Abstract: Methods and apparatus for determining encoding parameters of an encoder or a transcoder which yield an encoded signal of optimal measurable properties are disclosed. For a video signal, the encoding parameters may include quantization granularity, a measure of display resolution, and a frame rate. The measurable properties of an encoded signal may include a fidelity index, a relative size, and a relative flow rate. Reference data records quantifying properties of sample signals encoded according to experimental sets of encoding parameters are used to define parameters of conjectured analytical functions characterizing the encoding or transcoding functions. The analytical functions are then used to generate granular tables of estimated measures of encoded-signal properties. A fast search mechanism relies on the granular tables, together with sorted arrangements of the granular tables, to determine, in real-time, preferred encoding parameters for multimedia data streams received at an encoder or a transcoder.

Abstract: A large-scale switching system configured as a global network or a large-scale data center employs switches arranged in a matrix having multiple rows and multiple columns. The switching system supports a large number of access nodes (edge nodes). Each access node has a channel to each switch in a respective row and a channel from each switch of a respective column. Thus, an access node connects to input ports of a set of switches and output ports of a different set of switches. Each access node has a path to each other access node traversing only one of the switches. Controllers of switches of each diagonal pair of switches are integrated or mutually coupled to provide a return control path for each access node. The switches may be arranged into constellations of collocated switches to facilitate edge-node access to switches using wavelength-division-multiplexed links. The switches are preferably fast optical switches.

Abstract: A method and a system for distributed computation of a routing table for a vast communication network are disclosed. The network nodes are arranged into multiple groups with each group associated with a respective network controller. A network controller of a group acquires characterizing information of links emanating from local nodes of the group, communicates the information to each other network controller, reciprocally receives characterizing information from other network controllers, and determines a generic route set from each local node to each other node of the network. The network controllers collectively determine an inverse routing table identifying all routes traversing each individual link in the entire network and exchange node or link state-transition information for updating individual route sets affected by any state transition. Thus, the processing effort of routes generation and tracking network-elements states is distributed among multiple coordinated network controllers.

Abstract: Multiple network controllers are interconnected in a full mesh structure, e.g., through a cyclical cross connector, to form a distributed control system for a network of a large number of nodes. A network controller acquires characterizing information of links emanating from a respective set of nodes, communicates the information to each other network controller, and determines a route set from each node of the respective set of nodes to each other node of the network. The network controller may determine, for each link included in the route set, identifiers of specific route sets which traverse the link. Accordingly, a state-change of any link in the network can be expeditiously communicated to network controllers to take corrective actions where necessary. A network controller may rank routes of a route set according to some criterion to facilitate selection of a favourable available route for a connection.

Abstract: Methods and apparatus for determining encoding parameters of an encoder or a transcoder which yield an encoded signal of optimal measurable properties are disclosed. For a video signal, the encoding parameters may include quantization granularity, a measure of display resolution, and a frame rate. The measurable properties of an encoded signal may include a fidelity index, a relative size, and a relative flow rate. Reference data records quantifying properties of sample signals encoded according to experimental sets of encoding parameters are used to define parameters of conjectured analytical functions characterizing the encoding or transcoding functions. The analytical functions are then used to generate granular tables of estimated measures of encoded-signal properties. A fast search mechanism relies on the granular tables, together with sorted arrangements of the granular tables, to determine, in real-time, preferred encoding parameters for multimedia data streams received at an encoder or a transcoder.

Abstract: A packet switch that scales gracefully from a capacity of a fraction of a terabit per second to thousands of terabits per second is disclosed. The packet switch comprises edge nodes interconnected by independent switch units. The switch units are arranged in a matrix having multiple rows and multiple columns and may comprise instantaneous or latent space switches. Each edge node has a channel to a switch unit in each column and a channel from each switch unit in a selected column. A simple path traversing only one of the switch units may be established from each edge node to each other edge node. Where needed, a compound path comprising at most two simple paths may be established for any edge-node pair. In a preferred configuration, the switch units connect at input to orthogonal sets of edge nodes. A distributed control system expedites connection-request processing.

Abstract: A single rotator successively connects a set of access ports to a set of memory devices and a multi-port controller and connects the set of memory devices and the multi-port controller to the set of access ports. The rotator has a set of inlets and a set of outlets and cyclically connects each inlet to each outlet during a rotation cycle. A set of inlet selectors connecting to the inlets of the rotator and a set of outlet selectors connecting to the outlets of the rotator are coordinated to concurrently connect the access ports to the memory devices and to the master controller through the rotator, and concurrently connect the memory devices and the master controller to the access ports. Each memory device connects to an inlet selector and a corresponding transposed outlet selector.

Abstract: An optical spectral-temporal connector, having multiple connector modules, interconnects a large number of nodes in a full-mesh structure. A wavelength-division-multiplexed link from each node is de-multiplexed into wavelength channels individually directed to different connector modules. Each connector module has a set of star couplers, each star coupler connecting to wavelength channels from a respective set of nodes through spectral translators. Each spectral translator cyclically shifts a spectral band of a wavelength channel so that, at any instant of time, spectral bands of signals at inlets of any star coupler are disjoint. A spectral router connects outlets of the set of star couplers to a respective set of nodes. A spectral-translation controller prompts each spectral translator to shift to a new spectral band. Several arrangements for time-aligning all the nodes to the connector modules are disclosed.

