Abstract: A method for high speed connection admission control based on traffic monitoring includes the steps of comparing a peak cell rate of a call with a previous real available bandwidth which is updated, admitting or rejecting connection of the requested call by the comparison, computing a new available bandwidth as the call is connected and storing asynchronous transfer mode (ATM) cells, computing from the stored asynchronous transfer mode (ATM) cells a monitoring value for a traffic of the call by a certain time period, computing a probability distribution function for a cell number from the traffic monitoring value, computing an equivalent bandwidth according to the probability distribution function, and computing a real available bandwidth from a difference between the equivalent bandwidth and a physical link bandwidth and updating the available bandwidth, so that link may be efficiently used under real time control with a relatively simple hardware by performing the connection admission control (CAC) scheme b

Abstract: A cell scheduling method and apparatus are described in which cells are efficiently scheduled in four steps. In a first step, a VC is selected for servicing and serviced if necessary. In a second step, cells from the serviced VCs are scheduled for transmission. In a third step, jitter is controlled. In a fourth step, final departure of cells is scheduled.

Abstract: A startup management system and method, particularly adapted for use in computer and other communication networks, is presented. Rate-based flow and congestion control mechanisms have been considered desirable, including to deal with the needs of emerging multimedia applications. Explicit rate control mechanisms achieve low loss because of a smooth flow of data from sources, while adjusting source rates through feedback. However, large feedback delays, presence of higher priority traffic and varying network conditions make it difficult to ensure feasibility (i.e., the aggregate arrival rate is below the bottleneck resource's capacity) while also maintaining very high resource utilization. The invention applies entry and early warning techniques which increase the initial connect rate of newly connecting sources.

Abstract: An internal network (16) is protected from being overloaded by an excessive number of data packets that originate from a source in an external network (10). In a preferred embodiment, data packet gate (20) receives each incoming data packet and determines whether it came from a trusted source. If it was not from a trusted source, and the number of data packets received recently from the same source exceeds a threshold, then data packets from that source are rejected. Preferably, when incoming data packets from all non-trusted sources exceed another threshold, additional data packets from all non-trusted sources are rejected.

Abstract: A method is provided for admitting new requests for service in a shared resource having a capacity. The new request has service priority levels associated therewith. In one embodiment of the invention, for example, the shared resource may be a packet communications network and the service request may be a request to admit a new connection. The method proceeds as follows. First, for each service priority level on said shared resource, a total effective bandwidth is generated which is represented by a sum of individual effective bandwidths of previously admitted requests for service. Subsequent to receiving a new request for service having a specified priority of service level, a plurality of effective bandwidths are accessed for the new request. The plurality of effective bandwidths are respectively associated with the specified service priority level and service priority levels therebelow.

Abstract: A cell flow rate control method for an ATM switch can cope with various UPC forms while using the same hardware arrangement. The cell flow rate control method includes the steps of preparing a conformance condition table in which are stored conformance conditions for each connection determined for each cell loss priority in an ATM cell; and employing, for each cell loss priority, a plurality of conformance test components in accordance with the conformance condition stored in the conformance condition table.

Abstract: DVD reproducing apparatus which transmits variable-bit rate data on a digital serial bus having a predetermined transmission rate. The apparatus employs a reproducing device to reproduce data from a record medium in accordance with a control signal to produce variable rate data. The control signal is generated on the basis of at least two buffer storage state indicators corresponding to respective data buffers, one of which is incorporated into the reproducing device. The peak data rate of the variable rate data is detected, a rate of transmission of the variable rate data is established in accordance with the detected peak data rate, and the variable rate data is transmitted in accordance with the established transmission rate.

Abstract: In a link-level flow controlled system, a method and apparatus providing the ability to partition a buffer resource among multiple prioritized buffer subsets through definition of at least one threshold, the buffer resource being shared by a plurality of connections. Different category of service levels, in terms of delay bounds, are thus enabled. The presently disclosed link-level flow controlled system provides for zero cell loss. The shared buffer resource is divided among N priority pools, defined by N-1 threshold levels, each priority pool attributable to a respective category of service. Link-level counters and registers, disposed in a transmit element, as well as an indication of priority level associated with each connection, are employed in realizing the shared buffer resource.

