Abstract: A process for detecting upstream congestion within an ATM switch. The switch includes several junctions linked together by a cross-connector. In each input junction, the number of incoming cells bound for a same specified output port of a junction are counted. Results of the count supplied by the input junctions are transferred to the output port. Results of the counts in the output junction are aggregated and a congestion is declared in the output port if the aggregate number of cells is greater than a specified threshold value.

Abstract: A method and apparatus for communicating congestion control information between dissimilar protocols operating in heterogeneous internetworks at different layers of the International Standards Organization (ISO) Open Systems Interconnection (OSI) 7 layer conceptual model for data networking. The method and apparatus provides direct end-to-end congestion control at the Transport layer across a TCP/IP and ATM internetwork utilizing ATM ABR and TCP sliding window flow control mechanisms. A network device that interconnects TCP/IP and ATM data networks for communication of data communicates network congestion detected by a protocol operating in the ATM data network to a heterogeneous protocol operating in the TCP/IP data network. The network device receives TCP data packets and stores them in a queue.

Abstract: An ATM communication apparatus excellent in reliability and economical efficiency and capable of performing congestion control at a high speed in an asynchronous transfer mode (ATM) communication network. For this purpose, there are provided in the ATM communication apparatus a mechanism for identifying a cell transmitting origin that has caused a congestion when the congestion is detected in a communication node and a mechanism for newly generating a congestion notifying RM cell and transmitting it directly to the cell transmitting origin, and there is provided a congestion control function for generating and sending an RM cell immediately to a communication terminal or a communication apparatus that is transmitting a cell which causes the congestion within a communication apparatus having a congestion cell buffer at the time of generation of a congestion of a cell buffer within the node.

Abstract: An apparatus for switching cells from entities in a network. The apparatus includes an input mechanism for receiving all cells by the apparatus from the network. The apparatus includes a memory mechanism for storing all cells received by the input mechanism that are to be stored in the apparatus. The memory mechanism is connected to the input port mechanism. The memory mechanism has an occupancy for cells. The apparatus includes an output mechanism for sending cells from the apparatus to the network. The apparatus includes a server for providing service to the cells at a service rate. The server is connected to the memory mechanism and the output mechanism. The apparatus includes a scheduler for providing service to the cells in the memory mechanism. The scheduler is connected to the server and the memory mechanism. A method for switching cells. An ATM switch which stamps Explicit Rate to ABR VCs for controlling ABR traffic flow on a given link of the ATM switch.

Abstract: In a broadband switching system for the switching of asynchronously transferred cells of data, a dynamic bandwidth controller (DBC) controls the application of data cells to an input port of the system. The data cells are supplied by a number of transmitting end-systems. When an end-system begins transmitting data cells, the DBC detects the presence of incoming cells and requests bandwidth from a connection admission control (CAC) forming part of the system. The switching system stores a table associating a number of signal sources connected to the input port with respective predetermined maximum transmission times and maximum transmission rates for the sources. When arrival of cells at the input port from one of the source is detected, the DBC and CAC operate together to allocate sufficient bandwidth in the switching system to allow the respective message size to be transmitted within the respective maximum transmission time. A guaranteed minimum rate of transmission is also guaranteed for the source.

Abstract: A method of measuring the round trip time (RTT) of a virtual circuit (VC) utilizing the Traffic Management mechanism of ATM and adapting the CRM (also known as XRM) Traffic Management descriptor parameter accordingly. The CRM parameter is setup adaptively and individually for a particular VC in real time while traffic is flowing so as to achieve better performance of the network. The invention comprises CRM calculation means, a database for storage of RM cell related information, including but not limited to, RM cell assigned sequence numbers, transmission times, reception times, etc., means for filtering the transmission and reception times. The CRM calculator functions to track the transmission and reception of RM cells from the source end station using a unique sequence number assigned to each RM cell. Filters can optionally be used to smooth the data recorded that is derived from RM cell transmission events, e.g., calculated round trip time (RTT).

Abstract: A load observation unit observes a load using each quality class buffer and the link (address management unit) accommodating quality class buffers. An ER computation unit computes an ER (explicit cell rate) for each quality class buffer. The ER can also be computed by the entire link. The ER computation unit defines the ER computed for the quality class buffer or the ER computed for the entire link, whichever is larger, as a first ER. Then, it compares the first ER with the MCR (minimum cell rate) set in the connection of the quality class buffer, and defines one of them whichever is larger as a second ER. Then, the value of the ER set in the ER field of the RM (resource management) cell arriving at the quality class buffer with the above described second ER, and the value whichever is smaller is set in the ER field of the RM cell.

Abstract: A method of measuring the Round Trip Time (RTT) if a Virtual Circuit (VC) utilizing the Traffic Management mechanism of ATM. The RTT is measured in real time individually for each new opened VC and/or for existing VC routes in the network. In addition, the RTT measurement method of the present invention can be used to determine the CRM parameter for a VC on an end to end basis, e.g., user to user or LEC to LEC, so as to achieve better performance of the network. The invention comprises a first embodiment that utilizes the SN field of a RM cell in measuring the RTT and a second embodiment that does not utilize the SN field in measuring the RTT. In addition, an application of the method is presented in determining the CRM parameter within the TM descriptor.

