Abstract: A balanced, bufferless switch scalable to high capacities and requiring less processing effort with less internal fabric expansion in comparison with prior-art switches. The balanced, bufferless switch employs a pre-switching or post-switching balanced-connector.

Abstract: A modular optical switch includes a set of optical switch modules connected in a mesh, a master controller for the whole optical node and a switch-module controller for each of the optical switch modules. The optical switch modules receive optical signals from, and transmit optical signals to, edge nodes based on connection requests received from the edge nodes. The master controller acts to select a path, using a simple or compound time-slot matching process, through the mesh of switch modules for each optical signal related to a connection request. Advantageously, the optical switch modules are fast switching, enabling the use of time-sharing schemes such as TDM, and the modular optical core node is made practical by efficient path selection at the master controller. A hybrid modular switch may include both optical and electronic switch modules, a master controller, and a switch-module controller for each of the switch modules.

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.

Abstract: A scalable router-switch that grows from a capacity of a few gigabits per second to hundreds of terabits per second is disclosed. In one embodiment, the router-switch comprises a plurality of switch units arranged in a plurality of combinations. Within each combination, each switch unit cyclically connects to each other switch unit to form a contention-free temporal mesh. Each switch unit belongs to a number of combinations and any two combinations have at most one switch unit in common. The router-switch further includes a distributed-control system which comprises an outer controller associated with each of the switch units and an inner controller associated with each combination. The structural simplicity significantly simplifies the operation and control of the router-switch.

Abstract: A high capacity switching node comprises a lattice structure of low-latency switch units and a plurality of balanced connectors interfacing electronic edge nodes to diagonal subsets of said switch units. The edge nodes may be collocated with the switch units or remotely located. The switch units may be bufferless, having optical switch-fabrics for example, thus requiring a compound vacancy-matching process. Using switch units each of dimension 64×64, a fast switching node having a dimension of the order of 10,000×10,000 can be constructed. With a typical wavelength-channel capacity of 10 Gb/s, the fast-switching node would scale to a capacity of 100 terabits per second, which is orders of magnitude higher than the capacity of known fast optical switches. A fast-switching optical switch of such scalability significantly reduces network complexity and cost.

Abstract: A scalable router-switch comprises a plurality of switch units each having consolidation means for data disassembling and reassembling. The switch units are arranged into switch modules and the switch units of each switch module are interconnected through a dual rotator to form a contention-free temporal mesh.

Abstract: A method and apparatus are provided for low latency loss-free burst switching. Burst schedules are initiated by controllers of bufferless core nodes and distributed to respective edge nodes. In a composite-star network, the burst schedules are initiated by any of a plurality of bufferless core nodes and distributed to respective edge nodes. Burst formation takes place at source nodes and a burst size is determined according to an allocated bitrate of a burst stream to which the burst belongs. An allocated bitrate of a burst stream may be modified according to observed usage of scheduled bursts of a burst stream. A method of control-burst exchange between each of a plurality of edge nodes and each of a plurality of bufferless core nodes 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.

Abstract: A fast 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: 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: A multi-grained high-performance rotorswitch scaling to high capacities is disclosed. In one embodiment, the rotorswitch comprises common-memory switch modules each of which cyclically accessing each other switch module for an access interval of a predefined value and transmitting, during the access interval, a number of data segments collectively having a duration not exceeding the access interval. The data segments transmitted to a given switch module during an access interval may be destined to several other switch modules. The switch modules may cyclically connect to each other using a plurality of rotators of the same rotational speed. In another embodiment, the rotorswitch uses rotators of different speeds connecting common-memory switch modules so that each of the switch modules has parallel cyclic access, possibly at different cyclic rates, to each other switch module.

Abstract: A high capacity distributed switching system comprises electronic edge nodes connected to a balanced bufferless switch which may be electronic or optical. The balanced bufferless switch comprises a balanced connector and a switch fabric. The balanced connector comprises an array of temporally cyclic rotator units having graduated rotation shifts and each having a prime number of output ports. The switch fabric may be a mesh interconnection of switch modules. Due to the use of the balanced connector, establishing a path through the switch fabric requires at most a second-order time-slot matching process for a high proportion of connection requests with a much reduced need for a third-order time-slot matching process required in a conventional mesh structure.

