Abstract: A packet-based telecommunications architecture is disclosed that, like virtual-circuit networks, preserves the sequential order in which packets are presented to the network, but does not require node-by-node call set-up or tear-down, unlike virtual-circuit networks. Further, the packet switches which compose the architecture can be more simple than those used in datagram or virtual-circuit networks. An illustrative embodiment of the present invention comprises determining the topology of a network of packet switches that are connected by communication links, associating at least two names with at least one of the packet switches, and populating the router tables in the packet switches so that for each name the packet switches and communication links form a elemental network with the topology of a sink tree with the named packet switch at the root of the tree.

Abstract: An SRTS clock recovery apparatus and method are provided. The apparatus broadly includes a controllable destination node clock generator such as a digitally controllable oscillator, a block for generating a local RTS-related value from the destination node clock and the system reference clock, and a comparator which compares the incoming RTS-related value to the local RTS related value to provide a feedback error or control signal which is used to adjust the controllable clock generator. If desired, a filter which filters the error signal can be provided in the loop. With the feedback loop as provided, when the destination node clock is faster than the source clock, the error signal will cause the destination node clock to slow, and vice versa.

Abstract: A system and method are disclosed for routing multicast packets in a subnetwork so as to conserve bandwidth in at least some of the network segments or collision domains of the subnetwork. In particular, multicast packets are only retransmitted in the network segments that are on a path to a host that is a member of the multicast group of hosts to which the multicast packet is destined.

Abstract: A multi-path digital signal processor for use in a telephony system provides a first data path for interfacing to a local area network, a second data path for interfacing to an industry standard computer backplane bus, and at least one third data path for interfacing to at least one time division multiplexed digital signal path. The Digital Signal Processor may transmit and receive data by any or all of these means to allow efficient data transfer and processing by the Digital Signal Processor in a telephony system.

Abstract: Disclosed is a method for the processing of data coming from an adaptation layer for the transmission of messages in the form of a flow of cells on an ATM type asynchronous transfer network, the cells comprising a header followed by an information field. According to this method, the cells are received by a receiver terminal having a working memory and are processed so that the constituent data elements of a message are stored continuously in this memory. For this purpose, the method consists in reserving a memory location with a given maximum size in the working memory of the terminal and in continuously recording the constituent cells of one and the same message at this location. Application to transmission on an ATM network.

Abstract: A test system exactly checks the integrity of data in an ATM system, and generates a test cell of a desired band. In the first aspect of the system in which data stored in an ATM cell are transmitted in an 8-bit parallel format in the ATM system, a test cell generating device connected to an input line outputs a test cell having 1 in all of the eight bits or having zero in all of the eight bits, and the test cell confirming device connected to an output line of the ATM switch detects the above described data. In the second aspect, the test cell generating device provided in an input trunk outputs a test cell of a desired band based on a ratio between two optional integers N and n (N.gtoreq.n), the state of a buffer of the ATM switch is monitored, and a load test is conducted to determine whether or not any cell has been destroyed.

Abstract: A DS3 level access, monitor and test system for a telephone network. The system provides selective, and hitless, bit overwrite in any of the embedded DS1, DS0 and subrate channels in a DS3 signal. Multiple DS0 and subrate channels can be tested via the asynchronous time slot interchange in conjunction with the recombiner of the present invention. The present invention further includes a lookahead reframer for framing to the DS3 signal. The present invention also includes a facilities data link (FDL) handler for capturing the FDL channel data in every DS1 channel in a DS3 signal. A high speed bit-for-bit compare is interfaced to a protect path to provide 1:1 fault protection in the system of the present invention. Full time performance monitoring on DS1 and DS3 signals is performed by a shared resource. The system of the present invention provides an integrated approach to synchronization measurement and relative synchronization.

Abstract: The present invention relates to an efficient point-to-point and multi-points routing system and method for programmable data communication adapters in packet switching nodes of high speed networks. The general principles of this efficiency are the following:First, data packets are never copied, only packet pointers are copied for each destination: Space in Buffer Memory is saved, the number of instructions is significantly reduced improving the packet throughput (number of packets per seconds that the adapter is able to transmit). and the routing is independant of the packets length.Second, no overhead is generated by the multi-points mechanism in the real time procedures: the underrun/overrun problems on the ouputs are reduced and the efficiency of the adapter in term data throughput (bits per second) is significantly improved.Third, each output is processed independently by means of interrupts: lines are managed in real time and lines of different speed or protocol can be supported in parallel.

Abstract: The routing paths between origin and destination nodes in a packet switching network are selected more efficiently by reducing the total number of links potentially visited by the routing algorithm. The path selection technique involves two phases, the first phase for principal links identification, and the second phase for selection of the best point-to-point path in the network. Principal paths are minimum hop count paths with a transmission delay less than a specified threshold. The algorithm limits the screening of the network links in the second phase to the principal links and excludes the secondary links. The exploration of a much smaller number of links has the advantage to considerably reduce the computation time required for the path selection. The fact the number of principal links is generally small compared with the total number of links potentially explored, allows to limit the additional processing time necessary in case of unsuccessful attempt.

