Nortel Networks Corporation

Northern Telecom Limited

Northern Electric Company Limited

Alan S Chapman

Nadir Nizamuddin

Hsiang-Tsung Kung

Elwyn Brian Davies

Terence N Thomas

Alan M Redmond

Ronald J Maginley

Hsiang T Kung

David J Robertson

John W Williams

Scott Alexander Inrig

William Anthony Gage

Biswajit Nandy

Michael Alain Gazier

Jeffrey T Gullicksen

Dhananjay Damodar Godse

Jeffrey Fitchett

Robert S Morley

Gregory M Bernstein

Timothy J Littlewood

Philip K Edholm

Abderrahmane Lakas

Jeremy G Ethridge

Bruce Robert Barrett

Kenneth Gullicksen

According to the present invention, a technique for delivering content over a network having endpoints and nodes that store content is provided. In one embodiment, the technique is realized by first launching a request for content from a requesting end point. Then propagating the request over the network to the nodes. While the request propagates, it leaves a trail at the nodes and, when content matching the request is located, a copy of the content is returned to the requesting endpoint over the trail left by the request.

Content networks

A method and apparatus for controlling congestion at a node in a data network. The node includes an input for receiving traffic units from the network, an output for releasing traffic units to the network and a control unit. The control unit is responsible for estimating a level of data occupancy of at least a portion of the network by looking at the traffic units received at the input from a remote node in the network. When the data occupancy level reaches a certain threshold, the node issues a control signal to the remote node such that the remote node lowers its rate of traffic units input in the network. By estimating the network data occupancy level, congestion at the node can be effectively foreseen and controlled.

Method and apparatus for forecasting and controlling congestion in a data transport network

An apparatus for implementing a collision avoidance mechanism in a bufferless network. The apparatus includes first and second inputs for receiving traffic units from first and second source points, respectively. The traffic units from the first source point arrive at the first input on a basis of a first traffic pattern. The traffic units from the second source point arrive at the second input on a basis of a second traffic pattern. The apparatus further includes a traffic detection unit and a notification unit. The traffic detection unit is operative to monitor the traffic units received at the first and second inputs for detecting the first and second traffic patterns. The notification unit is operative to generate a control signal for transmission to either one of the first and second source points on a basis of the detected first and second traffic patterns. This control signal is directive to regulate at least in part the traffic pattern of the traffic units sent from either one of the first and second source points such that a possibility of collision is reduced.

Method and apparatus for collision avoidance in bufferless networks

An admission controller and its method of operation for controlling admission of data flows into an aggregate data flow are described. Admitted data flows are aggregated into an aggregate data flow for transmission by a router, for example, over a data network. The aggregate data flow typically follows a pre-established path through the network; for example a multi-protocol label switched (MPLS) path. The path has minimum and maximum bandwidth limits assigned to it. The admission controller controls admission of new data flows into the aggregate data flow by granting or denying new session requests for the new data flows. Congestion notifications received from the network and bandwidth limits of the path are considered in determining whether to grant or deny a new session request. In this way, the admission controller provides elastic sharing of network bandwidth among data flows without exacerbating network congestion and while remaining within the path's bandwidth limits. The data flows may include transaction oriented traffic.

Admission control for aggregate data flows based on a threshold adjusted according to the frequency of traffic congestion notification

In accordance with a method and apparatus for managing aggregate flows of data in a differentiated services (DS) network, fairness issues are improved by enforcing congestion control at the edges of the DS in a TCP-friendly manner network, rather than relying on congestion to accumulate at the core. This is done by establishing a credit system for each aggregate flow through the edge. Only if credit is available for the flow, will data from an edge node be forwarded to the edge node's DS traffic conditioner where the data packets can be marked using DiffServ labels. When credit is not available, the data will be queued at the edge node. Each time data belonging to an aggregate flow is forwarded to the traffic conditioner, the amount of credit for the flow is decremented. Credit for the flow is incremented only when control packets can be inserted into the flow. Specifically, the present invention establishes control flows associated with each aggregate flow. A control packet (i.e. a header packet) is injected into the flow for every fixed amount of data belonging to the flow. Credit generation, and hence the queueing of aggregate flow data at the edge, is thus determined by the state (or the congestion window) of the associated control flow.

Method and apparatus for aggregate flow control in a differentiated services network

Methods and apparatus for accelerating a router in a communications network are described. In one embodiment, a router accelerator includes a forwarding table for associatively storing a destination address and a next hop address. If a destination address of a packet matches a destination address in the forwarding table, then logic forwards the packet to a next hop. A router may be coupled to at least one network port through the router accelerator. In another approach, the network includes at least one host and at least one router. The host has at least one routing table for associatively storing a second-level destination address, a second-level next hop address and a first-level next hop address. A router accelerator includes redirect logic for storing the second-level destination address in a second-level next hop address entry in the at least one host routing table. This causes the host to request a first-level next hop address corresponding to the second-level destination address. An accelerator table responds to the host's request with the bound first-level next hop address. In another approach employing host routing tables, a router accelerator includes request logic for requesting from the router a second-level next hop address in response to the first-level next hop address. Redirect logic stores the second-level next hop address in a second-level next hop address entry in the at least one host routing table. This causes the host to request a first-level next hop address corresponding to the second-level next hop address.

