AT&T has shown cross-vendor interoperability of software control over optical networks using the OpenROADM platform. The carrier next plans to tie that work with a software-defined networking (SDN) controller as part of its ECOMP operating system.

Although AT&T turned its ECOMP software over to the Linux Foundation where it morphed into the Open Network Automation Platform (ONAP), AT&T still uses ECOMP internally as its proprietary SDN platform.

In a blog post, Chris Rice, senior vice president of AT&T Labs, and Kathy Tse, director of AT&T Labs’ photonic platform development group, said the test showed interoperability between reconfigurable optical add/drop multiplexers (ROADMs) from different vendors and common management APIs.

AT&T did not release names of the vendors that were part of the interoperability trial.

AT&T was one of the founding members of the OpenROADM initiative, which began in 2016. Besides AT&T, carrier members of the group include SK Telecom, Orange, Saudi Telecom, Telecom Italia, Deutsche Telekom, and KDDI. Vendor partners include Ciena, Fujitsu, Nokia, Cisco, Coriant, Juniper Networks, and Infinera.

ROADMs are like a network switch that manages data traveling across fiber optic lines. Adding software control allows for dynamic bandwidth management. AT&T is using an SDN controller to provide centralized traffic control over its inner-city network.

AT&T is planning to begin deploying its OpenROADM-based equipment in Dallas as part of a metro-area sized trial. The carrier will then move to deploy the technology in all of its ROADM deployments.

AT&T’s OpenROADM MultiSource Agreement is one of several open optical networking initiatives currently underway. Others include the Telecom Infra Project’s Open Optical Packet Transport Group, the Open Networking Foundation (ONF), and the Optical Internetworking Forum (OIF).

IHS defined an open optical network architecture as a combination of hardware and software. The hardware is typically in the form of transponders/terminals, a ROADM, amplifiers, and associated products. The software includes network management, SDN control, analytics, and other applications abstracted from the hardware.

These two worlds are linked by APIs enabling northbound and southbound communications. The northbound interface transports information on the state of the network up to the applications. The southbound interface provides operational instructions down to the hardware.

In an open optical network system, the software component uses an open architecture consisting of open source code, open hardware, and open APIs.

However, the work is not without its controversy.

“Even with strong endorsements from major service providers, there remain many questions and some important barriers to be addressed before open optical networking becomes more widely accepted,” explained IHS Markit senior research director Heidi Adams, in a report. “Key concerns include the loss of spectral efficiency gains; system integration and maintenance; lack of operational tools to manage disaggregated networks; and slow or disparate standards development.”

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