Abstract: The present invention relates to configuring the quality of service in a label switched network. In particular, the invention relates to configuring quality of service for the return path of a bi-directional label switched path in a label switched network. The invention provides a method of configuring quality of service for a return path of a bi-directional label switched path within a network, the bi-directional label switched path having a forward path and a return path. A label information context for a quality of service configuration of the return path of a label switched path is configured separately from a quality of service configuration for the forward path. Path set up messages are formed containing a return path quality of service object indicating the quality of service configuration for the return path separately from a quality of service configuration for the forward path.

Abstract: A method of local path protection in a node on a shared alternative path of a network. The method comprising receiving a signal switched on a primary label switched path (LSP). The signal is switched by lambda-switching or time-division multiplex TDM switching. The method further comprises receiving identification information arranged to identify the signal, and forwarding the signal on the alternative path based on the identification information.

Abstract: A connection-oriented network has a first working path (W1) and a second working path (W2). A node (E) receives signalling to allocate resources for a part of a recovery path (R1) for the first working path (W1). The resources are shared by the recovery path (R1) for the first working path and a recovery path (R2a) for the second working path (W2). The node (E) stores an association between the shared resources and a node (A) on the first working path, identified in the signalling, which should be notified when the shared resources are used by the recovery path (R2a) for the second working path (W2). An RSVP-TE <NOTIFY_REQUEST> object in the signalling carries an address of the node to be notified. The node (E) sends an RSVP-TE Notify message to a node (A) on the first working path (W1) which indicates that the shared resources are in use.

Abstract: In a method of configuring quality of service for a return path of a bi-directional label switched path within a network a label information context for a quality of service configuration of the return path of a label switched path is configured separately from a quality of service configuration for the forward path. Path set up messages are formed containing a return path quality of service object indicating the quality of service configuration for the return path separately from a quality of service configuration for the forward path.

Abstract: A method of monitoring a communications network by monitoring packet errors in one of the paths having at least two optical sections coupled in series with a break in continuity of optical transmission monitoring between the optical sections, and monitoring a transmission quality of each of these optical sections. A state is detected in which the monitored packet errors do exceed an acceptable threshold, but at the same time the transmission quality of each of the optical sections is acceptable, and an indication is transmitted of the detection. This can cause a request for an alternative path for the packets, or cause adapting of these optical sections to reduce bit errors. This can enable handling of potential conflict between packet and optical layers, when the packet layer sees errors but the optical layer indicates no problem.

Abstract: A network element for a communications network having decoupled control and data planes may be in either a first state, the control plane and data plane are configured to interact, whereas, in the second state, the network element suppresses a control message for the data plane such that the configuration of the data plane is preserved. Accordingly, the network element may be in a second state when the data plane is undergoing maintenance such that there is no interaction between the control and data planes.

Abstract: Example embodiments presented herein are directed towards an optical testing node, and method therein, for establishing transmission parameters for optical communications in an iterative manner. The establishment of the transmission parameters may comprise adjusting various parameters such as a modulation scheme, a light path length, and/or a spectral width.

Abstract: A connection-oriented optical network (2) comprises nodes (10) and optical links (5) between nodes. Each node (10) has a power control unit (60) for controlling an optical amplifier (43) at the node. A node, in response to a requirement to set up a new connection in the network, signals to a power control unit (60) at each of a plurality of downstream nodes along a path of the new connection to cause the power control unit at the node to adjust the optical amplifier at the node to support a new optical channel to carry the new connection. The node (10) can signal to tear down an existing connection in a similar way. A downstream node determines a number of optical channels for which the optical amplifier can be adjusted concurrently, based on an existing number of active optical channels.

Abstract: Dynamic restoration involves routing and bandwidth assignment of an unplanned restoration path in a wavelength switched optical network (20), having regeneration nodes (60), nodes each having a ROADM (62) having drop paths and add paths. An electrical switch (68) provides configurable regeneration capacity by coupling selected drop paths to selected add paths. Some of the configurable regeneration capacity is kept for unplanned restoration paths. A PCE determines (120) routing and bandwidth assignments for an unplanned restoration path for the traffic flow to avoid a fault, and sends (130) configuration messages to the nodes to set up the unplanned restoration path dynamically and to configure the electrical switch to provide regeneration on the path. Keeping some reconfigurable regeneration capacity enables much longer unplanned paths to be found to avoid faults, and enables wavelength conversion if needed. Thus the reliability of finding at least one path avoiding the fault can be increased.

Abstract: A method in a node of a network comprises the steps of receiving a configuration command signal, the configuration command signal indicating that one or more configuration parameters are to be changed in the node and at least one other node of the network. A routing protocol message is modified to include the configuration command signal. The configuration command signal is communicated to the at least one other node of the network using the modified routing protocol message.

