Abstract: Method, system, and computer program product example embodiments of the invention are disclosed to provide multi-network secure video teleconferencing (VTC) for VTC endpoints. The embodiments of the invention provide distributed components to perform the necessary operations, rather than co-locating the components in the VTC endpoint. Some system components are located with the VTC endpoint, other components are placed in a network operations center (NOC) and still other components are distributed on the various networks.

Abstract: The present invention relates to an optical fiber access network and a communication protection method thereof. The optical fiber access network comprises an optical fiber communication system, a wireless communication system, a communication service switch device, a second optical network unit and a protection optical fiber. The wireless communication system is introduced to protect the optical fiber between the optical branching divider and the optical network unit in the optical fiber communication system. The protection optical fiber or the wireless communication system is used to protect the communication service respectively when there is a broken failure between the optical line terminal and the optical network unit in the optical fiber communication system. This invention overcomes the limit of the resource, protects communication service of the optical fiber communication system and improves the bandwidth utility of the communication system.

Abstract: The present invention discloses a service protection method and device based on an automatic switched optical network (ASON), which are adapted to restoring a service when a fault occurs in the connection of the service. The method comprises: comparing a dynamic restoration lag time of the service with a protection switching lag time of the service; and starting a protection switching process to restore the service if the dynamic restoration lag time is greater than the protection switching lag time; and starting a dynamic re-routing process to restore the service if the protection switching lag time is greater than the dynamic restoration lag time. By the present invention, the reliability of the network is enhanced and the self-healing capacity of the ASON is improved.

Abstract: In a fiber-optic communications system, a backup or redundant optical link is provided at the central office in parallel with the primary one in use. Parameters associated with the backup link, including its signal delay, its attenuation, etc. are stored at the time of installation. Upon failure of the primary link, switchover can be automatic, and the stored parameters are used to make adjustments necessary for the differences between the primary link and the backup link. In addition, having information on the differences between the two links, the central office is able to send control information downstream which is used at the remote site to control changes that must be made for upstream signals. For example, customer equipment can be signaled to adjust its timing for the next time slot or interface amplifiers can be adjusted to account for the change in attenuation.

Abstract: A system and method for responding to a failure in a communications network. The failure is detected by a router, which then transmits data from the protection port. A signal is sent from the router to a optical cross-connect system indicating the failure and causing the optical cross-connect system to connect the protection port of the router to a working port of the OXC.

Abstract: Systems and methods are described for restoring wavelength services in mesh networks using pre-configured, standby lightpaths. The standby lightpaths are pre-cross-connected lightpaths that provide connectivity between switching nodes having a fiber link of degree-2 or higher. The restoration method overcomes the problem of optical impairments for long haul connections, avoids wavelength power balancing delays, provides wavelength conversion for capacity efficiency, and allows sharing of links across nonsimultaneous failures.

Abstract: A method and a device for realizing an optical channel data unit (ODU) shared protection ring (SPRing) are disclosed by the present invention. The method includes: A first ODU of a first service transmitted in an optical line is taken as a protection granularity, where the first ODU is an ODUk that is directly multiplexed to the optical line; the first ODU is monitored, and a monitoring result is obtained; when the monitoring result indicates that a failure occurs, a switching is performed through cross of a second ODU of the first service, where the second ODU is an ODUm that is multiplexed to the first ODU, and m is smaller than or equal to k. Through the embodiments of the present invention, a protection switching speed may be accelerated.

Abstract: The embodiments of the invention provide a method of routing convergence in a control plane of an intelligent optical network, which includes: a function unit perceiving a service link state transmitting an alarm notification message indicating a failure in a service link to a routing protocol unit when the service link is in failure; the routing protocol unit confirming a service link failure in the control plane according to the alarm notification message. The embodiments of the invention also provide an apparatus of routing convergence in a control plane of an intelligent optical network. According to the embodiments of the invention, the establishment of a new service or re-routing may be implemented within several seconds or even hundreds of milliseconds after the service link failure in the control plane occurs.

Abstract: A system and method for dynamically adding/dropping wavelengths in a reconfigurable optical add-drop multiplexer (ROADM) transport network to form a wave division multiplexing virtual private network is disclosed.

Abstract: Techniques are disclosed for a broadband service provider to maintain continuity of service in the event that a broadband light source fails in a passive optical network which uses injection-locked transmitters. Generally, a first broadband light source is connected to a passive optical network. Should the first broadband light source fails, it is disconnected from the network, and a second broadband light source is connected to the network.

