An optical network node capable of being powered, comprising—a reflector arranged to reflect an optical signal, and—a switch arranged to direct the optical signal to the reflector in dependence on whether the optical network node is powered.

An ONU receiving an optical signal from an OLT including PON controllers includes: an optical receiver to convert, into an electric signal, an optical signal having a single optical wavelength set out of plural optical wavelengths; and a control frame extractor to extract and hold wavelength correspondence information indicating correspondence between MAC addresses of the PON controllers received from the OLT and the optical wavelengths. The control frame extractor, when receiving a wavelength switching request, extracts the optical wavelength after wavelength switching instructed in the wavelength switching request, obtains a setting address of the MAC address of the PON controller to which the ONU itself should be connected after the wavelength switching based on the extracted optical wavelength after the wavelength switching and the wavelength correspondence information, and determines whether a malfunction occurs based on a transmission source MAC address stored in a received control frame and the setting address.

An optical transmission device that transmits an optical signal in a specified wavelength band includes: a receiver, a monitor light unit, a wavelength selective switch and a memory. The receiver receives the optical signal. The monitor light unit outputs monitor light of a wavelength allocated outside of the specified wavelength band. The wavelength selective switch outputs the optical signal via a first port and outputs the monitor light via a second port. The memory stores information that indicates an optical power loss of a route through which the monitor light is transmitted.

A delay measuring device of a communication system that includes the delay measuring device sequentially transmitting and receiving frames having a known frame length, and a measurement object device serving as an object for measuring a round trip time by the delay measuring device, includes: an RTT measuring unit to measure a round trip time with respect to the measurement object device a number of times using information for delay measurement in the frame; an RTT change detection unit to detect a change of a value of the round trip time based on the values of the round trip time thus measured; and an RTT determination unit to determine a value of the round trip time to be adopted, from among the values of the round trip time, based on the change of a value of the round trip time.

A system for troubleshooting signals in a cellular communications network, and in particular, for determining the cause of distortion or corruption of such signals, includes a robotic or other type of switch. The robotic switch can tap into selected uplink fiber-optic lines and selected downlink fiber-optic lines between radio equipment and radio equipment controllers in a wireless (e.g., cellular) network to extract therefrom the I and Q data. The selected I and Q data, in an optical form, is provided to an optical-to-electrical converter forming part of the system. The system includes an FPGA (Field Programmable Gate Array) or the like, and an analytic computer unit, or web server, and SSD (Solid State Drive) and magnetic disk storage, among other components of the system. The system analyzes the I and Q data provided to it, and determines the cause, or at least narrows the field of possible causes, of impairment to transmitted signals. The system includes a display which provides the troubleshooting information thereon for a user of the system to review, or other form of a report, and may communicate the analytical findings to a remote location over a public or private internet protocol network.

According to a method, when it is detected that service traffic needs to be switched from a first optical layer path to a second optical layer path, a first internet protocol (IP) link associated with the service traffic needs to be determined, and an IP link used to transmit the service traffic is adjusted from the first IP link to a second IP link; an optical layer path of the first IP link is switched from the first optical layer path to the second optical layer path after the adjustment of the IP link is completed; and the IP link used to transmit the service traffic is adjusted from the second IP link to the first IP link after the switching of the optical layer path is completed. In this way, continuity of the service traffic can be ensured.

An optical network is provided that includes at least one strand of a plurality of strands of optical fiber optically connected to a first fiber distribution hub and an access terminal. The at least one strand optically is also connected to a second fiber distribution hub and the access terminal. The at least one strand thus provides a full duplex optical path in a first direction from the first fiber distribution hub to the access terminal and in a second direction from the second fiber distribution hub to the access terminal.

A method for detecting an optical network unit (ONU) in a passive optical network (PON), an ONU, a PON and an optical line terminal (OLT) are disclosed. In an embodiment the method include detecting an ONU identity code in an open uplink empty window or an empty timeslot, wherein the ONU identity code is a specific code stream sequence of the ONU that identifies a single ONU of the plurality of ONUs included in the PON system during the open uplink empty window or the empty timeslot and determining that the single ONU corresponding to the ONU identity code is a rogue ONU according to the ONU identity code.

Large photonic switches can establish optical paths between a large number of inputs and outputs. A distributed control architecture may be used in order to quickly establish the optical paths in large photonic switches. The distributed control architecture may provide a hierarchical control by grouping together endpoints, determining switching requirements between the groups and determining switching requirements within the groups.

A communication network (1) comprising an optical transport domain network (2) having optical transport nodes connected to each other via physical optical links, packet switched networks (3) each having a boundary router (4) connected to an optical transport node of said optical transport domain network (2) via an access link (5); and a network management apparatus (6) adapted to perform an automatic bandwidth management of said communication network (1), wherein said network management apparatus (6) is adapted to activate or deactivate virtual links (VL), tributary ports and cross-connections between virtual and access links in the optical transport domain (2) in response to data traffic statistics of data transmitted on said access links (5).