Abstract: In one embodiment, a trigger to add a leaf node to a multicast group of a computer network is detected, and the leaf node may determine a root node of the multicast group to request a path between a tunnel tree and the leaf node of the multicast group. In response to the multicast group having an existing tree, a reply is received from the root node with a computed path to add the leaf node to the tree at a selected node of the tree. The leaf node may then be added to the multicast group tunnel tree over the computed path at the selected node.

Abstract: In one embodiment, a first path computation element (PCE) operates between first and second network domains, and is adapted to service requests from path computation clients (PCCs) in at least the first domain. In response to a backup event (e.g., failure of a second PCE), a backup PCE in the second domain may be informed of path computation information for the first domain used by the first PCE, and tunnels may be bi-directionally established between the first PCE and the backup PCE. Once the tunnels are established, the backup PCE may be advertised into the first domain, and the backup PCE may operate to load balance service requests for the first domain through the bi-directionally established tunnels.

Abstract: A technique enables an intermediate network node to efficiently process link-state packets using a single running context (i.e., process or thread). The intermediate network node floods received link-state packets (LSP) before performing shortest path first (SPF) calculations and routing information base (RIB) updates. In addition, the node limits the number of LSPs that are permitted to be flooded before the node performs its SPF calculations. More specifically, if the number of link-state packets that are flooded during a flooding cycle exceeds a first predetermined threshold value, the node performs the SPF calculations before additional packets may be flooded. The intermediate network node also limits how long its RIB update may be delayed in favor of flooding operations. When the number of LSPs flooded after the SPF calculations exceeds a second predetermined threshold value or there are no more packets to be flooded, the node updates the contents of its RIB based on the SPF calculations.

Abstract: A technique controls distribution of reachability information for a tail-end node of a traffic engineering (TE) label switched path (LSP) to a head-end node of the TE-LSP in a computer network. The TE-LSP preferably spans multiple domains of the network such that the tail-end node resides in a domain (“tail-end domain”) that is different (remote) from the domain of the head-end node (“head-end domain”). According to the inter-domain information distribution technique, the head-end node requests the remote reachability information from the tail-end node, which may employ an Interior Gateway Protocol (IGP) to transmit the information to a border router of the tail-end domain. The tail-end domain border router then shares this information with at least a head-end domain border router. The head-end node thereafter requests that the head-end domain border router release the reachability information into the head-end domain. The head-end node uses the remote information to calculate routes, i.e.

Abstract: A fast reroute (FRR) technique that may be deployed at the edge of a network having first and second edge devices coupled to a neighboring routing domain. If the first edge device detects a node or link failure that prevents it from communicating with the neighboring domain, the first edge device reroutes at least some data packets addressed to the neighboring domain to the second edge device. The second edge device receives the rerouted packets and then forwards the packets to the neighboring domain. Notably, the second edge device is not permitted to reroute the received packets a second time, e.g., upon identifying another inter-domain node or link failure. As such, loops are avoided at the edge of the network and packets are rerouted to the neighboring routing domain faster and more efficiently than in prior implementations.

Abstract: A technique protects traffic (IP) against the failure of a border router between two domains in a computer network using Fast Reroute and backup tunnels. The border router (i.e., the “protected border router”) announces/advertises a list of all its adjacent next-hop routers (i.e., its “neighbors”) residing in first and second domains interconnected by the protected border router. A neighbor in the first domain that is immediately upstream to the protected border router and that is configured to protect the border router (i.e., the “protecting router”) learns address prefixes (i.e., “protected prefixes”) reachable from the next-hop router in the second domain (i.e., “next-next-hops,” NNHOPs to the protected prefixes from the protecting router). The protecting router calculates a backup tunnel to each NNHOP that excludes the protected border router, and associates each backup tunnel with protected prefixes accordingly.

Abstract: A technique protects against the failure of a border router between two domains in a computer network using Fast Reroute and backup tunnels. According to the technique, the protected border router advertises a list of all its adjacent next-hop routers (i.e., its “neighbors”). A neighbor in the first domain that is immediately upstream to the protected border router and that is configured to protect the border router (i.e., the “protecting router”) selects a neighbor in a second domain (i.e., a “next-next-hop,” NNHOP) to act as a “merge point” of all the NNHOPs of that domain. The protecting router calculates a backup tunnel to the merge point that excludes the protected border router and associates the backup tunnel with all “protected prefixes.” The merge point then “stitches” additional backup tunnels onto the backup tunnel to provide a stitched tunnel to each remaining NNHOP.

Abstract: A system and method routes data traffic over a unidirectional link of a computer network configured to implement a routing protocol, such as the ISIS routing protocol. To that end, the invention extends the ISIS routing protocol to allow dynamic discovery of neighboring routers (i.e., neighbors) that are connected via the unidirectional link and subsequent establishment of an adjacency between the neighbors over the link. Adjacency establishment is illustratively effected through the use of novel type/length/value (TLV) encoded formats appended to ISIS Hello packets to convey information between the neighbors.

Abstract: In one embodiment, an inter-domain routing protocol stores an inter-domain routing protocol route having an associated next-hop address. A routing table is searched for an for an intra-domain routing protocol route that may be used to reach the next-hop address of the inter-domain routing protocol route. Such route is marked as an important route for convergence. Later, in response to a change in the network requiring a routing table update, the intra-domain routing protocol route marked as an important route for convergence is processed by an intra domain routing protocol before any other intra-domain routing protocol routes are processed that are not marked as important routes for convergence.

