Bechtolsheim invented Sun's first workstation product and has a reputation as a brilliant systems designer. He left Sun for the first time in 1995 to found a Gigabit Ethernet company that was later acquired by Cisco Systems. He returned to Sun four years ago to design its Galaxy line of industry-standard servers. His return was supposed to help make Sun a hardware leader again at a time when its pricey Unix servers were falling from favor.

Networking stayed close to Bechtolsheim's heart, however. He cofounded Arista Networks at about the same time he returned to Sun and held a seat on Arista's board. Along with his appointment as chairman and chief of product development Thursday, Arista also named Jayshree Ullall, a senior vice president with Cisco Systems, as its president and chief executive officer.

Arista, which shipped its first products earlier this year, aims to "solve the problem of interconnecting large data centers with high-speed Ethernet," Bechtolsheim said.

"One unfortunate thing here is that people are focused on me leaving Sun, but the exciting part is actually this cloud networking story we are building here," he said.