All-optical switching is the future direction of development, but also from the current development trend, this "future" is not far away. Many in the industry view: ROADM-based networking and scheduling is not sensitive to the rate applicable to ultra-high-speed optical networking and scheduling transmission systems, but also can greatly reduce power consumption and floor room. After years of gradual improvement technology, functionality and performance, CDC-F ROADM (ie colorless and directionless without conflict and supports flexible grid capacity reconfigurable optical forked Multiplexer) device has matured, basically solved the light layer networking encountered many problems. Some foreign operators in the deployment of 100G networks have begun to do large particles using ROADM traffic scheduling, a direct transition to an all-optical network. March 2015, Verizon announced the adoption of Ciena and Cisco's packet optical transport platform Metro 100G deployment, CDC-F ROADM technology for the first time to get a commercial scale. In the same month, Alcatel-Lucent announced that Verizon will use its latest CDC-F ROADM technology to upgrade Verizon's long-haul optical transport network.

Currently, reconfigurable OADM has become the development direction. In addition to using the optical switch dynamically select the upper and lower wavelengths, the use of a tunable filter is a hot spot.

OADM equipment in long haul and metro networks are useless.
◆ In the trunk applications, OADM device of choice up and down business intermediate nodes.

The main function of OADM is separated from the multi-wavelength channels or insertion of one or more wavelengths, there are fixed and reconfigurable two types.

The main advantage of OTN is fully backward compatible, it can build on existing SONET / SDH management functions on the basis of not only the existence of a fully transparent communication protocol, but also for WDM-end connectivity and networking capabilities, It provides a light layer interconnect specification ROADM, and added sub-wavelength aggregation and grooming.

This article discusses the function of WDM technology OADM based systems, the node structure and its products and applications, and its drop multiplexing tributary signals in wavelengths, called optical channel. OADM node device is one of the key equipment of all-optical network.