Abstract: An intelligence-defined optical tunnel network system includes multiple Optical Switch Interconnect Sub-systems (OSIS), in which a first OSIS is configured to transmit a first lateral transmission optical signal via a first line to a second OSIS, and transmit a second lateral transmission optical signal via a second line to the second OSIS. The second OSIS includes a failover sub-module and a micro-control unit. The failover sub-module is configured to output one of the first and the second lateral transmission optical signal based on a selective signal. The micro-control unit is configured to output the selective signal to the failover sub-module to control the failover sub-module output the second lateral transmission optical signal if a signal intensity of the first lateral transmission optical signal is lower than a threshold value.

Abstract: Systems, methods, and non-transitory computer-readable media are provided for performing channel swapping techniques for swapping bundles of optical channels in an optical network, such as a C+L band system, based on frequency band sensitivity. In one embodiment, a method includes swapping a first group of channels or first portion of spectrum in a more-sensitive frequency band with a first set of replacement channels or first portion of replacement spectrum using a first swapping technique. The method also includes swapping a second group of channels or second portion of spectrum in a less-sensitive frequency band with a second set of replacement channels or second portion of replacement spectrum using a second swapping technique that is different from the first swapping technique. The first and second swapping techniques are based at least in part on the number of channels or portion of spectrum that can be swapped at any given time instance.

Abstract: A method of interfacing a memory controller and a memory device in a memory system includes transmitting a control signal between the memory controller and the memory device using a time division multiplexing (TDM) communication process, and transmitting data between the memory controller and the memory device using a serializer/deserializer (SERDES) communication process. Data communication in the memory system is performed via a physical channel and a plurality of virtual channels corresponding to the physical channel.

Abstract: Examples herein involve dividing a ring protection network into multiple ring protection networks. Examples include detecting a disconnection in a ring protection network, determining whether an owner of the ring protection network is in a new ring protection network divided from the ring protection network, and establishing an owner of the new ring protection network based on whether the owner of the ring protection network is in the new ring protection network.

Abstract: An optical transceiver includes a wavelength-tunable transmission unit configured to transmit an optical transmission signal, a wavelength-tunable reception unit configured to receive an optical reception signal, a wavelength table configured to store a plurality of combinations of a transmission wavelength and a reception wavelength, an input terminal configured to input a wavelength selection signal, and a control unit configured to select one combination of the transmission wavelength and the reception wavelength from the wavelength table based on the wavelength selection signal, and perform transmission wavelength control for setting the selected transmission wavelength in the wavelength-tunable transmission unit as a wavelength of the optical transmission signal and reception wavelength control for setting the selected reception wavelength in the wavelength-tunable reception unit as a wavelength of the optical reception signal.

Abstract: In the elastic optical network, there has been the problem that processing steps increase that are required to re-optimize client signals to be concentrated; therefore, an optical network controller according to an exemplary aspect of the present invention includes reallocation detection means for monitoring an operation status of at least one of an optical communication channel and an optical node device that constitute an optical network, and determining, based on the operation status, whether or not to reallocate a client signal accommodated in an optical path set in the optical network; design-candidate exclusion means for designating, as a design exclusion object, at least one of the optical communication channel and the optical node device that are associated with an optical path targeted for reallocation that accommodates the client signal that the reallocation detection means has determined to reallocate; optical path design means for determining an alternative route for the optical path targeted for

Abstract: A module, system and method adjusts a tunable filter to have an adjustable frequency response based on one of an outbound optical signal on a transmit channel and an inbound optical signal on a receive channel. The tunable filter is in an optical path of the outbound optical signal and in an optical path of the inbound optical signal. The transmit and the receive channels are configured as part of a channel plan of a bidirectional (bi-di) dense wavelength division multiplexing (DWDM) system.

Abstract: An inline-bypass switch system includes: a first inline-bypass switch appliance having a first bypass component, a second bypass component, a first switch coupled to the first bypass component and the second bypass component, and a first controller; and a second inline-bypass switch appliance having a third bypass component, a fourth bypass component, a second switch coupled to the third bypass component and the fourth bypass component, and a second controller; wherein the first controller in the first inline-bypass switch appliance is configured to provide one or more state signals that is associated with a state of the first inline-bypass switch appliance; and wherein the second controller in the second inline-bypass switch appliance is configured to control the second bypass component based at least in part on the one or more state signals.

