Abstract: Round trip travel time of cells in an asynchronous transfer mode (ATM) communication network is measured by injecting a time stamp into test cells in a first test instrument, transmitting these test cells to a remote node in the network, looping the test cells back from the remote node to an originating node, and detecting their arrival. Preferably the time stamps are injected into test cells configured as OAM-PM (operation, administration, and maintenance performance management) cells. A time-of-departure stamp is injected into the payload of the test cell on transmission, and a time-of-arrival time stamp is appended upon its receipt. The time-of-arrival and time of departure time stamps are compared to determine the actual round trip travel time of the cell within the network. This information can then be used to optimize network traffic flow, especially for available bit rate virtual connections.

Abstract: A method of Distributed Call Control is provided in a Distributed Transit Private Branch Exchange (PBX) comprising a plurality of Nodes forming a wide area network, and a plurality of D-channel Server Modules (DSMs). The DSMs are located in predetermined ones of the Nodes with each DSM coupled to at least one associated PBX via at least one D channel. The method includes the following steps. First, a listing of all Exchange Codes (ECs) handled by a DSM and each associated PBX coupled thereto is stored in a local routing table of a memory in the DSM. Second, a listing of all ECs handled by all of the other DSMs of the Distributed Transit PBX and their associated PBXs is stored in a remote routing table of the memory in each of the DSMs.

Abstract: A setup procedure employing distributed hop-by-hop routing reduces the number of signaling messages needed to establish a service (i.e., connection), thus enhancing network performance. A service is setup between an origination node and a destination node which are a part of a network of communication nodes interconnected by links. Each node maintains a topological database representing the network topology. Initially, a setup message for initiating the service is transmitted from the origination node to a neighboring node that serves as a local node. The topological database is then updated after the local node receives the setup message by eliminating links connected to a particular set of nodes. This set of nodes includes those nodes other than the local node that have previously transmitted a setup or failure message for the service.

Abstract: In an asynchronous transfer mode switched network, a source terminal sends a burst of data cells and a control cell at periodic intervals through network nodes to a destination terminal. Each network node includes a first buffer and a second buffer, and incoming data cells are stored into the first buffer and incoming control cells are stored into the second buffer. A transmit controller is connected to the first and second buffers for forwarding cells in the first and second buffers in a downstream direction with priority given to the control cells in the second buffer over the data cells in the first buffer. A congestion detector is connected to the first buffer for writing a congestion indication into a control cell which is either stored in or forwarded from the second buffer when the first buffer is filled to a predetermined storage level.

Abstract: A flow control apparatus is connected to an ATM switch having a plurality of input ports and a plurality of output ports provided among ATM exchanges through transmission links. A buffer is connected to the input port and temporarily stores ATM cells output from the ATM switch, wherein the ATM cells are transmitted through the ATM switch to the output port connected to a next ATM exchange. A controller sets up the ATM switch wherein first-free information cells conveying the free-buffer information of the buffer input to the input port are transmitted to the output port connected to a preceding ATM exchange. The controller also controls transmission of the ATM cells from the buffer based on second free-buffer information cells transmitted from the next ATM exchange and traffic parameters for guaranteeing transmission quality.

Abstract: An efficient distributed technique for setting up, taking down, and updating connections in a communications network, which is robust in the presence of failures. More specifically with this invention a path for a connection is computed and reservation requests are simultaneously sent through separate channels to each of a set of nodes of the path for the connection to reserve and determine if resources are available for the connection. Upon acknowledgement that the links for the connection are available and have been reserved, a setup message is sequentially transmitted between the adjacent nodes along the path until the setup messages reaches the destination node. The switches in each node then configure themselves in response to the setup message so as to establish the connection.

Abstract: A system and method for equalizing delay in a dynamic packet switching network using transmit and receive buffers. The network includes a plurality of user access stations each equipped with a transmit buffer and a receive buffer, and a plurality of switches and communication links interconnecting the user access stations. A control station having communication links to the switches and user access stations operates to set up and change transmission paths between the user access stations, and to control the buffers in the user access stations to equalize packet transmission delay through the network and to eliminate packet rate doubling upon changing transmission paths. The system also includes a buffer shifting feature whereby a controlled buffering in a transmitting user access station is gradually shifted to a buffer in a receiving user access station during a period of time following a change from a longer transmission path to a shorter transmission path.

