Abstract: A method and apparatus resynchronizes a link state database (LSDB) of a non-stop forwarding (NSF) router with the LSDB of a neighboring router (“neighbor”) while maintaining an existing adjacency with the neighbor in a computer network. An out-of-band resynchronization process executes on the routers to essentially maintain the existing adjacency between the router and neighbor, rather than resetting that adjacency as defined by a conventional resynchronization approach. By keeping the adjacency “up” from the perspective of a routing protocol, such as the Open Shortest Path First routing protocol, the adjacency can be used for continued data traffic to and from the NSF router.

Abstract: A router executes a flooding algorithm. The router maintains a list of neighbors within an area data structure. When a new neighbor arises on an interface belonging to an area served by the router, the router updates the neighbor data structure describing that adjacency by linking it to a corresponding entry in the list of neighbors. Utilizing information contained in the list of neighbors, as well as information describing the types of interfaces used by the neighbors in the list, the router marks each interface data structure within the area as either flooding-active or flooding-passive. Marking of the interface is performed in connection with an interface election process that selects a flooding-active interface on the basis of, e.g., interface cost, giving preference to faster interfaces. Thereafter, link state protocol data units (PDUs) are sent to the neighbors over those interfaces marked as flooding-active.

Abstract: A technique restores adjacencies between a non-stop forwarding (NSF) router and its neighboring routers during reload of routing protocol software on the NSF router within a computer network. When a new instance of the routing protocol software is re-loaded, each interface of the NSF router is placed in a special state that enables it to receive incoming Hello packets from its neighboring routers. When placed in the special state, the interface passively “listens” for incoming Hello packets from the neighbors to determine which neighbors send the packets. The router thereafter promptly creates and sends a unicast Hello packet to each neighbor from whom it has received an incoming Hello packet and creates associated neighbor data structures.

Abstract: A technique resynchronizes a link state database (LSDB) of a non-stop forwarding (NSF) router with the LSDB of a neighbor while maintaining an existing adjacency with the neighbor over a network interface of the router. According to the technique, the NSF router “pretends” to be a new router by establishing a “fake” adjacency with the neighbor over the same interface used for the existing adjacency with the neighbor. Believing that the fake adjacency is an adjacency established with the new router, the neighbor does not destroy the existing adjacency with the NSF router. This allows the NSF router to continue receiving and forwarding data traffic over the existing adjacency that was established before, e.g., reloading of routing protocol software on the router.

Abstract: A technique modifies an asynchronous flooding algorithm associated with a link state routing protocol operating within an area of a computer network from a per-interface to a per-neighbor paradigm. A router executes the flooding algorithm to distribute its local state over its interfaces and throughout an area of the network to each neighboring router with whom it has an adjacency. The router maintains a list of neighbors within an area data structure. When a new neighbor (adjacency) arises on an interface belonging to the area, the router updates the neighbor data structure describing that adjacency by linking it to a corresponding entry in the list of neighbors. Utilizing information contained in the list of neighbors, as well as information describing the types of interfaces used by the neighbors in the list, the router marks each interface data structure within the area as either flooding-active or flooding-passive.