Abstract: In an automatically switched optical network operating according to a wavelength plan, the wavelengths are assigned to an optical path based on availability, performance and SRS wavelength coupling reduction. First, the wavelengths are grouped in static bins based on their reach versus cost performance, and each bin assumes a ?Q of a middle wavelength. Then, the bins are moved into subsets of dynamic bins, constructed using bin constraints that account for the particulars of the respective optical path. The path is characterized taking into account the wavelength currently accessing at the end nodes, and the wavelength tandeming through the end nodes. Wavelength selection starts with the bins that satisfy the maximum number of constraints, and the wavelengths are checked sequentially against wavelength constraints; relaxed constraints are also applied when it is not possible to exactly satisfy one or more constraints.

Abstract: In one embodiment, a first device in a network identifies a first traffic flow between two endpoints that traverses the first device in a first direction. The first device receives information from a second device in the network regarding a second traffic flow between the two endpoints that traverses the second device in a second direction that is opposite that of the first direction. The first device merges characteristics of the first traffic flow captured by the first device with characteristics of the second traffic flow captured by the second device and included in the information received from the second device, to form an input feature set. The first device detects an anomaly in the network by analyzing the input feature set using a machine learning-based anomaly detector.

Abstract: A method, implemented in a network with a control plane, is described for creating a compound Service Level Agreement (SLA) call for a Time Division Multiplexing (TDM) service in the network. The method includes creating the call with a non-preemptible component and a preemptible component, the compound SLA comprising the non-preemptible component and the preemptible component; implementing endpoints for the call at a source node and a destination node; and responsive to a preemption event in the network, removing the preemptible component at the endpoints. A node and network are also described.

Abstract: Embodiments of the present invention provide a reconfigurable optical add-drop multiplexer apparatus, and relate to the field of communications, so as to solve the problem of inconvenient line failure detection. The ROADM apparatus includes: a first ROADM, a second ROADM, one splitting coupler, four optical amplifiers, and four couplers. The embodiments of the present invention are used in a communications line architecture.

Abstract: Methods and systems for network communications are disclosed. The target device receives a request for a network connection from an initiator device, the request indicating a desire to bypass transport communication layer processing. The target device accepts the request and sends a response to the initiator device indicating an agreement to bypass the transport layer processing. The target device then receives a frame from the initiator device and processes the frame by bypassing the transport communication layer processing.

Abstract: An optical transmission device in an optical transmission network including nodes, provided to one of the nodes, the optical transmission device including: a receiver to receive optical signals which have different wavelengths and are multiplexed, an optical detector to detect a strength of the optical signals, a switch to set switching control information including switching request information, each corresponding to one optical signal of the optical signals, and a transmitter to transmit the switching control information by an optical signal, wherein the switch sets, in information indicating a signal fail, the switching request information corresponding to the one optical signal in the switching control information based on the strength of one optical signal of the optical signals.

Abstract: A transmission circuit of a transmission device transmits a signal to a reception circuit of a reception device via a plurality of signal paths included in a communication line. A first interface circuit is connected to the transmission circuit and one or more signal paths. A second interface circuit is connected to the transmission circuit and remaining signal paths expect for the one or more signal paths. A third interface circuit is connected to the reception circuit and the one or more signal paths. A fourth interface circuit is connected to the reception circuit and the remaining signal paths. An operation for transmitting and receiving the signal via the plurality of signal paths is changed to an operation for transmitting and receiving the signal via the remaining signal paths when the one or more signal paths enter a disconnected state.

Abstract: The present invention discloses a distributed electrical cross apparatus, and a system and method for the distributed electrical cross apparatus implementing an SNC cascade protection. The apparatus includes a backboard and at least four single-boards integrated with electrical cross units, wherein the single-boards are inserted in the limited number of slots in the backboard, and these single-boards also set line-side service access units, client-side service access units and backboard access units. The present invention has both accessing of line-side services and accessing of client-side services in the same single-board, access and flexible scheduling of various services such as line-side services and client-side services and so on are implemented on the backboard with limited number of slots, and the function of the distributed electrical cross system processing various services is increased in the case of low cost.

Abstract: We propose an efficient procedure, namely disjoint pair procedure based cloud service embedding procedure that first maps working and backup virtual nodes over physical nodes while balancing computational resources of different types, and finally, maps working and backup virtual links over physical routes while balancing network spectral resources using the disjoint pair procedure.

