Techniques are described for advertising constraint-based path computation (e.g., flexible-algorithm) through a constrained network topology. For example, a network device comprises a memory and one or more programmable processors operably coupled to the memory, wherein the one or more programmable processors are configured to generate a packet including a segment identifier (SID) offset, wherein the SID offset is an offset value associated with the flexible-algorithm. The one or more programmable processors of the network device are also configured to send, to at least one other network device of the plurality of network devices, the SID offset to enable the at least one other network device to derive a node segment identifier for the at least one other network device to participate in the flexible-algorithm.

Networks comprising multiple non-overlapping communication topologies are presented. The networks can include a fabric of interconnected network nodes capable of providing multiple communication paths among edge devices. A topology manager constructs communication topologies according to restriction criteria based on required security levels (e.g., top secret, secret, unclassified, etc.). Established topologies do not have overlapping networking infrastructure to within the bounds of the restriction criteria as allowed by the security levels.

A method and apparatus for path computation includes generating, by a Path Computation Client (PCC), a path computation element communication protocol (PCEP) message, whereby the PCEP message comprises a characteristic associated with a level of protection of a Protection Label Switch path (LSP) with a Working LSP; and transmitting, by the PCC, the PCEP message to a Path Computation Element (PCE), for path computation.

A method includes: establishing, by a first network device, a first BMP session with a second network device, and establishing a second BMP session with a third network device; receiving a first BGP route set sent by the second network device, where the first BGP route set includes a BGP route sent by the second network device to the third network device; receiving a second BGP route set sent by the third network device, where the second BGP route set includes the BGP route received by the third network device from the second network device; and when detecting that the second BGP route set includes a first BGP route but the first BGP route set does not include the first BGP route, determining the first BGP route as an unavailable route.

The present invention provides a packet forwarding method and device. The method comprises: a first node receiving a packet for forwarding, wherein a destination address of the packet is a second node; the first node identifying, from topologies generated in advance, a target topology corresponding to the packet, wherein the topologies generated in advance comprise a first topology and a second topology generated according to an MRT algorithm, and a third topology obtained according to an SPF algorithm, wherein the first topology, the second topology and the third topology are different from one another; and the first node identifying, from the target topology, a next hop node for forwarding to the second node, and forwarding the packet to the next hop node. The present invention achieves an object of combining a segmented routing network and an MRT function.

A method and an apparatus for obtaining information about a forwarding path of a data packet in segment routing (SR) include, when a first path indicated by a plurality of path identifiers in initial information is a unique shortest path from a start node on the first path to an end node on the first path, the first path is indicated using a node-segment identifier (SID) of the end node on the first path instead of the path identifiers.

Systems and methods for permitted network risks in diverse route determinations introduce the concept of permitted network risks which are risks that may be present in a disjoint path calculation. This removes the binary logic in conventional shared risk path determination, i.e., either exclude or include. With the present disclosure, a network risk may be excluded (must never use) or shared (may use if needed). In an embodiment, if a route for a backup tunnel or path excluding all network risks is not possible, then a route for the backup tunnel or path may be found excluding some network risks of the primary tunnel or path except specified network risks that are determined/specified as permitted network risks. Such permitted network risks can be explicitly specified by a network operator or implicitly determined based on a category (e.g., node and/or equipment may be shared network risks whereas links may not).

Disclosed herein are systems, methods, and computer readable media for modifying IP backbone link weights such that multicast traffic and unicast traffic will not travel on a same path between nodes. The method comprises assigning link weights to nodes within an IP backbone such that multicast forwarding paths and unicast forwarding paths are failure disjoint, and delivering undelivered multicast packets using IP unicast encapsulation to the loopback address of next hop router on a multicast tree upon link/interface failure.

A path discovery process is provided for discovering a lowest cost combination of a plurality of paths from the source node to the destination node via links between pairs of nodes along the paths. A path discovery messages from a source node is forwarded through the network. Prior to forwarding the path discovery message a node tests one or more conditions for disabling the forwarding. Upon receiving an instance of the path discovery message, this may include testing whether no other instance of the path discovery message has both smaller cost and a previous path that contains only nodes that occur also in the path of the received instance. Furthermore, this may include testing whether a destination of the path discovery message was also a node to which a preceding node along the path has a further link, and a cost of the path from the preceding node to the next node via said further link is not larger than the cost of the path from the preceding node to the next node. Furthermore, this may include testing whether the node has a further link to the destination node and the cost associated with the link to the next node is not less than the cost associated with the further link to the destination node.

Techniques for identifying service paths for satisfying a service demand in a data communication network are disclosed. Aspects include identifying a plurality of vertices in a communications route cycle, the communications route cycle alternating through the plurality of vertices and a plurality of edges in a sequence; identifying a plurality of internal paths in the communications route cycle, each of the plurality of internal paths is disjoint to the plurality of edges; identifying a first internal path and a second internal path among the plurality of internal paths as a crossing pair of internal paths; detecting a failure of at least two edges among the plurality of edges; and identifying, based on the communications route cycle and the identified crossing pair of internal paths, a service path that satisfies the service demand in response to detecting the failure of the at least two edges.