Abstract: A switching system in an ATM switching system accommodating an ABR is constructed of an individual units connected to a transmitting terminal or a receiving terminal to implement an efficient bandwidth authorization, and a plurality of intra-system relay devices having transmission allowed rate calculating units. In this switching system, there are separated a transfer of a management cell between the transmitting terminal or the receiving terminal and the individual unit and a transfer of the management cell between the plurality of intra-system relay devices.

Abstract: The router, which serves as an egress of a first network, forms a frame out of a control frame, which is received through a virtual connection in the first network and is to be terminated at the router, and transmits the frame to a second network, i.e., to external of the first network. The router also forms a frame out of a data frame, which is received through the same virtual connection and is to be transferred through the router, and transfers the frame to the second network. The router, which serves as an ingress of a third network, receives the frame including the control frame, is able to change the information contained in another control frame to be transferred within the third network, based on the control information generated in the first network and contained in the received frame. Thus, each node in the networks can perform packet transfer control based not only on control/congestion information of its own network but also on control/congestion information of other networks.

Abstract: A cell is transferred from a source terminal to a destination terminal at a variable rate and, when a failure occurs in a path in which the cell transfer is performed, the cell transfer is maintained by assuring a frequency band in a bypass route different from the path in which the failure occurs and switching the failure path to the bypass route. In this operation, upper limits of the cell sending rates of the respective source terminals on the failure path and the bypass route are fixed during a time period from a time when the frequency band is assured on the bypass route to a time when the switching of path is completed. Since the increase of the source terminal sending rate is restricted on both the original route and the bypass route during the time period from the time when the frequency band is assured on the bypass route to the time when the switching of path is completed, the self healing of ABR becomes possible without loss of cell.

Abstract: A switching system in an ATM switching system accommodating an ABR is constructed of an individual units connected to a transmitting terminal or a receiving terminal to implement an efficient bandwidth authorization, and a plurality of intra-system relay devices having transmission allowed rate calculating units. In this switching system, there are separated a transfer of a management cell between the transmitting terminal or the receiving terminal and the individual unit and a transfer of the management cell between the plurality of intra-system relay devices.

Abstract: Systems and methods for implementing ABR (available bit rate) flow control in ATM (asynchronous transfer mode switches are provided. A partitioned architecture a featuring standalone ABR processing subsystem advantageously allows components to be changed with little impact on the switch's overal design. Both end-to-end and VS/VD (virtual source/virtual destination) flow control systems are provided as are both configurations for switches which are either standalone or connected to a switching fabric.

Abstract: A method for consolidating backward resource management (BRM) cells in an available bit rate point-to-multipoint tree including a root, a plurality of leaves and a branch point interconnected between the root and the leaves. Initially, congestion information memory devices are reset. Then for each incoming return BRM cell to the branch point a determination is made whether the branch point has received a return BRM cell from a predetermined number of candidates in a candidate set of candidate-branches. If the branch point has not received a return BRM cell from the predetermined number of candidates in the candidate set then the congestion information from the incoming return BRM cell and the congestion information in the congestion information memory devices are consolidated in the congestion information memory devices.

Abstract: A device and algorithm for fairly allocating available bandwidth between contending connections at a contention point in a data network. The allocation is based on global queue size at the contention point and a weighted value assigned to the data traffic. The device and algorithm find particular application in an ATM network which supports the available bit rate (ABR) service category.

Abstract: An Asynchronous Transfer Mode (ATM) switch (8) and method of operating the same to allocate Available Bit Rate (ABR) communications therethrough is disclosed. The switch (8) receives resource management (RM) cells over a sequence of measurement periods. Within each measurement period, the message flow associated with a received RM cell is identified, and a flag (SEEN1) in a memory array (22) is interrogated to determine whether an RM cell for the message flow has yet been received in the measurement period. If not, a sum value (SUM) is updated with the current cell rate (CCR) of the flow and, if the CCR of the flow is equal to or greater than the highest cell rate (r1) yet measured in the measurement period, a highest cell rate field (r1) in memory and a count (m1) of flows having the highest cell rate are updated.

Abstract: An Asynchronous Transfer Mode (ATM) switch (8) and method of operating the same to allocate Available Bit Rate (ABR) communications therethrough. The switch receives resource management (RM) cells over a sequence of measurement periods. A plurality of rate levels are defined, each associated with a measurement period of a corresponding duration; the measurement periods being nested. Saved and current values of the number of flows associated with each level, and saved and current values of the aggregate rates of these flows, are retained in memory. RM cells are received during the various measurement periods, and the various numbers and aggregate rates are maintained for each rate level, including the use of estimates for flows that have changed rate level. A bottleneck rate is determined as the larger of the ratio of ABR bandwidth to ABR flows, or the largest cell rate plus surplus bandwidth derived according to this sum.

Abstract: An ATM system with ABR function is disclosed, that comprises a VS/VD. The VS/VD informs a downstream segment portion of a CCR area of a BRM cell folded back in an upstream segment. The downstream segment portion compares an ER area of the BRM cell with the CCR area. When the value of the CCR area is smaller than the value of the ER area, the downstream segment portion updates the ER area with the value of the CCR area.