Abstract: Disclosed herein are optical distribution networks and corresponding methods for providing physical-layer redundancy. Example embodiments include a head-end passive optical splitter-combiner (OSC) to split optical signals from an Optical Line Terminal (OLT) onto primary and secondary optical paths for redundant distribution to optical network terminal(s) (ONTs), a passive access OSC for tapping the redundant signals, and an optical switch for selecting between the redundant signals and providing an ONT access to the selected signal. Example optical distribution networks and corresponding methods provide multiple drop points, a fully cyclical path, and autonomous protection switching, all at low cost. A further advantage of these networks and methods is that where faults may occur, maintenance may not be required for a certain time.

Abstract: The invention discloses a system, a method and an apparatus for optical network protection. The system includes: an output control apparatus for obtaining protection mode information configured by a system and controlling an input signal to be output from a set line corresponding to said protection mode information; and a detection control apparatus for detecting powers of signals transmitted on an active line and on a standby line, if it is determined that the active line is abnormal and the standby line is normal according to detection results, then controlling the input signal to be output from a protection line corresponding to the protection mode information; if it is determined that the active line is normal, or that the active line and the standby line are abnormal according to the detection result, then controlling the input signal to be output from a set line corresponding to the protection mode information.

Abstract: A node of an optical transport network system transmits optical wavelengths to an adjacent node through an operational line. An apparatus for protection switching of the optical transport network system transmits only an optical channel with a fault among a plurality of optical channels composed of flexible optical channel data units in an optical wavelength of the operational line, via a reserve line.

Abstract: A method for shared mesh restoration includes configuring a switch to allow sharing of a plurality of backup line cards across a plurality of node degrees associated with a reconfigurable optical add/drop multiplexer (ROADM). The switch is communicatively coupled to the ROADM. The method further includes configuring a number of backup line cards coupled to the switch. The number of backup line cards is based on determining a number of active backup lightpaths for each of a plurality of network failures associated with each of the plurality of node degrees of the ROADM, identifying which node degree and failure has the largest number of active backup lightpaths for all of the plurality of node degrees of the ROADM and for each of the plurality of network failures, and determining the number of backup line cards to configure based on the identified largest number of active backup lightpaths.

Abstract: A node device in an optical transport ring network including plural node devices connected in a ring form using plural optical transmission paths so that optical transport frames of a working line and a protection line are transmitted using the plural optical transmission paths, includes a control information transmitter, when a failure occurs in the optical transmission paths, transmitting the optical transport frame to an opposing node device as a transmission destination node in the optical transmission paths, the optical transport frame including switching control information; and a switcher receiving the optical transport frame including switching control information, the optical transport frame being transmitted to the node device as the transmission destination node, forming a loop back to fold a transmission path between the plural optical transmission paths, and switching the optical transmission path from the work line to the protection line.

Abstract: A method, a network, and a node each implement the transmission of Automatic Protection Switching (APS) switching coordination bytes across an OTN network. A working signal and a protection signal are received, one of which is designated as an active signal. The active signal is encapsulated in an Optical channel Data Unit (ODU) signal. APS switching coordination bytes from the working and protection signals are placed in an overhead segment of the ODU signal. The ODU signal is transmitted into and received from an Optical Transport Network (OTN) network. The working and protection signals are recreated based on the active signal encapsulated in the ODU signal and the APS switching coordination bytes in the overhead segment. The recreated working and protection signals are transmitted. In this manner, a single ODU signal may be used to transmit both the working and protection signals.

Abstract: Due to demand for more network bandwidth, a need for multi-user optical network topologies has, and will continue to, increase. A method or corresponding apparatus in embodiments of the present invention provide for an availability determination tool for determining and displaying wavelength and subrate availabilities within a network. Benefits of embodiments of a tool include allowing a user to identify the availability and capacity of any wavelength on any network, via an interactive graphical user interface, such as by using three-dimensional representations. In one embodiment, the disclosed availability determination tool allows users to locate and view any combination of available wavelengths between nodes in an optical network topology, and generate graphical and tabular reports of the availability in order to maintain an efficient and organized method or apparatus for determining and controlling wavelengths in a network.

Abstract: An optical network has an optical line termination coupled to a backbone network, in particular to an optical long haul network and a local exchange coupled to an optical access network. The local exchange provides an optical connection between an optical network unit of a tree topology and the optical line termination, which is part of a ring topology. There is also described a method for processing data in such an optical network.

