Abstract: A method of converting a permanent connection, such as a PVC, into a signalled permanent connection, such as an S-PVC, in a connection-orientated network, such as an ATM network, without service disruptions. The method includes the steps of: (a) establishing signalling links between each network node along the path of the permanent connection; (b) providing information to identify the cross-connections along the path; (c) incorporating the cross-connect identification information in a call set-up message; (d) signalling the call set-up message along the path from a source network node to a destination network node; and (e) associating the cross-connection of each node along the path with the appropriate signalling links in order to form the signalled permanent connection. The cross-connect identification information may be a unique call identifier for the permanent connection, in circumstances where the call identifier is associated with the permanent connection cross-connections prior to Step (d).

Abstract: A quick-starting low-voltage DC power supply circuit has a switch mode DC to DC converter connected to a DC supply source. A low-dropout-regulator (LDO) connected in parallel with the switch-mode DC to DC converter, and a diode is connected in series with the output of the low-dropout-regulator connecting the output of the low-dropout-regulator to the output of the switch-mode DC to DC converter. The arrangement is such that the start-up output voltage of the circuit is the output voltage of the low-dropout-regulator and the long-term output voltage of the circuit is supplied by the switch-mode DC to DC converter output.

Abstract: A method and apparatus for statistics collection in a data communications network is presented that utilizes a lower level protocol to locally verify the status of the nodes included in each of the various segments within the network. Indications as to the functional status of each of the nodes included in each of the segments are maintained based on periodic status checks. This set of indications can then be referenced to determine whether or not statistics requests should be issued to particular nodes such that those nodes that are not properly functioning are not be polled. By ensuring that any statistics requests that are issued are being issued to functional nodes, statistics polling bandwidth which may have been wasted on non-functioning nodes is conserved, thus improving the likelihood that the statistics for the various portions of the network can be retrieved in a timely and loss-less manner.

Abstract: A method and apparatus for generic support of frame relay services in a communications network is presented. This is accomplished by defining a bit field that indicates whether or not particular functions or services (including frame relay services) are supported by a particular node or other network component. The bit field for each component within the communications network is communicated to the network manager, which stores the bit fields for each component within a database. The database is then utilized to perform network management functions, as it informs the network manager whether a particular service/feature is available on the network component to which the bit field corresponds.

Abstract: A method and apparatus for controlling data congestion in a frame relay/ATM internetworking system is presented. In one embodiment, received frame relay frames are monitored in an internetworking switch to detect an indication, of congestion. When an indication of congestion is detected, the egress traffic provided to the source of the congestion indication is reduced, which may lead to local congestion in the internetworking switch. When congestion within the internetworking switch has arisen and a resource management cell is received along an ATM ingress path, an ATM, backward resource management cell is generated having a set congestion indication bit that informs additional ATM nodes of the congestion. In another embodiment, ATM cells are received in an internetworking switch and monitored to detect an indication of congestion.

Abstract: The method of buffering packets in a digital communications device includes defining an n-level hierarchy of memory partitions, wherein each non-top level partition has one or more child partitions at an immediately lower level of the hierarchy. The memory partitions at the top-most level are pre-configured with a target memory occupancy size, and the target occupancy for each memory partition situated at a lower level is recursively computed in a dynamic manner based on the aggregate congestion of its parent partition, until the target occupancies for the bottom-most memory partitions are determined. Each traffic flow which uses the buffer is associated with one of the memory partitions at the bottom-most level of the hierarchy and packet discard is enabled in the event the actual memory occupancy of a traffic flow exceeds its target occupancy.

Abstract: A control system for selectively isolating a power supply from a common bus is provided. The control system comprises a connection to an output path of an output signal of the power supply and a resistive element providing a variable resistance between an input terminal and an output terminal. The input terminal is connected to the connection and the output terminal is connected to the common bus. The resistive element further comprises a control terminal allowing adjustment of the variable resistance. A control element provides a control signal to the control terminal; the control element is responsive to current flowing between the output path and the common bus.

Abstract: A computer communications network comprises a plurality of interconnected ATM switches forming a WAN or LAN area network over which ATM cells are transmitted, and a plurality of user devices including LAN interface adapters for connection to one or more to local area networks (LANs). An interface device connects at least some of the respective ATM switches to the LAN interface adapters. The interface adapts the ATM cells for transport over the LANS. The user devices can thus communicate through the LAN interface adapters transparently with the wide area network.

Abstract: A system and method for combining multiplexing and modulation schemes to deliver high and low bandwidth services over a wireless link. The system includes a base station (BTS) with a transmitter for point to multipoint communications to a plurality of network interface units (NIUs) located at customer locations within a geographic area serviced by the base station. In addition to receiving downstream communication from the BTS, each NIU is equipped to communicate in a point to point manner with the BTS. According to the invention time division multiple access multiplexing (TDMA) and quadrature phase shift key (QPSK) modulation is employed for low bandwidth services and frequency division multiplexing (FDM) and quadrature amplitude modulation (QAM) is used to supply high bandwidth services.

Abstract: Apparatus and method for shaping ATM cell traffic emitted onto a virtual path connection in an ATM network are described. Component virtual channel connections are arbitrated at an aggregation point utilizing an arbitration technique. The technique provides both virtual path shaping and controllability of underlying virtual channel connections with an improved fairness performance amongst all the aggregating virtual channel connections.

Abstract: A switch-mode power converter that powers the fan or blower unit in a communication system is used to suppress the audio band noise, thereby eliminating any need for additional passive or active filters used in the prior art. The frequency response of a switch-mode DC/DC converter is set by a control loop. By modifying the feedback amplifier compensation network in the control loop such that the frequency control loop bandwidth of the converter is substantially less than the AC load of the fans or blowers, the invention eliminates the need for additional filtering beyond that inherent in the power converter.