Abstract: The invention relates to a method and a system for routing messages or frames through network nodes connected to each other by network links and connected to a plurality of terminals by different input/output ports also called network attachment cards (NAC) in a multi-node communication network. In such a configuration, each terminal equipment stores a network table. The network table is updated in the terminal itself by a network manager which may by the way limit the access of the terminal to some terminals of the network. To route an incoming message or frame from a source terminal (T1) to the destination terminal (T7), a routing algorithm is implemented in each NAC. Each NAC has a different and unique integer address in the node, each node has a different and unique prime number address greater than the number of NACs in the node. Each terminal connected to a node sends frames with a routing identifier (RI). The different RIs are located in the network table.

Abstract: A method and system are disclosed for scheduling the assignment and writing of cells from cell sources into a outgoing bitstream transmitted from each device of an ATM communications network. The timeslots are organized into fixed length cycles which cycles each have a sequence of N timeslots, where N is an integer >1. Furthermore, each cycle is divided into at least one round comprising a variable length subsequence of the timeslots of the cycle. During each timeslot of a uniform timeslot clock, at least one subset of the sources is identified. Each subset corresponds to a round. One cell from each subset is assigned to, and written into, a respective timeslot of the corresponding round. During each timeslot of the timeslot clock, each of the sources is assigned a priority state depending on how many cells of that source have been previously assigned to timeslots during the current cycle and whether or not that source has a cell available for assignment to a round during that timeslot.

Abstract: LAN's are customarily used for pure data communication. Voice communication via a LAN is only possible with the constraint of other subscribers being subjected to long waiting periods during the relatively long occupation time. The present LAN expands the functionality of work stations connected to the LAN, by using ATM technology to meet the communication requirements of an office environment. A network node or a conventional work station (3) is expanded by means of a unit which performs switching technology functions, so that terminals of the most different types (4, 5, 6, 7) can access the LAN via interface circuits (41, 51, 61, 71), resulting in a private network with distributed telecommunication installations. In this way, real-time connections with different bandwidth requirements, such as for example video conferences and pure voice transmission, are made possible. The thus expanded ATM-LAN is suitable for all types of communications taking place in an office.

Abstract: A switching system for integratedly switching voice, data, image information and the like. The switching system comprises a plurality of front-end modules each adapted to perform a switching processing in association with a subscriber line or a trunk line, and a single or a plurality of central modules for interconnecting the plurality of front-end modules in star-type fashion and switching information prevailing between the front-end modules, in unit of block accommodating the information and a header added thereto to contain connection control information and in accordance with the contents of the header. The front-end modules are connected to the central module via inter-module highways each having frames occurring at a predetermined period and time slots contained in each frame to carry blocks.

Abstract: A frame relay switching apparatus in a frame relay network employs a frame format used in a frame relay communication between a plurality of terminals, performed by identifying a destination by a data link connection identifier (DLCI) in an address field. Priority or non-priority information for an identifier provided in a frame being transmitted for identifying a destination terminal is registered for each DLCI so that a zone assigned to each of them is not overflown, to prevent a frame having a priority DLCI from being discarded. In case of congestion, all frames having identical non-priority DLCIs are discarded at the same time. The switching apparatus includes a plurality of transmitting buffers provided at each outgoing line, and a common buffer, which can be shared by a plurality of lines. A congested line writes a received frame in the common buffer and takes the frame out from the common buffer to write it in a respective transmitting buffer when the congestion has been resolved.

Abstract: The invention relates to a local network operating in the asynchronous transfer mode (ATM), comprising a plurality of stations (10) which are each coupled to transmitting and receiving ring lines (16, 19) via a network interface (9) which comprises at least one switch (11) and which stations are provided for transmitting cells. The switch (11) is arranged for relaying a user cell containing information relating to the user from a receiving ring line (16) to the transmitting ring line (19) and/or to the station (10) or from a station (10) to the transmitting ring line (19) in response to status information.

