In this paper, a hybrid WDM---TDM-based optical access network architecture has been proposed that aims to provide optical line terminal (OLT) protection and partial feeder fiber protection without using any or minimal redundant OLT or any separate protection feeder fiber. The architecture is termed as minimal redundant shared OLT protection (MRSO) architecture. MRSO provides load shared OLT protection, where the ONUs of the failed OLT are supported by either another operational OLT that is lightly loaded in times of failure or by a redundant OLT located somewhere in the network. An appropriate control mechanism to enable communication among the mutually supporting OLTs has also been introduced. The control protocol enables distributed failure detection, updating of traffic load condition, and failure recovery. In MRSO, the remote node of the failed OLT can determine the node (OLT) that can take over the services along with the associated protection path depending on the current load condition. The paper further presents a new procedure for calculating availability of service for providing shared OLT protection. The availability of network service per end user subject to different failure scenarios within the proposed network architecture has been explored. Finally, our cost and scalability comparison shows that the proposed architecture provides significant cost and scalability benefit over previously proposed OLT protection schemes while achieving higher levels of network availability.
['Anirban Kanungoe', 'Goutam Das']
A minimal redundant shared OLT protection for hybrid WDM---TDM optical access networks