vFTTH Enables a Unified FTTx Management

Although FTTx has been extensively deployed worldwide, there are many OAM problems related to it. Traditionally, ONUs are managed in different ways in FTTC, FTTB, FTTdp, and FTTH applications; therefore, operators have to ensure their FTTx networks have multiple OAM modes and that their network element management systems (EMS) support multiple protocols. This not only increases maintenance costs but also raises the bar for interoperability so that purchasing replacement becomes more difficult. Therefore, there is a pressing need for a solution that simplifies network OAM.

The Call for Simple FTTx OAM
OAM for FTTx ONUs encompasses equipment deployment, service activation, version upgrade, and device replacement. Equipment at the link layer is usually deployed through OMCI/extended OAM. Depending on the specific scenario, services can be remotely activated through SNMP, OMCI/extended OAM, TR069, the auxiliary Web, or Telnet. Version upgrade may be implemented through OMCI/extended OAM and FTP. Diverse management modes and protocols complicate the network management system, and the management interoperability also involves multiple interoperability standards.
Moreover, network elements are deployed differently in a different FTTx network:
● Equipment does not necessarily need to be deployed in order to activate services. In FTTH mode, equipment needs to be deployed to activate new services. However, in FTTC, FTTB, and FTTdp modes, equipment only needs to be deployed when services are activated for the first subscriber.
● FTTH equipment supports plug-and-play; however, FTTC, FTTB, and FTTdp devices do not support it now.
● An operator may have different electronic work orders or dispatch work orders for different FTTx equipment. This leads to many differences in equipment deployment and OAM. The operator’s work order system needs to differentiate between various kinds of FTTx equipment and have multiple work order interfaces. This makes EMS upgrade less convenient when the southbound interface is modified and increases the complexity of FTTx OAM.

To simplify network OAM and reduce costs, it is necessary to develop a new OAM solution that enables FTTx equipment to be deployed with fewer management protocols and decreases device and EMS complexity. FTTH is generally viewed as the final stage of FTTx development, and the use of the FTTH OAM mechanism to reconstruct FTTB, FTTC, and FTTdp modes is worthy of further research. This gives rise to an innovative virtual FTTH (vFTTH) solution.

vFTTH: An Innovation in FTTx OAM
vFTTH is designed to unify OAM of various MDU, MTU, SBU, and DPU terminals in FTTC, FTTB, and FTTdp scenarios. Through virtual emulation, a terminal originally shared by several users can serve as multiple FTTH optical network terminals (ONTs). This makes the management of MDU, MTU, SBU, and DPU similar to that of FTTH ONTs.
vFTTH uses advanced virtualization technology to emulate multiple MAC addresses and forwards and manages the traffic of each MAC path. This innovative mechanism enables EMS protocols and procedures, service activation, electronic work orders, and dispatch work orders to be fully shared by FTTH devices. A virtual MAC (vMAC) can be considered as a virtual single family unit (vSFU) where
● vMAC/vSFU has basic functionalities similar to a stand-alone SFU.
● Each vMAC/vSFU maps one or multiple UNIs. When a UNI port associated with the vMAC is activated for the first time, the MAC registration process is initiated. After that, the MAC registration process is still initiated, even if the UNI port is idle. In this way, ONUs are always registered on the OLT.
● Each vMAC/vSFU has an independent forwarding domain.
● Each vMAC/vSFU responds to the time window sent by the OLT.
● Multiple vMACs/vSFUs adopt a random competition mechanism for registration on the OLT.
● Each vMAC/vSFU has an independent management channel and a full range of FTTH management modes such as OMCI/extended OAM, Web and Telnet.
● vMAC/vSFU has standard VLAN processing capability.
● vMAC/vSFU only keeps port cache and forwarding.

vFTTH changes OAM modes in traditional multiuser FTTC, FTTB, and FTTdp scenarios. These scenarios are considered as a stack of individual FTTH users. vFTTH enables multiple users to share MDU, MTU, SBU, and DPU that are used as multiple FTTH ONTs. However, the cost of the MDU, MTU, SBU, and DPU is much lower than that of multiple ONTs. The original FTTC, FTTB, and FTTdp management protocols and modes are united in FTTH mode so that operators can implement unified management without differentiating the MDU, MTU, SBU, DPU, and SFU. In a future FTTx network, MDUs, MTUs, SBUs, DPUs, and SFUs will share an EMS platform and will be managed remotely through OMCI or extended OAM. This lowers the requirements for network management, reduces the types of work orders and interoperability threshold, and conforms to FTTH-focused broadband construction. vFTTH is a breakthrough technology that will lead worldwide FTTC, FTTB, and FTTdp reconstruction.

vFTTH in Full Compliance with FTTH Deployment Procedure
vFTTH is deployed in compliance with the FTTH deployment procedure. In an FTTdp scenario, an eight-port DPU is installed in the corridor (Fig. 1). The DPU virtually generates eight vMACs to emulate eight users, each of which has one UNI port.

The vFTTH deployment procedure is as follows:
● The CRM system accepts user service requests.
● The CRM system calls in the resource-management function to confirm resources and generate customer orders.
● The CRM system dispatches customer orders to the service-activation system, which handles FTTx service orders. This involves dispatching an FTTx resource-configuration order to the resource-management system for automatic resource configuration, an activation work order to the automatic activation system for automatic device activation, and an outside construction work order to the construction scheduling system for manual construction implementation, and an integrated test system to perform a service quality test.
● The resource-management system configures network equipment and lines and updates their states.
● The automatic activation system interfaces with the network-management platform associated with all FTTx products and automatically activates these products. The activation involves authenticating user billing account and OLT/ONU based on the SN or LOID. 
● The construction-scheduling system dispatches construction orders and controls the manual construction implementation process. At the user premises, the engineer powers on the device and uplinks the port. If authentication is based on the LOID, the LOID needs to be separately entered and the corresponding vSFU is activated.
● The integrated test system performs a quality test after the service has been activated.
● The service-activation system sends a completion acknowledgement to the CRM system after the service passes the test.
● The CRM system sends an advice of charge to the billing system after receiving the completion acknowledgment. The billing system is responsible for collecting and billing for related FTTx products. 

vFTTH products are deployed in exactly the same way as FTTH products. Activating a port of a vFTTH product is the same as activating an SFU in FTTH. Both the links and services of vSFUs are configured through OMCI/extended OAM. Service forwarding of a vSFU is also the same as that of SFU. Even some key points for vFTTH OAM such as dying gasp, long-lasting phosphorescence protection, optical link detection, device replacement, and version upgrade, also borrow from the FTTH OAM logic. From a management perspective, multi-user devices that are reconstructed using vFTTH virtualization are the same as a stack of multiple FTTH ONTs.
FTTx is deployed according to local conditions. Although FTTH is the main scenario, FTTC, FTTB, and FTTdp will not disappear overnight; it will be around for a long time because of low equipment cost. Therefore, unified OAM of FTTC, FTTB, and FTTdp will continue to be a concern of operators. vFTTH virtualization technology unites the OAM schemes of FTTB, FTTC, and FTTdp towards FTTH OAM mode and reduces both opex and capex. The technology is worthy of continuous and in-depth study and will have a long-term impact on FTTC, FTTB, and FTTdp construction.