ONF Launches Stratum Open-Source SDN Project

Google is donating seed code to Stratum, a reference platform that will make white-box network switches more easily programmable.


The growing adoption of software-defined networking over the past several years has given a boost to makers of networking white boxes. The separation of the network operating system, control plane and network tasks from the underlying proprietary hardware meant that organizations could run that software on white-box switches and servers that are less expensive than those systems from the likes of Cisco Systems, Juniper Networks, Dell EMC and Hewlett Packard Enterprise.

Network virtualization technologies such as software-defined networking (SDN) and network-functions virtualization (NFV) have proven to be a particular boon for hyperscale cloud providers like Google and Facebook and telecommunications companies like AT&T and Verizon, which are pushing increasingly massive amounts of traffic through their growing infrastructures. Being able to use less expensive and easily manageable white boxes from original design manufacturers (ODMs) has helped these organizations keep costs down even as demand rises.

For example, AT&T officials have made white boxes a key part of their larger efforts to transform the telco’s infrastructure, with Chris Rice, senior vice president of Domain 2.0 design and architecture at AT&T, and John Medamana, vice president of network platforms at AT&T, writing in a blog last year that “being able to mix and match standardized hardware configurations with different software protocols is a critical element of white box. It’s how you get a more open, flexible and cost-effective alternative to traditional proprietary, integrated networking equipment.”

In January, AT&T officials said the company was open-sourcing its Disaggregated Network Operating System (dNOS) to help other service providers accelerate their use of white boxes in their infrastructures.

In response to the trend toward SDN and white boxes, established vendors such as Dell EMC and HPE have created open-networking businesses that enable customers to run third-party networking software atop branded networking gear.

Now the Open Networking Foundation (ONF) has a new open-source project underway to create a reference platform that will make white boxes more easily programmable and that will support a new set of SDN interfaces that the group also is introducing. The Stratum project and new interfaces are aimed at making the data plane more programmable, beyond what the OpenFlow protocol can enable.

“Today, we take it for granted that network operators choose and customize the control plane software for their network; the largest cloud providers and service providers have made the leap already,” Nick McKeown, a professor at Stanford University and co-founder of ONF, said in a statement. “The network should be as easy to program as a server. By lifting protocols out of hardware and into software, we will unleash a Cambrian explosion of innovation in networking, just as we have seen in compute.”

Stratum is aimed at accelerating the adoption of a new generation of switching silicon, creating a wide selection of white-box switches from a range of ODMs and creating an open-source platform for fully programmable data planes. Project members also want to ensure that Stratum will be able to be used in both existing system and new programmable silicon that is coming onto the market.

The founding members of the project include two cloud providers—Google and Tencent, from China—and telcos China Unifcom, NTT and Turk Telekom/Netsia. Members also include networking vendors Big Switch Networks, VMware and Ruijie Networks; ODMs Delta, Edgecore Networks and QCT; and silicon vendors Broadcom, Barefoot, Cavium, Mellanox and Xilinx. Stratum also involves other open-source projects, including CORD (Central Office Re-architected as a Datacenter), ONL (Open Network Linux), ONOS (Open Networking Operating System) and OVS (Open vSwitch).

Google is providing the initial source code for Stratum from software that comes from the hyperscaler’s production network.

“Google runs its network based on SDN control of a broad array of hardware switches managed through a well-defined specification for switch programming and control,” Amin Vahdat, Google Fellow and technical lead for networking at Google Cloud, said in a statement. “With Stratum, large companies have a new option for building smarter and more reliable networks.”

The ONF is building the new set of SDN interfaces off of the work it’s done creating the OpenFlow protocol and will address pipeline definition, pipeline control, device configuration and device operations. ONF officials noted that while OpenFlow only defined ways to control the forwarding behavior of the network, the new interfaces will make it possible for users to not only redefine that forwarding behavior, but also manage all aspects of the data plane.

Stratum makes use of the P4 language and P4Runtime as well as open-source protocols gNMI, OpenConfig and gNOI, all developed by Google. The project is in an incubation phase, with only participating companies having access to the code. Other companies can join, but they have to contribute a full-time engineer to the effort. A complete release of the project under the Apache 2.0 license is expected in early 2019.