Google and Broadcom boost ONF’s Stratum project for P4 in telco networks

The P4 programming language is of rising interest to operators which want to adopt software-defined networking (SDN), and Google is behind the latest project of the Open Networking Foundation (ONF), the platform for many of these telco-grade initiatives. The search giant has contributed code for three protocols to an open source project called Stratum, which will use P4 and open interfaces to manage large networks for operators and data centers.

The group aims to release open source code early next year for multiple networking platforms. As well as Google, the project members so far include switch-chip vendors
Barefoot Networks, Broadcom, Cavium and Mellanox; plus China Unicom and Tencent of China and Dell EMC. Google said it would “help grease the market” by introducing the software into its production systems even before the full code release, targeting a date later this year.

Last year, the ONF shifted its attention from the OpenFlow protocol to the more powerful P4, which originated with Barefoot and has been heavily pushed by AT&T (a Barefoot customer). Stratum will use the P4 language and runtime, and three open source protocols which Google helped develop — gNMI, OpenConfig and gNOI.

“We’re at an interesting inflection point,” Timon Sloane, VP of marketing and ecosystems for ONF, told EETimes. “We learned a ton from OpenFlow, but it has limitations, so the community strategically shifted to P4 and the P4 runtime to solve problems in a more comprehensive way.”

He acknowledged that ONF is no longer actively developing OpenFlow, which has been used by Google and telcos to access the data forwarding pipeline of network ASICs – but cannot access all the functions, and does not allow the pipeline to be programmed, unlike P4. Critically, OpenFlow did not support full multivendor interoperability because adjustments were needed for each ASIC.

The inclusion of Broadcom in the Stratum group is a feather in the cap for the ONF, since the chipmaker had previously been scornful of P4, and dismissed the idea that customers would want to program a network chip’s pipeline. If they did, it would offer its own C++ tools, it said when asked about the issue just a week earlier, at the launch of Jericho2 (see separate item). However, Broadcom is not expected to run P4 programs natively on its chips, but to write translation layers.

The same would go for network OEMs which still rely on ASICs rather than merchant silicon in their equipment. The biggest of those, Cisco, has not expressed interest in P4 to date.

At the recent Mobile World Congress, the ONF demonstrated its latest P4 code, running on white box switches based on chips from Barefoot, Cavium and Mellanox (Broadcom had not undergone its conversion at that point). The operators supporting this demonstration included AT&T, China Unicom, Comcast, Deutsche Telekom, NTT Group and Turk Telecom, plus Google.

The ONF and its supporting telcos said they were using MWC to raise awareness and support for P4 and ensure a broad ecosystem develops. Chip and vendor partners involved in the demo were ARM and Intel, plus Ciena, Netsia, Radisys and Mariner Partners. Quanta and Delta are among the existing white box vendors, but other, bigger names are needed to convince telcos that a robust ecosystem will develop – and there need to be far better proof points in mobile.

So far, ONF has P4 code for access networks in field trials but says software for the mobile core is one or two years behind that stage. The end goal is that P4 should help enable a fully open network, based on commodity hardware, from central core to distributed edge cloud.