Cumulus Networks Chief Technology Officer JR Rivers is leaving the open-networking company he co-founded nine years ago.

CEO Josh Leslie confirmed Rivers’ departure in an emailed statement to SDxCentral. “As a company co-founder, he has been a tremendous asset to Cumulus from the very beginning and has helped the company become the innovative leader it is today,” Leslie wrote. “I want to thank JR for all his contributions and wish him the best in future endeavors.”

Rivers could not immediately be reached for comment.

Rivers served as Cumulus’ founding CEO from January 2010 until March 2016, when Rivers announced that Leslie would succeed him as CEO and Rivers would take the role of CTO.

The company is best known for its Linux network operating system (NOS), which runs on more than 30 hardware platforms from a dozen vendors including Dell EMC, Hewlett Packard Enterprise (HPE), Mellanox, and Lenovo. Two years ago it expanded its portfolio with a performance monitoring product called NetQ.

Earlier this year it partnered with Nutanix on an integrated product that combines Nutanix’s hyperconverged infrastructure stack with Cumulus’ open networking software. And in March, Cumulus Linux became the first network operating system to support Facebook’s Minipack, which Facebook contributed to the Open Compute Project (OCP).

Cumulus has long been active in OCP and has championed open networking since its founding. “We live to compete with Arista and Cisco,” Leslie said in an earlier interview. “That’s what we do every day.”

The company has raised $134 million to date.