Abstract: A Local Area Network (LAN) Switch includes conventional switching functions and integrated Remote Monitoring (RMON) Universal Feature Card (UFC). The UFC allows simultaneously statistically monitoring the traffic on all ports, 100% monitoring of the traffic on one port, and monitoring the internal LAN Switch switching fabric to obtain RMON statistics about the operation of networks attached to the LAN Switch.

Abstract: A digital communication system includes a receiver and a transmitter in communication with the receiver over a communication link. The transmitter includes a buffer circuit which receives input data signals for transmission and a control signal. The buffer circuit outputs buffered data signals. A symbol encoder circuit receives the buffered data signals and provides the control signal. The symbol encoder circuit outputs data symbols over the communication link. The buffered data signals are supplied to the symbol encoder circuit in accordance with the control signal. The data symbols may be encoded with a number of data bits. The encoding may be done by voltage-level encoding.

Abstract: A method and system for controlling congestion on a packet switched radio channel (PRCH) is disclosed. A PRCH congestion control function determines if the average time delay for packet calls on the PRCH is within a delay alarm level. If the average time delay is not within the delay alarm level, it is then determined which packet calls to expel from the PRCH in order to decrease the average time delay. The determination of congestion may be made for each of the uplink and downlink of a PRCH separately, or, on the combined uplink and downlink of the PRCH.

Abstract: A traffic shaper that feeds cells into an asynchronous-transfer-mode virtual-path-switching network has two queues per virtual path: a first queue providing a regular class of service, and a second queue providing a variable class of service. Cells are taken from the first queue in preference to the second queue, combined traffic from the two queues is kept within a peak cell rate, and traffic from the second queue is kept within an allowed cell rate. Forward resource-management cells are inserted at certain intervals in the cell flow taken from the second queue, and the allowed cell rate is adjusted according to backward resource-management cells received in reply. A third queue for priority cell traffic, limited to a priority cell rate lower than the peak cell rate, may also be provided.

Abstract: A packet-based transmission system is disclosed in which resource management packets containing cell rate information are processed at a single ABR server. The server receives forward resource management packets and routes them without modification to their destination. The server also receives reverse resource management packets which it processes by updating their corresponding cell rate information based, for example, on cell rate information received from the forward cells.

Abstract: A communication network includes a number of network nodes linked together by transmission paths. A network manager controls acceptance of calls onto transmission paths by classifying an incoming call and selecting from the database an appropriate mean to peak bit rate distribution. This selected distribution is then used with the monitored transmission path load to determine a posterior distribution which reflects the load. The decision to accept or reject the call is made on the basis of the posterior distribution by a call acceptance algorithm considering the effective bandwidth for example.

Abstract: A method of automatic baud rate detection disclosed includes use of low cost hardware to detect framing errors, detect actual transitions in a serial transmission, and calculate transitions in the character received. A current baud rate is taken as being correct, too low, or too high as a function of a comparison between actual transitions and calculated transitions in combination with detection of framing errors. A binary search among conventional baud rates establishes a correct baud rate for a low cost automatic baud rate detection receiving device within three "sign on" character presentations.

Abstract: Rate shaping is provided in per-flow queued routing mechanisms for statistical bit rate service.

Abstract: Rate shaping is provided in per-flow output queued routing mechanisms having output links servicing multiple physical layers.

Abstract: This invention provides rate shaping in per-flow output queued routing mechanisms for available bit rate (ABR) service in networks having segmented ABR control loops.

Abstract: A process for renegotiating, during a communication, the parameters of a traffic contract on an ATM network.The present invention relates to a renegotiation process, during a communication on an ATM network, of the parameters of the traffic contract that relates to this communication. It is characterized in that it consists:a. in predicting, for a predetermined period of time between two successive renegotiations, the maximal length that would be reached by a virtual file fed by the traffic of said communication, for at least a given thruput rate of said file.b. in deducing from said maximal length one or more new parameters for the traffic contract, andc. in renegotiating with the network on the basis of said (new) traffic parameter or parameters for said period of time.

Abstract: An apparatus and method for generating a congestion indication bit to be written to the CI field of a backwards RM ATM cell to be transmitted by a network interface utilizes a slot.sub.-- type congestion signal for indicating that the number of slots available for receiving cells is below a threshold limit, and a CI.sub.-- VC signal for indicating that the buffer space consumed by cells received on a particular VC has passed a threshold value. The CI bit in a backward RM cell for the VC when either the slot.sub.-- type congestion signal is set or the CI.sub.-- VC bit is set or the EFCI bit was set in the last data cell received by the network interface or the CI bit was set in the last forward RM cell transmitted by the network interface.

