Abstract: Switching architectures for WDM mesh and ring network nodes are presented. In mesh networks, the switching architectures have multiple levels—a network level having wavelength routers for add, drop and pass-through functions, an intermediate level having device units which handle add and drop signals, and a local level having port units for receiving signals dropped from the network and transmitting signals to be added to the network. The intermediate level device units are selected and arranged for performance and cost considerations. The multilevel architecture also permits the design of reconfigurable optical add/drop multiplexers for ring network nodes, the easy expansion of ring networks into mesh networks, and the accommodation of protection mechanisms in ring networks.

Abstract: In an optical communication network that includes a plurality of interconnected network nodes, a method includes storing in each network node, and for each communication channel that traverses the node, one or more impairment margins of respective impairments that affect the communication channel. A potential communication channel that traverses a subset of the nodes in the network is identified. A quality of the potential communication channel is evaluated by processing the impairment margins stored in the nodes in the subset.

Abstract: In an optical communication network that includes a plurality of interconnected network nodes, a method includes storing in each network node, and for each communication channel that traverses the node, one or more impairment margins of respective impairments that affect the communication channel. A potential communication channel that traverses a subset of the nodes in the network is identified. A quality of the potential communication channel is evaluated by processing the impairment margins stored in the nodes in the subset.

Abstract: Switching architectures for WDM mesh and ring network nodes are presented. In mesh networks, the switching architectures have multiple levels—a network level having wavelength routers for add, drop and pass-through functions, an intermediate level having device units which handle add and drop signals, and a local level having port units for receiving signals dropped from the network and transmitting signals to be added to the network. The intermediate level device units are selected and arranged for performance and cost considerations. The multilevel architecture also permits the design of reconfigurable optical add/drop multiplexers for ring network nodes, the easy expansion of ring networks into mesh networks, and the accommodation of protection mechanisms in ring networks.

Abstract: In an optical communication network that includes a plurality of interconnected network nodes, a method includes storing in each network node one or more cross-talk margins of respective communication channels that traverse the node. A potential communication channel that traverses a subset of the nodes in the network is identified. A quality of the potential communication channel is evaluated by processing the cross-talk margins stored in the nodes in the subset.

Abstract: Switching architectures for WDM mesh and ring network nodes are presented. In mesh networks, the switching architectures have multiple levels—a network level having wavelength routers for add, drop and pass-through functions, an intermediate level having device units which handle add and drop signals, and a local level having port units for receiving signals dropped from the network and transmitting signals to be added to the network. The intermediate level device units are selected and arranged for performance and cost considerations. The multilevel architecture also permits the design of reconfigurable optical add/drop multiplexers for ring network nodes, the easy expansion of ring networks into mesh networks, and the accommodation of protection mechanisms in ring networks.

Abstract: An optical add/drop module of a reconfigurable optical add/drop multiplexer node includes a first set of optical switches configured to receive respective first optical signals, at respective channel receive ports, to be added to a first wave division multiplexed optical signal and to direct the first optical signals to, in a first state, at least one fully functional transmit degree port, and in a second state, to at least one partially functional transmit degree port; and a second set of optical switches configured to receive respective second optical signals to be dropped from a second wave division multiplexed signal via, in a first state, a fully functional receive degree port, and in a second state, via a partially functional receive degree port, and to direct the second optical signals to respective channel transmit ports. An auxiliary device can be used to make the partially functional ports fully functional.

Abstract: An apparatus includes a first optical switching complex, a second optical switching complex in optical communication with the first optical switching complex, and an optical add/drop module in optical communication with the first optical switching complex and the second optical switching complex. At least one of the optical switching complexes includes a wavelength selective switch that is configured to be arranged in a cascaded configuration that, when so configured, results in an increase in a number of available transmit and receive ports available per degree of the apparatus.

Abstract: Switching architectures for WDM mesh and ring network nodes are presented. In mesh networks, the switching architectures have multiple levels—a network level having wavelength routers for add, drop and pass-through functions, an intermediate level having device units which handle add and drop signals, and a local level having port units for receiving signals dropped from the network and transmitting signals to be added to the network. The intermediate level device units are selected and arranged for performance and cost considerations. The multilevel architecture also permits the design of reconfigurable optical add/drop multiplexers for ring network nodes, the easy expansion of ring networks into mesh networks, and the accommodation of protection mechanisms in ring networks.

Abstract: Various example embodiments are disclosed. According to an example embodiment, a method may include determining that a transmission of a data signal over a path of a wavelength division multiplexed (WDM) optical network using a group of optical subcarriers is not optically feasible; determining that the transmission of the data signal over the path using a subset of the group of optical subcarriers is optically feasible; activating subcarriers for the subset of optical carriers while deactivating one or more optical subcarriers of the group, at least one deactivated subcarrier provided between at least two activated subcarriers of the group; and transmitting the data signal over at least a portion of the path using the activated subcarriers of the group.

