N:1 Protection design for minimizing OLTs in resilient dual-homed long-reach passive optical network

Long-reach passive optical networks (LR-PONs) prove to be a suitable candidate for future broadband access networks. The longer reach of the feeder fiber in a LR-PON enables us to consolidate a large number of end users. The longer reach also eliminates a degree of electronic processing by eliminating the metro network and connecting the local exchanges (or the central offices) directly to a consolidated metro/core (MC) node. However, longer reach makes the feeder fiber more vulnerable to failures, and therefore, for resiliency purposes, a dual-homed architecture is proposed. For the usual case of 1 + 1 protection, the dual-homed secondary MC node would contain duplicate resources that would take over in the event of the failure of any of the individual working optical line terminals (OLTs) or the entire primary MC node in the case of a catastrophe. In this work we propose an Nl1 protection mechanism to reduce backup OLTs in a resilient dual-homed LR-PON deployment. We model the problem as an integer linear program and solve it for Irish and UK network deployments. Our results show that the percentage of backup OLTs can be reduced by 6 times for Ireland and by 4 times for the UK compared to a 1 + 1 protection deployment scenario.