Abstract: A spectral-temporal connector interconnects a large number of nodes in a full-mesh structure. Each node connects to the spectral-temporal connector through a dual link. Signals occupying multiple spectral bands carried by a link from a node are de-multiplexed into separate spectral bands individually directed to different connector modules. Each connector module has a set temporal rotators and a set of spectral multiplexers. A temporal rotator cyclically distributes segments of each signal at each inlet of the rotator to each outlet of the rotator. Each spectral multiplexer combines signals occupying different spectral bands at outlets of the set of temporal rotators onto a respective output link. Several arrangements for time-aligning all the nodes to the connector modules are disclosed.

Abstract: Access switches of moderate dimensions are interconnected through central switches of large dimensions to form a large-scale switching system. The central switches are configured as latent switches which scale easily to large dimensions. Each access switch has asymmetric connections to the ingress sides and egress sides of the central switches so that paths from an originating access switch to a destination access switch through the central switches are subject to staggered switching delays permitting an access controller of any access switch to select an available path of minimum switching delay for a given flow. Using access switches of 128 dual ports each and central switches of 4096 dual ports each, a switching system of 524288 dual ports is realized. At a port capacity of 10 Gigabits/second, the access capacity exceeds five petabits per second and the bulk of traffic experiences a switching delay below two microseconds.

Abstract: A latent space switch based on a single rotator and an array of memory devices is disclosed. The switch interfaces with external nodes through a set of access ports. The rotator has a set of inlets and a set of outlets with each inlet connecting to each outlet during a time frame organized into time slots. During each time slot, an inlet alternately connects to an access port and a memory device while a transposed outlet of the inlet alternately connects to the same memory device and another access port. Multiple temporal multiplexers submit upstream control messages from the access ports to a multi-port master controller. Multiple temporal demultiplexers distribute downstream control messages sent from the master controller to the access ports.

Abstract: Independent switches arranged into multiple switch planes interconnect nodes coupled to data sources and sinks to form a switching node which scales gracefully from a capacity of a fraction of a terabit per second to hundreds of terabits per second. The switches of each switch plane are arranged in a matrix. Each node connects to an inlet of a selected switch in each column and an outlet of a selected switch in each row in each switch plane. A route set for each directed node pair includes simple paths, each traversing one switch, and compound paths, each traversing two switches. The connectivity of nodes to switches ensures that each switch may be selected to handle data flow of any directed node pair and that all simple paths leading to any node traverse switches which receive data from mutually orthogonal sets of nodes. This feature equalizes flow rates through the switches.

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 switching system having a number of nodes interfacing with external network elements and interconnected through independent switches is disclosed. The network may serve as a large-scale data center or a geographically distributed network. The nodes are arranged into a number of formations. Within each formation, the nodes are divided into a number of disjoint sets of nodes. The nodes of each set of nodes are interconnected through a respective switch and are selected so that each set of nodes of any formation is orthogonal to each set of nodes of each other formation. With such a structure, each node has a set of routes to each other node, each route of which traversing at most two switches. The switching system may grow in both capacity and coverage without disturbing an already installed configuration. A switching system of an access capacity of multiple petabits/sec and large coverage is thus realizable.

Abstract: Access switches of moderate dimensions are interconnected through central switches of large dimensions to form a large-scale switching system. The central switches are configured as latent switches which scale easily to large dimensions. Each access switch has asymmetric connections to the ingress sides and egress sides of the central switches so that paths from an originating access switch to a destination access switch through the central switches are subject to staggered switching delays permitting an access controller of any access switch to select an available path of minimum switching delay for a given flow. Using access switches of 128 dual ports each and central switches of 4096 dual ports each, a switching system of 524288 dual ports is realized. At a port capacity of 10 Gigabits/second, the access capacity exceeds five petabits per second and the bulk of traffic experiences a switching delay below two microseconds.

Abstract: A switching system formed of a number of nodes interfacing with external network elements and interconnected through a number of independent switches is disclosed. The switches are arranged into a set of primary switches, a set of secondary switches, and a set of tertiary switches and each node connects to a respective primary switch, a respective secondary switch, and a respective tertiary switch. The connection pattern of nodes to switches is selected so that any set of nodes connecting to any primary switch, any set of nodes connecting to any secondary switch, and any set of nodes connecting to any tertiary switch are mutually orthogonal. A distributed control system sets a path from any node to any other node traversing at most two switches. The switching system may serve as a large-scale data-switching center or a geographically distributed network.

Abstract: Methods of optimal encoding of signals to be compatible with characteristics of target receivers while meeting constraints pertinent to sizes of encoded signals or capacities of paths communicating signals to the target receivers are disclosed. The methods are based on analytical modeling of the encoding process guided by experimental data relating measured performance indicators of encoded signals of diverse classifications to respective encoding parameters. A computationally-efficient technique is devised to determine optimal encoding parameters based on pre-processed data derived from the analytical models. The methods may be implemented at an encoder of original signals or a transcoder of pre-encoded signals.

Abstract: A single transposing rotator successively connects a set of access ports to a set of memory devices and the set of memory devices to the set of access ports. A set of inlet selectors connecting to rotator inlets and a set of outlet selectors connecting to rotator outlets are coordinated to concurrently connect the access ports to the memory devices through the rotator, and concurrently connect the memory devices to the access ports. Each memory device connects to an inlet selector and a corresponding peer outlet selector. Multiple temporal multiplexers submit upstream control messages from the access ports to a multi-port master controller. Multiple temporal demultiplexers distribute downstream control messages sent from the master controller to the access ports. Alternatively, the multi-port master controller may connect to selected inlet selectors and corresponding peer outlet selectors for successively receiving upstream control messages and sending downstream control messages.

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: 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.