Abstract: An adaptive routing protocol for a data communication system that operates in the connection mode. Therefore, the nodes have a function of detecting their neighboring nodes, which permits establishing sessions with their neighbors without previously knowing them, so as to transmit to them recognition messages which indicate their own identifier. Each node additionally has a double identifier of which one identifier is formed by the serial number of the node, so that the serial number can be detected in the system before any configuration and this, more particularly, by a terminal dedicated to managing the system entrusted with the remote configuration of the nodes.

Abstract: A scheme for controlling a congestion in the communication network, capable of realizing a recovery from the congestion state by the operation at the lower layer level for the communication data transfer alone, without relying on the upper layer protocol to be defined at the terminals. In a communication network including first and second node systems, a flow of communication data transmitted from the first node system to the second node system is monitored and regulated by using a monitoring parameter. On the other hand, an occurrence of congestion in the second node system is detected according to communication data transmitted from the second node system, and the monitoring parameter used in monitoring and regulating the flow of communication data is changed according to a detection of the occurrence of congestion in the second node system.

Abstract: A circuit and method for optimizing efficiency in transferring a block of data having a plurality of frames of limited size from a memory element. The circuit comprises a transmit ("TX") DMA engine and a TX Segmentation engine. The TX DMA engine is responsible for accessing overhead information for the block of data within a TX data buffer from a data descriptor dedicated to that particular TX data buffer. The TX DMA engine is further responsible for reading the block of data from the memory element to be stored local thereto. The TX Segmentation engine is responsible for segmenting the block of data into a plurality of cell packets corresponding in number to the plurality of frames. Each cell packet contains in common the overhead information for the block of data to avoid the TX DMA engine re-accessing the data descriptor to obtain the same overhead information for each frame being transferred.

Abstract: A technique for permitting continued use of IP (Internet Protocol) routing protocols in an Asynchronous Transfer Mode (ATM) network is implemented in each ATM system having route-computing responsibilities. When a call setup request is received, the routing system determines, from the ATM address of the target system, whether a routing protocol must be implemented. If a routing protocol must be implemented, data in an ACN (ATM Cluster Number) field and an HN (Host Number) field in the target ATM address is read and is imported into an IP-format address. This IP-format address is used in implementing the IP routing protocol.

Abstract: A system for distributed control in wireless cellular and personal communication systems includes separate servers for performing call control and connection control functions, thereby obviating the need for a mobile switching or other switch to be anchored for the duration of a call. During a registration procedure, visiting location servers track only roaming mobiles, rather than tracking both roaming mobiles as well as mobiles located in their home network. Direct signalling links between servers and base stations, or other servers, located in different networks allow roaming mobiles to contact their home networks for service at all times, thereby obviating the need for passing signalling information for mobiles when they are not involved in a call. The use of multicast signalling with asynchronous transfer mode switches, permits specified channel control functions to take place concurrently in channel servers associated with base station and switches that form a segment of the route for a call.

Abstract: A method and a facility for communication between packet mode supporting units interconnected in the core of a communications installation by point-to-point links that are physically structured and time governed in identical manner, a packet being transmitted between two packet mode support units of the installation after the unit desiring to transmit has previously sent a request to the destination unit and the destination unit has responded with a corresponding acknowledgment. The communications facility constitutes a distributed type asynchronous switch in which each packet mode support unit includes a packet communication circuit to which the point-to-point links terminating at the unit are connected via a switching module. The communication circuit conditions each of the packets that is to be transmitted to another packet mode supporting unit of the installation in the form of a sequence of cells, and also performs inverse conditioning.

Abstract: An ATM exchange which is comprised of a multistage cascade connection of ATM switches of self-routing module structures which are provided with a plurality of outgoing lines and incoming lines, wherein it provides at the output side and the input side of the ATM switches output side conversion interfaces and input side conversion interfaces both for connection of adjoining ATM switches and uses optical cables to connect the output side interfaces and input side interfaces facing thereto. By this, it is possible to maintain the correct exchange operation even if the length of the transfer lines (outgoing lines and incoming lines) laid between ATM switches becomes greater along with extension of the ATM switches in the exchange.

Abstract: Asynchronous Transfer Mode Local Area Network (ATM LAN). The ATM LAN is implemented as a set of MAC entities which share a common group address space for the purposes of establishing multicast connections. Each station has one or more ATM MAC entities per physical connection to an ATM network. The network ATM LAN service provides the station with ATM LAN configuration information needed for ATM MAC operation. Included in this information is the number of ATM LANs the network has configured for that station.

