A method for determining the link latency of an optical transmission link, (a) wherein the optical transmission link comprises an end node (102, 104) at each end thereof and one or more pass-through nodes, wherein each pair of neighboring nodes (102, 104, 106) is connected, at a connection port (110, 112) of each node, by an optical connecting path, and wherein each pass-through node comprises an optical pass-through path between its connection ports (110, 112), the optical connecting paths and optical pass-through paths forming an optical link path (108, and (b) wherein a delimiter device (118, 120) comprising a delimiter element is provided at each connection port (110, 112) of each node, wherein the delimiter element forms a demarcation within the optical link path, the method comprising the steps of: (c) measuring, for each pair of neighboring nodes (102, 104, 106), a section latency by (i) transmitting a section probe signal from a first one of the pair of nodes (102, 104, 106) to the second one of the pair of nodes (102, 104, 106), (ii) measuring, at the first node (102, 104, 106), a first time delay of a first reflection signal, which is created by the delimiter element of the delimiter device (118, 120) of the first node (102, 104, 106) by reflecting a power portion of the section probe signal, and a second time delay of a second reflection signal, which is created by the delimiter element of the delimiter device (118, 120) of the second node (102, 104, 106) by reflecting a power portion of the section probe signal received from the first node (102, 104, 106), and (iii) calculating the section latency as half the difference between the second time delay and the first time delay, (d) determining, for each pass-through node either theoretically by calculation taking into account the length and optical properties that influence the wavelength-dependent group velocity or by measurement, a pass-through latency of an internal optical pass-through path between the delimiter elements of the delimiter devices (118, 120) of the respective pass-through node, (e) adding all section latencies and pass-through latencies in order to obtain the link latency of the optical link path. (a) wherein the optical transmission link comprises an end node (102, 104) at each end thereof and one or more pass-through nodes, wherein each pair of neighboring nodes (102, 104, 106) is connected, at a connection port (110, 112) of each node, by an optical connecting path, and wherein each pass-through node comprises an optical pass-through path between its connection ports (110, 112), the optical connecting paths and optical pass-through paths forming an optical link path (108, and (b) wherein a delimiter device (118, 120) comprising a delimiter element is provided at each connection port (110, 112) of each node, wherein the delimiter element forms a demarcation within the optical link path, (c) measuring, for each pair of neighboring nodes (102, 104, 106), a section latency by (i) transmitting a section probe signal from a first one of the pair of nodes (102, 104, 106) to the second one of the pair of nodes (102, 104, 106), (ii) measuring, at the first node (102, 104, 106), a first time delay of a first reflection signal, which is created by the delimiter element of the delimiter device (118, 120) of the first node (102, 104, 106) by reflecting a power portion of the section probe signal, and a second time delay of a second reflection signal, which is created by the delimiter element of the delimiter device (118, 120) of the second node (102, 104, 106) by reflecting a power portion of the section probe signal received from the first node (102, 104, 106), and (iii) calculating the section latency as half the difference between the second time delay and the first time delay, (i) transmitting a section probe signal from a first one of the pair of nodes (102, 104, 106) to the second one of the pair of nodes (102, 104, 106), (ii) measuring, at the first node (102, 104, 106), a first time delay of a first reflection signal, which is created by the delimiter element of the delimiter device (118, 120) of the first node (102, 104, 106) by reflecting a power portion of the section probe signal, and a second time delay of a second reflection signal, which is created by the delimiter element of the delimiter device (118, 120) of the second node (102, 104, 106) by reflecting a power portion of the section probe signal received from the first node (102, 104, 106), and (iii) calculating the section latency as half the difference between the second time delay and the first time delay, (d) determining, for each pass-through node either theoretically by calculation taking into account the length and optical properties that influence the wavelength-dependent group velocity or by measurement, a pass-through latency of an internal optical pass-through path between the delimiter elements of the delimiter devices (118, 120) of the respective pass-through node, (e) adding all section latencies and pass-through latencies in order to obtain the link latency of the optical link path.