For the telecom networks, software-defined networking (SDN) brings an extra wrinkle — the question of how to make all the old telecom software cope with this new, dynamic environment.

Operations support systems and billing support systems (OSS/BSS) are the software that overhangs a telco's entire business. They're crucial, but they were developed for the old telecom networks, where connections were made one at a time and stayed in place for a while.

And they won't change easily, as a couple of sessions at this week's Ethernet and SDN Expo, in New York, highlighted.

"The current OSS system is broken, and it's going to be replaced," said Ralph Santitoro, director of strategic market development for Fujitsu Network Communications (pictured above). "You can no longer patch it. It's too expensive; it's a 20- to 25-year-old architecture; it doesn't follow the new paradigms."

"We need an action-state-centric approach," said Carl Moberg, vice president of marketing at Tail-f Systems. While that sounds very action-packed, what he meant was that the new OSS would have to be a real-time beast, acting on information that keeps it in sync with network state.

But the issue goes beyond the need to provision connections quickly. SDN messes up a traditional OSS's entire understanding of the network. For example, provisioning can become a multilayer affair, with packet and optical layers provisioned in conjunction — going against the current model of isolated network layers.

The presence of the SDN controller also presents a challenge.

"Management and orchestration with this controller is radically different," said Margaret Chiosi, distinguished network architect at AT&T. "This whole concept of an OSS and an EMS [element management system] all the way down, it's actually probably archaic."

Some service providers are already building now OSSs to match the new realities of the network, Santitoro said. Another option would be for telcos to split the problem, keeping today's OSS/BSS running while putting new management structures in place for newer networks, said Nirav Modi, director of software innovations at Cyan.

Some software vendors are trying an end-around, offering ways to provision without messing with the OSS layer. Amartus CEO Michael Kearns presented his company's software-defined service orchestration software, which lets a carrier describe an abstract model of a service. Amartus' Chameleon OS then translates it into terms the OSS can understand.

"You don't leave it up to the OSS to deliver the service, because multiple stovepipe apps [would be] involved," Kearns said.

Maybe the biggest change for telecom operators, though, will involve the multiple organizations of people who now run the network. If everything goes according to plan, manual configuration will be gone, and network operators will become programmers.

"That's a much more difficult problem for telcos to resolve, and if I was the CEO of a telco, that's the issue that would be keeping me up at night," said Graham Finnie, chief analyst with Heavy Reading. "It's probably going to involve redundancies and whole groups being removed from the telco."