Metro networks are entering a period of profound change and disruption driven not only by the continued growth in metro IP traffic but, even more significantly, by the changing demands and requirements for network services driven by the cloud. The gap between the flexible and on-demand requirements of cloud applications and the static nature of today’s metro networks is unprecedented, and is leading network operators globally to radically re-think how networks are built and operated. In short, cloud services (Layer C) are the business drivers for metro network transformation, part of the intelligent transport (Layer T). While NFV will ultimately drive the virtualization of hundreds of network functions, not all functions will be virtualized. The job of the next generation metro transport network will be to combine state-of-the-art photonic innovations with the right mix of packet switching in order to support Layer C. Heavy Reading outlines the key building blocks for next generation metro networks in this whitepaper.