Abstract: Embodiments include methods of controlling a client layer of a multi-layer communication network that also includes a server layer. Such methods include receiving, at a client physical network controller (PNC), an indication of at least one characteristic associated with one or more paths between server network nodes in the server layer. The indication is received from a multi-domain service controller (MDSC) in the multi-layer communication network, and the server layer is controlled by a server PNC. Such methods include, based on the at least one characteristic, computing one or more paths in the client layer that facilitate protection and/or restoration for the one or more paths in the server layer. Other embodiments include complementary methods performed by a MDSC, as well as client PNCs and MDSCs configured to perform such methods.

Abstract: Methods for segment routing in a software-defined networking (SDN) system are disclosed. In one embodiment, a method includes receiving a plurality of values of maximum segment identifier (SID) depths, each from one network element of the SDN system, and identifying a path for a packet to transmit through a plurality of network elements, where a plurality of SIDs corresponding to the plurality of network elements is ordered to represent the path. The method further includes splitting the path into a plurality of sub-paths based on the values of the maximum SID depths of the plurality of network elements, where each network element, for the path, is allocated to process a number of ordered SIDs, and where the number is within the network element's maximum SID depth, and causing packet forwarding of the packet along the plurality of sub-paths based on SIDs allocated to the network elements.

Abstract: Embodiments include methods of controlling a client layer of a multi-layer communication network that also includes a server layer. Such methods include receiving, at a client physical network controller (PNC), an indication of at least one characteristic associated with one or more paths between server network nodes in the server layer. The indication is received from a multi-domain service controller (MDSC) in the multi-layer communication network, and the server layer is controlled by a server PNC. Such methods include, based on the at least one characteristic, computing one or more paths in the client layer that facilitate protection and/or restoration for the one or more paths in the server layer. Other embodiments include complementary methods performed by a MDSC, as well as client PNCs and MDSCs configured to perform such methods.

Abstract: A method in a controller node for performing segment routing in a non-packet data network comprising a plurality of nodes, comprises receiving information relating to the topology of the non-packet data network connecting the plurality of nodes, the non-packet data network forming a data plane network. The method comprises computing a segment routing path to be taken for non-packet traffic data through the data plane network, wherein the segment routing path is computed using segment identifiers, SIDs, relating to a data communication network, DCN, coupled to the plurality of nodes. The method comprises sending the computed segment routing path to an ingress node of the data plane network.

Abstract: Aspects provide a method (10, 100, 150, 160) of controlling a multi-layer communication network comprising a client network and a server network. The method comprises obtaining (12;164) from the server network at least one path characteristic for a path in the server network between server network nodes; and providing (14, 152, 166) to the client network an indication of the at least one path characteristic of the server network.

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: 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: 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: Methods for 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 are disclosed. The methods may be implemented at the first node, the second node, or a control node. The first and second nodes communicate in-band control messages. These messages are encoded using a size of the packets of the control messages, and provide information about the first node and a first interface used by the first node for sending the control messages. The first and second nodes also communicate link messages with the control node. The link messages comprise information received in the in-band control messages and information about a second interface used by the second node for receiving the in-band control messages.

Abstract: Methods for segment routing in a software-defined networking (SDN) system are disclosed. In one embodiment, a method includes receiving a plurality of values of maximum segment identifier (SID) depths, each from one network element of the SDN system, and identifying a path for a packet to transmit through a plurality of network elements, where a plurality of SIDs corresponding to the plurality of network elements is ordered to represent the path. The method further includes splitting the path into a plurality of sub-paths based on the values of the maximum SID depths of the plurality of network elements, where each network element, for the path, is allocated to process a number of ordered SIDs, and where the number is within the network element's maximum SID depth, and causing packet forwarding of the packet along the plurality of sub-paths based on SIDs allocated to the network elements.

Abstract: A connection-oriented network has a working path and a segment recovery path for a segment of the working path. The working path has a branch node at an end of the segment where the segment recovery path connects to the working path. The branch node is not located at an end node of the working path. Control plane signalling is received at an end node of the working path from a node along the working path, indicating that a failure has occurred along the working path. The end node determines, from the received control plane signalling, if the failure has occurred outside the segment of the working path. When it is determined that the failure has occurred outside the segment of the working path, a notification is sent to the branch node. The notification is an instruction not to reroute to the segment recovery 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: 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: 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: Aspects provide a method (10, 100, 150, 160) of controlling a multi-layer communication network comprising a client network and a server network. The method comprises obtaining (12;164) from the server network at least one path characteristic for a path in the server network between server network nodes; and providing (14, 152, 166) to the client network an indication of the at least one path characteristic of the server network.

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: A method in a controller node for performing segment routing in a non-packet data network comprising a plurality of nodes, comprises receiving information relating to the topology of the non-packet data network connecting the plurality of nodes, the non-packet data network forming a data plane network. The method comprises computing a segment routing path to be taken for non-packet traffic data through the data plane network, wherein the segment routing path is computed using segment identifiers, SIDs, relating to a data communication network, DCN, coupled to the plurality of nodes. The method comprises sending the computed segment routing path to an ingress node of the data plane network.

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: 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.