###### Abstract
In contrast, other proposals focus on moving certain features of current PON devices to external SDN controllers to achieve a centralized SDN control of the network, for example, bandwidth allocation policies or PON devices registration [15; 16; 17; 18; 19; 20; 21; 22; 23]. In this way, PONs are Point to MultiPoint (P2 MP) networks based on a tree topology between the Optical Line Terminal (OLT) and the Optical Network Terminals (ONTs). In the upstream channel, from the ONTs to the OLT, PONs show a multipoint to point topology and every ONT shares the same transmission channel. Therefore, a MAC (Medium Access Control) protocol is required inside this channel in order to avoid collisions among data from different users (ONTs). Dynamic Bandwidth Allocation (DBA) based on Time Division Multiple Access (TDMA), is the most used strategy to share the channel capacity among ONTs (users) cycle by cycle, since the OLT dynamically distributes the available bandwidth depending on the current demand of users (ONTs) and its contracted services. The cycle time is the total time in which all ONTs connected to the PON transmit in a round robin discipline (TDMA). As it can be noticed, the allocation process inside PON infrastructures is made between the OLT and the ONTs cycle by cycle, so its global outsourcing to an external SDN controller can cause an inefficient network performance in the bandwidth allocation process due to the latency between the SDN controller and the OLT, since SDN controllers are outside PONs at a certain distance. However, it could be worth that some decisions regarding DBA policies, such as the maximum bandwidth assigned to specific services (such as voice, video or data), can be managed by the SDN controller to provide an efficient and global SDN network management and configuration of the PON, although these policies do not imply the cycle-by-cycle control of the bandwidth allocation process, which would cause low efficiency due to the distance between the SDN controller and the OLT. As a consequence, in this paper, we propose designing and implementing an SDN management layer over a GPON testbed able to deal with some service configuration strategies, such as the maximum allowed bandwidth to services, according to the real-time QoS requirements of network subscribers (ONTs). These global policies do not require a cycle-by-cycle communication between the SDN management layer and the OLT, thereby not degrading performance despite the distance between the SDN infrastructure and the PON. In contrast to other existing approaches, that most of them propose service provisioning or DBA policies by means of simulation models, we demonstrate the feasibility of moving specific strategies over a legacy GPON testbed which has implemented an end-to-end SDN solution using the OpenFlow protocol and SDN virtual switches (Open Virtual Switch, OVS) [24] connected to OLTs and ONTs, all of them controlled by an external SDN controller, in our case OpenDayLight (ODL) [25]. Therefore, we propose both a SDN solution over a GPON testbed and the implementation of an SDN management layer that deals with service configuration policies inside the GPON testbed. In fact, we propose that the SDN management layer can be able to provide and configure real-time Internet services and their associated maximum bandwidth to users that contract Internet plans according to their real-time demand and contracted bandwidth requirements using the SDN controller and the OpenFlow protocol. Furthermore, we check the viability of our proposal by designing a new business model for network operators and providers. The paper is organized as follows. Section 2 describes the state of the art regarding the integration of SDN in PONs. Section 3 explains the experimental implementation of our SDN approach over GPONs and the description of the online service configuration policies over our network scenario. Section 4 presents the experimental results and discussion of our SDN-GPON proposal using a particular business model.