Cisco is buying Cariden Technologies, a privately held ISV whose software is used in capacity planning, designing and engineering networks. It's paying about $141 million in cash and retention incentives.

Cariden, whose clients include Verizon, Deutsche Telecom, SingTel and Swisscom, specializes in optimizing traffic management and visibility on service provider networks.

The acquisition is seen as part of Cisco's very necessary move into software-defined networking (SDN). This summer Cariden announced a blueprint for infrastructure SDN - the visibility and control of network resources.

It also supports Cisco's Open Network Environment strategy, a k a Cisco ONE, by providing sophisticated wide area networking (WAN) orchestration capabilities.

Cariden is bound for Cisco's Service Provider Networking Group to enable multi-layer modeling and optimization of optical transport and IP/MPLS networks.

Cisco said, "With global service providers converging their Internet Protocol (IP) and optical networks to address exploding Internet and mobile traffic growth and complex traffic patterns, Cisco's acquisition of Cariden will allow providers to enhance the visibility, programmability and efficiency of their converged networks, while improving service velocity." It's supposed to advance Cisco's nLight technology for IP and optical convergence.

Cisco bought two other companies last month: Wi-Fi company Meraki for $1.2 billion and SDN house Cloupia for $125 million. Counting Cariden, Cisco spent nearly $1.5 billion buying in props for cloud computing. It's got $45 billion in the bank.

The deal is supposed to close by the end of January.