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: 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 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 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: 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: 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: 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: Techniques for security association management on a home and foreign agent are described. In one embodiment, in response to a first mobile network registration request from a mobile node, a remote authentication facility is accessed to retrieve a security association for the mobile node for authenticating and providing a first network connectivity to the mobile node, wherein the security association is associated with a lifespan. The security association is inserted in a local security association database (SADB) to create a security association entry, wherein the security association entry includes the lifespan. A second mobile network registration request from the mobile node after the first connectivity is terminated is received and the security association entry in the local SADB that corresponds to the mobile node is used to provide authentication of the mobile node without having to access the remote authentication facility again if the lifespan associated with the security association entry is valid.

Abstract: Techniques for Mobile IP bulk registration revocation are described herein. According to one embodiment, a first mobile agent of a mobile IP network sends a registration revocation message to a second mobile agent of the mobile IP network. The registration revocation message includes information identifying multiple home IP addresses of multiple mobile nodes whose registrations are to be revoked. In response to the registration revocation, the second mobile agent terminates bindings of services associated with multiple mobile nodes identified by the multiple home IP addresses and sends an acknowledgement message to the first mobile agent. Other methods and apparatuses are also described.

Abstract: The present invention elects an area border router from a plurality of potential area border routers by determining a full set of all areas attached to a router. A determination is made as to a full set of area pairs from the determined full set of areas. Routers are identified in a first area of the determined full set of areas that are reachable through an intra-area route in the first area, and routers are identified in a second area of the determined full set of areas that are reachable through an intra-area route in the second area. If there is a router that is unreachable through either an intra-area route in the first area or an intra-area route in the second area, then declare the first router to be an area border router, else new first and second areas are selected.

Abstract: A method and apparatus for managing network communication that operate on the idea that if a new neighboring node is already reachable as represented in a shortest path data structure that the local node consults, there is no urgency in doing a full database synchronization between the local node and the neighboring node. The present invention delays database synchronization as long as possible to reduce unnecessary OSPF packets traversing communication links between nodes of the network. Since unsynchronized neighbors remain in 2-way state, OSPF updates are not flooded over the corresponding interfaces.

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: A method and apparatus for hierarchical redundancy for a distributed control plane. In one embodiment of the invention, control plane processes are distributed among a plurality of processing entities including an active primary control processing entity and multiple secondary processing entities. Each of the secondary processing entities performs a dual role; an active role and a standby role. An application redundancy manager (ARM) instantiated on the active primary control processing entity manages the redundancy services for the secondary processing entities. For each secondary processing entity, the ARM selects one of the secondary processing entities to act as a backup for another one of the secondary processing entities. Upon a failure of one of the secondary processing entities, the ARM causes the secondary processing entity backing up the failed secondary processing entity to transition its standby role to an active role regarding the services provided by the failed secondary processing entity.

Abstract: A method and apparatus for a distributed control plane. In one embodiment of the invention, a primary control card distributes control plane process instances among one or more secondary cards, including a secondary control card and/or one or more Advanced Service Engine (ASE) cards. The primary control card associates particular control messages with particular control plane process instances. Upon a line card receiving a control message that is associated with a particular control plane instance, the line card forwards the control message directly to that particular control plane instance.

Abstract: A method and apparatus for a distributed control plane. In one embodiment of the invention, a primary control card distributes control plane process instances among one or more secondary cards, including a secondary control card and/or one or more Advanced Service Engine (ASE) cards. The primary control card associates particular control messages with particular control plane process instances. Upon a line card receiving a control message that is associated with a particular control plane instance, the line card forwards the control message directly to that particular control plane instance.

Abstract: A method and apparatus for hierarchical redundancy for a distributed control plane. In one embodiment of the invention, control plane processes are distributed among a plurality of processing entities including an active primary control processing entity and multiple secondary processing entities. Each of the secondary processing entities performs a dual role; an active role and a standby role. An application redundancy manager (ARM) instantiated on the active primary control processing entity manages the redundancy services for the secondary processing entities. For each secondary processing entity, the ARM selects one of the secondary processing entities to act as a backup for another one of the secondary processing entities. Upon a failure of one of the secondary processing entities, the ARM causes the secondary processing entity backing up the failed secondary processing entity to transition its standby role to an active role regarding the services provided by the failed secondary processing entity.

Abstract: Techniques for security association management on a home agent and a foreign agent are described herein. In one embodiment, in response to a first mobile network registration request from a mobile node, a remote authentication facility is accessed to retrieve a security association for the mobile node for authenticating and providing a first network connectivity to the mobile node, wherein the security association is associated with a lifespan. The security association is inserted in a local security association database to create a security association entry, wherein the security association entry includes the lifespan.

Abstract: Techniques for Mobile IP bulk registration revocation are described herein. According to one embodiment, a first mobile agent of a mobile IP network sends a registration revocation message to a second mobile agent of the mobile IP network. The registration revocation message includes information identifying multiple home IP addresses of multiple mobile nodes whose registrations are to be revoked. In response to the registration revocation, the second mobile agent terminates bindings of services associated with multiple mobile nodes identified by the multiple home IP addresses and sends an acknowledgement message to the first mobile agent. Other methods and apparatuses are also described.