Abstract: A network element that has a broadcast interface to a broadcast network becoming operational determines whether at least one alternate path exists to the broadcast network. The broadcast interface is to carry traffic on a label switched path. If an alternate path exists, the broadcast interface will not be advertised to the broadcast network until label distribution protocol (LDP) is operational with all neighbors on the broadcast interface.

Abstract: An automated key transition method is executed by a node in a network. The network includes a set of nodes utilizing a current key identifier. A key identifier specifies an authentication protocol and an authentication key for use in the authentication of intermediate-system to intermediate-system (IS-IS) protocol data units. The method includes a set of steps including receiving a message at the node, where, the message includes a most recent key identifier to replace the current key identifier, verifying whether all reachable nodes in the set of nodes have advertised the most recent key identifier, continuing authentication using the current key identifier until all reachable nodes in the set of nodes have been verified to advertise the most recent key identifier, and switching authentication at the node to use the most recent key identifier upon verification that all reachable nodes in the set of nodes have advertised the most recent key identifier.

Abstract: A network element of a communications network includes a fresh route queue, a stale route queue, a Routing Information Base (RIB), a network interface, and a routing protocol module. The network interface receives link state information from other network elements. The routing protocol module determines a plurality of routes from the link state information. The routing protocol module identifies among the plurality of routes a subset of routes that are present in the stale route queue, adds the subset of routes to the fresh route queue, and deletes the subset of routes from the stale route queue. The routing protocol module then remove routes in the RIB that correspond to any routes remaining in the stale route queue, and moves the routes from the fresh route queue to the stale route queue. Related methods for managing routes in a RIB of a network element are disclosed.

Abstract: An automated key transition method is executed by a node in a network. The network includes a set of nodes utilizing a current key identifier provided by a group key management server or provisioned manually. A key identifier specifies an authentication protocol and an authentication key for use in the authentication of intermediate-system to intermediate-system (IS-IS) protocol data units. The method includes receiving a message from the group key management server that includes a most recent key field to replace the current key identifier, advertising the most recent key identifier to all reachable nodes, verifying whether all reachable nodes have advertised the most recent key identifier, continuing authentication using the current key identifier until all reachable nodes have been verified to advertise the most recent key identifier, and switching authentication to use the most recent key identifier upon verification that all reachable nodes have advertised the most recent key identifier.

Abstract: A network element is configured to reduce the synchronization costs for implementing Open Shortest Path First (OSPF) Nonstop routing (NSR). The reduced synchronization costs are achieved by reducing the number of acknowledgement messages that are needed to be sent though reliable inter-process communication (IPC) between the active OSPF instance and the standby OSPF instance. The number of acknowledgement messages is reduced by tracking the link state advertisements (LSAs) that have been sent by the active OSPF instance to the standby OSPF instance and by the standby OSPF replying with an acknowledgement of only the last LSA in a group of LSAs received from the active OSPF instance, where the group can have a variety of boundaries such as a group of LSAs in an IPC message. This avoids having a significant number of acknowledgement messages sent through the IPC.

Abstract: Open Shortest Path First (OSPF) Non-stop Routing (NSR) with frozen standby LSDB is described. A network element includes a first OSPF instance initially acting as an active OSPF instance and a second OSPF instance initially acting as a standby OSPF instance. The second OSPF instance receives LSAs from the first OSPF instance and installs the LSAs in its LSDB. The LSAs in the LSDB are only aged by the active OSPF instance. If and when the second OSPF instance becomes the active OSPF instance, the second OSPF instance then ages the LSAs in the LSDB and processes each of the LSAs according to the aging of that LSA, where processing includes one of purging that LSA and refreshing that LSA.

Abstract: A method is executed by a router for improved Intermediate System to Intermediate System (IS-IS) protocol and Neighbor Discovery (ND) protocol execution to avoid dropped data traffic caused by Media Access Control (MAC) address resolution for next hops of routes determined by the IS-IS protocol. An IS-IS adjacency is established between the router and a neighbor router over a link, where a MAC address for the neighbor router is received from the neighbor router. A routing information base (RIB) is updated to include the neighbor router as a next hop for at least one destination address by the IS-IS process. The MAC address of the neighbor router is provided to an ND process to update the RIB, a forwarding information base (FIB) or L2 forwarding table of at least one line card of the router to include the MAC address of the neighbor router in response to the providing of the MAC address to the ND process.

Abstract: A network element is configured for synchronizing dynamic OSPF data between an active OSPF instance and a backup OSPF instance. Upon an OSPF data synchronization event, the active OSPF instance synchronizes dynamic OSPF data with the backup OSPF instance. Upon receiving the dynamic OSPF data, the backup OSPF instance determines whether the requisite data structures exist. If the data structures do not exist, the backup OSPF instance returns a NACK to the active OSPF instance and clears its dynamic OSPF data. Responsive to receiving the NACK, the active OSPF instance resynchronizes its dynamic OSPF data with the backup OSPF instance.

Abstract: OSPF NSR with link derivation synchronization is described. When a network element having an active OSPF instance and a standby OSPF instance attempts to create a FULL adjacency with a neighbor network element using a neighbor data structure of the active OSPF instance, and if and when a switch causes the second OSPF instance to act as the active OSPF instance, neighbor information is retrieved from the LSAs of the standby OSPF instance and a link is derived between the network element and the neighbor network element based on the retrieved neighbor information. In one embodiment, the standby OSPF instance retrieves virtual neighbor information from its LSAs and derives a virtual link between the network element and the neighbor network element based on the retrieved virtual neighbor information without having to synchronize the neighbor information between the active and standby OSPF instance.

