Most carrier services are currently bandwidth-based but will evolve to support more wavelength-based services, including O-VPNs and end-to-end wavelength services where the end user has the power to change the bit rate at will. The increased rate of deployment of intelligent OEO switches is driving the emergence of next-generation optical networks. The addition of an all-optical OOO switch holds the promise of making this network even more flexible and manageable. Together, the intelligent OEO switch and the all-optical OOO switch ensure a scalable next-generation network that can accommodate the dynamic nature of bandwidth-intensive broadband services .
This chapter also attempts to compare the merits of different switching technologies in the context of an AON. It shows that while electrical and optical switching have their distinct advantages, the combination of both at a single node results in additional advantages that neither technology has on its own. In the process, the role of photonic agility emerges as the bridge between three conflicting goals the carrier must balance:
Reduce CAPEX and OPEX
Future-proof the network to support changes in traffic demands 
Figure 10.26 shows how these goals can be balanced . If any two of the goals are supported and the third neglected, other solutions are more optimal. For example, if cost reduction and maximized revenues are pursued but forecast tolerance is ignored, a static AON ...