Abstract: A packet based telecommunication system, such as ATM, comprises a main data path and at least one bypass path, for bypassing a portion of the data path, the portion and the respective bypass defining a protection domain, the system comprising nodes for each of the domains, for monitoring respective domains and for issueing alarms in the form of packets, to other nodes downstream, with a domain identifier indicating the respective domain in which the alarm originated. At a given one of the nodes an alarm issued from a node upstream of the given node and a corresponding identifier, are detected. At the given node it is determined whether to trigger a rerouting of the data along one of the bypass paths which bypasses the domain monitored by the given node, on the basis of the detected domain identifier. Using the identifier, downstream nodes can determine more easily whether the alarm is caused by a domain which has a bypass path triggered by another node upstream.

Abstract: In a local area network path control system, hubs are connected in a ring and classified into two groups. Each of terminals has two LAN controllers. One of LAN controllers is connected to one of the hubs belonging to one of the groups while the other is connected one of the hubs belonging to the other group. One of the LAN controller is used as an active controller and the other is used as a standby controller. Each of the terminals has a destination information table registering destination IP addresses and destination MAC addresses of the other terminals. When the terminal detects failure occurring between the active controller and the corresponding hub, it changes the active controller from one to the other of the two LAN controllers. Furthermore, the terminal notifies a newly MAC address for communicating with the terminal to the other terminals.

Abstract: The present invention relates to a guard apparatus for avoiding the malfunction of a communication apparatus due to an error in the received data in the specific location of a frame on the receiving side of an optical communication system using a SONET/SDH network. If a B2 error, a frame pattern error or an out-of-frame is detected for a received frame, this guard apparatus stops the operation for tri-stage protection for the data of the K1 and K2 bytes, and outputs data outputted for a received frame received one frame before the above-mentioned received frame. If these errors are not detected, the guard apparatus selects and outputs the non-protected data of the K1 and K2 bytes in the above-mentioned received frame. Thus, the extraction of data with an error due to an optical degradation can be avoided and thereby the malfunction of a communication apparatus in an optical communication system can be avoided.

Abstract: The preferred embodiment of the present invention is a cable modem apparatus for reliably providing a personal computer access to the Internet through a cable television link and a public switched telephone network link. The invention includes: a cable television link failure detector connected to the cable television link; a message generator connected to the cable television link failure detector, where the message generator is configured to generate at least one message responsive to the cable television link failure detector; and a message transmitter connected to the message generator, where the message transmitter is configured to transmit the at least one message through the public switched telephone network link to cause Internet communications to be communicated to the personal computer through the public switch telephone network link.

Abstract: Redundancy ring communication apparatus having a plurality of communication channels, that comprises normally used and redundant amplifier channels that are interconnected using selectively controllable switches. Pairs of amplifier channels may be selectively coupled together using controllable switches and hybrid couplers.

Abstract: An asymmetrical network for coupling customer-premises Internet hosts such as personal computers to the Internet. The head end of a CATV system has a high-bandwidth connection to the Internet. The down link connecting the personal computers to the Internet is the cables provided by the CATV system; the up link is a telephone connection to the head end. A router is connected to the down link by means of an RF modem, to the up link by means of an analog modem, and to a LAN which is connected to the Pcs. The router routes IP packets for the hosts that are received on the CATV cable to the hosts via the LAN; it routes IP packets from the hosts that are destined for the Internet to the head end via the telephone line. The asymmetrical network conserves IP addresses and addresses on the CATV cable by dynamically allocating the IP addresses for an RF modem's hosts and an address on the CATV cable for the RF modem in response to a request made by the RF modem via the telephone line.

Abstract: A switch is provided for use in a communications system for transmitting traffic from a first user to a second user. The first and the second users are interconnected by a primary communications path and a redundant communications path. The switch includes a first port configured to receive hello communications indicative of a proper operation of the primary communications path and a second port for receiving data communications. A switch control monitors the receipt of the hello communications, directs the forwarding of received data communications up to a threshold capacity and, if the received data communications exceed the threshold capacity, drops at least a portion of the received data communications such that forwarded data communications are below the threshold capacity.