Abstract: The present invention provides optical network methods and systems. In one example, a method for handling packets in a node coupled to a ring and star subnetwork may include (a) receiving in the given node a data packet on the ring subnetwork, (b) detecting a failure on the ring subnetwork, (c) determining a new transmission path to the destination node, and (d) sending the data packet along the new transmission path. In another example, an EPON may include (a) a root coupled to a ring and star subnetwork, (b) ONUs coupled to the root via a splitter/combiner and a first fiber link, (c) a second fiber link coupled to a subset of ONUs and the star subnetwork, and (d) a WDM coupler on the first fiber link that separates a first waveband of wavelengths from a second waveband of wavelengths and guides the first waveband to the star.

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: The present invention discloses a passive optical network (PON) protection method, a switchover control device, and a PON protection system. In embodiments of the present invention, a protection optical line terminal (OLT) is connected to optical links of at least two working OLTs through the switchover control device; when a working OLT or working optical link fails, the switchover control device replaces the working OLT through the protection optical link, thus ensuring smooth communication. In addition, by using the networking mode of multiple working OLTs and one protection OLT, the embodiments of the present invention greatly saves the networking cost and facilitates the application of the PON technology.

Abstract: The present disclosure provides mesh restoration systems and methods with Optical Transport Network (OTN) links using a signaling and routing protocol, such as Optical Signaling and Routing Protocol (OSRP), Automatically Switched Optical Network (ASON), Generalized Multi Protocol Label Switching (GMPLS), and the like. The present invention includes an optical node, network, and method using the signaling and routing protocol for OTN lines of differing bandwidth granularities. The present invention utilizes OTN overhead for in-band signaling and may include capability for supporting SONET/SDH lines as well as OTN lines in the same system using the signaling and routing protocol.

Abstract: An apparatus and method for protection switching of an optical channel at each node in an optical network based on wavelength division multiplexing optical transmission technology are provided. The method can be applied to any node having at least two optical fiber inputs and outputs. The apparatus includes: a splitter receiving an electrical signal and splitting the received electrical signal into a plurality of electrical signals which are substantially identical to the received electrical signal; an output switching unit selecting output paths of the electrical signals split by the splitter according to an optical channel path control command of the optical network; and a plurality of optical transponders being assigned to the respective output paths of the electrical signals, converting the electrical signal input by the selection of the output switching unit to an optical signal, and transmitting the converted optical signal to another node of the optical network.

Abstract: A method of restoration for an optical network, the network comprising a plurality of nodes (40, 50) interconnected with each other by optical links (130), a subset of the nodes (40) each comprising a regenerator, the method comprising: storing (160) a quality of transmission parameter and a regenerator availability at each of the plurality of nodes (40, 50); notifying (170) a branch node (110) in response to detecting a failure (140) within a link (130) forming part of the path between a source node (20) and a destination node (30), wherein the branch node (110) is the neighbouring upstream node (40, 50) upstream of the link failure (140), the branch node (110) having a regenerator; the branch node (110) computing (190) a restoration segment (100) to a merge node (120) having a regenerator which is a neighbouring downstream node which is downstream of the link failure (140), the restoration path (100) being based on the quality of transmission parameter and regenerator availability information; restoring (18

Abstract: Interworking an Ethernet Ring network with an Ethernet network with traffic engineered trunks (PBT network) enables traffic engineered trunks to be dual homed to the Ethernet ring network to enable for protection switching between active and backup trunk paths in the PBT network. In one embodiment, the active path will terminate at a first bridge node on the Ethernet ring network and the backup path will terminate at a second bridge node on the Ethernet ring network. Trunk state information is exchanged between the bridge nodes to enable the bridge nodes to determine which of the active and backup paths should be used to forward data on the trunk. Upon a change in trunk state, a flush message is transmitted on the Ethernet ring network to enable the nodes on the Ethernet ring network to relearn the path to the new responsible bridge node.

Abstract: An object of the present invention is to continue to send and receive to/from a host when a failure has occurred in a storage device interface. A storage system includes a host and a storage device connected to the host via a communication line, wherein the storage device comprises a communication controller performing data communication with the host by using optical modules, and wherein the communication controller is provided with first optical modules performing data communication with the host; a second optical module performing data communication with the host, in place of a first optical module; and a controller switching, when a failure has occurred in any of the first optical modules, the first optical module in which the failure has occurred to the second optical module.

