Abstract: Systems and methods for monitoring the continuity between endpoints in a network are provided. A process, according to one implementation, includes entering a first list of one or more Segment Identifiers (SIDs) into a Bidirectional Forwarding Detection (BFD) request packet, the first list of one or more SIDs defining a Segment-Routing Traffic-Engineering (SR-TE) forward path from a source node to a destination node. The process also includes entering a second list of one or more SIDs into the BFD request packet, the second list of one or more SIDs defining an SR-TE reverse path back from the destination node that eliminates involvement of a BFD reflector of the destination node. Also, the process includes entering a revised-BFD request into the BFD request packet, the revised-BFD request having a Your Discriminator field set to a discriminator value associated with the source node.

Abstract: Optical link related wavekey information and other vendor specific information is distributed in a WDM network using an extension of the standard OSPF routing protocol. The extension makes use of a vendor attribute Link State Advertisement (LSA) which is a new type of opaque LSA. The vendor attribute LSAs include a Vendatt Link State Identifier (ID) field in the LSA header, and a Vendatt Type/Length/Value (TLV) structure. The Vendatt TLV includes a Vendatt-type field identifying the TLV as a Vendatt TLV, and an enterprise code field identifying the vendor whose equipment (node or network element) generates vendor attribute LSAs or is able to receive vendor attribute LSAs by the identified vendor. Vendor attribute LSAs of a specific vendor are designed to be ignored by nodes or network elements of other vendors.

Abstract: A method for monitoring lightpaths in an optical network comprising nodes interconnected by wavelength-multiplexed links is disclosed. Each lightpath is identified by a respective optical signature. A node stores identifiers of optical signatures of lightpaths designated to traverse the node and identifiers of adjacent nodes. Each node also maintains a record of all optical signatures it detects. A command-line interface associated with a selected node tracks a selected lightpath, designated to traverse the selected node, by propagating messages in an upstream direction, a downstream direction, or both, requesting other nodes to provide information pertinent to the selected lightpath. The selected node may also send messages to all its neighboring nodes requesting each to indicated detection, or otherwise, of the selected lightpath.

Abstract: A routing system and method are provided which use a composite cost in identifying routes. This allows a simple way of identifying the best route taking multiple metrics into account for each link simultaneously. The system allows for the inclusion of pruning constraints, and allows for various objectives such as bin packing or load balancing to be achieved.

Abstract: A method and system for allocating and controlling a hierarchy of labels in an MPLS network is provided. The hierarchy of labels, inserted into MPLS packets, is introduced so as to correspond to the hierarchy of sub-flows within a data flow. The labels have the established dependency so that positions of labels in the hierarchy identify a sequence of processing the labels and functions associated with the labels. The system for allocating and controlling the hierarchy of MPLS labels includes a first control plane mapper for releasing available labels, a first controller for assigning the released labels according to the hierarchy, means for transmitting the labels in the network, a second controller for detecting the labels, and a second control plane mapper for maintaining current label dependency within the hierarchy. If required, re-addressing of the hierarchy of labels may be performed to maintain flow-sub-flow association throughout two adjacent networks.

Abstract: A method for selecting two maximally disjoint shortest paths between a source node and destination node in a network is provided. The method comprises determining a first explicit route between the source and destination nodes by using an original link cost for each link in the network, transforming the network by introducing conditional link costs, determining a second explicit route between the source and destination nodes in the transformed network taking into account the conditional link costs, and determining the two maximally disjoint shortest paths between the source and destination nodes by coalescing the first and second explicit routes. Beneficially, the step of introducing conditional link costs comprises adding additional parameters to links in the network and determining the conditional link costs depending on the position of each link relative to the first explicit route.

Abstract: In an optical WDM network, each optical channel is modulated with a respective channel identity. Detectors, conveniently at multiplex ports of optical band filters, detect the channel identities of all of the optical channels in an optical signal at the respective points to produce respective channel lists. A network management system determines channel lists for through ports of the optical band filters, identifies matching pairs of channel lists to determine a topology of each node and to identify optical paths entering or leaving each node, and identifies matching pairs of channel lists for these paths to determine an inter-node topology of the network. The channel identity detector points can alternatively be at the optical paths entering or leaving each node.

