Northern Telecom Limited

Nortel Networks Corporation

Jatel Communications Systems Ltd.

George Frank Irwin

David Anthony Fisher

James Leslie Watchorn

Melhem I Chaar

Gary Michael Depelteau

John Edward Vincent

Tony Huang

Osama Bahgat

Ronald J Maginley

David J Robertson

Du-Tuan Lam

Michael F Kemp

Jalal Ebrahimi

Paul J Smelters

A packet switch has a switching unit (SU) for switching packets between network links and a computing unit (CU) connected to the SU through a network link for implementing software control functions over the SU. The SU is formed of different functional components interconnected by generic buses. The components communicate with one another using program data units (PDUs) that are formatted and transmitted according to a shared device protocol. The communication between the components occurs by placing PDUs in bus frames that are passed from component to component. Information is exchanged between the components by adding information to or dropping information from the fields of the PDUs, or by concatenating new fields to the PDUs, as the frames pass from component to component. By using a generic bus to implement PDU-based interconnections within the SU, all the components are forced to support a common interface. Changes to the implementations of any component's interface can thus be accommodated by changing the PDU format as opposed to changing the interfaces of connected components. The new packet switch architecture decouples the components on the switch so that they can be upgraded or otherwise modified independently of one another.

Message based packet switch based on a common, generic bus medium for transport

A communication system consisting of a number of modules that communicate with one another through a shared communications bus which accommodates different protocols. The system includes a bus clock for defining a frame having a plurality of time slots for communicating signals on the bus; and a bus management algorithm for specifying a receive assignment definition and a transmit assignment definition. The receive assignment definition defines a receive channel for each of the modules representing a set of the time slots, where the modules receive signals from the bus during the set of time slots prescribed by the receive channel. The transmit assignment definition defines a transmit channel for each of the modules representing a set of the time slots, where the modules transmit signals to the bus during the set of time slots prescribed by the transmit channel.

Generic bus system

A data packet processing system is provided for a router having a multiprocessor architecture comprising a master node and a processor array of multiple slave nodes. A packet switching software of the router is partitioned into a main forwarding program which is loaded in the master node, and a set of procedures which is loaded into the slave nodes. The system assigns to each data packet a program counter which defines a sequence of procedural calls in the main forwarding program. By stepping through the program counter in the master node, each procedural call is forwarded to and executed by one of the slave nodes.

Data packet processing system and method for a router

An apparatus for performing an address lookup to find a longest matching prefix for an N-bit input address in a packet data communication system that includes a memory (e.g. RAM) for storing a table containing a predefined portion of an N-bit address with an associated prefix search list containing prefix values that are candidates for the longest matching prefix. A binary search algorithm is used for selecting a specific prefix value from the prefix search list to structure the N-bit input address to form a search value. A search algorithm (e.g. a content addressable memory) is used for performing an associative search on the search value to find the longest matching prefix. The two types of memories (RAM and CAM) each provide specific functions. The RAM is used as a lookup table to provide an N/x-bit (0&lt;x&lt;N) binary decoding tree, and the CAM is used to provide an associative search of network addresses that are stored in logical bins that have a specific network prefix. By using the binary search algorithm that is guided by the lookup table data, the CAM can be probed to find the longest matching prefix.

Address lookup in packet data communication networks

A telecommunications apparatus for transporting ATM cells having either of isochronous units of payload data and asynchronous units of payload data, between receiving and transmitting ports includes a buffer for asynchronously queuing units of payload data received from the receiving ports and for subsequently transmitting the queued units of payload data in a time division multiplex data stream toward the transmitting ports. A timeslot interchanger is used to reorder a time defined sequence of isochronous units of payload data from the first data stream into a second time defined sequence of isochronous units of payload data in a second TDM data stream. An outgoing TDM data stream is assembled by transferring the first data stream into the outgoing data stream while substituting each payload occurrence of isochronous units from the second TDM data stream, into corresponding TDM locations in the outgoing data stream. The outgoing data stream is transmitted toward the transmitting ports whereby telephone calls are connected via the isochronous units of payload data. Delay typically inherent in telephone conversations connected via prior ATM facilities and the consequent severe echo often experience by users is substantially reduced.

Telecommunications apparatus and method

A switch module for time switching telecommunications data includes an input circuit for selecting data samples from a time slot in an input frame of data samples. The selected data samples are arranged into groups of uniform size, each group consisting of at least two data samples. The groups of selected data samples are stored in an orderly manner, in each of as many storage entities as there are data samples in each group. Thereafter in accordance with a predefined sequence peculiar to each of the storage entities, the data samples are simultaneously read out, group by group. An output circuit selects data samples into a selected group of data samples from among each of the readouts of each of the storage entities and transmits each selected group into an output frame of data samples. Hence a sequence of the data samples appears switched in the output frame with respect to the sequence of the data samples as they were stored from the input frame. The switch module as described inherently provides for switching of data samples, the data samples being permitted to occur at a rate faster than a cycle time of switch module operation.

Telecommunications switch apparatus and method for time switching

Communication paths in a digital key telephone system are operated by sequentially transferring bit states from origin channels associated with communication ports to exclusively dedicated time slots in a parallel transmission medium. Time slot bit states are selectively stored at designated memory locations corresponding to destination channels associated with the communication ports. The memory locations are read in synchronism with the channel occurrences and bit states from the designated memory locations are asserted in the corresponding channels, any remaining channels having predetermined bit states asserted therein.

Digital key telephone system

A simple but versatile communication switching system suitable for air traffic control and the like applications is provided. The system utilizes a central pulse amplitude modulation bus, is modular in structure, and provides the time division multiplexed representations of the auxiliary circuit terminations, such as radio and trunk circuits, on the central bus for direct access by all modules.

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Kanata, Canada

George Frank Irwin