Abstract: A communication network is provided having source and destination switching routers connected by two different communication paths. A primary label switched path is established on one of the communication paths and a secondary label switched path is established on the other label switched path. The source switching router can be enabled to place one or more data flows within the primary label switched path and can be enabled to place one or more of the same data flows within the secondary label switched path. The destination switching router stores a label identifying each data flow and a forwarding instruction and can be enabled to reference data carried within the primary or secondary LSP with the appropriate data flow label.

Abstract: The invention provides a method which involves inserting probe packets on a per service basis for transmission on a respective round trip; and for each service using the probe packets to calculate packet latency for probe packets which is representative of packet latency for all packets transmitted for the service. In some embodiments, data plane time stamps are used to accurately time probe latency. The invention also provides a method which involves inserting probe packets on a per service basis for transmission on a respective destination network element; and at the destination network element for a given service using the probe packets to calculate one way packet loss for the service.

Abstract: A method and system for allocating and controlling a hierarchy of labels in an MPLS network is provided. The hierarchy of labels, inserted into MPLS packets, is introduced so as to correspond to the hierarchy of sub-flows within a data flow. The labels have the established dependency so that positions of labels in the hierarchy identify a sequence of processing the labels and functions associated with the labels. The system for allocating and controlling the hierarchy of MPLS labels includes a first control plane mapper for releasing available labels, a first controller for assigning the released labels according to the hierarchy, means for transmitting the labels in the network, a second controller for detecting the labels, and a second control plane mapper for maintaining current label dependency within the hierarchy. If required, re-addressing of the hierarchy of labels may be performed to maintain flow-sub-flow association throughout two adjacent networks.

Abstract: A variable polarization independent optical power splitter is disclosed. An input light beam “A” is split into two output light beams “M” and “N” where the optical power ratio of the two output light beams “M” and “N” is adjusted to a desired ratio by controlling a variable polarization rotator, e.g. a liquid crystal unit. The polarization components “P” and “S” of the input light beam “A” are separated in a first polarization separator, then processed through the variable polarization rotator, and a second polarization separator. The polarization independence of the power split is thus achieved through the stratagem of processing the “P” and “S” polarized components of the input light beam “A” separately, resulting in four light beams “H”, “I”, “L” and “K”, which are appropriately combined in the polarization combiner to yield the output light beams “M” and “N” having the desired optical power ratio “R”.

Abstract: A monitor for monitoring the operation of a scheduler for controlling the departure of data cells is provided, comprising a detector for detecting the state of an internal element of the scheduler during a test, and determining means for determining whether the scheduler is operating as intended based on the detected state of the internal element.

Abstract: An interposer chip providing translation of data between DASL and Unilink protocols and operating in one of the line card mode or switch card mode is provided. Additionally, it provides compatibility of Unilink ports with EQ switch fabric, sub-port flow control and capability of DASL ports to support individual ports and link parallel ports.

Abstract: A method and apparatus are disclosed for operating an eVOA by modulating its attenuation. If an optical signal power is below a loss of signal (LOS) power threshold the eVOA attenuation is set to a maximum attenuation and then, periodically and quickly decreased and increased in steps while checking for the presence of optical signals above the LOS power threshold. The method is also used for operating a multiplicity of eVOAs while minimizing the risk of damage to optical network equipment.

Abstract: A method for automatic initialization of an optical network is provided. A network management system (NMS) performs remote determination of span losses and sets the operating points of network components. The initialization method comprises remotely and automatically setting target gains of optical amplifiers and signal power levels at transmitters and receivers to required operating values. The methods for initialization of the optical network of the embodiments include gain excursion minimization (GEM) for individual channels passing through amplifiers and/or pre-emphasis of the optical link, where channel powers at the transmitters are biased to compensate for the effects of optical amplifiers gain ripple.

Abstract: Channels in an optical WDM network are each identified by at least two dither tones with which the channel is modulated, the dither tones alternating with a predetermined periodicity so that at any instant each channel is modulated by only one dither tone. The dither tones are continuously generated at precise frequencies. Channel detection by detecting the dither tones, for channels having optical powers over a wide dynamic range, makes use of an FFT process which can detect dither tones for high power channels in a single operation. Coherent averaging of FFT results over time is used to detect dither tones for low power channels over multiple FFT operations.

Abstract: The invention describes a system for distributing a software file from a source to a plurality of targets in such a manner that only portion of the file is received and stored in a file distributor. The file distributor has a flow mediator, which provides data flow control in such a manner that the stored portion of the file is forwarded to the targets asynchronously in order to provide that each target receives the portion of the file at its own rate. A corresponding method for the distribution of software is also provided.

Abstract: A method for the simultaneous graphical display of paths of optical wavelength channels in a telecommunications network together with one or more channel attributes is provided. The graphical display of the network also shows the direction of data flow transported by the channels. An audible or visual alarm for an error condition for a channel attribute on a link in the network can be produced if requires. The operator can also obtain detailed information on a channel by positioning the mouse over a channel.

