Abstract: An asynchronous transfer mode (ATM) network or the like having a plurality of switches which may each be coupled with a central service provider over a virtual service path. Service requests, grants of service, and other control information for the network may then be communicated between each of said switches and the central service provider over virtual communication channels within said virtual service path. The disclosed method and apparatus provides for efficient communication of service requests and service grants without requirement to establish new communications paths between the individual switches and the central service provider for each request. Further, the ATM network may be managed by the central service provider as a logical star network.

Abstract: A network process that automatically identifies and isolates faulty stations or group of stations within a token ring communication network by a process running on an agent that is remote from the beaconing token ring network. Beacon frame counters and good frame counters are maintained by a probe station within the token ring network which provides the counter information to an agent running at a remote location. The remote agent detects a beaconing station in the network by either an incrementing of the beacon frame counter or a failure to increment of the good frame counter within predetermined amounts of time. Once a token ring network segment is determined to be beaconing, an iterative process proceeds through the token ring with commands sent from the remotely operating agent. Stations on the network are iteratively wrapped and unwrapped until the beaconing stations can be determined and isolated from the network.

Abstract: An apparatus for monitoring whether a cable is coupled to a port of a computer network. A free-running oscillator is initially set to a base frequency when a cable is not coupled to the port. If a cable is subsequently coupled to that port, the inherent capacitance of that cable loads one of the nodes associated with the oscillator. The result of this capacitance is that the oscillator is now running at a lower frequency. A frequency counter and threshold comparator are used to detect whether the oscillator frequency has fallen below a pre-determined frequency threshold. If the oscillator frequency has not fallen below this threshold, the port is not included in the network path. However, if the oscillator frequency has fallen below the threshold, this indicates that a cable has been coupled to the port. Consequently, the trunk port is inserted into the computer network's path.

Abstract: A supportive guide for circuit-card grounding comprises a conductive strip (40) attached to a base of an elongated track (50) that has a U-shaped cross-section defining a longitudinal slot (52) and staggered protrusions (68,70) located at the proximal end of the trak. The strip contains a plurality of spring contacts (42) protruding into the slot via a plurality of openings (60), formed in the base of the track. Snap-in posts anchor the base of the track to a chassis (84) such that the conductive strip is sandwiched therebetween.

Abstract: In a terminal coupled to a computer network, a circuit for compensating for the baseline wander of received digital signals. The terminal is AC coupled to the computer network by a coupling transformer. The received digital signal is summed with a correction signal. The resulting summed signal is input to a comparator. This comparator compares the summed signal to a predetermined baseline level. Thus, the output signal from the comparator is fixed at the baseline level. The correction signal is the difference between the summed signal and the output signal from the comparator. The correction signal is filtered and amplified before being fed back to the comparator.

Abstract: A concentrator having a single medium access controller for monitoring a plurality of communication lines is provided. Each of the communication lines corresponds to a network and carries identification signals periodically transmitted by devices on the corresponding network. The medium access controller includes a transmit unit and a receive unit. The transmit unit sequentially broadcasts concentrator identification signals over each of the communication lines. The transmit unit sequences through the communication lines at a rate to insure that a concentrator identification signal is sent over each communication line during a predetermined transmit interval. The receive unit sequentially monitors the signals on each of the communication lines. The receive unit monitors the signals on any given communication line for a predetermined monitoring period before sequencing to the next communication line.

Abstract: An apparatus and method of communicating between devices coupled to two networks. The first network comprises a terminal, containing an Ethernet interface, communication medium and an Ethernet interface contained in a concentrator. The second network comprises an Asynchronous Transfer Mode (ATM) interface contained in a switch, a communication medium and other components of an ATM network. Terminals transmit packets to other devices by: transmitting a packet to the concentrator, the concentrator segments the packet's information into ATM cells, and transmits the cells over the ATM network. The Terminals receive packets from other devices by: the ATM network transmitting cells to a concentrator, the cells being reassembled into Ethernet packets, then the packets being transmitted to the appropriate terminal.

Abstract: A data communications network providing for a multiport router and providing for use of an asynchronous transfer mode (ATM) switch or the like as a routing backplane or packet switching engine. A router front end formats ATM cells including providing routing information in the cell header. The routing information may comprise, for example, a destination port identifier in the VPI field of the cell header. The ATM switch then switches the cell from an input port, coupled with the router front end to an output port based on the routing information. The ATM switch may also translate the routing information to provide source identification information to the destination. In a described embodiment, the multiport router is used as a backplane bus in a network concentrator.

Abstract: An asynchronous transfer mode (ATM) network or the like providing for formation of resource hunt groups. The hunt groups are formed by devices of the same class (e.g., servers such as multicast servers) by devices registering with a central management supervisor (also referred to herein as a hunt group manager) through communication of hunt group registration requests over the virtual service path of the switches to which devices are attached. The central management supervisor communicates with an acknowledgement message back to the requesting device, again over the virtual service path. After formation of a hunt group, devices requiring the services of a device registered in the hunt group can communicate a request for establishment of a communication path to the central management supervisor. The central management supervisor then establishes a communication path with an available one of the devices in the hunt group.

