Abstract: A Common Public Radio Interface (CPRI) link involves using a protocol stack having a CPRI layer and an emulation layer to emulate a point to point link, to enable the CPRI link to operate over a packet switched network. The emulation layer can be a pseudowire emulation which encapsulates multiple CPRI frames in a packet with overhead. A multiplexing layer such as Internet Protocol (IP) or Multiprotocol Label Switching (MPLS) can be used, for sending the packet over an Ethernet network. The usual need for a point to point infrastructure for the CPRI link can be avoided and the CPRI link can be implemented over more complex but usually cheaper packet networks, thus reducing costs or enabling more widespread application over existing packet networks. This applies whether the packet network is dedicated to the CPRI link, or shared with other packets. It can be useful for distributed radio base stations.

Abstract: A label switched path through a network of nodes, is torn down by sending a message along the path from an ingress node. If there is a fault along the path, a path error message (2) is sent back along the path to the ingress node. The ingress node uses a different route bypassing the fault to alert (3) a further one of the nodes (NE5, NE6) on that path beyond the indicated fault, to cause that further node to continue the tearing down for other nodes on that path beyond the indicated fault by sending a further message (4) along the portion of the path beyond the indicated fault, to indicate to the other nodes to continue the tear down. This enables the ingress node to clean up the rest of the path beyond the fault, to avoid leaving unused capacity unavailable for reuse, and to avoid time consuming manual clean up.

Abstract: The present invention provides a method for enabling Segment Routing in a multi-domain network comprising a client network domain and a server network domain, where the client network domain is a packet network domain and the server network domain is a connected-oriented network domain. The method comprises assigning a network segment identifier to each of one or more potential paths through the server network domain between a pair of overlay network nodes in the client network domain, wherein the one or more potential paths are not pre-configured and the or each network segment identifier is suitable for inclusion in one or more data packets to indicate to at least one of the pair of overlay network nodes a preselected network segment routing for the one or more data packets. The present invention further provides a method for routing data packets in the multi-domain network.

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 method of realigning a node in a label switched network comprising a plurality of nodes and a node with a processor, a memory, and a network interface, for carrying out the method. The method includes periodically maintaining backup path status information for the node, restarting the node, and re-establishing label switched paths with the plurality of nodes using the backup status information. Communication with adjacent nodes is carried out in order to reconcile the path status information with respective path status information in the adjacent nodes in order to establish node realignment preferably judged against a threshold value for path reliability.

Abstract: A method of determining a path in an optical server network (31) comprises obtaining an indication of an amount of premium traffic from a client network (21). The method further comprises considering paths (48) utilising an elastic capability of one or more network elements (30) of the optical server network, and selecting a path from the considered paths, wherein the path is selected based at least partially on having at least a capacity to carry the amount of premium traffic.

Abstract: A data communications system has a plurality of nodes connected by a plurality of links. A subset of the links and nodes forms a worker path for carrying worker data through the communications system, and a further subset of links and nodes provides a protection path for carrying other data in the absence of a fault in the worker path and for providing an alternative path for the worker data in the event of a fault in the worker path. The alternative path is predetermined prior to the detection of a fault in the worker path.

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: 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 (300) of automatically discovering links between a first node of a first operating domain and a second node of a second operating domain of a communication network is disclosed. The method, performed in the second node, comprises receiving an in-band control message from the first node (302), the in-band control message being encoded using size of packets of the control message and providing information about the first node and a first interface used by the first node for sending the control message, and sending a link message to a control node (304), the link message comprising information received in the in-band control message and information about a second interface used by the second node for receiving the in-band control message.

Abstract: In a connection-oriented network a point-to-multipoint working path is established between a source node and a plurality of destination nodes using a number of working path intermediate nodes. A point-to-multipoint protection path is established for possible points of failure in the working path. Each protection path connects a first working path intermediate node upstream of a point of failure and destination nodes of the working path downstream of the first working path intermediate node. The point-to-multipoint protection path only connects to destination nodes of the working path and working path intermediate nodes which must be transited to reach the destination nodes of the working path.

Abstract: A method and a network node for managing allocation of network resources in restoration of traffic in a connection oriented network are disclosed. The method comprises restoring a first traffic from a first path on an alternative path if the first path is affected by a first failure and assigning a reserved status to resources of the first path no longer used for carrying the first traffic. If a second path is affected by a second failure the method comprises restoring a second traffic from the second path, wherein the restoration of the second traffic does not use the resources having the reserved status.

Abstract: An optical network is configured to provide an optical reroute over a backup path (2139) during a failure in a signal path (2133). The network comprises a first node (B). A second node (C) is coupled to receive a signal from the first node (B) via the signal path (2133), and a backup signal via the backup path (2139). The network is adapted to transmit a signal and a corresponding backup signal from the first node to the second node even when there is no failure in the signal path (2133), wherein the backup signal is blocked at the second node (C) when there is no failure in the signal path (2133). Embodiments of the invention utilize the broadcast and blocking functionalities of a wavelength selective switch (WSS) device. Such WSS devices enable, in the case of a failure of a link, the fast switchover of optical traffic onto local detours within a reduced time.

Abstract: In a connection-oriented network a point-to-multipoint working path is established between a source node and a plurality of destination nodes using a number of working path intermediate nodes. A point-to-multipoint protection path is established for possible points of failure in the working path. Each protection path connects a first working path intermediate node upstream of a point of failure and destination nodes of the working path downstream of the first working path intermediate node. The point-to-multipoint protection path only connects to destination nodes of the working path and working path intermediate nodes which must be transited to reach the destination nodes of the working path.

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: A method for controlling streaming of video content delivered over a communications network. The method comprises setting a transfer threshold of at least one buffer involved in delivery of the streamed video content based upon expected delays in the communications network, wherein the transfer threshold comprises a minimum amount of data to be contained in the buffer before data is forwarded from the buffer. Also provided are an apparatus and a computer program product configured to control streaming of video content delivered over the communications network.

Abstract: A method for setting up a new path for carrying traffic between border nodes of a client communications network through a server communications network. The method comprises, at a border node of the client communications network: receiving a request for reservation of resources from a first client node of the client communications network; determining that the border node does not have a path for carrying traffic through the server communications network having sufficient resources to meet the request; and, in response, initiating set up of a new path for carrying traffic between border nodes of the client communications network through the server communications network.

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.