Abstract: A switching node comprises edge nodes interconnected by independent switch units. The switch units are arranged in at least one switch plane and the switch units of each switch plane are arranged in a matrix having several rows and several columns. Each edge node has a channel to a switch unit in each column in each switch plane and a channel from each switch unit in a selected column in each switch plane. Simple paths, each traversing only one switch unit in a switch plane, may be established for any directed edge-node pair. Additionally, several non-intersecting compound paths, each comprising at most two simple paths, may be established for any edge-node pair. A significant proportion of traffic may be routed through simple paths. The switching node employs distributed control scheme and scales gracefully from a capacity of a fraction of a terabit per second to thousands of terabits per second.

Abstract: 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.

Abstract: 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.

Abstract: A technique for autonomous network provisioning based on establishing a relation between network performance indices, traffic measurements and resource capacities, which provides automatic provisioning recommendations for identified critical links is disclosed. The technique may be implemented in a network through collaboration across node controllers and network controllers. A method for the autonomous provisioning of a network, wherein a plurality of nodes of the network collaborate to determine required additional resources, may comprise the steps of receiving at least one network-state measurement comprising at least one of a traffic measurement and a performance measurement; determining at least one critical link based at least in part on the at least one network-state measurement; and formulating at least one link provisioning recommendation for the at least one critical link.

Abstract: 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.

Abstract: 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.

Abstract: A wide-coverage, high-capacity, switching network is modeled after a classical space-time-space switch. In the switching network, each of the space stages comprises geographically distributed optical space switches and the time stage comprises a plurality of geographically distributed high-capacity electronic switching nodes. User-access concentrators, each supporting numerous users, access the network through ports of the distributed optical space switches. A user-access concentrator is a simple device which need only have a single access channel to access the network, although two or more access channels may be used. Such a user-access concentrator can communicate with a large number of other user-access concentrators by time-multiplexing the access channel.

Abstract: A high capacity network comprises a plurality of edge nodes with asymmetrical connections to a plurality of switch planes, each switch plane comprising fully meshed fast-switching optical switch units. Upstream wavelength channels from each source edge node connect to different switch planes in a manner which ensures that upstream wavelength channels from any two edge nodes connect to a common switch unit in at most a predefined number, preferably one, of switch planes. Thus, switch units in different switch planes connect to upstream channels from orthogonal subsets of source edge nodes. In contrast, downstream wavelength channels from a switch unit in each switch plane connect to one set of sink edge nodes. In an alternate arrangement, the upstream and downstream asymmetry may be reversed.

Abstract: A last optical switch is needed to realize an economical and scaleable optical-core network. In the disclosed optical switch, switching is effected by rapid wavelength conversion. Either channel switching, Time Division Multiplex (TDM) switching or both may be provided by the fast optical switch. The operation of the fast optical switch is enabled by a fast scheduler. The throughput of the optical switch may be increased through a process of bimodal pipelined connection-packing. An in-band exchange of control signals with external nodes may serve to minimize the control overhead. Such control signals may include time-locking signals and connection-requests. A modular structure may be configured to comprise several fast optical switches to yield a high-speed, high-capacity, fully-connected optical switch.

Abstract: 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.

Abstract: An optical shell node is provided with an ability to perform time switching on signals received from subtending edge nodes and channel switching on signals received from other shell nodes and destined for the subtending edge nodes. The signals received from the subtending edge nodes may be aggregated into signals that are channel switched by optical core nodes or by other shell nodes toward destination edge nodes. A resultant network formed of these shell nodes along with channel-switching core nodes and subtending-upon-shell-node edge nodes is capable of expansion beyond a continental scale, can support large numbers of edge nodes and has a higher bit rate capacity than known optical network structures.

Abstract: 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.

Abstract: A network comprising a large number of electronic edge nodes interconnected through bufferless optical switch planes so that a signal from any edge node to any other edge node traverses only one switch plane scales to a capacity of hundreds of petabits per second while providing global geographic coverage. Each edge node is time-locked to each optical switch plane to which it connects to enable loss-free time-sharing of the network core despite the absence of buffers in the core. In an alternate implementation, a relatively small number of electronic switch units may be employed in a predominantly-optical core. In addition to scalability and high performance, the simple structure of the network significantly simplifies addressing and routing.