Abstract: Recovery from failure of a working path for communications traffic in a connection-oriented network, where the working path has a preplanned recovery path, involves initiating recovery by requesting computation of a new recovery path for the communications traffic to avoid the failure. If the recovery is not successful within a time limit, recovery is carried out using the preplanned recovery path. Determining if the recovery is not successful and initiating the recovery using the preplanned recovery path can be controlled by an ingress node of the working path. By trying to compute a new recovery path first, network resources can be used more efficiently, as the new recovery path is likely to reuse most of the working path, since it is computed knowing the location of the fault.

Abstract: Control of a label switched path established in a network is transferred between a management plane and a control plane of the network. A node (e.g., node C) receives a message indicating a change in control of the label switched path, the message identifying the label switched path by a cross-connection identifier corresponding to an entry in the control data stored at the node which identifies data plane ingress and egress segments cross-connected at the node. Control data at the node is updated based on the identified label switched path. The message includes a list of cross-connection identifiers for nodes (e.g., nodes C, E, and F) along the label switched path. The cross-connection identifier can be an mplsXCIndex.

Abstract: A network architecture is provided for enabling end-to-end paths to be computed across a plurality of network domains. The network architecture comprises a plurality of child path computation elements associated with a plurality of respective network domains, each child path computation element adapted to compute a path segment within its respective network domain. A parent path computation element adapted to compute an end-to-end path across a plurality of network domains in conjunction with the plurality of respective child path computation elements.

Abstract: In a communications network, a recovery segment is used to reroute a recoverable part of a path set up along an original route along links between nodes. When a defect is detected in the original route of the path, but is undetectable by nodes within the recoverable part, a reroute message is sent (5) from outside the recoverable part to an end node (N2,N4) of the recoverable part. This prompts the rerouting of the recoverable part over the recovery segment. Thus segment recovery becomes possible for these defects which cannot be detected at nodes in the segment. This extends the applicability of benefits of segment recovery such as reduced resources devoted to recovery, and flexibility to choose which parts of paths to protect. The end node can send a notify message beforehand, to request (3) notification of the defect as the reroute message.

Abstract: A method of configuring a path between an ingress node and an egress node in an optical communications network, the path comprising a first hop and a subsequent hop. The method includes: a) selecting a candidate hop for the first hop of the path; b) obtaining a value of a signal feasibility parameter for the candidate hop; c) determining whether said value lies within an acceptable value range and if one is, accepting said candidate hop for the first hop of the path, and if one is not, repeating steps a. to c.; d) selecting a candidate hop for the subsequent hop of path; e) obtaining a value of a signal feasibility parameter for a combined path comprising the first hop and the candidate hop for the subsequent hop of the path; f) determining whether said value lies within an acceptable value range, if one is, acceptable value range accepting said candidate hop for the subsequent hop of the path, and if one is not, repeating steps d. and e.

Abstract: A method of operating a control plane having a centralised network management system (10), control domain servers (20) and a plurality of forwarding elements (30), for controlling respective network entities (L2), and grouped into control domains (21, 22, 23). Each domain has a control domain server. Automatic checking for inconsistencies (110, 115, 210, 310, 320, 450) between the records held at the different parts of the control plane, involves comparing checklists of the records of the circuits stored at the different parts of the control plane. If an inconsistency is found, there is automatic updating (120, 220, 230, 460) of the records using a copy sent from another of the parts of the control plane. The checklists can avoid the need to forwarding entire copies.

Abstract: A border node of an optical network receives optical channel traffic parameter(s) associated with an optical channel from an optical channel originator external to the optical network. The received parameters are used to determine the suitability of at least one optical path within the optical network for an externally originating optical channel. If a suitable optical path is determined, an optical channel availability message indicating the availability at the border node of an optical path within the optical network for the optical channel is sent to the optical channel originator. The optical channel originator determines an available optical channel status of the optical channel from the received optical channel availability message for the optical channel.

Abstract: Setting up a label switched path (LSP) for traffic between nodes of a network, involves sending a request message requesting reservation of resources for the requested LSP, from an ingress node (10) via intermediate nodes (40) and returning an acknowledgement message to an upstream node along the path. Absence of an acknowledgement from the downstream node, that the request message was received, is detected. Whether the given node should react to the detected absence can be determined from an indication (R) in the request message. Thus other nodes can react more quickly to take remedial action, to reroute or to remove the resource reservations without a long wait for a time out or a refresh message from the waiting ingress node, to enable more efficient use of the resources.

Abstract: Example embodiments presented herein are directed towards an optical testing node, and method therein, for establishing transmission parameters for optical communications in an iterative manner. The establishment of the transmission parameters may comprise adjusting various parameters such as a modulation scheme, a light path length, and/or a spectral width.

Abstract: An existing path in a connection-oriented network requires resizing from a first size to a second size. Nodes exchange control plane signalling with other nodes which advertises available resources on links between nodes. A node on the existing path receives a request to establish a path capable of being resized to the second size. The node determines, using information acquired by the control plane signalling with other nodes, a new path between nodes capable of supporting the second size. The node signals to establish the new path and switches traffic from the existing path to the new path. The node causes the new path to be resized to the second size. Nodes exchange control plane signalling with other nodes which advertises whether a link supports resizing, such as OSPF-TE advertisements.