Abstract: A scheduling apparatus for a switch includes multiple schedulers which are assigned in a variety of ways to non-intersecting control domains for establishing connections through the switch. The control domains are defined by spatial and temporal aspects. The control domains may be dynamically selected and assigned to schedulers in a manner that achieves a high throughput gain. Control domains may be considered in a cyclic and/or a pipeline discipline for accommodating connection requests. The invention enables the realization of a highly scalable controller of a switching node of fine granularity that scales to capacities of the order of hundreds of terabits per second.

Abstract: A transit memory assembly of a rotator-based switching node is logically partitioned into two sections, one operated as a common-memory switch fabric and the other as a time-shared space-switch fabric. The composition of data received at input ports of the switching node determines adaptive capacity division between the two sections. Based on an indication of traffic type, a controller of at least one input port selects one of the two sections. The space-switch section enables scalability to a high transport capacity while the common-memory section enables scalability to a high processing throughput. The switching node includes rotators and a bank of transit-memory devices that facilitate the incorporation of any mixture of periodic, aperiodic, contention-free exclusive-access, concurrent-access, and multicast switching.

Abstract: In a communication network comprising nodes and links between the nodes, a controller node disseminates link state information. A nodal routing table exists at each node comprising routes between pairs of nodes. The nodal routing table is either populated by the given node based on network information received from the controlling node or populated at the controlling node and received by the given node. Each node receives heartbeat signals from its neighbouring nodes. An unexpected delay between heartbeat signals may be perceived as a failure of a link. The perceived failure of that link is reported by the perceiving node to the controlling node. Upon receiving link failure information from a node, the controlling node may determine a subset of nodes in the network influenced by the link failure and indicate the link failure to the determined subset of influenced nodes.

Abstract: A circulating switch comprises switch modules of moderate capacities interconnected by a passive rotator. Data is sent from a one switch module to another switch module either directly, traversing the rotator once, or indirectly through at least one intermediate switch module where the rotator is traversed twice. A higher capacity extended circulating switch is constructed from higher-capacity switch modules, implemented as common memory switches and having multiple ports, interconnected through a multiplicity of rotators preferably arranged in complementary groups of rotators of opposite rotation directions. A polyphase circulating switch having a low switching delay is derived from a multi-rotator circulating switch by providing programmable rotators having adjustable relative rotator-cycle phases. A low delay high-capacity switch may also be constructed from prior-art medium-capacity rotator space switches with mutually phase-shifted rotation cycles.

Abstract: A fast 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: A fast 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: At a master controller of a space switch in a node in a data network, a request is received from a source node that requests a connection to be established through the space switch. This request is compared to other such requests so that a schedule may be established for access to the space switch. The schedule is then sent to the source nodes as well as to a slave controller of the space switch. The source nodes send data bursts which are received at the space switch during a short guard time between successive reconfigurations of the space switch. Data bursts are received at the space switch at a precisely determined instant of time that ensures that the space switch has already reconfigured to provide requested paths for the individual bursts. The scheduling is pipelined and performed in a manner that attempts to reduce mismatch intervals of the occupancy states of input and output ports of the space switch.

Abstract: Expanding the coverage of a time-shared network comprising electronic edge nodes interconnected by bufferless fast-switching optical nodes is enabled by combining spatial switching with temporal switching. The output side of each edge node preferably connects to a large number of core switches through individual time-locked channels and the input side preferably connects to each of a small number of core switches through a channel band having a sufficiently large number of channels. Wavelength routers may be used to aggregate individually-routed channels into WDM links.

Abstract: An N-dimensional lattice network that scales to capacities of the order of a Yotta bits per second (1024 bits per second) includes a plurality of sub-nets of edge module switches interconnected by an agile switching core. The agile core may be distributed. In the N-dimensional lattice network, each edge module 408 is connected to N core stages, each core stage having an associated dimensional indicator. The input/output ports of each edge module are divided into (N+1) port groups. One of the port groups serves local sources/sinks while the remaining port groups are respectively connected to core stages in each of the N dimensions. This structure permits virtually unlimited capacity growth and significantly simplifies the routing and forwarding functions. The edge modules are addressed using logical coordinates, one coordinate being assigned for each of the N dimensions. This simplifies routing and permits each edge module to compute its own routing tables.