# Future Scenarios for Software-Defined Metro and Access Networks and Software-Defined Photonics
## Reasons for Software Defined Metro and Access Networks
### Benefits for Users and Regulatory Issues  
Programmable access network will enable a large variety of control functionalities, such as traffic management (tunneling and virtual LAN), access nodes configuration, and diagnostics and troubleshooting. For example, dynamic spectrum management can minimize the interferences among  
Figure 3: (**a**) Traffic growth in metro and backbone networks. (**b**) Metro and IP traffic growth.  
very high-speed digital subscriber lines (VDSLs) in fiber to the cabinet (FTTC) architecture, with further improvements in addition to the benefits of vectoring techniques [19]. Different classes of service and end-to-end traffic engineering can be actuated in order to guarantee pre-determined round-trip delay for mission-critical applications requiring high interactivity [10].  
Moreover, programmable capabilities in the access network can automate monitoring, fault, and performance management operations [19]. Programmable access networks and virtualized customer premised equipment (CPE) could empower customers for a profitable collaboration with their service providers for an improved quality of experience (QoE). For example, through a user-friendly application installed on the CPE, first the user can choose the services needed and configure their quality, secondly he/she can be informed of quality of service (QoS) in real-time and then can tune the quality in order to achieve a better adaptation to his/her expectations. In such a scenario, the user can control downstream and upstream bandwidth in real-time and prioritize traffic typologies for the different devices in the same LAN according to his/her needs [10].  
Obviously, the adoption of SDN/NFV approach in metro and access network and the commercial proposals for users must be compliant to regulatory dictates which are evolving to follow technological development. The European Commission (EC), for instance, has performed a public consultation in 2015 [20] to study the potential impacts of SDN and NFV on access-services demand. Most of the subject involved in the consultation (52% of the answerers) agree that the on-going virtualization of network infrastructures will have an impact on the future demand for wholesale access products, but not in the short term (more than 10 years needed according to the 55% of the answerers), as shown in Figure 4.  
It is possible that the adoption of the SDN paradigm in the access networks will contribute to a deregulation of wholesale service provisioning. In 2016, the Body of European Regulators for Electronic Communications (BEREC) has organized a public expert workshop on \"Regulatory implications of SDN and NFV\". In summary, the following highlights on fixed access networks emerged: SDN and NFV will probably provide alternative network operators with more control over the network of the incumbent; SDN and NFV will enable new type of services that may also be offered by new parties; it is too early to make definitive statements about the impact on access regulation [21]. Finally, according to a WIK-Consult forecast study on behalf of the EC, in the short term, SDN and NFV will give alternative network operators a higher degree of flexibility, but where these solutions can be a substitute for access to passive infrastructure is still uncertain [22].