Sycamore Networks, Inc.

Enterasys Networks, Inc.

Gridco Inc.

Cabletron Systems, Inc.

Naimish Patel

Richard A Barry

Anna Charny

Pattabhiraman Krishna

Robert J Simcoe

Paolo L Narvaez

Anthony Chi-Kong Kam

Eric Arthur Swanson

James M Simonelli

Jianying Zhou

Scott D Downer

William R Sears

Murat Azizoglu

Tao Yang

Jia Wu

Raymond Yinggang Xie

Kayi Lee

Farzana I Khatri

Marc Robidas

Anthony C K Kam

Joseph Zahavi

A modular, scalable, multi-function, power quality system provides a modular and scalable power conditioning system for utility networks. A configurable frame is coupled to an electrical input and an electrical output. A plurality of functional slots each including a receiving connector are coupled to the frame. One or more unique function subsystems are coupled to selected functional slots. Each unique function subsystem includes one or more electrical components coupled to the receiving connector of selected functional slots configured to define functional capability associated with the one or more functional slots. A plurality of identical power modules are disposed in selected functional slots of each of the one or more unique function subsystems. A controller coupled to each of the power modules is configured to enable the power modules in predetermined functional slots of the one or more unique subsystems to perform a predetermined function associated with the electrical input or the electrical output.

Modular, scalable, multi-function, power quality system for utility networks

A switching and control arrangement are provided along with a transformer arrangement such that semiconductor-based switches can be used in a medium DC voltage to AC inverter in a medium voltage to low voltage DC to DC converter. The switching arrangement on the secondary side of the transformer arrangement controls a current ramp up or down of switches on the primary side of the transformer that are used to convert DC to AC, thereby permitting for soft switching of those switches.

Apparatus and method for soft switching in a medium voltage to low voltage converter

Each span of a communication network, such as a BLSR ring, is assigned a unique span ID. When a node of the network detects a failure in a network span, the node exchanges commands, according to an automatic protection switching (APS) protocol, that request other nodes of the network to switch network traffic from a working span to a protect span. The commands specify the working span by its span ID, without necessarily specifying a source node ID or a destination node ID for the commands. The span ID occupies fewer bits in the commands than bits representing a combination of the source node ID and the destination node ID. Alternatively, the commands specify a destination node ID without a span ID or a source node ID, or the commands specify a source node ID without a span ID or a destination node ID.

Network span protection using span identifiers

A system is described where delay and bandwidth guarantees are implemented with a crossbar switch. A rate controller is provided as a front-end to a crossbar switch with an arbiter running a work-conserving arbitration algorithm. The system provides bandwidth and delay guarantees to all properly behaving flows independently of improperly behaving flows.

Method and apparatus for providing bandwidth and delay guarantees in combined input-output buffered crossbar switches that implement work-conserving arbitration algorithms

Indicia are provided to a client of Out-of-Frame errors and message bit parity errors that occur during the transmission of a message through a network, wherein the message includes the client data multiplexed with other data and formatted into a message that includes a plurality of transport overhead bytes. The transport overhead bytes of the multiplexed can include both defined bytes and undefined bytes. Predetermined bytes in the transport overhead may be used to store indicia of errors that are detected during the message transmission. These predetermined bytes are read by the client at the egress of the network. The transport overhead may contain both a section overhead portion and a line overhead portion and the predetermined bytes may be encoded in either a subset of the section or line overhead bytes. In addition, the indicia of errors may be encoded in an undefined portion of the section or line overhead. Alternatively, a portion of the section or line overhead that is defined may be redefined and used to store the encoded error indicia

Method for transparent multiplexing of SONET/ SDH streams

A method and apparatus are disclosed for spreading the component signals of a groomed input circuit through a three-stage CLOS switch network. The spreading algorithm includes sequentially evaluating each midstage switching module as to the availability of a connection between an assigned source switching module and an assigned destination switching module having sufficient spare bandwidth to accommodate one or more of the component signals. A load sharing algorithm can be used to spread the component signals among the midstage switching stages. In this way the available bandwidth of each of the midstage switching modules is evaluated for each of the component signals and each component signal is routed through the midstage switching module having the largest available bandwidth.

Traffic spreading to reduce blocking in a groomed CLOS communication switch

In a network having a trace capability, a method to track the connectivity of the network uses the trace messages. A network manager creates a list of ports in the network and uses that list to track the connectivity. For each port, the manager first checks whether there is a current connection and if it finds one, records the connection. For the unconnected ports, the manager enables the transmission of a trace message that identifies the transmitting port. When a trace detected message is received from a port, the network manager updates the list of ports with the connection just reported and disables the trace message that was detected. A port sending a trace message that is not detected is marked as not connected in the list. The method is useful in high bandwidth circuit-based networks, such as optical networks, composed of links of many types and utilizing differing protocols.

