Cisco just lost another top executive. Private equity firm Siris Capital announced today that Hilton Romanski, Cisco’s SVP and chief strategy officer, will become a partner and senior managing director of the firm’s investment team.

As a member of the Siris team, Romanski will identify investment opportunities and forge deals. He will also establish a new Siris office in Silicon Valley. The PE firm is headquartered in New York City.

Romanski is a long-time Cisco veteran. He joined the networking giant in 2000 and has handled more than $30 billion in acquisitions and 60 deals for the firm. Most recently, he handled Cisco’s $3.7 billion acquisition of AppDynamics. He also orchestrated the company’s $1.2 billion acquisition of Meraki and its $2.7 billion purchase of Sourcefire. In addition to handling Cisco’s acquisitions, he oversees the company’s $2 billion venture capital investment portfolio.

In a tweet, Cisco CEO Chuck Robbins congratulated Romanski on his new role:

But Romanski is the third senior-level Cisco executive to depart the company in the past month. In August, Christine Heckart, a marketing executive, left the company after only working there for nine months. And Yvette Kanouff, who served as SVP and general manager of Cisco’s Service Provider Business, also left the company.

Siris Capital is becoming a big player in the networking and virtualization space. The private equity firm owns Mavenir Systems and Pulse Secure, which purchased Brocade’s vADC business.