Nortel Networks Corporation

Rockstar Consortium US LP

Bilel N Jamoussi

Maged E Beshai

Osama S Aboul-Magd

Donald Fedyk

Peter J Ashwood-Smith

Peter Ashwood Smith

Yunzhou Li

Hamid Ould-Brahim

Dwight D Jamieson

David Benson

Gregory V Wright

Dan Adamski

Jagannath Shantigram

Paul J Beaubien

Maged E Beshal

The invention provides a method and network communication equipment for low latency loss-free burst switching. Burst-transfer schedules are determined by controllers of bufferless core nodes according to specified bitrate allocations and distributed to respective edge nodes. In a composite-star network, burst schedules are initiated by any core node. Burst formation takes place at source edge nodes and a permissible burst size is determined according to an allocated bitrate of a burst stream to which the burst belongs. The permissible burst size is subject to constraints such as permissible burst-formation delay, a minimum guard-time requirement, and permissible delay jitter. A method of control-burst exchange between each edge node and each bufferless core node enables burst scheduling, time coordination, and loss-free burst switching. Both the payload bursts and control bursts are carried by optical channels connecting the edge nodes and the core notes.

Rate controlled opitcal burst switching

Discard precedence priority of packets carrying an encoded video stream in a packet network is determined based on priority information included in the encoded video stream. A video streamer segments an encoded video stream and encapsulates the segment in an Internet Protocol (IP) packet. Priority information associated with the IP packet is determined based on at least one priority indicator associated with the segment that was included in the encoded video stream. Alternately, priority information associated with an Ethernet frame is determined based on at least one priority indicator associated with the segment that was included in the encoded video stream.

Method and system for packet discard precedence for video transport

The invention provides a method and network communication equipment for low latency loss-free burst switching. Burst-transfer schedules are determined by controllers of bufferless core nodes according to specified bitrate allocations and distributed to respective edge nodes. In a composite-star network, burst schedules are initiated by any core node. Burst formation takes place at source edge nodes and a permissible burst size is determined according to an allocated bitrate of a burst stream to which the burst belongs. The permissible burst size is subject to constraints such as permissible burst-formation delay, a minimum guard-time requirement, and permissible delay jitter. A method of control-burst exchange between each edge node and each bufferless core node enables burst scheduling, time coordination, and loss-free burst switching. Both the payload bursts and control bursts are carried by optical channels connecting the edge nodes and the core nodes.

Rate-controlled optical burst switching

Burst-switching nodes using a common-memory or a time shared space switch and employing flow-rate control are disclosed. Within a switching node, data bursts are segmented into data segments of a fixed size with some segments containing information bits as well as null bits. A switching node handles data streams allocated different flow rates and, for any data stream, the internal flow rate through the switching node can be higher than the external flow rate due to null padding of segmented data. The switching node is provided with a sufficient internal capacity expansion in order to offset the effect of null padding. A controller of the switching node is provided with a flow-rate-regulation apparatus to enable scheduling the transfer of data segments across the switching node in a manner that guarantees adherence to the allocated information flow rates.

Flow-rate-regulated burst switches

A time-shared network comprising edge nodes and optical core nodes may be dynamically divided into several embedded networks, each of which covering selected edge nodes. At least one of the edge nodes may host an embedded-network controller operable to form multiple-source flow-rate allocation requests each of the requests specifying flow-rate allocations to a plurality of paths from several source nodes to several sink nodes. A core node may also host an embedded-network controller or several embedded-network controllers. The time-shared network may use both time-division multiplexing and burst switching.

Virtual burst-switching networks

The invention discloses methods and apparatus for regulating the transfer of data bursts across a data network comprising electronic edge nodes interconnected by fast-switching optical core nodes. To facilitate switching at an electronic edge node, data bursts are organized into data segments of equal size. A data segment may include null data in addition to information bits. The null data are removed at the output of an edge node and the information data is collated into bursts, each carrying only information bits in addition to a header necessary for downstream processing. To ensure loss-free transfer of bursts from the edge to the core, burst transfer permits are generated at controllers of the optical core and sent to respective edge nodes based on flow-rate-allocation requests. Null-padding is not visible outside the edge nodes and only the information content is subject to transfer rate regulation to ensure high efficiency and high service quality.

Regulating data-burst transfer

In a first mode of burst communication in a telecommunication network comprising electronic edge nodes interconnected by bufferless core nodes, data bursts are formulated at the edge nodes, respective burst descriptors are communicated to a controller of a core node, and burst-transfer schedules are sent from the core node to respective edge nodes. In a second mode, each burst-stream is allocated a flow rate and a core node determines burst sizes and schedules burst-transfer permits. In a bimodal burst-switching network comprising edge nodes interconnected by core nodes, an edge node selects to send to a core node burst-transfer requests according to the first mode, or flow-rate-allocation requests according to the second mode, depending on proximity, storage capacity at the edge node, and delay-tolerance specifications.

Bimodal burst switching

A generalized virtual router is disclosed. A routing and switching apparatus includes a switching fabric and a matrix of switching and routing elements. At least some of the elements are interconnected by the switching fabric. A router control provides control for the switching fabric. The apparatus has both cross-connect and routing functionality.

Generalized virtual router

Methods and apparatus for scheduling transfer of data bursts in a network comprising electronic edge nodes interconnected by bufferless core nodes are disclosed. Each edge node comprises a source node and a sink node, and each core node comprises several bufferless space switches operating in parallel. Each space switch has a master controller and one of the master controllers in a core node functions as a core-node controller. Each master controller has a burst scheduler for computing a schedule for transfer of data bursts, received from source nodes, to respective destination sink nodes. A core-node controller receives requests for bitrate allocations from source nodes and assigns each request to one of the master controllers of the core node. In one embodiment, a scheduler determines schedules for concatenated reconfiguration periods. In another embodiment, parallel schedulers determine schedules for overlapping reconfiguration periods.

Data burst scheduling

A wide-coverage high-capacity network that scales to multiples of petabits per second is disclosed. The network comprises numerous universal edge nodes interconnected by numerous disjoint optical core connectors of moderate sizes so that a route set for any edge-node-pair includes routes each of which has a bounded number of hops. A core connector can be a passive connector, such as an AWG (arrayed wave-guide grating) device, or an active connector such as an optical channel switch or an optical time-shared channel switch. The core capacity is shared. Thus, failure of a proportion of core connectors reduces network connectivity but does not result in a major service discontinuity. The network uses a source routing scheme where a set of candidate routes for each node pair is determined from the network topology and the candidate routes for a node pair are sorted according to their differential propagation delays. A method of measuring the differential propagation delay is also disclosed.

Expandable universal network

A core network shared by a large number of edge nodes comprises core nodes interconnected by core channels. Selected core channels are provided with buffers to enable temporal alignment of signals arriving at any core node from several other core nodes. A buffer may be provided at either end of a core channel. Otherwise, all other ports of the core node may be bufferless. Providing such buffers enables the construction of high-capacity wide-coverage network comprising a large number of core nodes shared by numerous edge nodes. Methods of temporal coordination among the network nodes are disclosed.

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Nashua, NH, United States of America

Bilel N Jamoussi