Abstract: In a connection admission controlling system, a call admission processing and allocating device judges whether or not a call is admitted in response to a peak rate of a traffic and allocates, as a temporary bandwidth, the peak rate to the call when the call is admitted. A resource controlling device has a connection call controlling table which holds call connection data of calls each of which has at least one of the temporary bandwidth and an effective bandwidth. A traffic measuring device measures a traffic of the call to produce a measured traffic. An effective bandwidth computing and allocating device has a new call controlling table which holds new call connection data representing data of calls each of which have the temporary bandwidth. The effective bandwidth computing and allocating device computes the effective bandwidth by using the measured traffic and allocates the effective bandwidth to the call.

Abstract: An asynchronous transfer mode (ATM) digital electronic communication system includes an ATM communication system interconnection and termination unit (ATMCSI/TU). This ATMCSI/TU includes both a programmable microprocessor and several hardware-implemented coprocessors. The hardware-implemented coprocessors are under control of the microprocessor, and are dedicated to the performing of repetitive tasks. Thus, the microprocessor is freed to perform supervisory tasks in the ATM in addition to performing tasks associated with actual communication of digital data packages (i.e., CS-PDU's) in the ATM system. Thus, the APU is freed from doing repetitive data manipulation tasks, while these tasks are performed by one or more hardware-implemented coprocessors using memory mapped data structures and linked lists of data.

Abstract: The traffic shaping system according to the principles of the present invention increases the connection-carrying capacity of a network node by shaping the data cells to increase the admissible number of connections. In accordance with certain embodiments of the present invention, the traffic shaping system uses a data buffer at the ingress of the network node to selectively buffer classes of data cells. As such, the traffic shaping system exploits differences in delay tolerances between traffic classes to shape the less delay sensitive traffic classes to reduce the effective bandwidth of a connection of the particular traffic class and thereby increase the nodal connection-carrying capacity. Certain embodiments of the traffic shaping system operate within a framework to provide parameters for the traffic shaping system which increase the connection-carrying capacity for the node while meeting quality of service requirements for the data cells.

Abstract: An adaptive error detection and correction apparatus for an Asynchronous Transfer Mode (ATM) network device comprises a sensing unit for sensing a congestion condition in the ATM network and a global pacing rate unit for adaptively reducing a maximum allowable transmission ratio of ATM cells containing information to idle ATM cells in response to a sensed congestion condition. A processor stores a number corresponding to a relatively high maximum allowable transmission ratio in the global pacing rate register in the absence of a sensed congestion condition, and stores a number corresponding to a relatively low maximum allowable transmission ratio in the global pacing rate register in response to a sensed congestion condition. A controller adjusts the maximum allowable transmission ratio in accordance with the number stored in the global pacing rate register.

Abstract: A local system issues an ICMP echo request packet with a size based on an initial PMTU value corresponding to that of the local system's interface MTU. When an ICMP needfrag error packet is received by the local system, this signifies that the initial PMTU value was too large for packets of corresponding size to be transmitted through the Internet without fragmentation. The value is accordingly decreased by the local system and a next ICMP echo request packet transmitted through the Internet. The process iterates until an ICMP echo request packet is successfully transmitted through the Internet to a target system. In response thereto, the target system transmits an ICMP echo response packet back through the Internet to the local system, thereby indicating that the last-sent ICMP echo request packet from the local system had the correct PMTU value which is thereafter assumed to be the correct PMTU.

Abstract: Policing method and policing circuit for parallelly conducting a plurality of policing which are dependent on policing items in the policing for defining the traffic of an asynchronous transfer mode network are provided. A plurality of traffic monitor circuits 11 parallelly and independently conduct the traffic monitoring of a plurality of items for the input cell for the communication service to be provided by the asynchronous transfer mode network. Each monitor circuit monitors only the violation of the traffic independently and outputs the result. A total determination circuit determines whether to tag, discard or pass the input cell in accordance with a determination rule prescribed for the communication service based on a CLP value contained in a header of the input cell and the monitor result parallelly obtained from the respective monitor circuits to conduct the policing.

