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ONF’s published reference designs start to be deployed

Operators are already deploying the first reference designs published by the Open Networking Foundation (ONF). Three of the ONF’s five reference designs have now been made public. 

Just over a year ago, eight operators - AT&T, Comcast, China Unicom, Deutsche Telekom, Google, NTT Group, Telefonica and Turk Telekom - took the step to design key components of their edge and access networks after becoming frustrated with what they perceived as foot-dragging by the systems vendors.  

AT&T is deploying one of the reference designs - the SDN-enabled broadband access scheme (SEBA). Deutsche Telekom and Telefónica have also said they will deploy SEBA during 2019 and 2020. 

Andrew Fuetsch, president AT&T Labs and CTO of AT&T, said in a keynote talk at the recent Open Networking Summit North America event that SEBA is resulting in more commoditised hardware solutions and that such open source solutions are bringing higher speeds and better services across AT&T’s wireline infrastructure.

Meanwhile, an undisclosed operator has deployed a second reference design - Trellis, a leaf-spine switch fabric that supports network functions virtualisation (NFV). Trellis can be deployed as part of SEBA although the operator is deploying it for a different application, says the ONF.  

The final of the three published reference designs is the Open Disaggregated Transport Network (ODTN). However, unlike SEBA and Trellis, ODTN is not yet available as a deployable platform, what ONF calls an exemplar platform


Reference designs

The ONF started developing four reference designs as part of the open source organisation’s ongoing cloud optimised remote data centre work, known as CORD. In addition to SEBA, Trellis and ODTN, it is developing a next generation software-defined networking (NG-SDN) solution, previously known as Unified, Programmable & Automated Network (UPAN). 

In February, the ONF announced a fifth reference design dubbed Converged Multi-Access and Core (COMAC) that combines 5G mobile and fixed access.

A reference design defines the assembly of components used for key platforms in the access and edge of the network. By creating reference designs, the operators are defining what they need while also committing to deploy the resulting solutions in their networks. This gives the vendors working alongside the operators a confidence that the work will lead to sales. 

The components making up a reference design may be ONF-developed but need not be. They may also be open-source or a vendor-specific solution.

In parallel, the ONF operators have been working with vendors to develop an exemplar platform that is a working implementation of a reference design. The ONF only publishes a reference design once the specification is complete and the associated exemplar platform is ready for trialling. However, the ODTN reference design work is an exception in being published while its exemplar platform is unfinished. 

“The ONF board felt the work was substantial and mature enough that it was worth getting out there,” says Timon Sloane, the ONF’s vice president of marketing and ecosystem.   


CORD evolution

The ONF is known for its software-defined networking (SDN) work - the OpenFlow protocol and ONOS open-source SDN controller - and for its CORD open networking access and edge projects.

Originally known as the Central Office Re-architected as a Data Centre, CORD comprises two key initiatives: a broadband residential CORD (R-CORD) and a mobile CORD (M-CORD). “Once we had the foundation [of SDN], we created R-CORD, the first incarnation, and then we did M-CORD for the mobile space,” says Sloane. 

The ONF has since disaggregated both M-CORD and R-CORD into their access and core components. “We realised they both covered a pretty big space,” says Sloane.  

R-CORD has been disaggregated into the SEBA reference design and VOLTHA, an open-source abstraction of broadband hardware. Meanwhile, M-CORD has been split into Open Radio Access Network (ORAN) and a newer project, the Open Mobile Evolved Core (OMEC).

The ONF has also upgraded Trellis to not only provide a leaf-spine architecture switch fabric for inside a data centre but also as a multi-tier architecture that spans sites.

Meanwhile, the ODTN reference design is based on first a point-to-point and then a multi-point dense WDM (DWDM) scheme that connects the CORD edge to the network core.  

The ONF has been working with the Telecom Infra Project’s (TIP) Open Optical Packet Transport group with a view to using its Cassini white box platform

“CORD has grown in scope and we recognised that people want to consume the inner pieces in separate ways and that they have separate value,” said Sloane. “And everything of CORD ride on the SDN stack that is being gracefully migrated to the next generation SDN.”

The SDN software stack is based on the ONF’s Stratum project and the P4 language, which is now under the ONF’s stewardship. Stratum provides a software layer that supports various application programming interfaces (APIs) and the underlying hardware. The Stratum project started in 2018 and builds on software provided by Google. In addition, the ONF is also developing a micro-service ONOS.      

The newest reference design, COMAC, creates a unified converged access for the radio access network and broadband, says Sloane.

First, the various elements of the fixed and mobile network access and core elements are disaggregated before convergence will bring a common framework for both. For example, a single subscriber management system for users will be used whether they are connected over broadband or mobile. This is a sophisticated project and will be developed in line with the work of the 3GPP and Broadband Forum organisations, says the ONF. 

“We expect this migration to [COMAC to] be smooth but to enable a whole new set of capabilities for all the applications that run above it,” says Sloane. 

Each time a new reference design is created within the ONF, it means operators committing yet more staff from different parts of their organisation to fulfil the project, says Sloane: “Additional people to pursue yet another angle of attack to transform and push their networks forward.”  


Next steps 

The ONF has started working on version 2.0 releases for SEBA, Trellis and the ODTN reference designs.

“This will be the case for some time as the work matures,” says Sloane. “There will be versions under development for the foreseeable future.”   

Operators have a ‘bunch of work’ they want to progress and drive via this work, he says: “We don’t see an end in sight right now.”


Further information

SEBA, click here

Trellis, click here

ODTN, click here

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