Abstract: A routing system and method are provided which use a composite cost in identifying routes. This allows a simple way of identifying the best route taking multiple metrics into account for each link simultaneously. The system allows for the inclusion of pruning constraints, and allows for various objectives such as bin packing or load balancing to be achieved.

Abstract: Methods, systems, computer readable media are provided which facilitate the selection of multiple paths through a network represented by a network topology which take into account shared risk which may exist between network resources. The method involves identifying a first path through the network topology from a source node to a destination node, the first path comprising a first sequence of network resources. For at least one shared risk group, a determination is made if any of the at least one shared risk group includes any of the first sequence of network resources, a shared risk group being a group of network resources within the network topology which have a shared risk. A topology transformation is performed of the network topology into a virtual topology which discourages the use of network resources in any shared risk group determined. A second path through the virtual topology is identified from the source node to the destination.

Abstract: Optical link related wavekey information and other vendor specific information is distributed in a WDM network using an extension of the standard OSPF routing protocol. The extension makes use of a vendor attribute Link State Advertisement (LSA) which is a new type of opaque LSA. The vendor attribute LSAs include a Vendatt Link State Identifier (ID) field in the LSA header, and a Vendatt Type/Length/Value (TLV) structure. The Vendatt TLV includes a Vendatt-type field identifying the TLV as a Vendatt TLV, and an enterprise code field identifying the vendor whose equipment (node or network element) generates vendor attribute LSAs or is able to receive vendor attribute LSAs by the identified vendor. Vendor attribute LSAs of a specific vendor are designed to be ignored by nodes or network elements of other vendors.

Abstract: Methods and systems for re-routing a connection through an explicitly routed network. The methods involve initially re-routing the connection to a reduced constraint connection through the network; establishing a fully constrained path through the network; subsequently re-routing the connection to the fully constrained connection through the network.

Abstract: A method to trace, detect, discover and monitor the nodes traversed by a light path from its source to its destination in an Optical Communication Network (OCN) is provided. In accordance with the embodiment of the invention, the system examines various provisioned and discovered optical nodes either sequentially or in parallel to determine whether a unique signature (wavekey) associated with the light path is present. Connectivity and mis-fibering problems are detected by sequentially examining provisioned nodes in the light path to determine if the wavekey associated with the light path can be observed. Control Network topology information is utilized to contact all nodes in the network to trouble-shoot mis-fibering problems.

Abstract: A method for selecting two maximally disjoint shortest paths between a source node and destination node in a network is provided. The method comprises determining a first explicit route between the source and destination nodes by using an original link cost for each link in the network, transforming the network by introducing conditional link costs, determining a second explicit route between the source and destination nodes in the transformed network taking into account the conditional link costs, and determining the two maximally disjoint shortest paths between the source and destination nodes by coalescing the first and second explicit routes. Beneficially, the step of introducing conditional link costs comprises adding additional parameters to links in the network and determining the conditional link costs depending on the position of each link relative to the first explicit route.

Abstract: Methods and systems for re-routing a connection through an explicitly routed network. The methods involve initially re-routing the connection to a reduced constraint connection through the network; establishing a fully constrained path through the network; subsequently re-routing the connection to the fully constrained connection through the network.

Abstract: A routing system and method are provided which use a composite cost in identifying routes. This allows a simple way of identifying the best route taking multiple metrics into account for each link simultaneously. The system allows for the inclusion of pruning constraints, and allows for various objectives such as bin packing or load balancing to be achieved.

Abstract: A routing system and method are provided which use a composite cost in identifying routes. This allows a simple way of identifying the best route taking multiple metrics into account for each link simultaneously. The system allows for the inclusion of pruning constraints, and allows for various objectives such as bin packing or load balancing to be achieved.

Abstract: A method and system for allocating and controlling a hierarchy of labels in an MPLS network is provided. The hierarchy of labels, inserted into MPLS packets, is introduced so as to correspond to the hierarchy of sub-flows within a data flow. The labels have the established dependency so that positions of labels in the hierarchy identify a sequence of processing the labels and functions associated with the labels. The system for allocating and controlling the hierarchy of MPLS labels includes a first control plane mapper for releasing available labels, a first controller for assigning the released labels according to the hierarchy, means for transmitting the labels in the network, a second controller for detecting the labels, and a second control plane mapper for maintaining current label dependency within the hierarchy. If required, re-addressing of the hierarchy of labels may be performed to maintain flow-sub-flow association throughout two adjacent networks.