 can be rerouted via SDN control through the fiber network to get back to the office. If the office has a failure and the PE function needs to be relocated in a different AIC node, the SDN control can first recreate the PE function in the different AIC office, remove the existing trunk/wavelength to the first AIC office, and create a new trunk from the customer to the new AIC office. In that way, customer traffic can be restored after failures that today cannot be addressed. SDN control can also be used to offer new services. The packet network tends to have utilization that varies during the day by more than a factor of two or more. Since the network sizing is designed to the busy hour, there is a lot of idle capacity during the non-busy hours. Customers could request "bandwidth calendared" services to run at some point in the future. These are services that are not time critical, such as backing-up data from one data center to another. The SDN controller will man- age the acceptance of these services into the network at a specific point of time where capacity is assured. Assuming the customer agrees to the time, duration, bandwidth, etc., the SDN controller will then create MPLS tunnels dedicated to the customer at the appropriate time, and do whatever Building the Network of the Future Capacity Inventory portal database Multi-Layer Directed Data Collection algorithms Graph Controller Plug-in Plug-in Plug-in RESTCONF: NetConf BGP-LS Configuration, configuration activation, Alarms, Tunnel State activation topology routes changes ROADM Node Controller Network Flexible ULH Network FIGURE 13.23 Multilayer control. centralized tunnel management and trunk/wavelength creation might be necessary to support the cus- tomer demand. Figure 13.24 depicts the historical and projected core utilization trend. It is important to note that not only has utilization improved but survivability has also improved and the amount of packet loss while the network converged after a failure or while costing a core node for maintenance has