Abstract: A method for verifying the integrity of data payloads of ATM cells passing through a switching device involves computing a payload integrity verification code for the payload portion of an ATM cell. The payload integrity verification code may be generated according to any error detection or error correction scheme. Preferably, the payload integrity verification code is stored in a portion of the standard ATM cell header which is not used while the cell is passing through the switching device. Preferably the payload integrity verification code is stored in all, or a portion of, the virtual path identifier or virtual connection identifier fields. The invention allows for the immediate identification of cells having corrupted payload data. Different actions may be taken on the detection of errors in the ATM cell header and ATM cell payloads respectively.

Abstract: In an N×N packet switch, for example an ATM switch, multicast connections receive backpressure signals from congested output ports in the switch core. The cells in the connections are destination address modified not to send to the congested output port, but to continue sending to the other output ports in the connection. The multicast cells may include a user selected primary route identification and be queued in a unicast input queue for the primary route before being destination address modified. Destination address modification for congestion may be accompanied by partial packet discard, through destination address modification of the remaining cells forming part of a multiple cell packet to remove the destination address for the congested port (whether or not it is now congested) where one of the multiple destination addresses of one of the cells in the packet has been modified to remove the destination address of the congested output port.

Abstract: A method and apparatus for per connection queuing of multicast transmissions. The method begins by receiving a cell associated with a multicast transmission. A multicast transmission typically includes a single ingress connection and a plurality of egress connections. The processing then continues by queuing the cell in a next available cell buffer of a root queue that is associated with the multicast transmission. Next, a determination is made as to whether a predetermined number of leaf queues (i.e., queues associated with egress queue identifiers) associated with the multicast transmission are empty when the queuing of the cell commences. Each of a plurality of leaf queues is associated with a corresponding one of the egress connections of the multicast transmission. A leaf queue will be empty when the corresponding egress connection has transported all of the data cells contained within the root queue associated with the multicast transmission.

Abstract: The method of the invention includes the step of transmitting a priority indicator containing information indicating the priority of network traffic over a connection to a downstream node in a communications network. The downstream node has a queue for queuing traffic received over the connection and the queue has an adjustable discard range. After transmitting the priority indicator, the network traffic is transmitted over the connection. When the priority indicator is received at the downstream node the discard range is adjusted to correspond to the priority indicated in the priority indicator. At the downstream node the network traffic is stored in the queue if a queue congestion measure is outside the discard range and discarded if the queue congestion measure is within the discard range. The priority indicator may be a Resource Management cell or may be provided in the header of a cell carrying the network traffic.

Abstract: The ATM apparatus for transmitting messages associated with a plurality of variable bit rate connections comprises ATM layer transmission equipment for receiving multiple messages, segmenting each received message into a plurality of smaller data units, such as 48 byte ATM adaption layer segmentation and reassembly protocol data units, and multiplexing such data units into a single stream for transport over a physical interface. A scheduler receives messages from each of the variable bit rate connections and transfers the messages to the transmission equipment in an order corresponding to the level of a leaky bucket associated with each connection.

Abstract: A method and apparatus for packet classification stores rules or parameters for classifying the packets in a memory structure. The memory structure receives a set of rule selection signals, where the memory provides a selected set of rules in response to the rule selection signals. A comparison block operably coupled to the memory receives a key, which is also preferably derived from the header information for the packet. The key includes the relevant information for classifying the packet according to the rules stored in the memory. The comparison block compares the key with each of the rules in the selected set of rules, and when a favorable comparison is determined, the comparison block provides an indication of the favorable comparison. A prioritization block operably coupled to the comparison block prioritizes the rules that resulted in a favorable comparison to determine a preferred rule, where the preferred rule includes the resulting classification information for the packet.

Abstract: An embodiment of the present invention provides a method for network management that allows the configuration of IP links in one step, via a GUI form, even though the management protocols available at the two end links (routers) may differ. According to one embodiment, the method comprises gathering information from the user, validating this information, and then sending this information to the appropriate router(s). According to one embodiment, the method enables a user to specify various configurations when provisioning an IP link, for example, the type of IP link (Point-to-Point, Point-to-IP, or Point-to-Subnet), the numbering type (Numbered or Unnumbered), the application type (MPLS and/or IP Forwarding), and the sub-layer interfaces to be used (Packet Over Sonet, Asynchronous Transfer Mode, GigEthernet, and others).

Abstract: A method of improving the signalling performance reliability of an interface between a signalling agent and a network element. In the case of a non-redundant signalling agent, a primary link is established between a first Layer 2 port of the signalling agent and a first Layer 2 port of the network element; and, a primary backup link is established between a second Layer 2 port of the signalling agent and a second Layer 2 port of the network element. During normal operation of the primary link, the primary link is maintained in an active state in which all signalling messages directed to the interface are transferred between the Layer 3 segments over the primary link. The primary backup link is maintained in a standby state in which the primary backup link is active between the second set of Layer 2 ports, but inactive between the Layer 3 segments.

Abstract: A method and network element for feedback control for adjusting a rate of message transmission over a connection in a network is provided. The connection comprises a source and destination linked by forward and backward message paths. The source has instructions for setting a message transmission rate for the connection provided by feedback messages received, each containing an explicit rate of transmission. The method comprises steps: receiving feedback messages from the backward path; extracting an explicit rate being carried by each feedback message received; storing each feedback message received in a queue; retrieving a stored feedback message and, substantially when it is transmitted, marking it with an explicit rate determined from an extracted explicit rate pertaining to another message received more recently and a rate determined from a state of congestion of the network element; and externally transmitting the feedback message over the backward message path once so marked.