Systems and methods include, responsive to a request for capacity change of X channels, X is an integer>1, on an optical section and at an Optical Add/Drop Multiplexer (OADM) node in an optical network, dividing optical spectrum on the optical section into M slots, M is an integer>1, such that the capacity change of X channels takes a maximum of N steps, N is an integer>1; and performing the capacity change of X channels in up to the N steps in an interleaved manner that changes a subset of the X channels in each of the N steps. For each step, the performing can include a maximum of M/N slots of the M slots with spacing between each of the M/N slots not used for the capacity change in a corresponding step. The spacing can be f, (N+f), (2N+f), . . . , M over the optical spectrum, where f is each step, f=1, 2, . . . , N.

An optical network including a plurality of gateway nodes interconnected with a plurality of intermediate nodes with segments of fiber. The network includes a plurality of devices, such as reconfigurable optical add drop multiplexers, optimally placed at various nodes throughout the network. The device placement is optimized with an integer linear programming analysis considering span definition such that any given span involves some number of segments not exceeding a number of segments that would require wavelength regeneration, cost of placement of a device at a given node, cost of wavelength regeneration, and various parameters and constraints.

An optical network including a plurality of gateway nodes interconnected with a plurality of intermediate nodes with segments of fiber. The network includes a plurality of devices, such as reconfigurable optical add drop multiplexers, optimally placed at various nodes throughout the network. The device placement is optimized with an integer linear programming analysis considering span definition such that any given span involves some number of segments not exceeding a number of segments that would require wavelength regeneration, cost of placement of a device at a given node, cost of wavelength regeneration, and various parameters and constraints.

An optical communications network comprises optical data links interconnected by add-drop nodes, the optical data links comprising data channels. The data channels are allocated into equal-sized bins. In response to a first data channel request between a given source-destination pair, one of the equal-sized bins is assigned to the data channel request. In response to requests for additional bandwidth for the same source-destination data channel request, unused channels within the assigned equal-sized bin are allocated to the data channel request. In response to subsequent data channel requests between different source-destination pairs, additional unallocated equal-sized bins are assigned to the subsequent data channel requests. In response to subsequent data channel requests when resource sharing for one equal-sized bin, data channels in the last equal-sized bin are assigned using the reverse channel assignment process. Reverse channel assignment can also be used for other bins as an option.

Embodiments of the present invention provide a method and an apparatus for increasing and decreasing variable optical channel bandwidth. The method for increasing includes: sending a higher order optical channel data unit (HO ODU) frame to which a timeslot increase indication is added to a second NE; starting from a next HO ODU frame, mapping, by an NE, a bit stream formed by a flexible optical transport data unit (ODUflex) bit stream at a first rate and an idle data bit stream to Y timeslots of the HO ODU frame; sending an ODUflex frame to which a rate increase indication is added to the second NE; and starting from a next ODUflex frame, mapping an ODUflex bit stream at a second rate to the Y timeslots of the HO ODU frame.

It is difficult to improve the wavelength-band utilization rate of an optical network as a whole while operating the optical network stably; and therefore, an optical network controller according to an exemplary aspect of the present invention includes optical wavelength region setting means for setting a wavelength region in an optical transmission line between a plurality of optical nodes composing an optical network using wavelength division multiplexing system dividing the wavelength region into consecutive regions of a first wavelength region and a second wavelength region; optical path setting means for setting a first optical path in the first wavelength region and a second optical path in the second wavelength region, the second optical path differing from the first optical path in a route; and control unit for instructing the plurality of optical nodes on a central wavelength and a usable band of signal light for the optical node to transmit based on a setting by the optical path setting means.

There is provided a tray which is connected to a plurality of transmitters that multicarrier-transmit a plurality of parallel signals by optical subcarriers. The framer selects time slots to be allocated to a path to be accommodated such that the number of optical subcarriers corresponding to the time slots satisfies a predetermined condition on the basis of empty time slots which are specified by path accommodation information indicating a correspondence between paths allocated to a client signal and time slots in a signal frame and the optical subcarriers corresponding to the empty time slots indicated by time slot information indicating a correspondence between the time slots and the optical subcarriers, and sets the selected time slot in the path accommodation information. The framer sets a client signal to the time slots on the basis of the path accommodation information.

Methods and systems for determining optical network utilization efficiency include generating a random demand set and calculating a demand fill ratio (DFR) based on the random demand set. The random demand set includes network demands for a given optical network topology that provide 100% of the wavelength slots in the optical network topology. The DFR may be calculated using different wavelength assignment algorithms, such as a first fit wavelength assignment algorithm, from the randomly generated demands in the random demand set. The DFR may be calculated without and with wavelength conversion nodes.

An optical network including a plurality of gateway nodes interconnected with a plurality of intermediate nodes with segments of fiber. The network includes a plurality of devices, such as reconfigurable optical add drop multiplexers, optimally placed at various nodes throughout the network. The device placement is optimized with an integer linear programming analysis considering span definition such that any given span involves some number of segments not exceeding a number of segments that would require wavelength regeneration, cost of placement of a device at a given node, cost of wavelength regeneration, and various parameters and constraints.

A network design device includes a processor. The processor determines a second wavelength allocation based on a first wavelength allocation that indicates a wavelength allocation for a plurality of optical lines established in a wavelength division multiplexing optical network. The processor searches for a disconnection target optical line that is requested to be disconnected in order to realize a transition from the first wavelength allocation to the second wavelength allocation from among the plurality of optical lines. The processor generates procedure information that indicates a procedure of the transition from the first wavelength allocation to the second wavelength allocation based on a difference between the first wavelength allocation and the second wavelength allocation and a searched disconnection target optical line.