Abstract: Transmission system for transmitting an MPEG-2 transport stream from a transmitter (10) to a receiver (14), provided with a return channel (16) through which the receiver (14) can transmit selection criteria for the selection of MPEG-2 sections to the transmitter (10). The transmitter (10) has a selector (38) which receives the desired criteria and then filters the sections according to these criteria before transmission.

Abstract: A telephony system having automatic timing adjustment for diverse routing of HFC systems has a signal stream routing through a signal line loop between a head-end and at least one communication unit. If a fault occurs within the signal line loop, recognized by the head-end when a short uplink burst from the communication unit does not align within a predetermined timing window, the head-end will cycle through predetermined delay parameters corresponding to various alternate signal line loops made up of redundant signal lines. Once the predetermined delay parameter corresponding to the current alternate signal line loop is determined, normal operation of the system resumes.

Abstract: A redundant structure control device for an exchange having an (N+1) redundant structure, capable of separately dealing with trouble that has happened at any line and trouble that has happened at any line interface device, in an ATM exchange having a redundant structure. When line trouble monitoring means detects line trouble, routing control means arranges frame tag attaching means so that a frame coming from a line interface device originally connected with a line at which trouble has happened toward the line at which trouble has happened may be sent out to a spare line.

Abstract: The invention provides for a method for transporting a SONET formatted asynchronous transfer mode (ATM) signal and/or a synchronous transfer mode (STM) signal on a line switched ring over a unidirectional path. The SONET formatted ATM signal comprises cells mapped into a STS-Mc or m×STS-1s while the STM signal comprises STS-1s/VTs mapped STS-W. A unidirectional line switched ring is provided for transporting the STM STS-W using a unidirectional path switched protection protocol and the ATM STS-Mc using a unidirectional line switched protection protocol. A ring node comprises input and output ring interfaces, an STS management block, an ATM cell management block, and a non-ATM payload management block. The STS management block routes the traffic to the ATM cell management block and to the non-ATM payload management block, according to the traffic type. The STS management block also provides the UPSR protection for the STS-1s and ULSR protection for the STS-Mc.

Abstract: A label switching router which includes a data relay controller for transferring IP datagrams and controlling the transfer, detecting any transfer IP datagram satisfying a particular condition, and controlling an ATM switch based on a detection result and an ATM switch for switching between adjacent nodes for transferring ATM cells. An operation state of the data relay controller is monitored and a user-specified VP route is set to the ATM switch according to a fault circumventing route table, thereby continuing communication between the adjacent nodes on both side of this ATM switch if a fault occurs on the data relay controller.

Abstract: The channel protection facility in a two-fiber bi-directional line switched ring network may be significantly enhanced by protecting the service channels in one of the fibers with corresponding protection channels in the other fiber and vice-versa. Thus, if a failure occurs such that the content of the service channels cannot be forwarded to an upstream point, then, without having to perform a wavelength conversion function, the service channels may be substituted for the protection channels in the other fiber and forwarded to the upstream point in the opposite direction via the ring network.

Abstract: To revert the topology of a network to its original or normal state after an alternate route has been found for bypassing traffic away from a malfunctioned link that has since been repaired, an Operation Support System (OSS) sends to each of the custodial sender/chooser nodes and the tandem nodes that form the alternate route respective commands to revert the operation(s) that each node had performed during distributed restoration. The OSS is able to identify the custodial nodes by the fact that those nodes perform more operations than the tandem nodes. The operations that were performed during the distributed restoration process were recorded and the thus restored topology of the network is mapped and stored. Upon receipt from the different nodes that the malfunctioned link has been repaired, the OSS sends to each of the nodes a specific command to perform the inverse of the operation(s) that that node had performed during the restoration.

Abstract: Flow control is implemented at a given node in a network of LAN switches by having the node monitor the occupancy levels of buffers or queues. When a buffer is found to be occupied or filled beyond a predetermined threshold level, a pause command is generated for the source currently supplying traffic to the buffer. A pause time PT is calculated using an equation which takes into account: the transmission rate of the identified source, the transmission rate of the output link servicing the congested buffer and queue length that can be occupied without a congestion condition being declared. To reduce the chance that queue lengths will “oscillate” about their threshold point due to multiple sources resuming transmission at the same time, each calculated pause time is adjusted to a randomly selected value PT(ran) falling within a range of PT±kPT where k may be on the order of fifty percent.