Abstract: Techniques and a control architecture (apparatus and logic) are provided for an adaptive hybrid DWDM-aware computation scheme. The architecture is one that is a hybrid of a centralized control scheme and a distributed control scheme that performs adaptive physical impairment computations for an optical network. A central control server is connected to multiple client control devices each of which resides in a node in a dense wavelength division multiplexed (DWDM) optical network, wherein each client control device is part of an optical control plane associated with the optical network. The control server obtains data for path route analysis from the client control devices.

Abstract: Switching architectures for WDM mesh and ring network nodes are presented. In mesh networks, the switching architectures have multiple levels—a network level having wavelength routers for add, drop and pass-through functions, an intermediate level having device units which handle add and drop signals, and a local level having port units for receiving signals dropped from the network and transmitting signals to be added to the network. The intermediate level device units are selected and arranged for performance and cost considerations. The multilevel architecture also permits the design of reconfigurable optical add/drop multiplexers for ring network nodes, the easy expansion of ring networks into mesh networks, and the accommodation of protection mechanisms in ring networks.

Abstract: In one embodiment, techniques provide a mechanism for tracking wavelengths in a DWDM network. In particular, embodiments of the present invention also provide for connection tracking using a slowly modulated pilot tone in a DWDM network without dedicated hardware for the generation and the diction of the tone.

Abstract: Various example embodiments are disclosed. According to an example embodiment, a method may include determining that a transmission of a data signal over a path of a wavelength division multiplexed (WDM) optical network using a group of optical subcarriers is not optically feasible; determining that the transmission of the data signal over the path using a subset of the group of optical subcarriers is optically feasible; activating subcarriers for the subset of optical carriers while deactivating one or more optical subcarriers of the group, at least one deactivated subcarrier provided between at least two activated subcarriers of the group; and transmitting the data signal over at least a portion of the path using the activated subcarriers of the group.

Abstract: Switching architectures for WDM mesh and ring network nodes are presented. In mesh networks, the switching architectures have multiple levels—a network level having wavelength routers for add, drop and pass-through functions, an intermediate level having device units which handle add and drop signals, and a local level having port units for receiving signals dropped from the network and transmitting signals to be added to the network. The intermediate level device units are selected and arranged for performance and cost considerations. The multilevel architecture also permits the design of reconfigurable optical add/drop multiplexers for ring network nodes, the easy expansion of ring networks into mesh networks, and the accommodation of protection mechanisms in ring networks.

Abstract: Techniques and a control architecture (apparatus and logic) are provided for an adaptive hybrid DWDM-aware computation scheme. The architecture is one that is a hybrid of a centralized control scheme and a distributed control scheme that performs adaptive physical impairment computations for an optical network. A central control server is connected to multiple client control devices each of which resides in a node in a dense wavelength division multiplexed (DWDM) optical network, wherein each client control device is part of an optical control plane associated with the optical network. The control server obtains data for path route analysis from the client control devices.

Abstract: In an optical communication network that includes a plurality of interconnected network nodes, a method includes storing in each network node one or more cross-talk margins of respective communication channels that traverse the node. A potential communication channel that traverses a subset of the nodes in the network is identified. A quality of the potential communication channel is evaluated by processing the cross-talk margins stored in the nodes in the subset.

Abstract: In an optical communication network that includes a plurality of interconnected network nodes, a method includes storing in each network node, and for each communication channel that traverses the node, one or more impairment margins of respective impairments that affect the communication channel. A potential communication channel that traverses a subset of the nodes in the network is identified. A quality of the potential communication channel is evaluated by processing the impairment margins stored in the nodes in the subset.

Abstract: An economic way of determining the chromatic dispersion along a link of a DWDM network is provided. A transmitter modulates the output signals of two lasers operating at two different wavelengths and the modulated output signals are sent into the link. Detectors at each one of a plurality of detection sites along the link determine a phase difference in modulation between the output signals of the two lasers. The chromatic dispersion for each detection site can be calculated from the modulation frequency and determined phase differences at that site.

Abstract: In one embodiment, first optical signal can be generated at a first end of an optical fiber segment at a first time. The first optical signal can be detected at a second end of the optical fiber segment at a second time. A second optical signal can be generated at a second end of the optical fiber segment at a third time in response to the detection of the first optical signal. The second optical signal can be detected at the first end of the optical fiber segment at a fourth time. A length of the optical fiber segment can be determined based on a difference between the second time and the first time, a difference between the third time and the second time, and a difference between the fourth time and the third time.