Abstract: Optical safety functions are incorporated into protection switching modules which maintain redundant pathways to avoid interruptions in optical network connections. The optical safety functions which lower optical power levels upon interruptions of optical connections are effectively combined with protection switching procedures which are also triggered by interruptions in optical network connections. The interoperation of protection and safety processes keep optical power levels below hazardous levels at system points which might be accessible to human operators.

Abstract: A method and apparatus for controlling traffic in an optical network having a plurality of OLTs for communicating with a plurality of PONs. A traffic controller receives traffic information concerning current traffic volume and, preferably with reference to a rules database, calculates the number of OLTs required to support the current traffic volume. A separate determination may be made whether a network reconfiguration is permitted at this time. If a reconfiguration is permitted, the traffic controller configures a traffic control switch to route the PON traffic to an from only the calculated number of OLTs. The traffic control switch may be implemented using a voltage-controlled optical fiber coupling or electronically, routing the traffic as electrical signals to and from electro-optical converters associated with each PON. The OLTs to be used may be selected by the traffic controller.

Abstract: A method, an optical add-drop multiplexer branching unit, and a system for disaster recovery of an optical communication system are provided. The method for disaster recovery of an optical communication system using an optical add-drop multiplexer unit (OADM) includes: detecting a transmission link fault in an optical communication system; and when a transmission link fault is detected, switching the state of a link where the transmission link fault occurs from pass-through to loopback, so that an optical signal input from a non-faulty end of the link is looped back to the end for outputting. In this way, when a transmission link fault occurs in an optical communication system, the power level of a link where the transmission link fault occurs can be maintained by using the solutions in the embodiments of the present invention, thereby keeping transmission performance stable.

Abstract: The fabric card includes at least one fabric card chip and at least two fabric card connector groups, where each fabric card connector group of the at least two fabric card connector groups includes at least two fabric card connectors, the number of fabric card chips is less than the number of at least two fabric card connector groups, each fabric card chip of the at least one fabric card chip connects to all fabric card connectors in at least one fabric card connector group, all fabric card connectors in the fabric card connector group that connect to the fabric card chip exchange data using the fabric card chip. This fully utilizes an exchange capability of the fabric card chip and saves system resources.

Abstract: Optical network protection devices and protection methods including: a working line; a protection line; a determination module configured to determine the protection type of optical network; a first judgment module configured to judge whether the working line is normal according to performance parameter values of service signal in the working line and switching conditions configured for multiplexing section protection when the protection type of optical network is the multiplexing section protection; a second judgment module, configured to judge whether the working line is normal according to performance parameter values of service signal in the working line and switching conditions configured for channel section protection when the protection type of optical network is the channel section protection; a switching module, configured to take the service signal in the protection line as an output signal when working line is abnormal.

Abstract: This concerns a protected long-reach PON having a plurality of terminals connected to a distribution network that is fed by both a main and back up feed, each feed including a head end and a repeater. The back up head end had access to a ranging table with data previously obtained by the main head end, thereby speeding up the switch over in the event of a fault with the main feed. In one embodiment, the repeater has a virtual ONU therein, allowing the back up repeater to be ranged by the back up head end, thereby yet further speeding up the ranging procedure. The main and back up repeaters are sufficiently equidistant from the distribution network to allow the back up head to perform normal scheduling without performing a ranging operation on each of the terminals, even if the different terminals transmit at slightly different wavelengths. This is achieved using the ranging information obtained with regard to the back up repeater.

Abstract: A method for realizing interaction of optical channel data unit (ODUk) protection tangent rings are provided. A node used for protection of the ODUk and a receiving unit, a sending unit, a protected receiving unit and a protected sending unit on the node are selected. A connection between a receiving service unit and the protected sending unit with the same transmission direction on the node is established, or a connection between a sending service unit and the protected receiving unit with the same transmission direction on the node is established. Two virtual nodes are established on the node if the node is an intersection node, and connections between the receiving service unit and the protected sending unit, and between the sending service unit and the protected receiving unit are established respectively in each direction of both directions through one of the virtual nodes.

Abstract: Systems and methods for distributing signals in an optical network are disclosed. In accordance with one embodiment of the present disclosure a method for distributing signals in an optical network comprises combining input signals into one or more output signals, determining, an availability status of optical lanes for carrying the output signals and distributing the output signals to optical transmitters associated with the optical lanes if the availability status indicates that the optical lanes are available.

