Abstract: A network element that acts as a hub in a hub and spoke topology is configured to limit the amount of topology and reachability information that is advertised to a set of one or more remote network elements that act as one or more spokes in the hub and spoke topology in a same routing area. The network element generates a set of one or two link state advertisements (LSAs) to advertise over an interface that connects at least one of the set of remote network elements to the network element, wherein the set of LSAs includes information that describes a connection to the set of remote network elements and one or more aggregate routes. The network element advertises, during a database exchange process with the one of the set of remote network elements, the set of LSAs to the one of the set of remote network elements.

Abstract: A network element that acts as a hub in a hub and spoke topology is configured to limit the amount of topology and reachability information that is advertised to a set of one or more remote network elements that act as one or more spokes in the hub and spoke topology in a same routing area. The network element generates a set of one or two link state advertisements (LSAs) to advertise over an interface that connects at least one of the set of remote network elements to the network element, wherein the set of LSAs includes information that describes a connection to the set of remote network elements and one or more aggregate routes. The network element advertises, during a database exchange process with the one of the set of remote network elements, the set of LSAs to the one of the set of remote network elements.

Abstract: A network element that acts as a hub in a hub and spoke topology is configured to limit the amount of topology and reachability information that is advertised to a set of one or more remote network elements that act as one or more spokes in the hub and spoke topology in a same routing area. The network element generates a set of one or two link state advertisements (LSAs) to advertise over an interface that connects at least one of the set of remote network elements to the network element, wherein the set of LSAs includes information that describes a connection to the set of remote network elements and one or more aggregate routes. The network element advertises, during a database exchange process with the one of the set of remote network elements, the set of LSAs to the one of the set of remote network elements.

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 first network element that receives an appropriation message from a second network element that indicates a target address which the second network element intends to appropriate for its use. In response to the appropriation message, the first network element broadcasts a discovery message to a plurality of network elements on the network to request a link-layer address in association with the first target address. The first network element receives a discovery response from the second network element with the first target address and the link-layer address of the second network element. Then the first network element updates a neighbor cache to include a pre-cached neighbor cache entry associating the link-layer address to the first target address. This prevents one or more future neighbor cache misses associated with the first target address.

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 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 first network element that receives an appropriation message from a second network element that indicates a target address which the second network element intends to appropriate for its use. In response to the appropriation message, the first network element broadcasts a discovery message to a plurality of network elements on the network to request a link-layer address in association with the first target address. The first network element receives a discovery response from the second network element with the first target address and the link-layer address of the second network element. Then the first network element updates a neighbor cache to include a pre-cached neighbor cache entry associating the link-layer address to the first target address. This prevents one or more future neighbor cache misses associated with the first target address.

Abstract: A network element that acts as a hub in a hub and spoke topology is configured to limit the amount of topology and reachability information that is advertised to a set of one or more remote network elements that act as one or more spokes in the hub and spoke topology in a same routing area. The network element generates a set of one or two link state advertisements (LSAs) to advertise over an interface that connects at least one of the set of remote network elements to the network element, wherein the set of LSAs includes information that describes a connection to the set of remote network elements and one or more aggregate routes. The network element advertises, during a database exchange process with the one of the set of remote network elements, the set of LSAs to the one of the set of remote network elements.

Abstract: A first network element that receives an appropriation message from a second network element that indicates a target address which the second network element intends to appropriate for its use. In response to the appropriation message, the first network element broadcasts a discovery message to a plurality of network elements on the network to request a link-layer address in association with the first target address. The first network element receives a discovery response from the second network element with the first target address and the link-layer address of the second network element. Then the first network element updates a neighbor cache to include a pre-cached neighbor cache entry associating the link-layer address to the first target address. This prevents one or more future neighbor cache misses associated with the first target address.

Abstract: A first network element that receives an appropriation message from a second network element that indicates a target address which the second network element intends to appropriate for its use. In response to the appropriation message, the first network element broadcasts a discovery message to a plurality of network elements on the network to request a link-layer address in association with the first target address. The first network element receives a discovery response from the second network element with the first target address and the link-layer address of the second network element. Then the first network element updates a neighbor cache to include a pre-cached neighbor cache entry associating the link-layer address to the first target address. This prevents one or more future neighbor cache misses associated with the first target address.

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: 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 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: A network element attempts to bring up an adjacency with a neighbor using a neighbor state machine (NSM) of an active OSPF instance, including: maintaining a neighbor data structure only in the active instance prior to the NSM transitioning to a Full state, delaying synchronization from the active instance to a standby OSPF instance of the neighbor data structure, maintaining tracking information of the NSM in only the active instance; installing LSAs received from the neighbor in both the LSDB of the active and standby instances, and, if and when the NSM of the active instance transitions to the Full state and all LSAs requested from the neighbor during database exchange are ensured to synchronize to the standby instance's LSDB, synchronizing from the active instance to the standby instance data item(s) of the neighbor data structure.

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 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.