Last week's SDN & OpenFlow World Congress covered some big trends, but a few short tidbits seemed worth mentioning on their own. They boil down to four truisms and one news bite.

So take a moment to nibble on these — and let us know your view in the comments, since there's a subjective tone to many items here. You can also catch up with all our Congress coverage on this page, and be on the lookout for even more news later this week.

1. NFV Rules This Land

Maybe it's because Deutsche Telekom is a key sponsor of the Congress and carriers were plentiful on the speaking agenda. But it feels like network functions virtualization (NFV) overran this show, a contrast to those innocent days when software-defined networking (SDN) discussions were all about OpenFlow and switches.

NFV is simply closer to reality than big-picture SDN is. And because the carriers are pushing NFV so aggressively, it's worked to the forefront of the conversation. That doesn't mean we should forget about SDN. It's more that NFV has become the first big use case for SDN, as Dan Pitt, executive director of the Open Networking Foundation (ONF), put it.

2. The Benefits of SDN/NFV Aren't Quantified

I overheard one service provider attendee talking to a colleague about the frustrations of dealing with SDN vendors. All he heard were promises of efficiencies and automation — the kinds of things routinely cited as SDN benefits. Too touchy-feely. "Just give me the [expletive] number," is what he told the vendor.

I don't know if that number was price savings, performance boosts, or both. It doesn't matter, because he never got the number.

There seems to be a hesitation to promise numbers out of SDN and NFV. Granted, that's partly because the implementations are infinitely varied, so — "It depends." But it's still bothering some customers. The model for total cost-of-ownership is still unclear, said Nicolas Fischbach, director of strategy, architecture, and innovation at Colt, during his presentation.

Even some of the prices aren't settled — or, at least, they aren't well thought-out, Fischbach said. He related the story of one vendor working on one component for virtualized customer premises equipment (vCPE). The component was going to cost more than a physical CPE device.

3. There's More Than One 'Orchestration'

This is one I'm hoping to write more about soon. The basics of NFV are pretty much in place, thanks to the ETSI industry specifications group (ISG), and the concept of moving network functions into software has never been hard to understand. The question all along has been how to manage these virtualized functions, in terms of creating them, connecting them, keeping track of network state, informing OSS and billing systems — the list goes on.

Consultant Tom Nolle of CIMI Corp. (who wasn't at the Congress) has been railing about this for a long time, and it led to the formation of the CloudNFV and ExperiaSphere efforts he's worked on.

So, orchestration is starting to get serious attention, or at least serious lip service. But "orchestration" refers to multiple functions. HP's Saar Gillai — who's replaced Bethany Mayer to become HP's general manager of NFV — gave me this example: OpenStack could orchestrate pools of resources in NFV, and its role would be activated by another orchestrator, through APIs.

Gillai doesn't think it's realistic to expect one overall Orchestrator to oversee all these orchestrations. If 2015 becomes the year of "orchestration" hype, prepare for a long year — a lot of products will be using the same word to refer to different parts of the NFV stack.

4. Open Source Might Be Reaching Overload

Axel Clauberg of Deutsche Telekom put it well during his keynote.

"The question is: How many open-source projects do you actually need to get an open environment? ... How far can you actually split up your resources and invest in parallel activities reinventing the wheel? I think we should limit ourselves in this area."

5. Cisco Has a New Name for Tail-f

Having been acquired, Tail-f is now Cisco's multiservice play, the Cisco Network Services Orchestrator. No, it will not solve all your orchestration problems. (See Item No. 3.) But Cisco is at least talking the talk about using Yang models to reuse services across different types of gear.

Of course, this ties back into NFV. The mapping between services and network resources isn't abstract enough, which means services will still have hard-coded ties to the OSS, said Paolo Campoli, Cisco's sales CTO, during his presentation. Freeing up that mapping — making it easy to apply to multivendor networks — is an area worth some extra effort, he said.

There was — and still is, understandably — plenty of skepticism about whether Tail-f's multivendor strategy would be preserved after the Cisco acquisition. Cisco's first step seems promising, but I would expect carriers to still be scouting for alternatives.