Abstract: Fault tolerance may be achieved in a branched optical communication system such that a fault in one optical path may not affect optical signals coupled from a healthy optical path. In general, a flexible branching unit is configured, when adding and dropping channels, to select channels from a healthy path and not from the faulty path (e.g., a trunk path or a branch path) to prevent non-uniform channel loading on the trunk path after the branching unit. In this manner, a fault detected on the trunk path may not affect signals from the branch path and a fault detected on the branch path may not affect signals from the trunk path, thereby providing fault tolerance. A flexible branching unit may also be capable of adjusting the number and selection of channels that are added and dropped at the branching unit.

Abstract: Optical network terminal (ONT) power failure management. A system for permitting a customer of a telecommunication company, for whom fiber to the premises (FTTP) has been installed, to control operating features associated with operation of a battery backup unit (BBU) which is used, during power failure, for powering the ONT associated with the FTTP installation and the customer's telephone(s). The controlling of these features includes utilization of signal-controlled switches, which are manually over-rideable by the customer, thereby providing the desired operating feature control.

Abstract: An approach is provided for performing fault recovery using composite transport groups (CTGs). A first logical channel is established within a composite transport group, wherein the first logical channel is established over a first link associated with a first service provider to a customer premise equipment (CPE) node configured to transport packets. A second logical channel is established within the composite transport group, wherein the second logical channel is established over a second link associated with a second service provider to an optical node. Packets are received over the first logical channel. Packets are received over the second logical channel if the first logical channel experiences a fault condition, wherein switching to the second logical channel is transparent to the CPE node.

Abstract: An optical transmission device includes a first optical output unit including a chip and outputting an optical signal having a predetermined wavelength according to a temperature, a second optical output unit including a chip of which a temperature is controlled independently of the chip of the first optical output unit and outputting an optical signal having a predetermined wavelength according to a temperature, a failure detecting unit detecting a failure of the chip in operation of the first optical output unit, a switching unit switching its operation to the chip of the second optical output unit whose output optical signal has a same wavelength as that of the optical signal of the chip in operation of the first optical output unit when the failure detecting unit detects the failure, and a transmitting unit transmitting the optical signal output from the chip of the second optical output unit.

Abstract: First and second switching device are connected by a number of signal paths. The first switching device receives an instruction to switch from a first one of the signal paths to a second one of the signal paths. The first switching device performs, in response to the received instruction, a first switching operation to connect the first path, at an input of the first switching device, to the second path, at an output of the first switching device. The second switching device receives the instruction to switch from the first path to the second path and detects a loss of signal on the first path as a result of the first switching operation performed by the first switching device. The second device performs, in response to detecting the loss of signal on the first path, a second switching operation to connect the first path, at an output of the second switching device, to the second path, at an input of the second switching device.

Abstract: The invention relates to a remote interface device (12) for terminating a remote optical fiber link, with a network input (14), a network output (15), a customer input (17) and a customer output (16) for data signals, characterized in that the device (12) is designed such that during normal operation, only data received at the customer input (17) is sent onto the network output (15), that the device (12) is further designed such that in case of a failure at the network input (14) or a failure at the hardware of the remote interface device (12), the network output (15) is closed, i.e. no signal at all is sent onto the network output (15), and in case of a failure at the customer input (17), a dedicated auxiliary signal only is sent onto the network output (15). The inventive device allows the use of the full data transfer capacity for customer's data during normal operation, and allows distinction between different types (provider, customer related) of connection failures.

Abstract: An amplifier node, in an optical network, includes a first switch connected to a working path from which network traffic is received; a second switch connected to the working path to which the network traffic is transmitted; and two amplifiers that interconnect the first switch and the second switch, where the network traffic travels from the first switch to the second switch via a first amplifier. The amplifier node also includes a controller to receive an instruction to switch the network traffic from the first amplifier to a second amplifier that enables the first amplifier to be repaired; send, to the first switch and the second switch, another instruction to switch the network traffic from the first amplifier to the second amplifier; receive an indication that the network traffic is traveling via the second amplifier; and send a notification that the first amplifier can be repaired based on the indication.

Abstract: A transmission speed of a protection (backup) line using 1G-OLT unit and 1G-ONU unit is set to be lower than a transmission speed of a working (primary) line using 10G-OLT unit and 10G-ONU unit. A priority and band of each communication service in ONU are preset individually and separately every LLID for a working (primary) line and a protection (backup) line. When bands are allocated to the protection (backup) line, the band allocation is performed so as to secure a minimum number of bands of each communication service. A monitoring controller refers to a predetermined band information table according to an operation state of the working (primary) line or the protection (backup) line with respect to a downstream signal packet.