Abstract: A communication system comprising an Asynchronous Transmission Mode ("ATM") network and at least one demultiplexing device. The demultiplexing device receives information cells which include a header, containing the destination to which the cells are to be transmitted, and data. The demultiplexing device comprises at least one input access for receiving the cells, a plurality of output accesses, at least one network circuit, a plurality of service circuits and a common data line. The network circuit has an input access, a header analyzing element, a routing table and a combining element. At least one of the output accesses are assigned to each of the service circuits. The routing table produces a routing information signal which determines the destination to which the cells are to be transmitted. The combining element combines the information signal and the data and transmits the same on the common data line.

Abstract: A routing scheme for an ATM switching network includes a plurality of switching nodes, each of which includes individual storage for storing routing messages for each outgoing link. A call at a source node is routed through one possible routing path which requires only one or two links to complete a connection to a destination node. In such case, one of the routing paths is selected based on link state information concerning only the possible routing paths. If the call requires a route path which includes three or more links to the destination node, the source node performs a predefined sequential routing to its neighboring node before the neighboring node negotiates with selected intermediate nodes for a connection involving two links. The routing messages stored at each node are processed independently and simultaneously by each node. The main requirement is that routing decisions must be based on true link-state information.

Abstract: In a telecommunications switching network which has a plurality of sub-networks, each sub-network having a plurality of User Network Ports, the Destination and Source addresses in a cell-header carrier by a cell switched by the network are each divided into a Port Address part and a Sub-Network Address part, the Source Sub-Network part being implicit while the cell remains in the Source Sub-Network and similarly the Destination Sub-Network part is implicit when the cell arrives in the Destination Sub-Network, the Source and the Destination Sub-Networks being linked via a Cross-connect switching device wherein the address formats are changed.

Abstract: A novel ATM network provided which includes one or more ATM gateways for interfacing a plurality of T1 or fractional T1 signals with a higher bandwidth ATM network switch. In order to provide high speed and bandwidth utilizing relatively inexpensive and standard components, the data is stored in a memory, such as a video RAM, and pointers are utilized to indicate the type of each piece of data stored in the memory, including its priority for transmission to an ATM switch. In one embodiment of this invention, a plurality of pointer pools are used, each corresponding to a data type having a given priority. Pointers are placed into an appropriate one of the pools to define the order in which data will be transferred to the ATM switch in accordance with the priority of the data type and the receiving bandwidth of its destination in the ATM network. In one embodiment an HDLC controller is used which is suitable for framing a plurality of channels of data received on an incoming data path, such as a T1 channel.

Abstract: A two-stage cell routing filter mechanism employs a customer premises associated flag bit field in ATM data cells being serially transmitted from a host digital terminal's data transport path through an optical fiber to a downstream optical network unit associated with a plurality of customer premises equipments. The first stage of the cell routing filter is comprised of a look-up table (LUT) and an associated comparator mechanism. The state of each bit of the flag field of an ATM cell preamble will indicate whether or not the ATM cell is intended for the customer premises equipment associated with the bit. A downstream optical network unit contains an associated set of ATM cell filters associated with customer premises equipment. Each customer equipment cell filter examines a given bit position in the flag field portion of each received ATM cell preamble, to see whether the flag field bit of the preamble of the received ATM cell is set to prescribed bit value (e.g.

Abstract: A communication adapter transfers synchronous or multimedia and asynchronous or packet data between a network which may be of a FDDI type and a host system in real time. The adapter can manage data transfer in both directions between the system and the network and automatically switches between multimedia and packet data while holding the token. The adapter includes a queue manager having a synchronous threshold register and counter and a packet data threshold register and counter. The queue manager is coupled among a host bus; a storage means; a FDDI network; and bandwidth control logic. The queue manager in conjunction with the bandwidth control logic can dynamically switch the adapter from transmitting packet or synchronous data to the FDDI without exceeding bandwidth. The queue manager is also adapted to initiate capture of the token on a FDDI and commence transmission of synchronous or packet data frames to the ring as early as possible.

