Fibre network for interrogating fibre-optic sensors in a first Passive Optical Network and in a second PON, the fibre network comprising - a test signal transceiver for emitting query signals and for receiving response signals, wherein the response signals originate from the query signals, - a first PON comprising a first light source for generating first telecommunication signals and comprising a first fibre-optic sensor, wherein the first PON is adapted to transmit the first telecommunication signals to a plurality of subscribers, and wherein the first PON is optically connected to the test signal transceiver such that query signals from the test signal transceiver can be fed into the first PON and propagate in the first PON to the first fibre-optic sensor, and such that the test signal transceiver can receive response signals from the first fibre-optic sensor through the first PON, - a second PON comprising a second light source for generating second telecommunication signals and comprising a second fibre-optic sensor, wherein the second PON is adapted to transmit the second telecommunication signals to a plurality of subscribers, and wherein the second PON is optically connected to the test signal transceiver such that query signals from the test signal transceiver can be fed into the second PON and propagate in the second PON to the second fibre-optic sensor, and such that the test signal transceiver can receive response signals from the second fibre-optic sensor through the second PON, wherein the fibre network further comprises a query signal splitter, for feeding a query signal, emitted by the test signal transceiver, into the first PON and the second PON simultaneously, and for feeding response signals from the first PON and second PON into the test signal transceiver, wherein the query signal splitter is optically connected to the test signal transceiver and to the first and second PONs (10, 11) such that the query signal splitter can feed one query signal, emitted by the test signal transceiver, into the first PON and the second PON simultaneously, and such that the query signal splitter can feed response signals from the first PON and second PON into the test signal transceiver, wherein the query signal splitter is a power splitter, wherein the first and/or the second fibre-optic sensor is optically connected to the PON (10, 11), which comprises the respective fibre-optic sensor, by a sensor fibre, wherein the sensor fibre comprises a reflector at a far end of the sensor fibre, and wherein the query signal splitter is a symmetric splitter and has a splitting ratio of 1:4, 1:8, 1:16, 1:32, of 1:64, or higher. - a test signal transceiver for emitting query signals and for receiving response signals, wherein the response signals originate from the query signals, - a first PON comprising a first light source for generating first telecommunication signals and comprising a first fibre-optic sensor, wherein the first PON is adapted to transmit the first telecommunication signals to a plurality of subscribers, and wherein the first PON is optically connected to the test signal transceiver such that query signals from the test signal transceiver can be fed into the first PON and propagate in the first PON to the first fibre-optic sensor, and such that the test signal transceiver can receive response signals from the first fibre-optic sensor through the first PON, - a second PON comprising a second light source for generating second telecommunication signals and comprising a second fibre-optic sensor, wherein the second PON is adapted to transmit the second telecommunication signals to a plurality of subscribers, and wherein the second PON is optically connected to the test signal transceiver such that query signals from the test signal transceiver can be fed into the second PON and propagate in the second PON to the second fibre-optic sensor, and such that the test signal transceiver can receive response signals from the second fibre-optic sensor through the second PON,