Abstract: The present invention discloses a fiber sensing system with self-detection mechanism which utilizes a central office to control secondary ring architecture formed by fiber sensor, remote node and optical coupler primarily. The secondary ring architecture is connected serially to form a primary ring architecture. The central office has a tunable laser light source that can deliver the light source to the fiber sensor. Since the fiber sensor has reflective ability, all light source signal sent by the tunable laser light source will be detected and measured by the fiber sensor. Thus central office can detect all signals reflected by the fiber sensor and produce a spectrum for analyzing fault point locations. The present invention can greatly enhance survivability and sensing capacity of all fiber sensors, so that when a fault point caused by environmental change within the fiber, it will not effect the overall operation of the sensing mechanism.

Abstract: The design of optical telecommunication networks is such that there is provision of end-to-end path restoration to specified demands under up to two links or nodes failures. Restoration routes are provided on Path Protecting Preconfigured Cycles (PP-PCs), where each demand is assigned one or two restoration routes and restoration wavelengths on a segment of one cycle. Splitting of demand across multiple restoration routes is not allowed. All restoration routes and restoration wavelengths are predetermined where multiple demands may share restoration wavelengths without resorting to intermediate switching or wavelength conversions along restoration routes. First, numerous candidate PP-PCs are generated. Assignment of demands with common failure scenarios are allowed, under certain conditions, to the same PP-PC. Next, a set of PP-PCs is selected from among the candidates, while minimizing total reserved restoration wavelengths cost and ensuring that all demands are protected as required.

Abstract: A transmitting apparatus obtains cross-connect information on an input side and an output side, reserves the information as a cross-connect for management shift, adds object information formed of that cross-connect information and others to a signaling message for transmission and reception, and also updates the reserved cross-connect for management shift to shift path management.

Abstract: An optical communication system has two or more active interfaces, each controlling the transmission and reception of optical signals between a communication network and one or more subscriber terminals according to control information pertaining to the individual subscriber terminals. The control information used by all the active interfaces is stored in a memory. The optical communication system also has a standby interface that is functionally equivalent to the active interfaces, and an optical switching apparatus that switches data transmission paths among the network, the active and standby interfaces, and the subscriber terminals. If a fault is detected in an active interface, the standby interface extracts the control information of the faulty interface from the memory, and the optical switching apparatus switches the data transmission paths so that the standby interface replaces the faulty interface.

Abstract: Systems and methods are described for restoring IP traffic flows routed in an IP network in less than 100 ms after the IP network sustains a network failure. The systems and methods are a two-phase fast reroute that uses distributed optimized traffic engineering during backup tunnel restoration and end-to-end tunnel restoration that maximizes sharing among all independent failure scenarios and minimizes the total capacity, total cost, or a linear combination of the two. For defined failure condition scenarios, restoration traffic is routed using pre-computed backup tunnels using a constrained shortest path first method where link weights along the path are chosen dynamically and depend on available and total capacity of the link, latency, and other cost measures such as IP port costs. During the capacity allocation phase, the method reuses capacity already allocated for other independent failure scenarios as much as possible but also adds capacity, if necessary.

Abstract: The subject matter described herein includes providing virtual 1:N automatic protection switching and dynamic, in service configuration change for optical network interface equipment. According to one aspect of the subject matter described herein, a method for providing virtual 1:N automatic protection switching (APS) for optical network interface equipment is disclosed. The method includes configuring N optical network interface cards (ONICs) as working cards, each working card having sending and receiving optical interfaces, wherein N is an integer greater than 1. A single ONIC is configured as a protection card for providing N optical interfaces for providing redundant interface protection for each of the optical interfaces on the N working cards.

Abstract: A technique for carrying out protection of data traffic in a multi-channel multi-section optical communications network by simultaneously using Optical Multiplexed Section (OMS) protection and Optical Channel (OCH) protection; the technique comprises selection of a working optical signal in an OCH protected optical channel, in case of a fault in a section of the network, by relying on an indication associated with OMS switching functionality that is required to overcome the mentioned fault.

Abstract: [PROBLEMS] To certainly restore path information to its original status when a trouble occurs on a network. [MEANS FOR SOLVING PROBLEMS] After reactivation, an apparatus control part (11) generates, based on a switch information list (123a) and an I/F information list (123b) stored in a nonvolatile storing part (123), link information that is prior to the reactivation and used for determining all adjacent communication apparatuses (10). The apparatus control part (11) acquires, via a control network (20) from all the adjacent communication apparatuses (10) described in the generated link information, held path information held by adjacent communication apparatuses (10) Thereafter, the apparatus control part (11) decides, based on a definition information list (113b) stored in nonvolatile storing part (113), a path sequence such that the path of a lower order layer is placed before the path of an upper order layer.

