The move to production highlighted Day One of the SDN & OpenFlow World Congress, as carrier speakers on Tuesday spotlighted progress in their efforts around software-defined networking (SDN) and network functions virtualization (NFV).

They noted a few frustrations as well — concerns about the vendor community and about the open source projects that are setting the direction for these new networking technologies.

Deutsche Telekom, host to the last few Congresses (this year's edition, like last year's, is being held in the Düsseldorf suburb of Neuss, Germany), is going into production with its Real-Time Network and Service Management, said Axel Clauberg, the vice president and CTO who's spearheaded much of the carrier's SDN work.

VPNs were a popular use case cited by Tuesday's speakers. Clauberg started that pattern by talking about the VPN service launched in March as part of DT's Pan-European Network. "This is really a key initiative within Deutsche Telekom, because it is a complete change in the way we are introducing services," he said.

Claudia Nemat, DT's head of Europe and technology, had approached Clauberg in June 2014 about launching the Cloud VPN service in time for Mobile World Congress the following March, a tight nine-month deadline.

"Sometimes you have to admit you've had a dark moment. I just said, 'Yes, we'll do that,'" Clauberg said. Using Cisco gear and Canonical's OpenStack distribution, his team managed to get the product ready, but it was difficult. "For such an approach, you need to have a team which is willing to deliver in a true DevOps mode. If you have an old way of thinking" — that is, grouping software updates into formalized releases — "it won't work."

His mention of OpenStack is important, by the way. Carriers have become sensitive to vendor lock-in, and that goes for things like cloud orchestration. One way around that is to find open source alternatives — OpenStack being an obvious choice, he said.

At the same time, Clauberg criticized the number of open source initiatives springing up — a complaint he'd shared last year. Among his concerns is that carriers are being spread too thinly among different efforts. He also cautioned against trying to craft formal SDN/NFV standards just yet, "because we are just gaining the first operational experience. After we do that, that is the time to make standards."

Like Clauberg, Vodafone’s David Amzallag, head of network virtualization, talked about a VPN service. Vodafone's VPN offerings differ by country; the hope is that SDN and NFV can create "one single VPN product worldwide," he said.

The unified VPN service will be the first example of what Vodafone is calling its Application-Ready Network. Amzallag gave no timeframe for the project but said it would be launched "soon."

Vodafone expects SDN and NFV benefits to come on the operational side, in areas such as automation. The carrier's larger goal is to build one end-to-end SDN and NFV platform, one common set of ingredients for building new networks. What's missing are the interfaces to connect all those pieces and smooth the differences between vendors.

"We find ourselves slowing down" for the lack of them, Amzallag said.

Orange, like other large carriers, is starting to move to trials from proofs-of-concept, but that also means the carrier is done with science experiments. "If I do not have a use case, I will not start the transformation of my networks," said Noël Foret, vice president of network control.

For vendors' that's a downside to SDN and NFV becoming more "real:" Carriers want to see the technologies' rewards quantified. Concrete savings are "what I have to demonstrate to my CEO," Foret said, warning vendors that they need to stop "overselling" their SDN technologies.

Verizon likewise has taken a hard line with vendors. In this case, it's about the SDN-related work the carrier has already done: "If the solution required that I redo the back office, I didn't do it," said Shawn Hakl, vice president of enterprise networking and managed services.

He was talking in particular about the launch of Verizon's SD-WAN service in August — a service that has picked up tens of millions of dollars in contracts already, Hakl noted. Verizon is aiming to expand its SDN work to "full scale" deployments by 2017, but Hakl won't accept new technologies that force him to redo any of the SD-WAN work.

That comment seemed aimed at products that introduce proprietary technologies for the sake of vendor lock-in: "You're not going to lock me in. you're going to lock yourself out," he said.