Abstract: A technique propagates reachability information for a tail-end node of a traffic engineering (TE) label switched path (LSP) to a head-end node of the TE-LSP in a computer network. The TE-LSP preferably spans multiple domains of the network such that the tail-end node resides in a domain that is different (remote) from the domain of the head-end node. The inter-domain information propagation technique employs an Interior Gateway Protocol (IGP) to transmit the remote reachability information from a target node residing in the same domain as the tail-end node to the head-end node. The head-end node uses the remote information to calculate routes, i.e., address prefixes and associated attributes, reachable from the tail-end node for insertion into its routing table.

Abstract: A technique gracefully shuts down network resources, such as nodes, interfaces and protocols, in a data network in a manner that minimizes network disruption. The technique may be used with both connectionless and connection-oriented networking systems. A node gracefully shuts down a network resource associated with the node by i) notifying other nodes in the network that the resource is being gracefully shutdown, ii) waiting for a condition to occur, and iii) when the condition occurs, shutting down the resource. The condition may include the expiration of a predetermined amount of time and/or monitoring the resource to determine if the resource has reached a certain level of activity. In response to receiving a notification that a resource is being gracefully shutdown, a node takes action to reroute traffic around the resource. If no alternative route is available, the node may continue to route traffic to the resource until it is shut down.

Abstract: A technique configures an intermediate network node to automatically determine whether a route advertised by a routing protocol is important for fast convergence in a computer network. As used herein, an important route needed for fast convergence is a route advertised by the routing protocol, such as an exterior gateway routing protocol, as a next-hop address, since external connectivity relies on such a route. A routing information base process executing on the node stores the advertised route and, notably, interacts with an interior gateway routing protocol (IGP) process executing on the node to identify the route as an important route. Identification of an important route, in turn, allows IGP to process the route in a high priority fashion, thereby facilitating fast convergence.

Abstract: A method and apparatus are disclosed for performing a shortest path first network routing path determination in a data communications network based in part on information about links that are associated as shared risk link groups. Micro-loops are avoided in computing shortest path first trees by considering whether links are within shared risk link groups. In a first approach, for each link state packet in a link state database, listed adjacencies are removed if the link between the node originating the LSP and the reported adjacency belongs to a shared risk link group for which one component (local link) is known as down, and a shortest path first computation is then performed. In a second approach, during the SPT computation and after having added a first node to a path, each neighboring node is added to a tentative tree if and only if, a link between the first node and the neighboring node does not belong to a shared risk link group for which one component (local link) is known as down.

Abstract: In one embodiment, a node receives traffic sent from one or more sources toward one or more destinations (e.g., Multipoint-to-Point, MP2P traffic). The node may detect a burst of received traffic based on one or more characteristics of the burst traffic, and, in response, may dynamically apply traffic shaping to the burst traffic. The traffic shaping is adapted to forward burst traffic received below a configurable threshold at a configurable pace and to drop burst traffic received above the configurable threshold. In addition, the node may also store the burst traffic dropped by traffic shaping, and forwards the stored burst traffic toward its destination after a configurable delay.

Abstract: An apparatus and method as described for constructing a repair path for use in the event of failure of an inter-routing domain connection between respective components in first and second routing domains of a data communications network. The apparatus is arranged to assign a propagatable repair address for use in the event of failure of the inter-routing domain connection and to propagate the repair address via data communications network components other than the inter-routing domain connection.

Abstract: A method and apparatus for the dissemination of non-routing information to nodes of a network is provided. A new type of IS-IS packet (called a NRI IS-IS packet) is described that exclusively carries non-routing information. When the NRI IS-IS packet is received by a router, the router may send the NRI IS-IS packet to an appropriate component responsible for processing non-routing information, without analyzing, verifying, and validating the information carried in each TLV and sub-TLV of the NRI IS-IS packet. Advantageously, the time it takes for routers of the network to achieve convergence is decreased since a IS-IS packet reader need not analyze, verify, and validate information not related to network topology and IP routing. Therefore, when NRI IS-IS packets are received, there is no impact in the convergence time of nodes in the network.

Abstract: In one embodiment, a node identifies a plurality of equal cost best paths to a destination, the best paths having one or more associated links. The node receives dynamic link utilization information for the associated links, and determines an amount of traffic to the destination to forward over each of the equal cost best paths, the amount being dynamically dependent upon the dynamic link utilization of the associated links for each equal cost best path.

Abstract: In one embodiment, an apparatus and method are described for constructing a repair path in the event of non-availability of a routing domain component of a routing domain comprising, as components, links and nodes. The apparatus is arranged to receive respective network repair addresses from each of the far-side and near-side advertising node for use in the event of non-availability of a routing domain component between the advertising node. The apparatus is further arranged to advertise the near-side advertising node network repair address to one or more far-side nodes via a path external to the routing domain.

Abstract: An apparatus for providing reachability in a routing domain of a data communications network having as components nodes and links therebetween for a routing domain—external destination address is described. The apparatus is arranged to advertise destination address reachability internally to nodes in the routing domain and associate a reachability category with said internal advertisement of said destination address reachability.

Abstract: A technique protects against failure of a network element using Multi-Topology Repair Routing (MTRR) in a computer network. According to the novel technique, a protecting node (e.g., a router) maintains Multi-Topology Routing (MTR) databases for a first topology and at least a second topology. The protecting node determines whether any acceptable repair paths are available in the first topology for a protected network element (e.g., node, link, etc.) of the first topology. If not, the protecting node may establish a repair path (e.g., for Fast ReRoute, FRR) in the second topology for the protected network element.