Recently, at the "ODC'2019 China Optical Communications Development and Competitiveness Forum", Zhang Chengliang, the deputy general manager of China Telecom Technology Innovation Department, published a report on the theme of "open and decomposed optical network". Zhang Chengliang said that the opening and decomposition of optical networks are often decoupling. Opening mainly refers to the decoupling of the vertical, control plane and data plane; the decomposition is mainly horizontal, and the hardware decoupling of the data plane.


China Telecom is planning to collect 10G and below optical modules to promote existing network applications

Zhang Chengliang said that the driving force for the horizontal and data plane hardware decoupling of the optical network mainly comes from the generalization of hardware, thereby reducing costs. Manufacturers can focus on professional components, focus on innovation, and reduce overall research and development costs. Operators can choose the best components to avoid vendor lock-in and achieve innovation and flexibility as network demand grows.

According to Zhang Chengliang, there are currently two different decomposition methods. First, the terminal equipment and the optical line system are partially decomposed; second, each functional module in the network is decomposed into independent devices, thereby achieving complete decomposition.

Regarding the decomposition of equipment functions, Zhang Chengliang believes that taking advantage of the opportunity of optical network decomposition, the possible development direction of transmission equipment forms is from the chassis type to the blade type that adapts to the data center rack, and the equipment power and cooling methods can be optimized .

In terms of optical module and board decomposition, Zhang Chengliang said that by decomposing the optical module from the board, module manufacturers can focus on module research and development, reducing module volume and module power consumption. Equipment manufacturers can reduce overall R & D investment, improve board integration, and reduce board power consumption. According to Zhang Chengliang, pluggable optical modules can reduce equipment cost, volume and power consumption, and their use should continue to be promoted. Circuit test module, promote standardization work, such as CFP2-DCO, and guide its wide application in the industry;

The client-side module promotes separate centralized acquisition under conditions. At present, China Telecom is planning to try centralized acquisition of optical modules of 10G and below.

Regarding the decomposition of the terminal equipment and the optical line system, Zhang Chengliang believes that the partial decomposition method of the Open Line System (OLS) is less difficult than the complete decomposition method. You can use more advanced terminal equipment to independently upgrade and expand capacity on demand. Terminal equipment supports different manufacturers, which can lift the binding of terminal equipment from manufacturers. The change in equipment form brought by decoupling helps promote energy saving and emission reduction of transmission equipment. However, the OLS method also brings issues such as performance evaluation and operation and maintenance management and control that need to be resolved.

Zhang Chengliang pointed out that for OLS, the submarine cable system has taken a step ahead. Especially in the Open Cable construction mode, there have been corresponding advances in the definition of standards, key technologies and test methods, which should be actively promoted and joined.

In Zhang Chengliang's view, the decomposition of optical transmission equipment can begin with the OLS terminal equipment (Pizza Box) facing the metropolitan data center interconnection (DCI) business needs, first the Pizza Box, and then promote its decoupling from the OLS system. It seems that this is the most likely solution for decoupling transmission equipment. It can be the first to be used in metropolitan high-capacity point-to-point WDM or FOADM rings. In the future, it will evolve based on further decomposition such as OLS.

According to Zhang Chengliang, in terms of opening up the optical network, China Telecom has implemented the management and control of client OTN equipment of different manufacturers, adopting Netconf + YANG standard interface, and adopting GCC to realize the interworking between client OTN and central office OTN. Zhang Chengliang said that the client OTN equipment used by China Telecom is provided in a gray box form and is open to the north. It is uniformly controlled by China Telecom's self-developed UMS. It is understood that the trial of the existing network has been completed in Guangdong Telecom.

Zhang Chengliang emphasized that unified access OTN management and control is an important part of the next-generation network management architecture of the transport network, a requirement for CTNet2025 network transformation, and the direction of industry development. China Telecom has carried out corresponding development and pilot work, and will further improve the management and control system to promote its application in China Telecom's existing network.