Abstract: A method and apparatus for simulating signal interference in one communication channel within a communication system, such as cellular or wireless subscriber telephone and/or data systems. The communication system may be of a cellular type in which users from a plurality of cells communicate information signals between one another using at least one base station and code division multiple access (CDMA) spread spectrum type communication signals. The base station is included in a first of the cells and has a transmitter from which information is transmitted to subscriber units over at least one communication channel. The disclosed method includes the step of determining a first composite signal energy associated with signal transmission from the base station transmitter over a first set of simulated communication channels. The simulation method further contemplates estimating a first average data rate for the first composite signal energy.

Abstract: A subscriber system (10), operating in combination with other similar subscriber systems, for collectively and swiftly distributing multiple copies of digital data to a large number of other subscriber systems. The subscriber system (10) receives digital data and stores it on a storage device (38). An autonomous digital data communication subsystem (42) then obtains a copy of the digital data directly from the storage device (30) and transmits that data to another subscriber system. The autonomous digital data communication subsystem (42) includes transceivers (72, 82, 102 or 104) for exchanging digital data with ISDN communication channels (46, 44a, 44b or 44c). The transceivers (72, 82, 102 or 104) receive the digital data from a random access memory ("RAM") (56) included in the autonomous digital data communication subsystem (42). A SCSI controller (52) exchanges the digital data between the RAM (56) and the storage device (38) of the subscriber system (10).

Abstract: A digital private branch exchange system and methods of operating same are provided. A system is capable of providing improved and integrated conferece calling, voice mail, music on hold, and call forwarding features, without being subject to the typical problems associated with the prior art.

Abstract: In a ring network system comprising a plurality of nodes, each node is provided with a node information table which is logically divided into node areas each corresponding to a single node within the ring network. Each node collects node information stored in the node information tables of the two adjacent nodes by regularly accessing the node information tables of those nodes, and updates the contents of its own node information table. As a result of the above information collecting operation that is performed by each node, all the node information can be stored in the node information table of each node.

Abstract: The user of a local computer node (i.e., a caller) selects a remote computer node (i.e., a callee) for a computer conference call from a display containing a directory of possible callees. In one embodiment, the directory is an alphabetical combination of a network list maintained by a network administrator and a personal list for the caller. The user of the caller can access and edit the personal list, but only access the network list. When displayed to the user, the possible callees from the personal list are distinguishable from the possible callees from the network list.

Abstract: One or more interrogating commander stations and an unknown plurality of responding responder stations coordinate use of a common communication medium. Each commander station and each responder station is equipped to broadcast messages and to check for error in received messages. When more than one station attempts to broadcast simultaneously, an erroneous message is received and communication is interrupted. To establish uninterrupted communication, a commander station broadcasts a command causing each responder station of a potentially large first number of responder stations to each select a random number from a known range and retain it as its arbitration number. After receipt of such a command, each addressed responder station transmits a response message containing its arbitration number. Zero, one, or several responses may occur simultaneously.

Abstract: An ATM switching system architecture of a switch fabric-type is built of, a plurality of ATM switch element circuits and routing table circuits for each physical connection to/from the switch fabric. A shared pool of memory is employed to eliminate the need to provide memory at every crosspoint. Each routing table maintains a marked interrupt linked list for storing information about which ones of its virtual channels are experiencing congestion. This linked list is available to a processor in the external workstation to alert the processor when a congestion condition exists in one of the virtual channels. The switch element circuit typically has up to eight 4-bit-wide nibble inputs and eight 4-bit-wide nibble outputs and is capable of connecting cells received at any of its inputs to any of its outputs, based on the information in a routing tag uniquely associated with each cell.

Abstract: In a device and a method for performing a switching control to a standby system in a hybrid system including a duplex system and a backup line, communication is performed without using a backup line when a line is switched in an exchange. The device includes a first exchange having a pair of communication multiplexers and a communication line management processor. The backup line uses a public network. A second exchange is provided for interchanging between a line connected via the first exchange and the backup line using the public network. A normal notification signal is transmitted to the opposite communication party or second exchange when one of the communication multiplexers is switched to the standby system. A regulation releasing signal is transmitted after the switching operation so that communication is performed without using the backup line.

Abstract: A private automatic branch exchange for an integrated services digital network, comprising primary rate interface boards. Each of the primary rate interface boards has a frame structure of 32 channels and layer-1, layer-2, layer-3 and operating system software to perform a subscriber's telephone function through interfacing with a data distribution board and a data switching board. Each of the primary rate interface boards provides a 2048 Kbps interface between the private automatic branch exchange and a central office exchange.

Abstract: A protocol for transferring audio data and control/status data between audio functional units. The protocol involves multiplexing the audio data and control/status data. The multiplexed data is then transferred between a first audio unit and a second audio unit on two wires, each corresponding to the direction of data flow, and according to a clock and a synchronization pattern on third and fourth wires respectively.

Abstract: The hybrid medium access control MAC system is configurable to the type of communication required to support a desired application or service. The MAC system analyzes services requested from a settop terminal, or a network controller client, and determines the best MAC component for transmitting signals upstream based on the resources required by the service and the available network resources. A portion of the upstream channel spectrum is allocated to each of the MAC components: 1) POP; 2) assigned static TDMA; 3) assigned dynamic multi-rate TDMA; and 4) random slot reservation--dynamic slot allocation TDMA. Depending upon the communication requirements of the service desired, the configurable MAC system will select the MAC component best suited to support the service. A frequency agile transmitter is then tuned to the channel which has been preallocated for the selected MAC component(s).