A communications network, comprising a first optical line terminal, a second optical line terminal, and customer-premises equipment, wherein the first optical line terminal is connected to at least one second optical line terminal through a first passive optical network, PON, interface, and the second optical line terminal is connected to at least one customer-premises equipment through a second PON interface; wherein during data downstream transmission, the first optical line terminal is configured to send a first optical signal in a first PON protocol to the at least one second optical line terminal, and the second optical line terminal is configured to process the first optical signal and send a processed first optical signal in a second PON protocol to the at least one customer-premises equipment; and during data upstream transmission, the customer-premises equipment is configured to send a second optical signal in the second PON protocol, to the second optical line terminal connected to the customer-premises equipment and the second optical line terminal is configured to process the second optical signal and send a processed second optical signal in the first PON protocol to the first optical line terminal, characterized in that the second optical line terminal is configured to perform protocol conversion on the first optical signal, when the first PON interface and the second PON interface correspond to different protocols, and the second optical line terminal is configured to perform denoising and signal enhancement on the first optical signal, when the first PON interface and the second PON interface correspond to a same protocol, wherein each of the first optical line terminal and the at least one second optical line terminal comprises the first PON interface, the second PON interface, and an Ethernet interface, and wherein during data downstream transmission, the Ethernet interface of the first optical line terminal is configured to receive a first electrical signal sent by a network side device, and during data upstream transmission, the Ethernet interface of the first optical line terminal is configured to send a second electrical signal to the network side device. during data downstream transmission, the first optical line terminal is configured to send a first optical signal in a first PON protocol to the at least one second optical line terminal, and the second optical line terminal is configured to process the first optical signal and send a processed first optical signal in a second PON protocol to the at least one customer-premises equipment; and during data upstream transmission, the customer-premises equipment is configured to send a second optical signal in the second PON protocol, to the second optical line terminal connected to the customer-premises equipment and the second optical line terminal is configured to process the second optical signal and send a processed second optical signal in the first PON protocol to the first optical line terminal, characterized in that the second optical line terminal is configured to perform protocol conversion on the first optical signal, when the first PON interface and the second PON interface correspond to different protocols, and the second optical line terminal is configured to perform denoising and signal enhancement on the first optical signal, when the first PON interface and the second PON interface correspond to a same protocol, wherein each of the first optical line terminal and the at least one second optical line terminal comprises the first PON interface, the second PON interface, and an Ethernet interface, and wherein during data downstream transmission, the Ethernet interface of the first optical line terminal is configured to receive a first electrical signal sent by a network side device, and during data upstream transmission, the Ethernet interface of the first optical line terminal is configured to send a second electrical signal to the network side device.