Abstract: An optical bi-directional line switched ring for performing adding and dropping of traffic into the traffic path and for performing ring and/or span protection switching. The optical bi-directional line switched ring include a plurality of nodes, each node having multiple input demultiplexer/output multiplexer sections, a command and control channel having multiple fibers, and up to N-1 slave circuits. Each multiple input demultiplexer/output multiplexer sections has an input demultiplexer to receive and demultiplex signals from a fiber and an output multiplexer to receive the demultiplexed wavelengths from internally and multiplex them into an outgoing signal. The command and control channel can be a standard bi-directional line switch that has one channel coupled to each fiber of the system.

Abstract: For restoration of a network a plurality of possible alternative routes are determined. Messages are passed between nodes along the alternative routes to determine a spare capacity of each link in the alternative routes. An alternative route is selected from the possible alternative routes on the basis of a database of the determined link spare capacities for each of the possible alternative routes, built up at a chooser node at one side of the failed part of the network.

Abstract: Nested APS is implemented in a simple configuration for synchronous transmission systems such as SONET and SDH. Bits 5 to 8 of the received K1 byte are compared with line numbers of lines terminated at the receiving node, and when they do not match, the received K1 byte is sent via a first selection circuit for further transmission. At the same time, the K2 byte incoming from the opposing direction is redirected via second selection circuit for transmission.

Abstract: A device for enabling automatic restoration of network access for user lines within a communication system. The user lines interface with groups of transmission lines that include dedicated transmission lines which are connected to the user lines, idle transmission lines and reserved transmission lines. The device includes a line manager that makes a number of transmission lines among the groups of transmission lines available for user lines which have a dedicated transmission line in a group of transmission lines that fails and a reprovisioning element that couples each of such user lines to a respective available transmission line. The device may also include a monitor that delays the coupling of such user lines if a sufficient number of transmission lines are not available.

Abstract: A voice storage device monitors wireless signals from a plurality of fixed terminals and a plurality of mobile terminals, which are connected to a main unit. When a channel establishment signal is generated by one mobile terminal, the voice storage device detects this signal, and prepares for recording the contents of a speech communication. Subsequently, the fixed terminal generates a channel assignment signal. Thereafter, the voice storage device detects a call setup signal (an ID signal and control information) exchanged between the mobile and fixed terminals, and waits for detection of a response signal which is generated by the mobile terminal and indicates that the call is answered. Upon detection of the response signal, the voice storage device starts a storage operation of voice data at a corresponding one of different storage positions in units of mobile terminals, which position is specified by the call setup signal.

Abstract: A method for managing transmission lines within a communication system which enables the automatic restoration of network access for user lines. The communication system includes user lines interfaced with groups of transmission lines and each group of transmission lines includes dedicated transmission lines which are connected to the user lines, idle transmission lines and reserved transmission lines. The method makes a number of idle transmission lines among the groups of transmission lines available for coupling by user lines which have a dedicated transmission line in a group of transmission lines that fails. The method determines the minimum number of transmission lines to be reserved by a comparison of the numbers of certain types of transmission lines in the different groups.

Abstract: To signal a failure in a mixed PDH/SDH network in order to enable this network to provide a service such as a protection mechanism, an alarm indication has to be provided to an SDH node in the event of that failure. A PDH node linked to that SDH node creates an alarm data stream and provides this alarm data stream to the SDH node in the event of any of:an internal PDH node failure; anda link failure between the previous node and the PDH node; andupon reception of such an upstream created alarm data stream;The SDH node creates the alarm indication in the event of any of:a link failure between the PDH node and the SDH node; andupon reception of such an alarm data stream coming from the PDH node.

