An information processing apparatus, includes: a memory that stores a wavelength defragmentation program; and a processor that performs, based on the wavelength defragmentation program, operations of: selecting an optical line according to a specific sequence in design information to allocate optical lines for respective optical wavelengths within a network; moving a selected optical line to a move-to optical wavelength; stopping, when movement of the selected optical line to the move-to optical wavelength is difficult, a selection of the optical line according to the specific sequence; and selecting a new optical line from optical lines indicated in a priority list.

Provided are wavelength switching and configuration methods and devices for a Passive Optical Network (PON). The switching method includes the following operations. An Optical Network Unit (ONU) responds to a ranging request message sent by an Optical Line Terminal (OLT) on a first uplink wavelength supported by the ONU. The ONU receives ranging information sent by the OLT. The ONU uses the received ranging information as ranging information about a second uplink wavelength of the ONU, and performs data transmission on the second uplink wavelength according to a bandwidth allocation from the OLT. A path transmission time difference caused by a wavelength interval between the first uplink wavelength and the second uplink wavelength is less than a corresponding fault tolerance range when the OLT receives data. The ranging information is obtained by the OLT according to a ranging response sent by the ONU on the first uplink wavelength.

A method for determining a path in an optical network, implemented by one or more controllers associated with a control layer, includes receiving a path request specifying start and end points, an associated bandwidth, and a longevity parameter providing an anticipated length during which the path is required; determining a route in the optical network through a routing algorithm executed by the controller, wherein the routing algorithm utilizes the start and end points, the associated bandwidth, and the longevity parameter to determine the path; and provisioning the path through a plurality of switches along the route.

A system for performing failover switches in an optical network, such as a time and wavelength division passive optical networks (TWDM PON) like NG-PON2, includes a backup optical line terminal (OLT) for backing up communications of a primary OLT. The backup OLT is configured to allocate small upstream time slots, referred to herein as “de minimis” time slots, to at least one optical network terminal (ONT) communicating with the primary OLT during normal operation. When a failure occurs that prevents communication between the ONT and the primary OLT, the ONT autonomously tunes to the upstream and downstream wavelength pairs of the backup OLT and begins to transmit data to the backup OLT in the de minimis time slot allocated to it. The presence of data in the de minimis time slot indicates the occurrence of a failover switch to the backup OLT, and the backup OLT then begins to allocate time slots to this ONT, which is normally serviced by the primary OLT according to its normal TDM algorithm.

The invention relates to a method for establishing a communication channel, preferably an embedded control channel, between a central network node and at least one network unit to be integrated in a communication network including the central network node and an arbitrary but limited number of network units. The central network node is adapted to create and output a wavelength-division multiplex (WDM) downstream signal including downstream channel signals to be transmitted to the network units and to receive a WDM upstream signal including upstream channel signals created by the network units.

Slots (311) for transmission of data of a particular transmission type over an optical network are allocated by selecting a first available slot (313_2) at an ordinal position corresponding to a multiple of n and allocating the selected first available slot and the next n−1 consecutive slots (313_4, 313_5) from the selected first available slot (313_3), if all n−1 consecutive slots (313_4, 313_5) are available, for transmission of data of the particular transmission type. The data is transmitted over an optical network comprising a plurality of nodes (305, 327) interconnected by optical sections (301, 309, 329, 331) the nodes (305, 327) supporting a plurality of transmission types, wherein transmission of data of the particular transmission type requires a predetermined number n of consecutive slots. Alternatively the slots may be divided in groups (333, 335, 337) and slots are allocated to a group in which all slots are available.

An optical filter system, preferably including an optical input, one or more sets of filters, and/or a control module. A method for optical filter operation, preferably including operating an optical filter system in a normal mode, assessing filter alignment, and/or shifting filter assignments.

This optical path setting device comprises: a transmission characteristic calculating means for calculating an inter-endpoint transmission characteristic that is a characteristic for transmission between endpoints of an optical path accommodating traffic in a plurality of optical communication systems; a required wavelength bandwidth determining means for determining a required wavelength bandwidth that is a wavelength bandwidth meeting an arrival performance of the optical path on the basis of the inter-endpoint transmission characteristic; and an accommodating wavelength band determining means for determining, as an accommodating wavelength band for accommodating the optical path, a common wavelength band that is a wavelength band where an optical path having the required wavelength bandwidth can be allocated, and that is common to the plurality of optical communication systems.

Wavelength-based random access in an optical communications network for a wireless communications system (WCS) is disclosed. An optical network unit(s) (ONU(s)) is configured to generate a random access signal comprising an unsolicited buffer occupancy (BO) report to request uplink allocation as soon as the ONU(s) receives a non-periodic uplink data burst. The ONU(s) then sends an optical random access signal including the unsolicited BO report to an optical line terminator (OLT) based on a random access wavelength, which is so determined not to cause any interference with a downlink optical communications signal(s) and an uplink optical communications signal(s) being regularly communicated between the OLT and the ONU(s). As a result, it is possible to reduce access delay at the ONU(s) for sending the non-periodic uplink data burst without requiring frequent polling from the OLT, thus helping to reduce signaling overhead and improve throughput of the optical communications network.

If wavelength defragmentation is performed during the operation of an optical network, an instantaneous interruption of a network arises; consequently, data are lost; therefore, an optical network control method according to an exemplary aspect of the present invention includes monitoring a data volume of a client signal to be transmitted using a plurality of optical subcarriers; and performing synchronously, depending on a variation in the data volume, an optical subcarrier changing process of changing an active optical subcarrier, of the plurality of optical subcarriers, to be used for transmitting the client signal, and a remapping process of remapping the client signal onto an active optical subcarrier after having been changed.