AT&T said it used an internally developed software-defined networking (SDN) controller to help the company complete the first part of a multi-phase trial testing 400 Gb/s Ethernet (GbE) data speeds. During the trial, AT&T was able to establish a 400 GbE connection between New York and Washington, D.C.
An AT&T spokesman told SDxCentral that the SDN controller operates in the company’s Enhanced Control, Orchestration, and Management (ECOMP) framework using an OpenDaylight design. AT&T originally created ECOMP, but the platform is now in the process of being merged with the Open-O project by the Linux Foundation. The new name for the combined group is the Open Network Automation Platform (ONAP).
AT&T said the controller accepts user requests to configure the 400 GbE circuits between endpoints and then uses a previously auto-discovered inventory and topology database to determine the shortest path over which to configure that circuit.
Once the path is established, the SDN controller pushes requests to implement the configuration down into the ROADM Node Controller (RNC). ROADM, which stands for reconfigurable optical add-drop multiplexer, is a traffic flow’s on-ramp to the optical network and is carried on one of dozens of wavelengths traveling down an optical fiber.
In AT&T’s case, the RNC was provided by a ROADM technology supplier that knows how to set specific photonic parameters along the path to implement the connection. The RNC used a REST API to perform this function.
AT&T said it initially allowed the application to route the connection on the shortest path from New York to Washington, D.C. It then added a constraint that made the direct fiber between New York and Washington, D.C. unavailable for the 400G circuit, causing the app to select a new path via the Philadelphia ROADM. The app selected the next best available path, and the RNC took care of all the detailed parameter configuration needed to remove the old connection and create a new one.
This test was important for AT&T because it determined that if AT&T were to have a fiber cut, the SDN controller would be alerted and be able to reroute traffic.