Abstract: The present disclosure provides a passive optical network (PON) system and a method for protecting the service of the system for service recovery and fault locating in case of a failure of the network, wherein the PON system comprises an optical line terminal (OLT), an optical distribution network (ODN) and an optical network terminal (ONT) equipment protection group comprising a plurality of ONT equipment groups, each of which is connected to at least one of other ONT equipment groups within the ONT equipment protection group for the mutual protection relationship. The PON system of the present disclosure does not require equipment and link redundancy for backup, contributes to reduced cost and improved utilization of resources, and provides a means for diagnosing any faults of the links and equipment in the network.

Abstract: A method and apparatus for fault notification in an optical network are described herein. In one embodiment, an exemplary process includes detecting at a node that at least a portion of a first unidirectional path of an optical circuit is down, where the first unidirectional path is originated from a first terminating node. In response to the detection, the node signals the first terminating node by removing at least a portion of light of a second unidirectional path in an opposite direction of the first unidirectional path of the optical circuit, to indicate a path between the node and the first terminating node is down. Other methods and apparatuses are also described.

Abstract: A method for implementing Automatic Protection Switching (APS) between an active board and a standby board includes detecting Synchronous Digital Hierarchy (SDH) data of main services, wherein the SDH data is received by a working port of the active board from a working line. If the SDH data received by the working port is detected as abnormal, SDH data of main services received by a protection port of the standby board is selected from a protection line, and service processing is performed for the SDH data.

Abstract: The present invention discloses a linear protection method for an optical network, used for protecting a failed service path in the optical network, and the method comprises: setting priorities of services carried on service paths participating in linear protection of the optical network as service priorities; selecting, from the service paths participating in the linear protection, a service path of which the service priority is lower than that of the failed service path as a protection path, and bridge switching the service on the failed service path to the protection path. The present invention implements protection of service paths according to the priority of the service carried on the failed service path, and enhances the security of service paths.

Abstract: Embodiments introduce redundant optical channels to significantly extend the lifetime of parallel optical transceivers. A plurality of transmitters, N, transmit on a plurality of optical channels, where N is an integer number of optical channels greater than 1. One or more redundant channels, M, are also provided. N+M multiple input shift registers provide multiple paths for signals from each of the transmitters to connect to N+M laser diodes. In the event up to M of the N+M laser diodes fail, the multiple input shift registers connect the N transmitters to functioning ones of the N+M laser diodes thus extending the life of the device. A corresponding scheme is also described for the receiver side.

Abstract: An optical transmission device includes a wavelength multiplexing/demultiplexing unit, a plurality of transponders, an optical switch unit and a controller. The controller includes a table in which a plurality of items at least including priority order, a transmission label, a receiving label and a receiving label expected value correspond to the respective transponders. And the controller rewrites the transmission label of the transponder corresponding to the client device of the lower priority order than the priority order of the client device connected to the transponder of the irregular input, upon the optical signal provided by the wavelength multiplexing/demultiplexing unit to one of the transponders being irregular, and controls the label-changed transponder for which the transmission label has been rewritten so that the label-changed transponder provides the wavelength multiplexing/demultiplexing unit with the optical signal including the rewritten transmission label.

Abstract: The design of telecommunication networks is such that there is provision of end-to-end path protection to multiple demands under a single link or node failure in the networks. Restoration routes are provided on Preconfigured Virtual Cycles (PVC's), where each demand is assigned one restoration route and specific restoration wavelengths on a segment of one cycle. Multiple demands may share restoration wavelengths, and the number of restoration wavelengths may vary among the PVC links. First, a plurality of candidate PVC's are generated where each demand may be assigned to multiple candidates. Assignment of demands with common failure scenarios are allowed, under certain conditions, to the same PVC. Next, a set of PVC's is selected from among the candidates, while minimizing total reserved restoration capacity and ensuring that all demands are protected. Next duplicate assignments are eliminated. Finally, conflicts of wavelength assignments are resolved. The invention focuses primarily on optical networks.

Abstract: A system, method, and computer readable medium for passive optical network rogue optical network unit diagnostics, comprises, detecting an alarm of a network, correlating the detected alarm to a bandwidth map, and selectively disabling an optical network unit upstream to the detected alarm on the bandwidth map for a pre-determined interval.

