Listwin will become president and CEO of the merged company, which has not been named yet.
Cisco has a minority stake in the company.
Listwin joined Cisco in 1990 as a marketing manager and rose up to become the No. 2 executive at the company, and one of only two Cisco executive vice presidents. He led Cisco's corporate marketing, service provider and consumer lines of business. Those duties will now be assumed by Chambers, Senior Vice President Kevin Kennedy and Senior Vice President Charlie Giancarlo, respectively. Listwin's decision to leave Cisco was made rapidly over a matter of days, Chambers told Wall Street analysts in a conference call Tuesday. This is a very difficult decision for me, but the opportunity to be CEO aligned with my longstanding career goals.