Abstract: A method for managing a telecommunication network comprising the steps of identification, by the central controller, of an updated condition of availability of resources of the network, and association of a plurality of updated sequences of instructions, comparison of the plurality of updated sequences of instructions with a plurality of not updated sequences of instructions associated with the last condition of availability. In case that the plurality of updated sequences of instructions is different from the plurality of not updated sequences of instructions, a step is provided of sending an updated sequence of instructions to each nodal device, on the basis of the service class of the data traffic of the device. A step is furthermore provided of checking, by the local controller, a condition of service of the data traffic at time ranges ?, said updated sequence of instructions associating to each condition of service an optimal working status to be attributed to the data traffic.

Abstract: A method for managing a telecommunication network comprising the steps of identification, by the central controller, of an updated condition of availability of resources of the network, and association of a plurality of updated sequences of instructions, comparison of the plurality of updated sequences of instructions with a plurality of not updated sequences of instructions associated with the last condition of availability. In case that the plurality of updated sequences of instructions is different from the plurality of not updated sequences of instructions, a step is provided of sending an updated sequence of instructions to each nodal device, on the basis of the service class of the data traffic of the device. A step is furthermore provided of checking, by the local controller, a condition of service of the data traffic at time ranges ?, said updated sequence of instructions associating to each condition of service an optimal working status to be attributed to the data traffic.

Abstract: 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.

Abstract: Traffic recovery is supported at a switching node (20) of an OpenFlow network (5). The switching node (20) has a flow table (23) for storing flow entries (24) which determine forwarding of received packets between the ports. A switching node (20) installs (102) a flow entry for a back up path in the flow table (23). The switching node (20) renews (104, 105) the flow entry for the backup path based on at least one of: (i) an association between the flow entry for the backup path and a flow entry for a working path at the switching node, wherein the flow entry for the backup path is renewed when the flow entry for the working path is used to forward a received packet; (ii) receiving a flow entry renewal packet from another switching node on the backup path. A backup path can be configured for each of multiple points of failure in the working path.

Abstract: A method of changing the spectral position of a lightpath between a source node and a destination node of an optical network. The optical network uses a flexible grid for spectral allocation and the lightpath has been allocated first spectral resources at a first spectral position. The method comprises, at the source node, reserving additional spectral resources for the lightpath which are contiguous in frequency with the first spectral resources. The method comprises re-tuning a light source at the source node such that the lightpath moves in frequency from using the first spectral resources at the first spectral position to using second spectral resources at a second spectral position, wherein the second spectral resources comprise at least some of the additional spectral resources. The method comprises releasing at least some of the first spectral resources. The source node continues to send traffic over the lightpath during the re-tuning.

Abstract: A path computation client (PCC) can request a path computation element (PCE) to compute a path across a wavelength switched optical network. PCC sends a request which identifies end nodes. The end nodes can support a plurality of possible values of a transmission parameter, such as modulation format or Forward Error Correction (FEC) type. The PCE computes a path between the end nodes and sends a reply to the PCC. The reply identifies the path between the end nodes and identifies a selected value of the transmission parameter for the computed path. The reply can comprise a spectrum assignment for the path. The reply can be a PCE Communication Protocol (PCEP) Reply message.

Abstract: In an optical communications network using bandwidth variable wavelength switching, routing and spectrum assignment for a traffic request for x sub-carriers of a super-channel, involves checking for an existing super-channel having sufficient potential sub-carriers not currently active. If not found, then possible paths for a new super-channel are identified and a path is selected and sub-carriers assigned. By trying first to use inactive potential sub-carriers of an existing super-channel, fewer super channels overall are needed, and thus fewer super transponders are needed. This can reduce blocking probabilities and can reduce capital costs. The search for possible paths can try to avoid or reduce overlap with spectrum of existing super channels, or compare possible paths by weighting according to amounts of overlap.

Abstract: Routing and bandwidth assignment of new paths of different bandwidths, occupying different numbers of adjacent frequency slots in a wavelength switched optical network, involves selecting a route, and assigning a set of adjacent frequency slots. The assignment can place wider bandwidth ones of the new paths at an opposite end of a spectrum of the available frequency slots, to an end where narrower bandwidth ones are placed. A size of sets of available adjacent slots remaining after the assignment is likely to be increased, compared to a conventional first fit assignment. A wider subsequent new path can sometimes be accommodated along all or some of the route and thus the blocking probability can be lowered. The selecting of which of the possible routes to use can be made dependent on which has more sets of available adjacent frequency slots, or which has a wider gap between occupied slots.

Abstract: A method of configuring an optical path, comprising: selecting a path from a first to a second node in an optical communications network; identifying each wavelength that may be used continuously across the path and selecting a transmission wavelength for the optical path one of the identified wavelengths for which: a fixed wavelength direction-bound add/drop transponder add operable at said wavelength is available at each node; if that first requirement is not met, a fixed wavelength direction-bound add/drop transponder or a fixed wavelength directionless add/drop transponder operable at said wavelength is available at each node; and if that second requirement is not met, a tunable wavelength direction-bound add/drop transponder or a tunable wavelength directionless add/drop transponder operable at said wavelength is available at each node.

Abstract: Traffic recovery is supported at a switching node (20) of an OpenFlow network (5). The switching node (20) has a flow table (23) for storing flow entries (24) which determine forwarding of received packets between the ports. A switching node (20) installs (102) a flow entry for a back up path in the flow table (23). The switching node (20) renews (104, 105) the flow entry for the backup path based on at least one of: (i) an association between the flow entry for the backup path and a flow entry for a working path at the switching node, wherein the flow entry for the backup path is renewed when the flow entry for the working path is used to forward a received packet; (ii) receiving a flow entry renewal packet from another switching node on the backup path. A backup path can be configured for each of multiple points of failure in the working path.