Abstract: A method for selecting two maximally disjoint shortest paths between a source node and destination node in a network is provided. The method comprises determining a first explicit route between the source and destination nodes by using an original link cost for each link in the network, transforming the network by introducing conditional link costs, determining a second explicit route between the source and destination nodes in the transformed network taking into account the conditional link costs, and determining the two maximally disjoint shortest paths between the source and destination nodes by coalescing the first and second explicit routes. Beneficially, the step of introducing conditional link costs comprises adding additional parameters to links in the network and determining the conditional link costs depending on the position of each link relative to the first explicit route.

Abstract: A method for determining locations and gain settings of optical amplifiers in an optical network is provided. The method comprises evaluating allowable amplifier locations and successively eliminating selected locations until no further locations can be eliminated without the network violating predetermined specifications. This systematic method is applicable to a variety of network topologies and takes into account existing network limitations. In one embodiment, the method for determining the locations and gain settings of the amplifiers uses the amount of operating margin in the network to select locations to be eliminated. In another embodiment, the method is repeated a number of times with different selections of amplifier locations, and the method providing the arrangement with the least number of amplifiers is chosen.

Abstract: A method for determining locations and gain settings of amplifiers in an optical network is provided. The method comprises evaluating allowable amplifier locations, randomly generating sets of amplifier locations from the allowable amplifier locations, and applying genetic operations to the sets of amplifier locations until a predetermined exit condition is satisfied. This systematic method is applicable to a variety of network topologies and takes into account existing network limitations. In one embodiment, the method for determining the locations and gain settings of the amplifiers uses the amount of operating margin in the network to select sets of locations to be eliminated. In another embodiment, the method takes into account and determines the placement of dispersion compensation modules (DCMs), choices of which are provided by DCM placement procedures.

Abstract: A communications network has data and dedicated control network communication links between nodes. The control network is automatically and reliably created by each node determining each of its neighbor nodes to which it has a direct data link, each node having at least two neighbor nodes, and establishing a control network link for communicating control network traffic directly with each of these neighbor nodes. Each control network link can, if a dedicated control network link is not available, use bandwidth of a data link between the respective nodes, a link selection protocol being based on shared risk link groups and available bandwidth.

Abstract: The invention describes methods and systems for monitoring the performance of an optical network by introducing a fiber identification (FID) tag and/or bundle identification (BID) tag which are unique to the fiber section and to the bundle of fibers respectively. The FID tag is introduced by marking an optical signal, traveling through a section of fiber, with a low frequency dither tone whose frequency is unique to the fiber section. Similarly, the BID tag is introduced by marking an optical signal, traveling through a section of fiber in a bundle of fibers, with another low frequency dither tone whose frequency is unique to the bundle section. Detecting of the FID and BID tones either alone or along with an optionally introduced channel identification (CID) tone is provided.

Abstract: The invention provides improved methods and systems for a precise and selective cross-talk cancellation and pilot tones deletion in optical amplifiers. The method for cancellation of cross-talk among multiple channels occurring in a traditional optical amplifier comprises: detecting tones at an input and an output of a Smart Optical Amplifier that includes a traditional optical amplifier and a Cross-talk Cancellation Unit; comparing the detected tones at the input and output of the Smart Optical Amplifier; generating destructive tones with such amplitudes and phases so as to cancel cross-talk; and eradicating cross-talk at the output of the Smart Optical Amplifier by applying the destructive tones in the Cross-talk Cancellation Unit. Eight different embodiments that correspond to different combinations of traditional optical amplifier types and the type of technology (analog or digital) used in processing and control of signals are described.

Abstract: A method of transmitting packets from the source edge router through the label switch router to the destination edge router, comprising the steps of: assigning different protocol type indicators at the source edge router to user MPLS packets and to non-user MPLS packets of at least one additional protocol type; at the label switch router, forwarding MPLS packets received from the source edge router or another label switch router in such a manner as to preserve the protocol type indicator of the packet transport protocol of each received MPLS packet; at the destination edge router, recognizing the protocol type indicator of the transport protocol of the MPLS packets received from the label switch router, and segregating the user MPLS packets from non-user MPLS packets. Preferably, user and non-user MPLS packets are assigned the same MPLS label and sent via the same label switched path. Corresponding enhanced MPLS network is also provided.

Abstract: A method and system for automatic allocation of port addresses in a network is provided. The node performs a self-discovery after initial power-up, and for each port on the node, using unique values associated with the port in the network hierarchy, applies a function that allows for an inverse function to the set of values to generate a default unique address for the port. A typical hierarchical structure in a network is the network area, node, and, within the node, the shelf, the card and the port. Next, the node sends a frame including the default port address and node identifier, from the port to a connected node. The node polls the port for a frame with network information associated with the connected port on the other node.

Abstract: A system and method for operating a plurality of eVOAs in an optical network is provided. The system comprises a number of eVOAs, each eVOA coupled to one or more optical taps and connected to a microcontroller. The microcontroller comprises a monitor signal processing controller for measuring the power of the optical signal at the eVOAs; a scheduler for continuously cycling and checking the eVOAs operating attenuations; a microprocessing controller for determining, setting, adjusting and updating the eVOA operating attenuation and a means for communications between the microprocessor and the other controller within the system. The microcontroller cycles through the plurality of eVOAs and controls one eVOA at a time according to a predetermined method of the eVOA operation. Individual eVOAs may be controlled according to the same or different methods of controlling operations thereof as required.