Abstract: Local area network operating in the asynchronous transfer mode (ATM) comprising a plurality of stations which are coupled each via a network interface, which interface comprises a coupling device and a control arrangement and transmits cells via the coupling device between send and receive ring lines, to at least one station and at least one control arrangement. A control arrangement comprises an access controller which is arranged for conveying, in dependence on the contents of the header field of a cell received from the coupling device, the cell or first parts of the cell and/or additional information to a bus system and units coupled to the bus system.

Abstract: A so-called "ELAN contronect network" is employed to interconnect sub-ELANs to form an ELAN. More specifically, the "ELAN contronect network" is a separate network for interconnecting the servers of the sub-ELANs, where a sub-ELAN is a part of an ELAN having its own LES and BUS that may also be configured as a stand-alone ELAN. Each of the sub-ELANs is connected to the ELAN contronect network via a point-to-point connection-oriented connection, e.g., an asynchronous transfer mode (ATM) connection and the ELAN contronect network is configured to present itself to each of the servers of the sub-ELANs as clients thereof. In a particular embodiment of the invention, the ELAN contronect network includes an address server, a broadcast/route server, a configuration server, multimedia servers, and at least one LAN hub interconnected over a high-speed backbone.

Abstract: In a switching network with a plurality of inlets and outlets and a plurality of interconnected switching nodes having inputs and outputs with respective addresses, a method is described of modifying a first set of outlets to which a cell stream is routed from one of the inlets to a second set of outlets to which this cell stream is to be routed, the addresses of the outputs of each switching node from which the cell stream is output being stored in a routing table of the node. The method includes the steps of transmitting a modification request message to the inlets from each outlet belonging to one but not to both sets and in each switching node receiving the modification request message on one of its outputs, selectively transmitting the request message to the inlets or transmitting a confirmation message to the above each outlet depending on the absence or presence in the node routing table of addresses of node outputs other than the one node output, respectively.

Abstract: A communication system comprising a network and an information multiplexing device for transmitting information cells from one of its accesses to another access. The multiplexing device includes a plurality of access terminals for transmitting information signals to a destination at a predetermined rate, at least one connecting terminal for one of the access terminals, a plurality of service circuits having queue elements for storing data and a common data line interconnecting the data outputs of the service circuits with the connecting terminal.

Abstract: An Intelligent Signaling Transfer Point (ISTP) of the common channel interoffice signaling (CCIS) network provides high level control of signaling message routing and of processing of calls relating to telephone services, broadcast services, interactive broadband services and packet switched data services. A network in accord with present invention includes central office telephone switching systems and local routers. Each local router also is coupled through a trunk circuit to one of the telephone switching systems. The local router selectively provides switched telephone call communications services to a plurality of telephone stations coupled thereto. The local router also receives broadband digital signals from a broadband trunk circuit and selectively supplies broadband digital signals to a plurality of digital terminals. The ISTP includes a data switch, a database and a program controlled processor.

Abstract: In advanced digital networks for providing selective point-to-point communications between subscriber's terminals and broadband server's equipment operated by a plurality of independent information service providers, routing through the network is controlled by functionality identified as a Level 1 Gateway. In an enhanced video dial tone network additionally providing an array of broadcast services from multiple providers, the Level 1 Gateway also provides high level control over at least some of the broadcast services. The Level 1 Gateway will perform a variety of functions including communications port management of transmissions of information between subscribers and servers, processing of billing information and session management. The Level 1 Gateway generates menus of providers and broadcast services, either as a function of providers and services available through a particular portion of the network or in a customized fashion specified by individual subscribers.

Abstract: A pool of multimedia servers, which may be geographically diverse, are available to be allocated to serve one of at least two ELANs served by an ELAN contronect network. These multimedia servers are a) connected to, b) dynamically allocated to sub-ELANs, and c) managed by, a multimedia server manager, which is included as part of the ELAN contronect network. In particular, each of the multimedia servers is capable of having its addresses dynamically reconfigured in response to commands from the multimedia server manager to match that of an ELAN to which it is being made available, so that the multimedia server becomes a part of that ELAN. The multimedia server manager obtains a layer-3 address from address server 427 of the ELAN contronect network which it then assigns to the multimedia server so that the multimedia server appears to be a part of the ELAN to which it is assigned to serve.