Abstract: In a communications network, shared spare routes and dedicated spare routes are provided between nodes of adjacent pairs and a dedicated spare path are provided between terminal nodes. Each of the dedicated and shared spare routes comprises a link or a series of permanently connected links. A first signal requiring a quick fault restoration performance is transmitted over the first working path and a second signal not requiring the quick fault restoration performance is transmitted over the second working path. The working paths and all working links are monitored to detect a path or link failure. If the first working path is affected by a path failure, the first signal is instantly switched to the dedicated spare path, and if it is affected by a link failure, the first working path is reestablished using one of the dedicated spare routes.

Abstract: A communications system has two transmission circuits, each transmitting a multiplexed signal in both ways. A repeating installation used therein selects either one of the two transmission circuits and terminates management information contained in a signal which flows through a transmission circuit selected by the selecting unit. The repeating installation sets the other non-selected transmission circuit to be in a high impedance state. The selection and termination are commonly performed for the two transmission circuits, and the repeating installation further extracts the management information transmitted and outputs the management information to be outputted. The management information includes a section overhead having management information concerning a repeating section of the communications system, and the repeating installation does not terminate management information concerning a multiplex section. One of the two transmission circuits includes a spare transmission circuit.

Abstract: The dynamic routing of a communication network is to adapt itself to the respective traffic load in the network in a way which optimizes network throughput. The routing according to the invention solves this problem by a route fan for holding alternate routes for the overflow traffic, an alternate route previously contained in the route fan being removed from the route fan without replacement as soon as it is established that it is no longer available.

Abstract: A method for restoring traffic in a network. The network includes plural distinct nodes interconnected by plural distinct spans, each span having working links and spare links. Each node has a digital cross-connect switch for making and breaking connections between adjacent spans forming span pairs at a node. Step 1: For each of at least two possible span failures, (a) find the number of restoration routes available in case of the occurrence of each span failure, (b) determine the resources used by each restoration route, and (c) determine the amount of flow to be restored for each span failure. Step 2: find, in a computer, the amount of flow f.sup.p to be restored along each restoration route that minimizes total unrestored flow for all possible span failures identified in step 1. Step 3: form connections at each digital cross-connect switch in the network along each restoration route before occurrence of one of the possible span failures identified in step 1 to permit the amount of flow f.sup.

Abstract: Carriers (51) in a cable telephony system (10) are prioritized (70) according to their usability. A local access manager (LAM) (27) creates a frequency list that ranks the carriers (51) based upon their frequency. When a cable fixed access unit (CFAU) (44) requests a traffic channel, the LAM (27) selects a traffic channel based on the channel's carrier usability. The LAM (27) also selects an alternative channel based on both the channel's carrier usability and the based on the number of carriers between the traffic channel and the alternate channel in the frequency list. When either the LAM (27) or the CFAU (44) determines the traffic channel is unacceptable during a call they transmit a "Switching to Alternate Channel" message. The CFAU (44) retunes to the alternate channel and transmits a "Re-Connect" request. The LAM (27) then transmits a new alternate channel and the call continues.

Abstract: A transmission apparatus comprises a main signal line block for transmitting a main signal and a monitor/control block for monitoring state of the apparatus and lines by collecting line switching information supplied from each unit which constitutes the main signal line block and controlling the switching operation between a working line and a protection line. The main signal line block and the monitor/control block are connected by an ATM link. An ATM routing unit in the main signal line block collects line switching information supplied from each unit and maps the line switching information in data portion of an ATM cell and transmits the ATM cell to the monitor/control block via the ATM link.

Abstract: A method and system for providing intelligent protection against access line failures in a telecommunications system including customer premises equipment connected by a plurality of access lines to a data transport network. The system detects a line fault on a first access line at the customer premises equipment. In response to the detection of a line fault, the system sends a query to the network management system of the data transport network to determine the origin of the line fault. The system receives a response to the query from the network management system and uses the response to deal with the line fault in an intelligent manner. Whenever the network management system responds to the query by indicating that the line fault originated in the data transport network, the system maintains the connection and waits for the failure to be resolved.

