Cumulus Networks founder JR Rivers today announced Josh Leslie to succeed him as CEO. Rivers, himself, is taking on the role of chief technology officer.

Leslie joined the company as vice president of sales in June 2015, and he’s been riding the company’s wave of good fortune since. He’s credited with adding about 200 new customers to the company’s customer base of more than 400.

In January, five-year-old Cumulus said it had raised $35 million in a C round that includes Andreessen Horowitz, Battery Ventures, Sequoia Capital, SV Angel, Wing Venture Capital, and new investor Top Tier Capital. The news was somewhat dampened by speculation that its valuation may have dropped from two years ago when it was valued in the $300 million range.

Previously, Leslie ran worldwide field operations at Instart Logic, and he also spent six years at VMware where he held roles in sales, operations, and business development.

For his part, Rivers writes in the company blog: “In the early days I was able to stay involved with the technology and products; however, as the company has progressed, I’ve had less time to spend in the areas that motivated me to start the company.”

Rivers moves into the CTO position at a time when cofounder and CTO Nolan Leake is “ready to start a slow transition out of company operations,” writes Rivers.

Cumulus Linux makes operating software for switches, particularly in data center networks. It runs on more than 30 hardware platforms from vendors including Dell, HPE, Edge-Core, Agema, Penguin Computing, Supermicro, Quanta, and Mellanox.

Photo: Leslie (L) and Rivers (R)