Abstract: A method of changing the spectral position of a lightpath between a source node and a destination node of an optical network. The optical network uses a flexible grid for spectral allocation and the lightpath has been allocated first spectral resources at a first spectral position. The method comprises, at the source node, reserving additional spectral resources for the lightpath which are contiguous in frequency with the first spectral resources. The method comprises re-tuning a light source at the source node such that the lightpath moves in frequency from using the first spectral resources at the first spectral position to using second spectral resources at a second spectral position, wherein the second spectral resources comprise at least some of the additional spectral resources. The method comprises releasing at least some of the first spectral resources. The source node continues to send traffic over the lightpath during the re-tuning.

Abstract: An optical transmission network comprises nodes which support a plurality of different wavelength channels and support at least a first bitrate traffic type and the second bitrate traffic type on respective wavelength channels. A connection of the second bitrate traffic type is established on an available wavelength, if the wavelength offers an acceptable quality of transmission using a first quality of transmission calculation. Alternatively, a connection of the second bitrate traffic type is established on a wavelength which is spaced, by a guard band, from wavelengths used for connections of the first bitrate traffic type, if the wavelength offers an acceptable quality of transmission using a second quality of transmission calculation. The second quality of transmission calculation is less stringent than the first quality of transmission calculation, and can ignore the effects of interference due to cross-phase modulation.

Abstract: In an optical communications network using bandwidth variable wavelength switching, routing and spectrum assignment for a traffic request for x sub-carriers of a super-channel, involves checking for an existing super-channel having sufficient potential sub-carriers not currently active. If not found, then possible paths for a new super-channel are identified and a path is selected and sub-carriers assigned. By trying first to use inactive potential sub-carriers of an existing super-channel, fewer super channels overall are needed, and thus fewer super transponders are needed. This can reduce blocking probabilities and can reduce capital costs. The search for possible paths can try to avoid or reduce overlap with spectrum of existing super channels, or compare possible paths by weighting according to amounts of overlap.

Abstract: A method of allocating a wavelength to a lightpath in a wavelength multiplex for use in an optical network comprising nodes connected by optical links, wherein the wavelength multiplex is adapted to support lightpaths of two different bitrates. The disclosed method allows for efficient allocation of wavelengths that prevents wasting bandwidth and mitigates detrimental effects of cross-phase modulation.

Abstract: 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.

Abstract: Routing and bandwidth assignment of new paths of different bandwidths, occupying different numbers of adjacent frequency slots in a wavelength switched optical network, involves selecting a route, and assigning a set of adjacent frequency slots. The assignment can place wider bandwidth ones of the new paths at an opposite end of a spectrum of the available frequency slots, to an end where narrower bandwidth ones are placed. A size of sets of available adjacent slots remaining after the assignment is likely to be increased, compared to a conventional first fit assignment. A wider subsequent new path can sometimes be accommodated along all or some of the route and thus the blocking probability can be lowered. The selecting of which of the possible routes to use can be made dependent on which has more sets of available adjacent frequency slots, or which has a wider gap between occupied slots.

Abstract: A path computation client (PCC) can request a path computation element (PCE) to compute a path across a wavelength switched optical network. PCC sends a request which identifies end nodes. The end nodes can support a plurality of possible values of a transmission parameter, such as modulation format or Forward Error Correction (FEC) type. The PCE computes a path between the end nodes and sends a reply to the PCC. The reply identifies the path between the end nodes and identifies a selected value of the transmission parameter for the computed path. The reply can comprise a spectrum assignment for the path. The reply can be a PCE Communication Protocol (PCEP) Reply message.

Abstract: A method of restoration for an optical network, the network comprising a plurality of nodes (40, 50) interconnected with each other by optical links (130), a subset of the nodes (40) each comprising a regenerator, the method comprising: storing 160) a quality of transmission parameter and a regenerator availability at each of the plurality of nodes (40, 50); notifying (170) a branch node (110) in response to detecting a failure (140) within a link (130) forming part of the path between a source node (20) and a destination node (30), wherein the branch node (110) is the neighbouring upstream node (40, 50) upstream of the link failure (140), the branch node (110) having a regenerator; the branch node (110) computing (190) a restoration segment (100) to a merge node (120) having a regenerator which is a neighbouring downstream node which is downstream of the link failure (140), the restoration path (100) being based on the quality of transmission parameter and regenerator availability information; restoring (180

Abstract: A method of configuring an optical path, comprising: selecting a path from a first to a second node in an optical communications network; identifying each wavelength that may be used continuously across the path and selecting a transmission wavelength for the optical path one of the identified wavelengths for which: a fixed wavelength direction-bound add/drop transponder add operable at said wavelength is available at each node; if that first requirement is not met, a fixed wavelength direction-bound add/drop transponder or a fixed wavelength directionless add/drop transponder operable at said wavelength is available at each node; and if that second requirement is not met, a tunable wavelength direction-bound add/drop transponder or a tunable wavelength directionless add/drop transponder operable at said wavelength is available at each node.

Abstract: A system, method, and node for a Routing Controller (RC) to obtain from a Path Computation Element (PCE), network resource path metrics across a plurality of domains in a communication network in which each domain includes a plurality of Border Nodes (BNs). The RC sends to the PCE, a first message requesting a first path computation between each pair of BNs. The first message contains a maximum metric-value that a path computation must not exceed for a Path Computation Client (PCC) to consider the path computation acceptable. The RC then sends a second message requesting the PCE to compute a subsequent path computation for each BN pair for which the first path computation did not exceed the maximum metric-value. The second message contains a minimum metric-value that a path metric must exceed for the PCC to consider the path metric acceptable. The RC then receives the computed subsequent path computation.