Method for port connectivity discovery in transparent high bandwidth networks

A switching method and apparatus operates as a work conserving network device. An arbiter using an arbitration algorithm controls a switch fabric interconnecting input ports and output ports. To switch cells, a virtual output queue of an input port is selected that corresponds to an output port with a lowest occupancy rating and a request is sent to this output port. In a greedy version of the algorithm, input ports may send requests to the lowest occupied output port for which they have a cell. In a non-greedy version, requests may only be sent if that input port has a cell for the lowest occupied output port in the entire network device. An output port that receives one or more requests from input ports uses an input port selection algorithm to select an input port from which to receive a packet. After as many input and output ports are matched as is possible in a phase, the packets for those matched ports are transferred across the switch. The switch fabric operates with a speedup of only twice that of the input port data rates and is still work conserving.

Method and apparatus for providing work-conserving properties in a non-blocking switch with limited speedup independent of switch size

A method is provided for optical filter card design that facilitates a relatively efficient filter assignment algorithm solution resulting in a filter design that reduces a probability of unnecessary wavelength regenerations.

Method for designing optical filter cards

A network including a control channel source node and a plurality of control channel destination nodes is interconnected by communications media in the form of a ring. The control and control channel destination nodes transfer information over a plurality of channels using wavelength-division multiplex techniques. The control channel source node transmits control information to all of the control channel destination nodes over a unitary control channel, and each of the control channel destination nodes drains off a portion of the energy of the signal comprising the control channel to facilitate decoding and processing of the control information contained therein. Each of the aspects, the control channel destination nodes can also generate status information for transfer to the control channel source node over the control channel. The control channel source node drains off the energy of the signal comprising the control channel to facilitate decoding and processing of the status information contained therein.

System and method providing control channel for wavelength-division multiplexed network

A wavelength-division multiplexed (WDM) system includes an optical communications link with one or more optical amplifiers cascaded from an input end to an output end. Each amplifier has a predetermined optical gain throughout a pass band, and passes optical signals in the pass band along the link. Transmitting optical communications equipment is coupled to the input end of the link and provides a WDM optical communications signal to the link. The WDM optical signal includes a number of spaced-apart optical signals, including data optical signals and at least one management optical signal, that reside in the pass band of the optical amplifiers. Receiving optical communications equipment coupled to the output end of the link receives the WDM optical communications signal, separates the management optical signal from the data optical signals, recovers management information from the separated management optical signal, and uses the recovered management information to carry out management functions. In one case, the management optical signal resides at an edge of the pass band of the optical amplifiers, for example at nm or nm in a system having optical amplifiers specified to operate from to nm.

Optical management channel for wavelength division multiplexed systems

A wavelength division multiplexed (WDM) optical communications network is configured and operated to enable transmitter output power for a given wavelength channel to be adjusted to achieve a desired optical signal-to-noise ratio (OSNR) for the channel independently of the power levels of other optical signals carried on the same path. Optical amplifiers in the optical links extending between the transmitter and an optical receiver are configured to operate with constant gain over a specified range of input optical signal power, and the links are configured such that the power level of the signal provided to each optical amplifier is within the specified range of input signal power to prevent the deep saturation of the optical amplifiers due to optical amplifier cascading. When a channel is being added or adjusted, the OSNR of the optical communications signal received by the receiver is measured, and the power of the signal transmitted by the transmitter is adjusted to attain a desired OSNR at the receiver. Due to the constant-gain operation and input power control of the optical amplifiers, the OSNRs of other signals carried on the path are not affected, so that it is unnecessary to adjust the output power of other transmitters providing signals to the path.

Optical power balancer for optical amplified WDM networks

An arbitration scheme for providing deterministic bandwidth and delay guarantees in an input-buffered crossbar switch with speedup S is presented. Within the framework of a crossbar architecture having a plurality of input channels and output channels, the arbitration scheme determines the sequence of fixed-size packet (or cell) transmissions between the inputs channels and outputs channels satisfying the constraint that only one cell can leave an input channel and enter an output channel per phase in such a way that the arbitration delay is bounded for each cell awaiting transmission at the input channel. If the fixed-sized packets result from fragmentation of variable size packets, the scheduling and arbitration scheme determines deterministic delay guarantees to the initial variable size packets (re-assembled at the output channel) as well.

Growing community of inventors

North Andover, MA, United States of America

Naimish Patel