Abstract: An apparatus and method is described that is used to design a minimal spares network for a given communications network. Three data files are used as input which describe the communications network. The information comprising such data files include the number and configuration of the nodes and spans, the current demand in terms of the required capacity between the source and destination nodes, current spare capacity (if any), and optionally current paths used to carry the demand traffic (including the presence or absence of glass-throughs). A three pass method is used to design an efficient and economical spares network from the given input data. A simulated cut is performed on each span in the communications network. From each simulated span cut, the affected demand traffic is identified and rerouted via spare capacity that is `purchased` on an incremental cost basis. Pre-purchased spares are used before new spares are purchased.

Abstract: A communication controller is disclosed with a plurality of service modules including a redundant service module and with a mechanism for substituting the redundant service module for any one of the service modules. The communication controller includes a redundancy module that distributes communication signals to the redundant service module via a distribution bus coupled to the service modules. The distribution bus is alternatively used to distribute a high speed communication link to the service modules for improved physical connectivity.

Abstract: The main storage, the communication interface portion and the circuit control module hold transmission data in the buffers until completion of the transmission has been confirmed. When a fault has occurred in the current operating system of the duplexed portions in the configuration elements of the host computer and the multi-circuit control unit, the duplexed portions are changed over from the current operating system to the stand-by system. In this case, information for reproducing data that has been lost due to the change-over is transmitted from the main storage and the circuit control module to the communication interface portion which has become the new current operating system. The communication interface portion which has become the new current operating system restarts the processing based on this information.

Abstract: A method is provided for detecting failure in a communication channel with at least two routes (A, B), through which at least two stations (X, Y) communicate. According to the method, at least one station repeatedly sends simultaneous messages on routes containing a sequence number, and receives messages from other station(s), containing an array of sequence numbers last received by other station(s) on each route. At least one station then detects failure of a route by comparing the sequence numbers of the array of the messages it receives. The method provides for failure detection independently of real time constraints. Also provided is a station for carrying out this method.

Abstract: Only when data inputted from first and second transmission paths agree with each other, a selector effects switching from the data from the first transmission path to the data from the second transmission path or from the data from the second transmission path to the data from the first transmission path. A transmission interface adds an overhead to the data of a payload outputted from the selector. A counter counts up at the timing of an overhead in the data inputted from the first transmission path based on an output signal from a multiframe synchronizing circuit that is associated with the first transmission path. In the absence of uninterrupted data switching by the selector, a parity bit is inserted into a random pattern generated by a random pattern generator, and the random pattern with the inserted parity bit is written into a memory while the counter is counting up.

Abstract: In a serial communication control device comprising first active and second reserved function blocks and a CPU section for delivering to the function blocks a serial datum comprising an address and a data value, an address giving arrangement gives a common value as the address value to the first and the second function blocks upon start up of the serial datum and first and second unique values as the address values to the first and the second function blocks after the start up to make the function blocks produce the data value corresponding to the address values coincident with the common or one of the first and the second unique values. Preferably, the second function block comprises an address selector in which the common value is set and which is quiescent to the first unique value given to the first function block after the start up. The common value may be identical with the first unique value during the build up.

Abstract: A method and circuit arrangement for transmitting message cells via redundant virtual path pairs of an ATM communication network is provided. Two alternative solutions are employed for the transmission of message cells via virtual path pairs respectively formed of an active path and of an alternate path. A first solution is that the message cells transmitted via the active path and via the alternate path of a path pair are conducted up to the output of the switching network lying at the end of the corresponding path pair. Dependent on the number of message cells arriving via the active path and via the alternate path, a forwarding of the message cells of the active path or of the alternate path occurs proceeding from this point. The second solution is that the message cells of the alternate path are first discarded at the input of the corresponding switching network.

Abstract: An architecture for a radio network having nodes that are subject to dynamically changing topology such as, e.g., a mobile radio network. The network is partitioned into a number of physical subnets wherein each physical subnet includes a certain number of network nodes in relatively close proximity to one another. Each node of each physical subnet is affiliated with a corresponding node of each of the other physical subnets, thus defining a certain number of virtual subnets. A desired communications path is routed from a source node of one physical subnet to a destination node of another physical subnet, by routing certain parts of the path within one or more physical subnets during a first transmission phase, and routing remaining parts of the path within one or more virtual subnets during a second transmission phase.