Network and service virtualization: Part 2 [Guest Editorial]

The second installment of the Feature Topic on network and service virtualization takes off from where Part I concluded: network function virtualization (NFV) deployment and operation. We are currently observing a transition from software-defined networking (SDN) focusing solely on programming packet-switching network elements based on lower-layer flow-oriented primitives toward the wider concept of infrastructure programmability. Such programmability extends vertically within the network stack to encompass optical layer capabilities as well as features located at upper layers of the traditional network stack. In addition, infrastructure programmability extends horizontally well beyond SDN to other resource stacks to encompass virtualized compute and storage resources.