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Backed by Industry Heavyweights, ONF Announces Next-Gen SDN Platform

The Open Networking Foundation (ONF) today announced next-generation software-defined networking (SDN) interfaces and a new open source reference implementation for white-box switches to support them.

In pursuit of a truly "software defined" data plane based on white-box switches, the ONF announced the Stratum project, backed by 23 founding members, including Google.

"Stratum is an open source project developing a reference implementation for white box switches supporting all the next-generation of SDN interfaces," the ONF said in a statement. "The project and its founding members plan to make Stratum solutions available on the broadest possible selection of networking silicon on a diverse selection of white box switches from a choice of ODM [original design manufacturer] vendors. Care is being taken to ensure that Stratum can be made available on both existing deployed systems as well as on state-of-the-art programmable silicon coming to market."

According to its site, Stratum is described as an open source, silicon-independent switch OS for SDNs that "exposes a set of next-generation SDN interfaces including P4Runtime and OpenConfig, enabling interchangeability of forwarding devices and programmability of forwarding behaviors. Stratum delivers a complete white box switch solution truly delivering on the 'software defined' promise of SDN."

Next-Generation SDN Interfaces
[Click on image for larger view.] Next-Generation SDN Interfaces (source: ONF).

The ONF described Stratum as a new paradigm that will provide benefits such as:

  • Speeding up operator adoption of each new generation of switching silicon (regardless of whether it is fixed, partial or fully programmable)
  • Empowering a supply chain of white box switching options with a complete open source software solution, thus providing a diversity of choice for operators
  • Providing an open source solution for fully-programmable data planes

In addition to being backed by cloud providers Google and Tencent, other organizations supporting Stratum include major telecom operators, networking vendors, white box ODM vendors, silicon vendors and various other open source projects, including CORD, ONL, ONOS, OpenSwitch, OVS, P4.org and SDKLT.

In fact, the ONF said, Google will open source the first code revision for Stratum, which it said will help launch the project from a solid software base originating from Google's production network.

The ONF said new next-generation SDN interfaces build upon projects like OpenFlow -- which only defined mechanisms that control forwarding behavior -- by completely redesigning that forwarding behavior while managing the configuration and operational aspects of the data plane.

These next-gen SDN interfaces include four major functional capabilities that expose all aspects of data plane control and management. As outlined by ONF, these include:

  • Pipeline Definition: The P4 language is used to define/document the logical data plane pipeline. On fixed or partially-configurable data plane silicon, P4 is used to document the logical pipeline that is exposed by the switch. On P4 programmable devices, this same P4 pipeline definition can be used to dynamically (re)define and/or upgrade the switch pipeline.
  • Pipeline Control: P4Runtime is used to dynamically program the forwarding pipeline tables in the switch. This can be thought of as a newer dynamic version of OpenFlow, where the Network OS and data plane can dynamically negotiate completely new pipeline configurations (unlike OpenFlow, which requires a revision of the specification).
  • Device Configuration: gNMI with OpenConfig data models is used to manage device configuration. Initial work in SDN did not address these requirements, and instead SNMP, Netconf and CLI were used in an ad-hoc manner (inhibiting interoperability).
  • Device Operations: gNOI is used for operations, for one-time events like device testing or reboots that do not required maintenance of state. This too was not specified in earlier SDN initiatives, resulting in inconsistent implementations and limiting interoperability.

While in an initial 'incubation' phase, Stratum's source code is only available to participating companies, and more firms are invited to participate as long as they dedicate a full-time engineer (or equivalent) to the project.

A full release of Stratum under the Apache 2.0 open source license is expected early next year, when many interoperable solutions that provide choice of silicon options are expected to be launched by various white box suppliers.

For now, ONF and partners are publicizing the project, soliciting feedback and new participation and supplying quotes of support from industry executives.

"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," said Amin Vahdat, Google Fellow and technical lead for networking at Google Cloud. "We are pleased to collaborate with the ONF and contribute to Stratum as an open source project for a well-defined API supporting hardware innovation and SDN interoperability in the largest enterprise cloud deployments. With Stratum, large companies have a new option for building smarter and more reliable networks."

About the Author

David Ramel is the editor of Visual Studio Magazine.

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