Verizon is announcing today that it's joined the Open Network Operating System (ONOS) project, becoming the fifth carrier member after AT&T, China Unicom, NTT Communications, and SK Telecom.

Verizon is expressing particular interest in ONOS’s open source work related to packet-optical convergence and the Central Office Reimagined as a Data Center (CORD). Even more particularly, the company will focus on mobile CORD (M-CORD) use cases and the use of M-CORD as an enabler of 5G.

M-CORD is similar to CORD in that it reduces all traffic down to packets, regardless of the network topology and proprietary boxes that have carried that traffic to a switching center.

“It’s very elegant,” says Bill Snow, VP of engineering with ONOS. “It doesn’t matter how the packet is arriving at the interfaces. It’s the same with building up the services that those packets go to.”

The ONOS software-defined networking (SDN) controller will control the leaf and spine fabric with commodity OpenFlow switches, and it will also handle services.

“As you instantiate services, those services have to talk, typically through a virtual LAN or virtual connection,” says Snow. “ONOS also creates those as a result of the Neutron interface from OpenStack.”

To date, M-CORD work within ONOS has been driven by SK Telecom. The Korean carrier is probably more focused on 5G than any of its competitors because it aims to have a 5G prototype network live for the 2018 Winter Olympics.

In terms of the original CORD development work, AT&T has led the charge, especially for the residential use case (R-CORD).

In addition, an enterprise use case (E-CORD) is in development with proofs-of-concept planned in March.