Naimish S Patel, 5041 Phillips St, Boston, MA 02114

6400479, Jun 4, 2002

Dec 20, 1999

09/467607

Jianying Zhou - Acton MA
Richard A. Barry - Brookline MA
Naimish Patel - North Andover MA

Sycamore Networks, Inc. - Chelmsford MA

H04B 1000

359134, 359161, 359166, 359177, 359187

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.

6433903, Aug 13, 2002

Dec 29, 1999

09/475298

Richard A. Barry - Brookline MA
Naimish Patel - North Andover MA

Sycamore Networks, Inc. - Chelmsford MA

H04J 1402

359124, 359127

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.

6549312, Apr 15, 2003

May 9, 2001

09/852428

Paolo Narvaez - Mountain View CA
Naimish Patel - North Andover MA
Farzana I. Khatri - Andover MA
Murat Azizoglu - Concord MA
Kayi Lee - Cambridge MA

Sycamore Networks, Inc. - Chelmsford MA

H04J 1402

359124, 385 24

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.

6563837, May 13, 2003

Feb 10, 1998

09/021245

Pattabhiraman Krishna - Marlboro MA
Naimish S. Patel - North Andover MA
Anna Charny - Sudbury MA
Robert J. Simcoe - Westboro MA

Enterasys Networks, Inc. - Rochester NH

H04L 1256

370413, 370415, 370417

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.

6681248, Jan 20, 2004

Apr 12, 2000

09/547944

William Sears - Lexington MA
Joseph Zahavi - Westford MA
Naimish Patel - North Andover MA

Sycamore Networks, Inc. - Chelmsford MA

G06F 15173

709223, 370254

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.

6754208, Jun 22, 2004

Aug 1, 2001

09/920434

Anthony Chi-Kong Kam - Cambridge MA
Naimish Patel - North Andover MA

Sycamore Networks, Inc. - Chelmsford MA

H04Q 100

370388, 370386, 370369, 340 26

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.

6839871, Jan 4, 2005

Feb 8, 2001

09/779190

Naimish Patel - North Andover MA, US
Richard A. Barry - Brookline MA, US
Paolo Narvaez - Mountain View CA, US
Anthony Chi-Kong Kam - Cambridge MA, US

Sycamore Networks, Inc. - Chelmsford MA

G06F 1100

714707, 714747, 714800

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.

6865154, Mar 8, 2005

Feb 25, 1999

09/257725

Anna Charny - Sudbury MA, US
Pattabhiraman Krishna - Marlboro MA, US
Naimish Patel - North Andover MA, US

Enterasys Networks, Inc. - Andover MA

H04L012/26
H04L012/16

370235, 370229, 370230, 3702301, 709230, 709231, 709232

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.