Openness is creeping into the historically closed world of optical networks, though the adoption of open optical networks is still in early days with a number of hurdles to overcome.

During a recent webinar on the topic, IHS Markit Senior Research Director Heidi Adams said the market is seeing increased pressure to adopt open software solutions “to deliver more open and interoperable optical networks.”

The move has seen a number of initiatives launched toward that goal, including the Open ROADM MultiSource Agreement, the Telecom Infra Project’s Open Optical Packet Transport Group, the Open Networking Foundation (ONF), and Optical Interworking Forum (OIF).

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

These two worlds are linked by application programming interfaces (APIs) enabling northbound and southbound communications. The northbound interface transports information on the state of the network up to the applications, while 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.

The various open initiatives already noted also look to further disaggregate the hardware into separate elements open to greater software control. These include the ROADMs, amplifiers, passives, line cards, switches, and chassis.

Joe Mocerino, principal solutions architect for packet optical networking at Fujitsu, noted during the webinar that the use of SDN is crucial to this move. He said the SDN layer provides a level of integration, visibility, and orchestration that can support end-to-end service level agreements.

“SDN control puts all of this together,” said Mocerino. “Integrating all of that and making it work is where it gets scary for service providers and where the SDN control really plays well.”

Mocerino added this should also reduce operating expense and provide better planning at a lower risk for operators.

A recent report from IHS Markit found a vast majority of service providers cited simplification and automation of network provisioning; simplification and automation of service provisioning; and service automation as the important drivers behind their SDN deployments.

However, breaking everything apart does come with challenges.

Adams said the nascent nature of the market does not include support for stringent interoperability needed to support deployments.

“Interoperability is critical here in terms of hardware disaggregation,” Adams said. “Open can include disaggregation, but is not required for open optical networks.”

There are also potential issues in that providing more choices for a customer could require unavailable resources or paralyze decision-making.

“Most providers are not AT&T and are more limited in resources,” said Scott Wilkinson, senior director for portfolio marketing at ECI Telecom, on the webinar. “For some people this idea of openness is terrifying.”

A more fundamental challenge comes from having the workforce necessary to handle the growing move toward these new network architectures. This is especially tough for smaller players.

“Networks are getting more complex and fewer people are available to work on them at smaller operators,” added Wilkinson.

Both Mocerina and Wilkinson said vendors are attempting to solve issues as quickly as possible as the market is not wavering on its desire for open optical networking solutions. This speed is also needed as vendors are looking to avoid either having standards applied across the market or the potential for greater fragmentation.

“There is a concern that we are moving from where we were in the past with dozens of proprietary implementations and carriers forcing interoperability,” Wilkinson explained. “Now carriers all have their own twists to add to speed up the process and are pushing that down to vendors. We are worried that we will have hundreds of carriers with proprietary implementations. ... If we get too open we get proprietary, and we don’t want that.

Wilkinson said vendors need to work on consolidating solutions or "it will force a standards group to come in, and no one wants that because standards are too slow.”

Despite the hurdles, Adams did provide hope that the market was moving towards a resolution that would allow for more open optical networking deployments.

“As an industry, we are moving towards a common vision of the building blocks and to define open interfaces, what’s open hardware and open software,” Adams said. “I do believe we are starting to evolve and mature key elements.”