Cisco Systems says it will acquire Riverhead Networks, a privately-held developer of security technology with 44 employees that is based in Cupertino, CA, for $39 million a cash-for-stock deal.

Upon close of the transaction, which is expected by the third quarter, Riverhead will become part of Cisco’s Internet Switching Business Unit, reporting to Luca Cafiero, senior vice president, and its products will be sold through Cisco sales channels.

Riverhead Network, founded in 2000, develops security technology that protects against Distributed Denial of Service (DDoS) attacks and other security threats in enterprise and service provider networks. By comparing traffic flows to learned profiles of normal traffic patterns, behavior, and protocol compliance, Riverhead’s technology can identify and mitigate known as well as previously unseen security attacks.

Cisco says its acquisition of Riverhead further enhances the company’s strategy of deploying proactive, self-defending, and self-healing networks, and building advanced security into the network infrastructure.

“This acquisition further enhances Cisco’s strategy to build secure intelligent global networks that seamlessly integrate security and other intelligent services with the network infrastructure,” said Cafiero. “Riverhead adds to Cisco’s extensive product portfolio that enables our enterprise and service provider customers to build secure, resilient, and intelligent networks with high performance and scalability.”