Operators team with ONF to develop open disaggregated optical transport

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The ONF has revealed a new an operator-led initiative called the Open Disaggregated Transport Network (ODTN) project, which aims to bring the benefits of open networking to the optical domain by building optical transport networks using disaggregated optical equipment, open and common standards, and open source software.

Founding operators China Unicom, Comcast, NTT Communications, Telefonica and TIM are collaborating to build this open source platform. Each of the five operators has committed to performing lab integration and evaluation of the platform for future transport applications, according to ONF.

Numerous optical equipment vendors are also contributing to the OTDN project, with NEC, Nokia, Oplink and ZTE contributing to the software platform and building full solutions, while CTTC is contributing from academia, and ADVA, Ciena, Coriant, CoAdna, Infinera and Lumentum are participating in lab and field trials.

ODTN aims to drive innovation by delivering an open-source platform for running multi-vendor optical transport networks. According to ONF, ODTN will enable an optical peripherals ecosystem that allows multiple components to be combined and assembled into complete solutions. Just as the SDN movement has disaggregated the data center and operator edge networks, ODTN aims to bring similar benefits to the optical transport network including best-of-breed choice, elimination of vendor lock-in, cost containment and accelerated innovation.

Operators experiencing rapid traffic growth can benefit significantly from disaggregation between the terminal equipment and the optical line system, ONF says. Disaggregation allows for the rapid adoption of the latest transponder technology, which advances at a much faster pace than the line system. Furthermore, open-source and SDN solutions also work to eliminate complex and proprietary element and network management systems (EMS/NMS), leading to their streamlined integration into production networks.

By facilitating choice, ODTN intends to enable a robust market of disaggregated optical peripherals from many suppliers that can be intermixed to build complete solutions. Suppliers can focus on specialty components (e.g., a transponder) without having to build a complete solution themselves, thus focusing on innovation while lowering overall R&D costs. Operators can also select best-of-breed components and avoid vendor lock-in, enabling innovation and flexibility as their network needs grow.

Historically, long-distance DWDM communications has been known to pose technological challenges due to the analog nature of optics. This complexity has long been the basis of reasoning for requiring vertically integrated solutions – however, ODTN is taking an approach designed to bridge this gap. To ease optical distance and transponder compatibility issues, ODTN will assume that every optical link uses a matched pair of transponders from a single vendor. But unlike single vendor solutions, the network can use a different brand of transponder for each colored wavelength link, and these transponders can run over an open line system from yet another supplier.

ODTN will leverage the ONF’s ONOS SDN Controller to automatically and transparently discover the disaggregated components and control the entire transport network as a unified whole, thus enabling multi-vendor choice.

The ODTN project will address increasingly complex network scenarios, starting with relatively simple point-to-point DCI (data center interconnect) solutions and then expanding to include meshed networks with ROADM capabilities.

Leveraging other projects

The ONF adds that while ODTN is the only open-source solution in the optical transport space, the project is leveraging other ongoing work which has focused on standardizing various interfaces and components.

For example, ODTN will leverage and expose TAPI as its northbound interface, leveraging the work coming out of the ONF’s Open Transport Configuration and Control (OTCC) project. Likewise, OpenConfig is the base southbound model and API for communicating to optical equipment.

The OpenROADM MSA defines interoperability specifications and data models for optical devices, networks and services. ODTN benefits from this effort and, over time, it helps the industry achieve transponder compatibility. This could eliminate the need to deploy transponders in matched pairs, further disaggregating the solution and enabling even greater deployment flexibility.

Meanwhile, TIP’s Open Optical & Packet Transport project is producing open DWDM architectures, models and APIs, covering transponders, open line systems, and routers. In time, the ODTN project hopes to benefit from the availability of open optical hardware coming from the TIP work. Similarly, the TIP project can leverage the open source work coming out of ODTN on TIP white box hardware building blocks (such as Voyager).

“Disaggregation is producing very effective results in many areas of networking, including the areas of Ethernet, RAN and PON broadband access. By disaggregating optical transport networks, we expect to yield similar benefits such as the ability to build more cost effective networks while giving us greater ability to innovate rapidly,” said Dr Xiongyan Tang, CTO of network technology research at China Unicom. “We believe that by applying open source to help build a platform out of the disaggregated optical components, we can help move the industry forward rapidly and enable accelerated innovation in the optical domain.”

“It is one of the most innovative technical challenges to deploy open SDN/disaggregation technologies into transport networks. We expect that it will dramatically shorten the service development term and reduce costs,” said Dai Kashiwa, director of NTT Communications and an ONF board member representative of the NTT Group. “The reference design and implementation for ODTN will accelerate this challenge, and provide common usefulness among many service providers.”

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