Silver Peak is a heavily-funded Santa Clara, Calif. company that deals with wide-area network acceleration.

The company’s software aids server centralization by enhancing the performance across a WAN. Its clients include both large companies with branch offices and municipalities.

The $21 million funding is Silver Peak’s fourth, from Artis Capital Management, Benchmark Capital, Duff Ackerman and Goodrich, Greylock Partners, J & W Seligman, and Pinnacle Ventures. The company has taken a total of $63 million to date.