis and control. This includes advanced telemetry, digital twin concepts and automation mechanisms that help operators understand what’s happening in their networks and make informed decisions.

Security is also addressed as a foundational requirement. Zero- trust principles and secure control frameworks are integrated into the network designs being developed, recognizing that future optical infrastructures must be robust against increasingly sophisticated attack vectors.

From research to real-world visibility

The work of SUSTAINET-advance is being fed into publications, demonstrations and broader industry collaboration, helping to share results with the wider optical community. Events such as OFC provide an important platform to exchange ideas, present progress and engage with partners, customers, and peers.

For Adtran, this visibility is about demonstrating sustained leadership in optical innovation and reinforcing our role as a committed European technology partner. Being deeply involved in collaborative programs like SUSTAINET-advance enables us to contribute to the direction of future networks while staying closely aligned with operator needs and regulatory priorities.

Strengthening Europe’s optical future

The challenges facing Europe’s digital infrastructure are complex and interconnected. Addressing them requires long-term collaboration, credible investment and a willingness to look beyond short-term product cycles. SUSTAINET-advance is one example of how this can be done in practice.

By coordinating this project, Adtran is helping to shape the foundations of sustainable, resilient optical networks that will support Europe’s digital ambitions for years to come. It reflects our belief that innovation thrives when industry and research work together, and that optical networking will continue to be a cornerstone of a secure, energy-efficient and technologically sovereign Europe.

Elements of this work are being demonstrated live in the OFC 2026 Demo Zone and at the SUSTAINET booth on the exhibition floor, where attendees can see how collaborative, data‑sovereign approaches to AI‑driven optical networking are being applied in practice. To learn more, visit Adtran in the Demo Zone and on the exhibition floor during OFC 2026.