The company would like to virtualize a network appliance called the broadband remote access server (B-RAS), said Robert Chen, director of cloud infrastructure and applications for China Mobile’s U.S. Research Center.
China Mobile is in a fiber to the home (FTTH) fervor, with plans to deploy fiber to 15 million homes per year, up from the original target of 10 million per year. The carrier has deployed to more than 65 million homes as of June and has reached a pace of 1.6 million deployments per month, Chen said.
Created for DSL and also used in FTTH deployments, the B-RAS is a network element that helps forward traffic into a carrier’s core network. The appliance is crucial for handling the number of consumer sessions involved, but it’s a technology that emerged in the early 2000s. It’s not exactly cloud-native.
China Mobile is still deploying these devices based on “probably a 15-year-old technology” and proprietary hardware, and now they’re becoming difficult to scale, Chen said.
Control Plane vs. Data Plane
China Mobile would like to virtualize the B-RAS, giving the virtualized version a control plane that’s housed in the cloud — a centralized model, in other words. But Chen believes the data plane should remain as it is today, running at the B-RAS location — a localized model. That means a bit of proprietary hardware might linger.
The separation of planes would mean the carrier could “scale and optimize them separately,” Chen said. But it would require China Mobile to pick an interface to run between the two, something like OpenFlow or Netconf. The carrier is working with standards bodies to see if it’s possible to standardize this interface.
One unexpected snag in this plan is the cost of the virtual B-RAS. Line cards for the current proprietary models “are still cheaper per [gigabit per second] than commodity servers,” Chen said.
That’s a surprising statement, given that servers are known for being cheap and telecom hardware, well, isn’t. Challenged on this point during a panel following his talk, Chen conceded that China Mobile might be getting line cards at lower prices than some other carriers would, due to factors including economies of scale.
On the same panel, Tom Tofigh, a principal architect with AT&T, also questioned the strategy of leaving the data plane as-is. That strategy wouldn’t create the kind of programmability that AT&T wants, he said.
“What I really want from my data plane is: I want to program it,” Tofigh said. “How do we introduce a new mirroring capability into the data plane? How do I introduce analytics into the data plane? How would I be able to slice it? I don’t think that exists today.”
Chen defended the strategy, though.
“If we can open up the control plane, that also provides some of the programmability,” he said. In his view, a centralized and smarter control plane would leave the data plane free to just handle quality-of-service.
Chen’s philosophy was backed up later in the day by slides from Walter Haeffner, a distinguished engineer with Vodafone Germany. Haeffner believes NFV deployments should take the partial step of virtualizing only the control plane, saving the data plane for later.
It’s worth noting that AT&T is being more aggressive with virtualization than most carriers are. Aiming to virtualize 75 percent of its network by 2020, AT&T has developed its own Enhanced Control, Orchestration, Management, and Policy (ECOMP) platform for software-defined networking (SDN) and plans to open-source the code early in 2017.