ent Protocol (SNMP) on traffic measurement on each link and LSP at minute-level frequency. The measurement data can complement BGP-LS and PCEP to achieve global optimal TE. Subsequent sections of this chapter will provide detail uses of these data. Building the Network of the Future From the data and measurement perspective, Figure 16.1 demonstrates two key aspects that are not available in pre-SDN networks: (1) real-time use of network data for traffic management in a coordinated and centralized control manner and (2) much shorter time horizon for integrated capac- ity planning. The remaining section describes what data are needed and how they are used for real- time traffic management (real-time network condition data); for iterative capacity planning (network resource inventory data), and for network performance analyses and SDN-controller monitoring. 16.2 USE OF REAL-TIME NETWORK DATA WITH SDN In this section, we will show an example of an IP/optical network (including backbone and edge locations) controlled by a centralized SDN controller (Figure 16.2). In addition, we will explain where and how we would need to measure real-time network data. Finally, we will identify how the SDN controller can use this data to support the following: Centralized TE using SDN controller to more efficiently manage TE tunnels, LSPs or flows (discussed in Chapter 11) Dynamically managing and reconfiguring the mapping between IP and optical layers using ROADMs to enable faster provisioning of resources Using the available spare capacity in the network (particularly during off-peak hours) to opportunistically provide new services such as bandwidth calendaring 16.2.1 EXAMPLE OF AN IP/OPTICAL NETWORK WITH SDN CONTROLLER Figure 16.2 expands upon what was depicted in Figure 16.1 to illustrate an example of an integrated IP/optical network and its interaction with the SDN controller. E[i] represents the IP edge routers; B[i], the IP core or backbone locations; and O[i], the optical nodes (ROADMs). A subset of the opti- cal nodes is co