Just a couple of weeks after leaving Big Switch Networks, Howie Xu has resurfaced at Cisco.

Xu hasn't discussed details about why he left Big Switch, but speaking to SDxCentral last week, he said that he likes being part of a product-flow cycle involving thousands of customers, a change from the "evangelizing" work that an SDN startup calls for.

Xu started Monday as a senior director responsible for all of Cisco's Cloud Networking Service Group engineering team, SDxCentral has now learned. It appears he'll be reunited with Saravan Rajendran, who's a VP in that group; they worked together to develop the Nexus 1000v when Xu was at VMware.

In a sense, Xu is picking up where he left off at VMware, where he'd led the virtual switching team -- a tiny, unnoticed corner of the company, back around 2006.

"At VMware, we did virtual switching for many years, but any time I would mention it, people would say, 'What does my Cisco admin think?'" he says. "You have to understand -- VMware was a pure server company back then. When we first started talking to Cisco, we didn't even have a dedicated PM [product manager] yet."

The talks with Cisco started in the summer of 2006, as Cisco sought a way to get in on virtual switching. Xu became the liaison working on what would be the Nexus 1000v, a jointly developed product that launched in 2008 and began shipping in 2009. Xu says VMware enabled other companies develop their virtual switches as well; IBM launched the DVS 5000V in 2012, and HP launched its FlexFabric Virtual Switch 5900V this year.

In many cases, the virtual switch has supplanted the top-of-rack switch as the first hop switch in the data center, so the idea has come a long way since those 2006 days. VMware got the early jump, but the market still looks wide open, because in many circles, VMware is still considered more of a server company than a networking company. One thing to watch at VMworld in August will be the extent to which VMware tries to strengthen its networking story.