Nortel Networks Corporation

Northern Telecom Limited

Altera Corporation

Rockstar Consortium US LP

Pts Corporation

Rpx Clearinghouse LLC

Bell-northern Research Ltd.

Nortl Networks Limited

John Gerald Gruber

Alan Frank Graves

Andrew John Bryant

Richard Vickers

Asghar Ebrahim Methiwalla

Jonathan L Bosloy

Hanan Anis

Andre John Van Schyndel

Reza Paiam

Gordon Harney

Frederick J Lalonde

Raza Paiam

Asghar E Methiwalla

Anil Chandan

Gregory P Burdett

An optical intensity control system for use with an optical switch providing individual signal paths between input and output ports. The system has optical splitters connectable to output multiplexers of the switch and has variable optical intensity controllers (VOICs) for insertion into the individual signal paths to individually control the intensity of optical signals present in the signal paths via intensity control signals. An equalizer is connected to the splitters and to the VOICs produces an estimate of the optical power of each individual switched optical signal and generates the intensity control signals. The equalizer is adapted to controllably isolate individual switched optical signals. In this way, individual and independent control of the power on each optical channel is provided.

Optical switch with power equalization

An optical intensity control system for use with an optical switch providing individual signal paths between input and output ports. The system has a optical splitters connectable to output multiplexers of the switch and also has variable optical intensity controllers (VOICs) for insertion into the individual signal paths. The VOICs individually control the intensity of optical signals present in the signal paths in accordance with intensity control signals. An equalizer is connected to the splitters and to the VOICs, for producing an estimate of the optical power of each individual switched optical signal and generating the intensity control signals. The equalizer is adapted to controllably isolate individual switched optical signals. In this way, individual and independent control of the power on each optical channel is provided, wavelength-dependent losses introduced by all the devices in the switch including the WDM devices at the output of the switch are accounted for and one optical coupler is required for each output optical fiber. Coarse equalization may be provided for each multiplexed optical signal either at the switch input or output, permitting a reduction in the dynamic range over which the VOICs inside the switch are required to operate.

A method is provided for seamless migration from a scaleable optical add/drop multiplexer to a network switching node in an optical transport network. The method includes: providing a pre-deployed optical add/drop multiplexer (OADM) at a network node in the optical transport network; introducing an additional optical add/drop multiplexer (OADM) at the network node; and interconnecting the pre-deployed OADM to the additional OADM using a photonic cross-connect switch, where the photonic cross-connect switch is operable to route optical signals amongst the optical transport lines connected to the pre-deployed OADM and the upgraded OADM.

Method of seamless migration from scaleable OADM to a network switching node

A connection verification system that provides substantially non-intrusive connection verification for an optical switch, achieved by correlating the low-frequency contents of the input and switched signals. The results of the correlation process are compared against a connection map to determine whether the switch has operated correctly and to identify, if possible, which mis-connections have taken place. The system includes a selection unit for controllably admitting individual ones of the input signals and individual ones of the switched signals and a verification unit connected to the selection unit, for controlling operation of the selection unit as a function of a connection map and performing relative-delay-dependent signal processing operations on the signals admitted by the selection unit so as to identify connections established through the switching unit and determine their consistency with the connection map. The relative-delay-dependent signal processing operations may be based on correlation or anti-correlation, depending on the operational requirements of the invention.

Connection verification for optical switches

A method is provided for seamless migration from static to agile optical networking at a network switching node in an optical transport network. The seamless method includes: providing an optical signal splitter at the input of thenetwork switching node, the signal splitter being adapted to receive an optical multiplexed signal having a plurality of data signals and at least one data signal being agile; providing an optical signal combiner at the output of the network switching node; and introducing a photonic cross-connect switch between the signal splitter and the signal combiner, where the photonic switch is operable to switch the agile data signals.