Abstract: An information processing method is disclosed according to the embodiments of the present invention. The method includes: A node receives a first message from overhead of a first dimension; the node searches for local configuration information, where the local configuration information includes the overhead of the first dimension of a protection path, a protection resource of the first dimension of the protection path, overhead of a second dimension of the protection path, and a protection resource of the second dimension of the protection path; according to the local configuration information and the first message, the node determines a protection path correlated with the first message and determines overhead of the second dimension correlated with the first message; and the node sends a second message to a node adjacent to the second dimension through the overhead of the second dimension correlated with the first message, according to the first message.

Abstract: An OADM device without a transponder unit does not mount the transponder in charge of separating a fault between the OADM device and an external device and is difficult to perform fault separation and to identify a fault interval. To solve this problem, for the OADM device without the transponder unit, the optical loop back function is provided by using such a switch as, for example, 2×2 optical switch. By identifying a fault developing interval by the use of the optical loop back function, fault separation at the time of occurrence of a fault can be facilitated.

Abstract: In a communication line switching method for an optical communications system in which a station-side line terminal apparatus and user-side line terminal apparatuses are connected via a plurality of redundant physical lines, the discovery of the station-side optical line terminal registering the user-side line terminal apparatuses, wherein the registered user-side line terminal apparatuses monitoring a time stamp drift error that is generated when a difference between a time stamp included in a received signal and a local time measured by the own apparatus is larger than a value set in advance and, when the time stamp drift error occurs, shifting to a deregistered state and waiting for registration by the discovery. The station-side line terminal apparatus switches a physical line from a working physical line to a backup physical line of the physical lines.

Abstract: A PON ring system and a method for realizing primary and backup link protection in a passive optical network (PON) are provided. A PON ring is established between at least two optical line terminations (OLTs) through at least two user side edge nodes or network side edge nodes. Each of the OLTs is coupled to any other OLT through the at least two edge nodes. Two links respectively in a clockwise direction and a counterclockwise direction exist in the PON ring, in which one link is a primary link and the other is a backup link. Node of the links adopt the transmission mode of “multiple sending and selective receiving”. Therefore, the present invention reduces the impact on the PON caused by single link failure in the network.

Abstract: The present invention discloses a method and device for processing an alarm in a ring optical transport network. The method comprises detecting alarm information in the ring network in real-time, and when generation of only an working ODUk alarm in the ring network is detected, performing a switching process of a 1+1 protection protocol on services carried on a working channel on which an alarm is generated; in the event that one working ODUk alarm has existed in the ring network, when generation of an alarm at a protection ODUk corresponding to the working ODUk on which the alarm has been generated is also detected, or when an optical multiplexed segment layer alarm is generated in the ring network, triggering a switching process of a channel shared protection protocol. The device comprises an alarm detection module and a switching triggering module.

Abstract: In a communication line switching method for an optical communications system in which a station-side line terminal apparatus and user-side line terminal apparatuses are connected via a plurality of redundant physical lines, the discovery of the station-side optical line terminal registering the user-side line terminal apparatuses, wherein the registered user-side line terminal apparatuses monitoring a time stamp drift error that is generated when a difference between a time stamp included in a received signal and a local time measured by the own apparatus is larger than a value set in advance and, when the time stamp drift error occurs, shifting to a deregistered state and waiting for registration by the discovery. The station-side line terminal apparatus switches a physical line from a working physical line to a backup physical line of the physical lines.

Abstract: A method, system and apparatus for single-fiber bidirectional ring network protection are disclosed in the present invention, wherein, one working path ring between various nodes in the single-fiber bidirectional ring network shares one sharing protection channel using a set wavelength, and when a fault occurs in a working path between certain two nodes, the method includes: controlling sharing protection apparatuses of a receiving end node and a transmitting end node of the failed working path to switch from a primary port to a corresponding standby port, controlling an intermediate node in the sharing protection channel corresponding to the working path to enable a standby port of the corresponding sharing protection apparatus, and establishing the sharing protection channel corresponding to the working path; transmitting a service signal carried in the failed working path through the newly established sharing protection channel.

Abstract: N optical transceivers are each connected to a respective electronic module in one-to-one relation such that a respective one electronic module controls a respective one optical transceiver. An electronic switch matrix provides cross-connect capability between the P redundant electronic modules and N electronic modules to the N optical transceivers. A system controller determines when an active N electronic module has failed, and configures the electronic switch matrix to switch a P redundant electronic module into the optical transceiver to which the failed electronic module was connected. A system switch module redirects traffic and routing information, under the direction of the system controller, from the failed module to the newly activated redundant module so that the redundant module assumes the functionality of the failed module.

