International Business Machines Corporation

Harmen R Van As

Hans Rudolf Schindler

Wolfram Lemppenau

Erwin A Zurfluh

Werner K Bux

Johann R Mueller

Pitro A Zafiropulo

Felix H Closs

Wolfram W Lemppenau

This invention is an implementation of a congestion control mechanism, especially for ATM networks supporting data services or other nonreserved bandwidth traffic, e.g. in multimedia applications. It reacts immediately upon detection of a traffic bottleneck by selectively and temporarily holding back the data traffic that is to pass the bottleneck (5). A congested node (3) transmits congestion notifications (36) containing routing label information and deferment information to upstream nodes (2), thus enabling selective, temporary throttling action. If congestions persist, further notifications may be spread backwards step by step, eventually reaching the sources. A specific implementation is given for PRIZMA type switching nodes.

Selective congestion control mechanism for information networks

Access control system for a multi-channel transmission ring

An apparatus for rapidly determining a control parameter t=t.sub.0 at which the sum S of n functions F.sub.i (i=1, . . . n) reaches a minimum, a maximum, or a given value, wherein each function F.sub.i (t) changes its first derivative only at given discrete values t.sub.ij of the control parameter t is described. The apparatus has a random access memory (RAM) addressed by the values t.sub.ij, a circuit for summing the second derivatives of the functions, a circuit to perform a double integration to evaluate S, and a comparator to determine the optimum control value; also disclosed is a new gate array (GA) which rapidly reproduces the addresses used to address the RAM while skipping all others. This gate array is advantageously used as a part of the apparatus for determining a control parameter. Further, the use of the devices in a communication network is described.

Gate array for accelerating access to a random access memory

Apparatus for determining the optimal value of a control parameter

This invention relates to a method and system for a collision free insertion and removal of circuit-switched channels in a self-adaptive transmission data structure carrying different classes of packet-switched traffic on a slotted Local Area Network (LAN). This network may have bus or ring topology. The different classes of traffic are asynchronous traffic (packet-switched), synchronous traffic (packet-switched, time sensitive), isochronous traffic (circuit-switched), and signalling on demand. The inventive self-adaptive transmission data structure permits an economic, flexible and bandwidth efficient integration of these different classes of traffic.

Collision-free insertion and removal of circuit-switched channels in a

In a communication system comprising several nodes and a scheduler interconnected by a serial transmission medium, data are transmitted in time slots. The scheduler marks time slots either as reserved if nodes have previously made a request and received a confirmation, or it marks time slots as gratis for free use by any node. Slots are also marked gratis if the have reached their destination or removal node. To achieve fairness between nodes in the reservation process, they count gratis slots they used. When making a request for reserving a number NR of slots, a node must also transmit the number NG of gratis slots used. The scheduler then determines, according to a given rule, the number NC of slots to be granted for each node. A special signalling technique is also disclosed for effective transmission of the numbers in the reservation and confirmation process.

Medium access technique for LAN systems

In a communication system comprising several nodes and a scheduler interconnected by a serial transmission medium, signalling information is transmitted by inserting it whenever required in the data stream in the form of basic data units (ADU). The scheduler inserts a request start and an end flag, and any node requiring allocation of a given type of service insert its request unit between the flags. Thus, the scheduler receives accumulated node-individual request information. The scheduler then sends a response comprising individual response units between two delimiting flags. Each node having made a request removes the respective individual response unit so that only the flags return to the scheduler. Special pipelined circuitry allows insertion and removel of the basic data units constituting the signalling information at very high speed without impeding the speed and timing of the passing data stream.

Insert/remove signalling in LAN systems

In a local area communication system comprising token rings (11) with synchronous bandwidth managers SBM (15) for issuing priority tokens for quasi-synchronous frames at regular intervals, the rings are interconnected by a time division muliplex PBX unit (21) via their SMB units. Buffers are provided in each SBM for synchronous information blocks transferred from and to the ring, and the TDM control (31) can independently access these buffers for TDM switching of the individual bytes of said information blocks. Besides this PBX interconnection for synchronous information or voice, the rings are also interconnected by a backbone bus or ring for transfer of asynchronous data between rings. A special slot rearrangement procedure is provided to improve the filling of time slots in the quasi-synchronous frames that are no longer used after release of a connection, to allow for adapting the frame length (number of issued slots) to the number of existing connections.

Growing community of inventors

Langnau am Albis, Switzerland

Harmen R Van As