Abstract: A method and apparatus of transmitting time critical messages over a network is provided. Data which has minimal bandwidth requirements, such as data packets utilized in applications such as twitch games, is received or generated in a network device. The data is classified as minimal bandwidth data and prioritized relative to other data for transmission before the other data. The data is then transmitted by the device to a second device on the network before the other data is transmitted.

Abstract: A local system issues an ICMP echo request packet with a size based on an initial PMTU value corresponding to that of the local system's interface MTU. When an ICMP needfrag error packet is received by the local system, this signifies that the initial PMTU value was too large for packets of corresponding size to be transmitted through the Internet without fragmentation. The value is accordingly decreased by the local system and a next ICMP echo request packet transmitted through the Internet. The process iterates until an ICMP echo request packet is successfully transmitted through the Internet to a target system. In response thereto, the target system transmits an ICMP echo response packet back through the Internet to the local system, thereby indicating that the last-sent ICMP echo request packet from the local system had the correct PMTU value which is thereafter assumed to be the correct PMTU.

Abstract: A method and apparatus for detecting and reporting flow imbalance of a data stream. A grab rate signal is generated measuring the rate at which a source machine can sequence and compress data from an input. Next, an outflow rate is generated measuring the rate at which the source machine can transmit the compressed data out to a network. When the compressed data arrives at a destination machine from the network, an arrival rate signal is generated measuring the rate at which the destination machine can re-sequence the compressed data for playback and decompression. Finally, a play rate signal is generated measuring the rate at which the destination machine can decompress and play the data to an output. The four rates are used in determining a flow imbalance signal and reporting the imbalance so that the user may correct any deficiencies in the data stream by modifying the quality/size or compression method used for the data transaction from the source.

Abstract: In an ATM network, the physical resources are shared by many connection and the bandwidth is allocated virtually to each connection. The connection admission control (CAC) algorithm uses traffic descriptors, desired quality of service (QOS) parameters etc., to compute a required bandwidth for a requested connection by which it makes a decision to admit or reject the connection. Unlike any prior CAC, the CAC of the invention for constant bit rate (CBR) service takes also into consideration the cells delay variation (CDV) for calculating the required bandwidth.

Abstract: The present invention relates to a method for controlling the peak cell rate spacing of multiplexed ATM traffic.

Abstract: A method regulates the admission control of, and requests for routing of, virtual circuits in a network by determining network resource requirements for the virtual circuits. In particular, the network resource requirements are based on a set of parameters used to control the flow of information from a communications device onto the virtual circuit. The requirements for network resources typically include buffer space requirements in network nodes and bandwidth requirements in network links, and the parameter used to control the flow of information are those associated with an access regulator. The network resource determination is made for the case where lossless performance in the network is required and in the case where statistical multiplexing with limited loss is allowed. Both constant bit rate and variable bit rate information is considered.

Abstract: In an input cell policing method in a network of an asynchronous transfer mode, according to information contained in a header field of each input cell, a group to which the cell belongs is identified. For each group, there are set a plurality of time frames having a predetermined length and mutually different phases to count the number of input cells in each time frame period. For each time frame, the count value of input cells is compared with a predetermined threshold value. An input cell for which the count value exceeds the threshold value in either one of the time frames is assumed to be an excess cell. The excess cell is discarded or a violation mark is added thereto.

Abstract: For each of a plurality of sources, which has a peak transmission rate p, the cells coming from the source are stored in a FIFO access buffer memory; reserves (R.sub.1, . . . , R.sub.i, . . . , R.sub.n) of tokens are allocated to the source, the reserves having respective determined token capacities (M.sub.1, . . . , M.sub.i, . . . , M.sub.n) and replenishing at respective rates (r.sub.1, . . . , r.sub.i, . . . , r.sub.n) verifying r.sub.1 >. . . >r.sub.i >. . . >r.sub.n and ##EQU1## a first cell is sent as soon as each reserve contains a number of tokens that is at least equal to the length of the cell, at a transmission rate corresponding to the bandwidth of the network; all reserves are decremented by a number of tokens corresponding to the length of the cell; once the first reserve R.sub.1 is exhausted, the message continues to be sent automatically at the replenishment rate r.sub.1 until the second reserve R.sub.

Abstract: A method for data flow rate detection useful with data flow rate control is introduced into a TCP packet communication environment which does not have data rate supervision by computing presumed speed based on latency between packets during the initial interchange of synchronization (SYN) packet and the acknowledgement (ACK) packet, presuming to know the initial length of each. This information may be utilized to determine potential rate of data flow for further use in making bandwidth allocation and rate enforcement decisions.