Abstract: In a fast optical switch comprising a plurality of star couplers, channel switching, Time Division Multiplex (TDM) switching, or both may be provided. The operation of the fast optical switch is enabled by a fast scheduler comprising at least two scheduler modules. The throughput of the optical switch may be increased through a process of bimodal pipelined connection-packing.

Abstract: A method and a network for a universal transfer mode (UTM) of transferring data packets at a regulated bit rate are disclosed. The method defines a protocol that uses an adaptive packet header to simplify packet routing and increase transfer speed. The protocol supports a plurality of data formats. The network includes a plurality of modules that provide interfaces to various data sources. The modules are interconnected by an optic core with adequate inter-module links. The adaptive packet header is used for both signaling and payload transfer. The header is parsed to determine its function. Rate regulation is accomplished using each module control element and egress port controllers to regulate packet transfer. The protocol enables the modules to behave as a single distributed switch capable of multi-terabit transfer rates. The advantage is a high speed distributed switch capable of serving as a transfer backbone for substantially any telecommunications service.

Abstract: A multi-stratum multi-timescale control for self-governing networks provides automatic adaptation to temporal and spatial traffic changes and to network state changes. Microsecond timescale reacting through the routing function, a facet of the lowest stratum, allows a source node to choose the best available route from a sorted list of routes, and to collect information on the state of these routes. Millisecond timescale correcting through the resource allocation function, a facet of the intermediate stratum, allows the network to correct resource allocations based on requirements calculated by the routing function. Long-term provisioning through the provisioning function at the higher stratum allows the network to recommend resource augmentations, based on requirements reported by the resource allocation function. The control is implemented in the network through coordination across edge node controllers, core node controllers, and network controllers.

Abstract: An optical core node that includes optical switching planes interfaces, at input, with multi-channel input links and, at output, with multi-channel output links. The number of channels per link can differ significantly among the links, necessitating that the input (output) links have different connection patterns to the switching planes. Such an optical core node requires new methods of assigning an incoming wavelength channel to one of the optical switching planes. The assignment of the channels of input and output links to input and output ports is established in a manner that increases input-output connectivity and, hence, throughput. Additionally, the networks that may be formed with such optical core nodes require new routing methods. A preferred method of selecting a path through the core node favors switching planes connecting to a small number of links. In a time-division-multiplexing (TDM) mode, the method of path selection is complemented by temporal packing of TDM frames.

Abstract: Rather than restricting a stream of data to a single channel within a multi-channel link between a source node and a core node, each channel is divided into time slots and the stream of data is distributed among these time slots in several channels. However, to ease the management of switching the stream of data at the core node, simultaneous time slots in each channel may be arranged into “stripes,” such that a particular stripe may only include data segments having a common destination. Switching these stripes of data at the core node requires that the source of such a stripe arrange the frame according to a frame structure provided by the core node. Advantageously, where the frame is striped across an entire link, the present invention provides for a variation on link switching that approaches the topological reach of TDM switching while maintaining relatively straightforward operation at the core node.

Abstract: A method of interleaving time-critical data packets and delay-tolerant data packets on a shared channel emanating from a control port of a switching node permits a strict time requirement for transmission of time-critical data packets to be met. A control circuit of the switching node stores a local time, an indication of a time required to transfer a delay-tolerant data packet waiting to be transferred, a comparator and a selector to control transfer of the time-critical and delay tolerant data packets.

Abstract: A method and apparatus for scheduling the 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 operated in parallel. Each source node is connected to at least one core node by an upstream link that includes multiple upstream channels. Each core node is connected to at least one sink node by a downstream link that includes multiple downstream channels. Any of the space switches can have either an electronic fabric or a photonic fabric. Each space switch has a master controller, and one of the master controllers in a core node is designed to function as a core-node controller in addition to its function as a master controller. Each master controller has a burst scheduler operable to compute a schedule for the transfer of data bursts, received from source nodes, to destination sink nodes.