Nortel Networks Corporation

Northern Telecom Limited

David Anthony Fisher

Alan Frank Graves

George Frank Irwin

James Leslie Watchorn

Michel Langevin

Melhem I Chaar

Todd D Morris

Gary Michael Depelteau

John Edward Vincent

Norman Allan Lyon

Tony Huang

Osama Bahgat

Michael F Kemp

Andrew Jocelyn Timms

Several rotator switch architectures are provided that enhance performance of a basic rotator switch. The rotator switches having double buffered tandem nodes, multiplexing two or more sources onto each tandem node, partitioning the rotator into two or more parallel space switches, two or more rotator planes multiplexing from/to source and destination nodes to provide data path redundancy, priority queueing on source nodes scheduled locally or globally, or redundancy in the schedulers are shown.

Rotator switch data path structures

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

Several rotator switch architectures are provided that enhance performance of a basic rotator switch. The rotator switches having double buffered tandem nodes, multiplexing two or more sources onto each tandem node, partitioning the rotator into two or more parallel space switches, two or more rotator planes multiplexing front/to source and destination nodes to provide data path redundancy, priority queueing on source nodes scheduled locally or globally, or redundancy in the schedulers are shown.

The invention is a novel method and apparatus for controlling the flow of traffic between a host digital terminal (HDT) and a plurality of optical network units (ONUs). Each ONU is connected to the HDT by optical fiber and to a plurality of subscribers by a respective plurality of subscriber drops (typically pre-existing copper twisted pairs). The bandwidth on the fiber, although large, is usually inferior to the total bandwidth that can be transmitted across the subscriber drops. Therefore, both upstream and downstream traffic may become congested at various &ldquo;choke points&rdquo; under certain circumstances of usage. Ordinarily, the data is buffered at the choke points, leading to the installation of large queues within each ONU. This solution is not only expensive, but is inadequate since the required queue size is dependent on the maximum transaction size, which has no hard upper bound. In contrast, the present invention provides a traffic shaper located in the HDT, which gives centralized control of the traffic flowing to and from the ONUs. Consideration of the priority and destination of each traffic cell is taken into account by the traffic shaper to ensure that the capacity of the fiber and of the individual drops is never exceeded, irrespective of the transaction sizes, thereby eliminating the need for costly buffers in the outside plant. Any maintenance or repairs of the traffic shaper can be easily effected without field visits, due to its centralized location.

Method and apparatus for traffic shaping in a broadband fiber-based access system

Novel traffic management schemes of a telecommunications network using the concept of virtual links is disclosed. As an example, if a switch connects via a high bandwidth link to an access mux that drives lower bandwidth links. The mux is a potential congestion point in the downstream direction (from high to low bandwidth links) because traffic can arrive at a greater rate over the high bandwidth link than it can exit through the lower bandwidth link. If all of the traffic destined for a particular low bandwidth link can be organized into a unique virtual link. This virtual link can be scheduled at a maximum rate not exceeding the bandwidth of the low bandwidth link, thus preventing the mux from ever becoming a congestion point. Therefore, the amount of mux buffering can be reduced to a very small amount (for jitter absorption). One advantage of this scheme in this example is potentially large cost reductions in the high volume access mux at the lesser expense of a more complex low volume switch.

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Kanata, Canada

David Anthony Fisher