Internet2, in collaboration with Cisco, is demonstrating a production-ready deployment of 400G ZR+ optics across its national backbone at OFC 2025—showcasing a major leap toward scalable, open, and power-efficient long-haul networking. The deployment integrates Cisco 8000 Series routers with QSFP-DD ZR+ coherent pluggables, enabling high-capacity optical transport over spans exceeding 1,500 kilometers without the need for external transponders. This marks a significant milestone in validating IP-over-DWDM architectures for research and education networks at national scale.
The Internet2 upgrade leverages QSFP-DD coherent pluggables operating in the open ZR+ standard, allowing direct insertion into router ports without the need for transponders. This simplifies the architecture, reduces power consumption, and supports high-density deployments. Internet2 reports successful 400G ZR+ transmission across spans exceeding 1,500 km using open line systems and commodity IP routers—critical for supporting data-intensive research in fields like climate science, genomics, and AI.
The network is designed with flexibility in mind, supporting a mix of short-haul and long-haul use cases, and demonstrating seamless interoperability among equipment from multiple vendors. Internet2’s architecture validates that ZR+ can meet production requirements in a multi-vendor ecosystem—aligning with global trends to adopt IP-over-DWDM as a primary model for scalable backbone evolution.
• Internet2 showcases operational 400G ZR+ deployment across long-haul national backbone.
• Uses QSFP-DD coherent pluggables integrated directly into IP routers.
• Demonstrates 400G transmission across >1,500 km spans using open line systems.
• Eliminates need for external transponders, reducing complexity and power usage.
• Multi-vendor interoperability validated in production use.
“Just a short time ago, we could only achieve 3,000 km distances using traditional module-based transponders, and the links were limited to 100 Gbps. Now, in collaboration with Cisco, Internet2 has demonstrated 400 Gbps at those same distances using coherent optics. This represents a remarkable improvement in achievable transmission distance, allowing us to provide highly efficient, targeted bandwidth to support emerging needs in the research and education community.” — Chris Wilkinson, Senior Director of Network Infrastructure and Operations, Internet2
“This breakthrough trial with Internet2 marks a game changer in long-haul networking. Cisco’s next generation 400G ULH coherent optics redefine capacity and flexibility, delivering unmatched performance and efficiency across vast distances.” — Bill Gartner, Senior Vice President and General Manager, Optical Systems and Optics, Cisco