Abstract: An optical apparatus is disclosed wherein increase of the number of wavelength selective switches provided for a standby system can be suppressed. The optical apparatus includes a plurality of upstream side optical devices and a plurality of downstream side optical devices configured such that a plurality of output ports to be set as output destinations of light from a plurality of input ports can be changed over for each wavelength. An upstream side standby switch connected at a plurality of inputs thereof individually to the input ports and can change over an output of light from the inputs for each wavelength. A downstream side standby switch is connected at an input thereof to the output of the upstream side standby switch and at a plurality of outputs thereof individually to the output ports and can output light from the input to the plural outputs thereof.

Abstract: A method for processing fault dependency of different levels of tandem connection monitoring is provided. The method comprises obtaining monitored coverage scopes of the different levels of tandem connection monitoring (TCM); locating a fault section according to an overlapping relationship between monitored coverage scopes of the at least two different levels of TCM at which the warnings are reported and performance degradation degrees of the at least two different levels of TCM, the fault section being located when warnings are reported in at least two different levels of TCM; and outputting location-related information that includes information of the fault section to a user.

Abstract: The present invention relates to prevention of erroneous connection in an optical network and, in particular, it provides an optical communication node having route switching function as well as an optical network system using the same in a wavelength division multiplex (WDM) network system. There is provided an optical communication node that is connected to a specific optical path in an optical network, the optical communication node having: an external network that is placed thereunder; and an interruption part for interrupting connection between the optical network and the external network, wherein the interruption part interrupts the connection until a sequence of changing a route is completed when the route setting of the optical path is changed.

Abstract: Optical network terminal (ONT) power failure management. A system for permitting a customer of a telecommunication company, for whom fiber to the premises (FTTP) has been installed, to control operating features associated with operation of a battery backup unit (BBU) which is used, during power failure, for powering the ONT associated with the FTTP installation and the customer's telephone(s). The controlling of these features includes utilization of signal-controlled switches, which are manually over-rideable by the customer, thereby providing the desired operating feature control.

Abstract: A method for performing a protection in passive optical networks. The method comprises forming a protection maintenance link between an active optical line terminal (OLT) and a standby OLT; forming a synchronization link between the active OLT and the standby OLT; computing a base differential distance value; continuously measuring round trip time (RTT) values by the active OLT using the protection maintenance link; periodically sending at least RTT values calculated by the active OLT to the standby OLT over the synchronization link; and computing, by the standby OLT, a new RTT value based on at least a RTT value measured by the active OLT and a standby differential distance value, when a switch-over action is triggered, thereby allowing the standby OLT to serve optical network units (ONUs) in the PON without performing a ranging process.

Abstract: An optical communication system includes an optical transmission terminal including a first transmitter for transmitting an optical signal, and a second transmitter for transmitting information that indicates the first transmitter transmitting the optical signal; and an optical receiving terminal including an optical receiver for receiving the optical signal and the information transmitted from the first and second transmitter, respectively, a storage device for storing a power value of the optical signal monitored in response to receipt of the information transmitted from the second transmitter, and a fault detector for detecting fault of the optical signal by continuously monitoring a power value of the optical signal received by the optical receiver in comparison with the power value stored in the storage device.

Abstract: The synchronization of trunk failover between two FC-AL switches when a primary trunk failure occurs is disclosed. If primary trunk T1 should fail, S1 bypasses the cascade port and sends a MaRK (MRK) ordered set out over duplicate trunk T2 to switch S2. In response, S2 sends an acknowledgement MRK ordered set over T2 back to S1. S1 then reconfigures the switch to establish T2 as the primary trunk, and acts as a masters in the failover process and initiates LIP ordered sets which are communicated to all devices in the system to initialize them. Note that when S2 receives the MRK ordered set and acknowledges it by sending an acknowledgement MRK back to S1, it acts as a slave in the failover process and does not attempt to initiate LIPs, thereby eliminating the possibility of multiple Loop Initialization cycles and reducing the time in which data cannot be transmitted.

Abstract: In a transmission apparatus, unlike in the conventional transmission apparatus, a protection switch is not arranged on the signal path, but a TSI having only the basic function performs the function of the protection switch as a substitute, a processing unit to perform the switching function at a low rate is artificially constructed on a TSI, the switch process of SONET protection type is artificially executed by the TSI, and a signal for controlling the TSI function is further controlled thereby to realize the protection switch function. The logic of switching at the main signal rate in addition to the conventional TSI function is deleted.