Abstract: A transmission apparatus includes a processor configured to recognize a number of working failures and a number of protection failures on a network for transmission of wavelength-multiplexed signal light, the number of working failures being the number of failures in signal light in wavelengths at a working entity and the number of protection failures being the number of failures in signal light in wavelengths at a protection entity, configured to perform path switching for each group of signal light in wavelengths that are different from each other and configured to select, when multiple failures occur, restoration processing, on a basis of the number of working failures and the number of protection failures.

Abstract: An optical communications system includes a MSAP and an optical transceiver mounted at the MSAP that communicates over an optical network to at least one optical network terminal (ONT). A first electronic module is operatively connected to the optical transceiver and configured to control the optical transceiver and mounted at the MSAP separate from the optical transceiver. A redundant second electronic module is supported within the MSAP and mounted separate from the optical transceiver. A Mux/Demux module interconnects and supports the first and second electronic modules to form an integral unit and mounted at the MSAP separate from the optical transceiver. The Mux/Demux module is configured to switch the second electronic module into communication with the optical transceiver upon failure of the first electronic module.

Abstract: A method for managing an optical network having a plurality of nodes interconnected by a plurality of fiber links includes installing one or more active reconfigurable optical add/drop multiplexer (ROADM) cards into a node and installing a spare ROADM card into the node. The one or more active ROADM cards are configured to pass optical traffic to and from the optical network. The installed spare ROADM card is remotely activated to pass optical traffic to and from the optical network, subsequent to configuring the one or more active ROADM cards, based on one of: an event or expiration of a time period.

Abstract: In accordance with embodiments of the present disclosure, a method for demand aggregation is provided. The method may include routing demands in a ring network such that a length for each routed demand does not exceed a route length maximum, and a load imbalance at each node in the ring network is minimized. The method may also include maximizing optical line card sharing by assigning routed demands sharing common ends to the same wavelength.

Abstract: An optical ring network has one or more working wavelengths and multiple protection wavelengths adapted to support the working wavelength(s). Routing tables may be used in network nodes to assign traffic of a failed working wavelength to a protection wavelength. The protection technique may be applied to networks employing, for example, Dense Wave Division Multiplexing (DWDM).

Abstract: A wavelength division multiplexing (WDM)-time division multiplexing (TDM) passive optical network (PON) remote terminal (RT) is provided. The wavelength division multiplexing (WDM)-time division multiplexing (TDM) passive optical network (PON) remote terminal (RT), includes: a WDM-TDM converter configured to convert a WDM downstream optical signal that is received from a central office terminal (COT) into a TDM downstream optical signal or to convert a TDM upstream optical signal that is received from an optical network terminal (ONT) into a WDM upstream optical signal; an error detector configured to detect an error; and a controller configured to, in response to an error being detected, transmit the WDM upstream optical signal to the COT via a first standby link or transmit the TDM downstream optical signal to the ONT via a second standby link.

Abstract: An optical line terminal (OLT) of a passive optical network (PON) detects a fault in an optical path configured as a single optical fiber core having an annular shape, divides the optical path into a right path and a left path having bi-directionality based on the fault position in which the fault has occurred, demultiplexes a plurality of downstream optical wavelength signals to be transmitted to at least one optical network terminal (ONT) of each group into an optical wavelength signal of the right path and an optical wavelength signal of the left path according to the position in which the fault has occurred, and outputs the same to at least one of the ONTs of each group.

Abstract: An optical splitter for a passive optical network for telecommunication signal transmission with an optical line terminal includes a wavelength selective optical electrical converter, an AC/DC splitter, an energy reservoir and optical switches, where the splitter comprises also a data transmission processing module by which the optical switches can be controlled according to data signals transmitted from the optical line terminal.

Abstract: Delivering multicast data traffic over a communication network includes a first network node delivering multicast data traffic to second network nodes. The first and second network nodes are connected by a transmission network in a ring architecture and implement a point-to-multipoint layer 2 protocol. A method includes at the first network node: collecting alarms signals indicative of a failure along the whole ring and of the second network nodes. Based on a current state of the alarm signals, delivering the multicast data traffic either in a first delivery direction along the ring, or in a second delivery direction along the ring opposite to the first delivery direction, or in both the first and second delivery directions. At each of the second network nodes: collecting alarm signals indicative of a failure of the transmission network locally to the second network node and of the second network node.