Telefónica is about to start its plan to virtualize some customers' set-top boxes, even though some pieces on the cloud side of the technology aren't quite ready yet. It's an interesting glimpse at how complicated virtualization can be — even in doing something as "simple" as moving broadband subscribers' services to the cloud.

Diego López, head of technology exploration for Telefónica I+D, gave an update on the project — which is being launched with subscribers in Brazil — at the SDN & OpenFlow World Congress, in Bad Homburg, Germany (near Frankfurt) on Tuesday morning. His talk was part of a day-long workshop put on by the Open Networking Foundation.

"It will be operational in less than a couple of months. That implies real users, real money behind it. We are risking our user base with this," he said.

What's missing are some of the virtualized functions that are to reside in the cloud — specifically, carrier-grade network address translation (NAT) and a carrier-grade broadband remote access server (B-RAS), both to be supplied by partner NEC. They'll be ready possibly in the first quarter, said Daniele Abbadessa, business development manager for NEC Europe, who shared the stage with López (see photo above).

Those and other virtualized functions would reside on the carrier-grade hypervisor that NEC has developed (and which goes under the ugly acronym CGHV, which we're going to avoid using for the moment).

The virtualized customer-premises equipment (vCPE), as Telefónica is calling it, has been in the works for a while. Telefónica and NEC first discussed the idea in February 2012 and formally announced the Brazil project in October.

The idea was to boil the set-top down to basics: a modem, switch, and WiFi access point. Everything else the set-top does would be source from the cloud, allowing Telefónica to update or deploy services quickly, without having to replace any customer equipment.

"This is something that we started considering in general for optical network [i.e., GPON access] clients, but we have found for sure it applies as well to our cable clients," López said.

The carrier-grade hypervisor is such a key component that NEC has decided to make it available on open-source terms "soon," figuring no carrier wants to be locked in, Abbadessa said. It's based on the CentOS enterprise-Linux operating system and KVM virtualization.

What makes it "carrier-grade" are features such as deterministic performance, which involves having control of the CPU's access to memory and to network interfaces, and things like high availability and fault tolerance. "Traditionally, these are in hardware. Now they have to move to software," Abbadessa said.

Those hypervisor requirements hammer home the point that network functions virtualization (NFV) is more than just "cloud," as López emphasized at the beginning of his talk.

One major difference is that the network requires "shape," he said. "The normal cloud is about a schedule-less service that you can locate anywhere because it's the end of the communication," he said. "The network is composed of middle points. It needs the elements to be in certain physical locations," sometimes close to the user, sometimes nearer to the network core.