Method of seamless migration from static to agile optical networking

A time simulation technique for determining the service availability (or unavailability) of end-to-end network connections (or paths) between source and sink nodes is disclosed. The failure could be either a single failure mode or a multiple failure mode. The time simulation apparatus includes a network representation having pluralities of nodes, links and connections; each plurality having various attributes such as relating to failure, recovery and repair mechanisms. The apparatus further includes a mechanism for selecting one instance from each of the pluralities of nodes, links and connections based on the attributes; a failure/repair module for performing a simulated failure and repair on the selected instances as appropriate; a mechanism for selecting a connection between source and sink nodes; and an arithmetic mechanism for calculating availability of the selected connection.

Time simulation techniques to determine network availability

An optical switch is equipped with a set of optical intensity controllers at its input, each intensity controller being driven to vary a corresponding WDM input traffic signal with a low power test signal. The switch is also equipped with optical splitters at its output and a path integrity analyzer connected to the splitters and to the intensity controllers. The path integrity analyzer generates or controls generation of the test signals applied by the intensity controllers. The path integrity analyzer also receives the tapped portions of the WDM output signals and separates them into their single-carrier components in order to recover a set of switched single-carrier optical signals. The path integrity analyzer is further provided with test signal detectors used to detect the presence of a test signal in each recovered switched single-carrier optical signal. The path integrity analyzer thus ascertains the integrity of the connection involving each switched single-carrier optical signal by comparing detected test signals to expected test signals that are derived from a connection map.

Optical switch with connection verification

A time simulation technique for determining the service availability (or unavailability) of end to and network connections (or paths) between source and sink nodes is disclosed. The method includes skips of (a) selecting a link between two network nodes; (b) performing a simulated link failure on the selected link; (c) sell sting a connection bet two network source and sink nodes; and (d) determining the unavailability and availability of the connection on under the simulated link failure condition. The method further includes (e) of repeating (c) and (a) and (b); and (f) of summoning the unavailability and availability of connections after each repetition until a predetermined number of connections have been selected, and until a simulated link failure has been performed on all links; or until the summed unavailability and availability has been determined to converge, whichever is earlier.

A bridge and roll method for doing an in-service switch (less than 50 ms) from one set of inputs and outputs on a primary photonic switch to another set of inputs and outputs on the same or a secondary photonic switch. The bridge and roll method facilitates maintenance, repairs and upgrades on the primary photonic switch. The bridge and roll method may be reversed in order to restore the original inputs and outputs on the primary photonic switch after maintenance, repairs or upgrades have been performed. The invention also provides a method for consolidating multiple wavelengths or multiple bands into single fibers.

System and method for bridge and roll in a photonic switch

A telecommunications network such as an ATM, Frame Relay or packet based network will be better managed by identifying nodes through which a virtual connection is routed between two end nodes. A new method of tracing the nodes on the route includes sending trace cells downstream of a monitoring node toward one or both end nodes. Each downstream node either loops back a trace cell identifying itself to the monitoring node or forwards the trace cell further. A plurality of trace cells sent along the route identify nodes located thereon. In one embodiment, the trace cell is an extension of the ATM FMOAM cell (ATM Fault Management OAM cell) specified for loopback functions.

Method of tracing the root of virtual connections

Method of tracing the route of virtual connections

In telecommunications involving more than one network, it is important to determine the location of a fault which may occur on a connection so that the responsible network administrator can be identified and appropriate remedial measures can be promptly performed. The invention allows sectionalization of trouble on a connection which spans more than one network administrative domain. It uses NE (near-end), FE (far-end) and Int. (intermediate) monitoring signals specific to separate layered entities associated with the connection.

Method of sectionalizing trouble on telecommunication network connections

Novel techniques are disclosed for continuously monitoring parameters of delay between two nodes in a telecommunication network such as an ATM or frame relay network. The techniques use measurement cells, i.e. test cells, test frames, performance management ATM OAM cells, or performance management frame relay frames. These cells or frames contain a timestamp indicating the time a cell or frame is sent and a delay value indicating a difference between reception and transmission times of the cell or frame. Near-end and far-end as well as unidirectional or bidirectional monitoring can be performed, to support single-ended monitoring.

Growing community of inventors

Orleans, CA, United States of America

John Gerald Gruber