Method and apparatus for accelerating OSI layer 3 routers

Multi-media networks will require that a data flow be given certain quality-of-service (QOS) for a network connection but pre-negotiation of this sort is foreign to the current data networking model. The real time traffic flow in the data network requires distinct limits on the tolerance to delay, and the variations in that delay. Interactive voice and video demand that the total delay does not exceed the threshold beyond which human interaction is unacceptably impaired. The present invention allows the network to discover the nature of the service for each traffic flow, classifies it dynamically, and exercises traffic conditioning by means of such techniques as admission control and scheduling when delivering the traffic downstream to support the service appropriately.

Dynamic traffic conditioning

A plurality of end devices are coupled via a shared port to an asynchronous network in which traffic is carried in cells. A cell multiplexer is disposed between the devices and the port and is adapted to multiplex cells from the devices to the port in the order in which they are received by the multiplexer. The multiplexer broadcasts cells received from the network to all of the devices. Each said device is allocated a respective VCI so that it can identify its own cells from the broadcast cells.

Providing access to a distributed data processing system

A key telephone system includes a plurality of ports linked by port associated bidirectional communication channels which are synchronously switched by transferring bit states between ones of the channels to provide communication paths between the ports as directed by a central processor. The ports are also linkable to and via the central processor by port associated message channels. An interface circuit is responsive to the central processor and message channel signals for regulating flow of messages received by the central processor and for effecting single and plural channel distribution of messages from the central processor. The message channels permit telephony operating features and functions to be provided either within the central processor or by appropriate apparatus means being connected at any of the ports. In such a telephone system at least one of said apparatus comprises a telephone station apparatus and another of said apparatus comprises a feature host apparatus. The telephone station apparatus has a plurality of functions stored therein and said feature host apparatus has a plurality of feature modules stored therein. Each such feature module comprises instructions for invoking a corresponding set of functions at said telephone station apparatus by means of an exchange of signalling and supervision messages between said feature host apparatus and said telephone station apparatus. The functions invoked provide the feature selected by a feature request action of a user at said telephone station apparatus.

Digital key telephone system

Relocation and/or replacement of terminal apparatus in telecommunications systems including, but not necessarily limited to, key telephone systems, usually entails reassignment of administration data; for example, features. When a station or terminal apparatus is moved physically from one port to another within a telecommunications system which comprises a plurality of ports connected to a central processor, interface means operative on initial connection of said terminal apparatus transmits to the central processor an identifier unique to such terminal apparatus within such system. The central processing means has storage for each said identifier together with administration data specific to said terminal apparatus and the number of the port to which said terminal apparatus set is connected. Following receipt of an identifier, the central processor updates said storage means to assign said administration data corresponding to said identifier to the present port.

A key telephone system includes a plurality of ports being linked by port associated bidirectional communication channels which are synchronously switched by transferring bit states between ones of the channels to provide communication paths between the ports as directed by a central processor. The ports are also linkable to and via the central processor by port associated message channels. An interface circuit is responsive to the central processor and message channel signals for regulating flow of messages received by the central processor and for effecting single and plural channel distribution of messages from the central processor. The message channels permit telephony operating features and functions to be provided either within the central processor or by appropriate apparatus means being connected at any of the ports.

A method for substituting one memory module for another, faulty, memory module comprises designating and marking a memory module as the substitute module, which, upon detection of a fault in the other memory module, is inhibited from responding to its own address when called, and responds to the address of the faulty module whenever the latter is called.

Method for providing a substitute memory in a data processing system

A TDM PCM communication system includes a plurality of user terminals, a switching network and a CPU for controlling the establishment of transmission paths between the user terminals and the switching network for the transfer of information between predetermined ones of the user terminals. An incoming path carries information bits from the user terminals to the switching network and an outgoing path carries information bits from the switching network to the user terminals. The switching network includes means for transferring single information bits each residing in a time slot period from the incoming path to the outgoing path. The transferring means includes an exchange means for effecting a bilateral exchange of information bits in fixed pairs of time slot periods, whereby paths for information bit transmission are periodically provided between ones of the user terminals, as determined by the CPU. PCM words are thereby exchanged bit by bit between user terminals enabled in fixed pairs of time slot periods.

TDM PCM Communication system

A pair of interchangeable memories is provided, one of which receives a PCM frame while simultaneously transmitting one, while the other of which, containing the previous frame, outputs the channel bits for parallel processing. Each simultaneous conference is assigned a temporary storage location in which the associated channels are accumulated to yield the total conference signal. Subsequently, each channel is subtracted from its conference total to produce the final conference signal. The final conference signals replace the unprocessed frame in the memory where, at the end of the current frame, it is interchanged with the other memory. And so on.

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Kanata, Canada

Alan S Chapman