Abstract: In digital transmission systems, adapted data units travel at a high throughput rate over large parts as a stream of fixed length data packets, called cells in this instance. The present method permits the measurement of characteristic magnitudes of the cell stream with respect to the respective individual connection to which they belong. It is based on storing from each arriving cell the identification data of the individual connection to which it is allocated, including its relative position in the cell stream. The memory is interrogated during a cell cycle time. A selection is made about which memory spaces within a defined area contain a predetermined identification data belonging to an individual connection. As a function of the selected memory spaces, the determined result, together with the magnitude and the position of the interrogated area, provides a decisive statement of the measured value.

Abstract: A test instrument for measuring the rate and size of bursts of cells received at a given node of an ATM network with respect to a particular virtual connection includes a cell filter for identifying cells belonging to the virtual connection. The "leaky bucket" algorithm is implemented for determining conformity with contractual performance standards, and for delineating the bursts.

Abstract: A scalable communications network employing shared logical nodes and a related method are provided. The network includes one or more sources for providing program streams. The program streams may comprise a number of frequency-division multiplexed program streams generated by media servers in an interactive network. Each such source is coupled to a corresponding logical node, which receives a corresponding set of program streams. One or more subscribers are allocated to a logical node according to an expected peak subscriber usage constraint. This constraint is met by allocating subscribers to a node so that an expected maximum number of simultaneously active subscribers within the node substantially avoids exceeding the number of program streams provided by the source corresponding to the node. Each logical node includes at least one physical node. Each physical node includes at least one subscriber.

Abstract: An adaptive error detection and correction apparatus for an Asynchronous Transfer Mode (ATM) network device comprises a sensing unit for sensing a congestion condition in the ATM network and a global pacing rate unit for adaptively reducing a maximum allowable transmission ratio of ATM cells containing information to idle ATM cells in response to a sensed congestion condition. A processor stores a number corresponding to a relatively high maximum allowable transmission ratio in the global pacing rate register in the absence of a sensed congestion condition, and stores a number corresponding to a relatively low maximum allowable transmission ratio in the global pacing rate register in response to a sensed congestion condition. A controller adjusts the maximum allowable transmission ratio in accordance with the number stored in the global pacing rate register.

Abstract: In an ATM network using a burst-level band-width allocation, a source terminal reserves, before a burst transmission, band-widths according to a peak rate of the burst and then sends the burst therethrough. When the transmission is finished, the band-widths are released. Where there exists a link to which the peak rate is not assigned, a non-reserving acknowledgement signal (NACK) is sent to the terminal and the reserved band-widths are released. On receiving the NACK, the terminal allocates a band-width with peak rate lower than that of the first request after a back-off time has elapsed, thereby minimizing the probability of a blocked transmission. The source terminal declares a minimum band-width together with the peak rate (maximum band-width) in the band-width request operation. Each node allocates the peak rate when the remaining band-width of a link controlled by the node is sufficient to allocate the peak rate.

Abstract: An apparatus having a buffer store connected to an input line upon which ATM cells are received, and an output line upon which ATM cells are transmitted is provided. A control device receives, for each cell, a channel identifier and a path identifier from which a first signal is generated indicative of a maximum delay value which is applied to the buffer store and used to schedule the particular cell for transmission on a calendar controlling a sustainable cell rate. The control device generates a second signal indicative of a minimum delay value which is applied to the buffer and, in conjunction with the first signal, is used to schedule the particular cell for transmission on a calendar controlling the peak cell rate. The apparatus can also handle routing information, where a group of channel connections define a Route which share a peak cell rate for the Route and are scheduled on the peak cell rate calendar.

Abstract: A connection admission control method for allocating many calls to a transmission line while guaranteeing the quality of service such as the cell loss ratio, where an average cell rate/peak cell rate comparator judges that a call requesting admission has a variable-speed traffic property when the average cell rate Ra and the peak cell rate Rp which are declared by the user are different. A traffic class judging portion determines the traffic class to which the call belongs on the basis of the peak cell rate. A required bandwidth calculator obtains the required bandwidth for guaranteeing the quality on the basis of the sum of the average cell rate of the call requesting admission and the average cell rates of all the calls that belong to the traffic class and that are already allocated to a transmission line, and outputs the calculated bandwidth as the estimated bandwidth.