Method for operating passive optical networks

The present invention refers to a method for operating at least a part of a passive optical network (PON), said network comprising a plurality of optical fibres, each optical fibre being connected on one end to a plurality of optical network units (ONUs) via an optical coupler, and on the other end to a switching device, said switching device being connected to a group of optical line terminals (OLTs) and allowing each optical fibre to be connected to an optical line terminals (OLTs) wherein the number of said optical line terminals (OLTs) is larger than the number of said optical fibres and wherein said switching device connects all said optical line terminals (OLTs) alternatively to said optical fibres according to an alternation principle.