A novel protection scheme for Ethernet PON FTTH access network

Large scale projects replacing copper network with optical fiber such as photonic-access-to-the-home (PATH) in Korea signify the age of fiber based network, making protection to fiber based network a crucial need. It is found that FTTH technology and Ethernet passive optical networks (EPONs), which represent the convergence of low-cost fiber infrastructure and low-cost Ethernet equipment, appear to be the most deployed access network. Most FTTH access networks are protected from failure by having redundant network equipments. These are not economical approaches, as the redundant systems are not efficiently utilized by the network. In this paper, the authors propose a protection method where redundant equipments are not required and protection is provided to end user through sharing of bandwidth during the failure time. A protection control unit and an optical switch is employed connecting 4 optical line terminations (OLT) with each one serving only 32 optical network units (ONU). Protection control unit collects information of ONUs served by each OLT and when an OLT fails, it instructs an active OLT to serve its original ONUs together with the ONUs served by the failed OLT. It also provides information of ONUs served and inform the involved 64 ONUs of their new timeslot allocation. Then, the signal is switched from failed OLT's line to the instructed active OLT. The results show that through sharing of bandwidth, adequate protection is provided without redundant equipment for more than one OLT failure.