Abstract: A method in a router for participating in computation of a constraint-based label switched path (LSP) that spans a plurality of areas to reach a destination is described. The method comprises computing a path segment that meets a set of one or more constraints to at least one border router of the first area, transmitting a path computation request message to a path computation element in a second one of the plurality of areas, receiving a path computation reply message from the path computation element, and stitching at least one of the set of computed path segments that are specified in the path computation reply message with the path segment computed by the router to form at least part of the constraint-based LSP.

Abstract: A method in a router for initiating fast flooding based fast convergence to recover from a network failure is disclosed. The method also starts with detecting a network failure. Responsive to the detected network failure, the router floods a layer 2 fast failure notification message out a set of one or more interfaces of the router. The fast failure notification message includes information that identifies the network failure and indicates to a router that receives the fast failure notification message to flood the fast failure notification message out its interfaces that are not blocked by a spanning tree protocol (STP) independently of updating its routing table to reflect the network failure. The method continues with the router updating a routing table to reflect the network failure.

Abstract: Methods and apparatus for a network element to handle LSID collisions to prevent different LSAs associated with different routes from sharing the same LSID. According to one embodiment, responsive to determining that a tentative LSID that is generated for a first route that is being added collides with an LSID that is assigned to an LSA for a second route, and that one of the first and second routes is a host route, the host route is suppressed. If the first route is the host route, suppressing includes not originating an LSA for the first route. If the second route is the host route, suppressing includes purging the LSA for the second route and not originating an LSA for the second route. Although the host route is suppressed, network reachability of the range subsuming the host route is provided through the route that is not the host route.

Abstract: Computing a constraint-based label switched path (LSP) that spans multiple areas is described. In one embodiment, a router in a first one of the multiple areas computes a path segment that meets a set of one or more constraints to at least one border router of the first area that lies in a path necessary to reach the destination. The router transmits a path computation request message to a path computation element (PCE) in a second one of the areas, which includes a set of one or more attributes for each computed path segment that are used by the PCE to compute one or more path segments towards the destination of the constraint-based LSP. The router receives a path computation reply message from the PCE that specifies a set of one or more computed path segments that meet the set of constraints and that were computed by one or more PCEs downstream from the router.

Abstract: A method, performed by a transmitter network element utilizing a link state routing protocol which has a maximum link state message size. The method is for providing information to avoid a disruption in data forwarding that would result from a receiver network element performing preferred route computations based on an incomplete set of link state messages. The method includes generating a complete set of link state messages having information indicating that the link state messages are the complete set of the link state messages. The complete set of the link state messages are collectively coherent with a link state of the transmitter network element. The method also includes transmitting the complete set of the link state messages, and the information indicating that the link state messages are the complete set of the link state messages, to a network. Also disclosed are transmitter network elements, receiver network elements, and methods thereof.

Abstract: A router detects a network failure and responsive to that failure, floods a fast failure notification message out a set of interfaces of the router. The fast failure notification message includes information that identifies the network failure and includes as its source MAC (Media Access Control) address a MAC address that is assigned to an interface that is coupled with the detected network failure and is not part of the set of interfaces of the router. The router updates a routing table to reflect the network failure. The flooding of the fast failure notification message is performed prior to completion of the routing table update to reflect the network failure.

Abstract: A network element that has a broadcast interface to a broadcast network becoming operational determines whether at least one alternate path exists to the broadcast network. The broadcast interface is to carry traffic on a label switched path. If an alternate path exists, the broadcast interface will not be advertised to the broadcast network until label distribution protocol (LDP) is operational with all neighbors on the broadcast interface.

Abstract: A network element is configured for open shortest path first (OSPF) non-stop routing (NSR) with reliable flooding. An active OSPF instance determines to flood a link-state advertisement (LSA). The LSA is synchronized with a backup OSPF instance including storing the LSA with a status that indicates that flooding is pending. The active OSPF instance attempts to reliably flood the LSA to a set of adjacent network elements of the flooding scope of the LSA. If flooding of the LSA completes, the active OSPF instance causes the backup OSPF instance to alter the status of the LSA to indicate that flooding is complete. If the backup OSPF instance becomes the currently active OSPF instance prior to the flooding of the LSA completing, then the new active OSPF instance attempts to reliably flood the LSA.

Abstract: A network element that has a broadcast interface to a broadcast network becoming operational determines whether at least one alternate path exists to the broadcast network. The broadcast interface is to carry traffic on a label switched path. If an alternate path exists, the broadcast interface will not be advertised to the broadcast network until label distribution protocol (LDP) is operational with all neighbors on the broadcast interface.

Abstract: A network element implementing Multiprotocol Label Switching to automatically create an optimal deterministic back-up Label Switch Path (LSP) that is maximally disjointed from a primary LSP to provide a reliable back up to the primary LSP. The network element receives a request for a generation of an LSP, determines that the request for the generation of the LSP is for the back-up LSP, locates each link of the primary LSP in a traffic engineering database, modifies each link of the primary LSP to have a link cost significantly greater than an actual link cost to discourage use of each link of the primary LSP in the back-up LSP, executes a Constrained Shortest Path First algorithm to obtain the back-up LSP, wherein the back-up LSP has a maximum disjointedness from the primary LSP due to a modified cost of each link of the primary LSP, and returns the back-up LSP.

Abstract: Fast flooding based fast convergence to recover from a network failure. A router detects a network failure, and responsive to that failure, transmits a fast failure notification message to a set of one or more routers. The fast failure notification message includes information that identifies the network failure and also indicates that the fast failure notification message is to be flooded by the set of routers independently of convergence. The router updates a routing table to reflect the network failure. The transmission of the fast failure notification message is performed prior to completion of the routing table update to reflect the network failure.