Abstract: An asynchronous transfer mode (ATM) network or the like providing for booting of switches from one or more boot servers. The booting process comprises the steps of a switch querying as to possible communication paths with a boot manager and then establishing a boot communication channel with the boot manager. Boot messages are then communicated over the boot communication channel. Importantly, boot messages may be transmitted between the booting switch and the boot manager through a neighboring switch and intermediate switches by using the neighboring switch's virtual service path to effect such communication. This allows communication of these messages through translation by the neighbor's and the intermediate switch's switch fabric and without need for utilization of the neighbor's or the intermediate switch's switch controller.

Abstract: A network process that automatically identifies and isolates a faulty station or group of stations within a token ring communication network in a timely manner. The present invention performs three different and separate processing strategies to identify and isolate faulty stations and or groups of stations within a token ring communication network. The processing of the present invention is accomplished simultaneously within the network management modules of each concentrator within the overall communication network. Upon receipt of beacon signals indicating a faulty station in the network, the present invention directs the NMM to isolate newly inserted stations or modules. If this is not successful then the present invention attempts a direct removal process if port address association data is present. If no port address association data is present then a brute force process is performed to identify and isolate the station or module that is generating a communication fault within the token ring network.

Abstract: A topology-independent method and apparatus for avoiding continuous looping of transmission of cells and for allowing broadcast of cells in a network implementing Asynchronous Transfer Mode ("ATM") or similar networking architectures. The disclosed method and apparatus provides for "misusing" fields in a cell header in order to provide for information identifying a cell as a broadcast cell and to provide for "expiration information" in the cell header. More specifically, a first station stores data in a first area of a cell intended for transmission on the network, where the first area is defined by standards to store certain information (in particular, it is defined in the preferred embodiment to store virtual path identifier information, VPI). The information stored identifies the cell as a broadcast cell. In other words, the field is "misused" to store this information.

Abstract: In a computer network having a cable for transmission of electrical signals between data terminal equipment and a device used to control and route data in the network, an apparatus for terminating the cable to minimize emissions radiating from the cable and susceptibility of the cable to outside interferences. The cable is comprised of unshielded twisted pairs of wires. Each twisted pair is individually terminated into a matching input impedance. The difference signals being conducted in each twisted pair produces common mode currents which sets up standing waves through the cable. Consequently, at each end of the cable, the common mode of the twisted pairs is terminated into a load having an impedance approximately equal to the common mode impedance of the twisted pairs. These loads effectively dissipate the energy from the standing waves, thereby minimizing emissions. Reciprocally, susceptibility is likewise minimized.

Abstract: A method and apparatus for associating stations to a port on a network concentrator. The network concentrator implements a network having a Ring based topology. Associating stations to ports provides for the coupling of multiple stations to a single port. Three maps are created which describe the network, a port map, a station map and an exit station map. The port map identifies the ports having one or more stations coupled to it. The station map identifies each station in the network. The exit station map identifies for each port with a station coupled to it, the station which transmits data into the port. By identifying the stations between two exit stations on adjacent ports in the network concentrator, the stations coupled to a port are determined. The identification of exit stations is facilitated by the use of an exit station detection circuit located at the port.

Abstract: An electromagnetic shielding clip for providing an electrical connection between two mating surfaces. The clip of the present invention comprises an electrically conductive sheet. The sheet is curved into a series of interconnected arc-shaped sections, each oriented opposite to the arc-shaped section adjacent to it. Two of the arc-shaped sections appear at opposite ends of the clip and are used to attach the clip to a mating surface through two parallel slots. Another arc-shaped section curves away from the parallel slots for contract to another mating surface. The present invention also includes a tool and method for inserting the clip.

Abstract: A network process that automatically identifies and isolates a faulty station or group of stations within a token ring communication network in a timely manner. The present invention performs three different and separate processing strategies to identify and isolate faulty stations and or groups of stations within a token ring communication network. The processing of the present invention is accomplished simultaneously within the network management modules of each concentrator within the overall communication network. Upon receipt of beacon signals indicating a faulty station in the network, the present invention directs the NMM to isolate newly inserted stations or modules. If this is not successful then the present invention attempts a direct removal process if port address association data is present. If no port address association data is present then a brute force process is performed to identify and isolate the station or module that is generating a communication fault within the token ring network.

Abstract: Apparatus for monitoring and displaying the status of a local area network. The network includes a hub with ports for connection to various data terminal equipment in a star configuration and for connection to other hubs of the network. The hubs each have different types of plug-in modules which have ports for connecting the hub to different types of network cable such as fiber optic cable, unshielded twisted pair cable and shielded twisted pair cable. Information is automatically provided to a control console identifying the types of modules and the location of the modules in the hub so that an image of the actual hub can be displayed on the screen of the control console. The actual hub image shows the location and types of modules installed in the hub. In addition, information regarding the connection of each of the hubs to other hubs of the network is obtained and provided to the control console.