Abstract: Techniques are described for synchronizing state information between a plurality of control units. A router, for example, is described that includes a primary control unit and a standby control unit. The primary control unit maintains router resources to ensure operation of the router. To ensure operation, the primary control unit receives state information from the router resources and maintains the state information for consumers, i.e. router resources that require or “consume” state information. Prior to updating the consumers with the state information, the primary control unit synchronizes the state information with the standby control unit. In the event the primary control unit fails, the standby control unit assumes control of the router resources. Upon assuming control, the standby control unit resumes updating the consumers with state information without having to “relearn” state information, e.g., by way of power cycling the router resources to a known state.

Abstract: State information is synchronized between a plurality of routing engines in a multi-chassis router according to a synchronization gradient. An example multi-chassis router is described that includes a primary routing engine and a standby routing engine in each chassis. According to the synchronization gradient, the primary routing engine of a control node updates state information on the standby routing engine of the control node prior to updating the primary routing engines of the other chassis. The primary routing engines of the other chassis update state information in respective standby routing engines prior to updating state information in consumers. If a primary routing engine fails, the corresponding standby routing engine assumes control of the primary routing engine's duties. Upon assuming control, a standby routing engine resumes updating state information without having to resend state information or interrupt packet forwarding.

Abstract: A multi-chassis network device sends state information to internal consumers within the multi-chassis device via a hierarchical distribution. As one example, a primary master routing engine within a control node of a multi-chassis router forwards state information to local routing engines within other chassis, which in turn distribute the state information to consumers on each chassis. Each local routing engine defers sending acknowledgement to the master routing engine until acknowledgements have been received from all consumers serviced by the local routing engine. Embodiments of the invention may reduce control plane data traffic and convergence times associated with distribution of state updates in the multi-chassis network device.

Abstract: State information is synchronized between a plurality of routing engines in a multi-chassis router according to a synchronization gradient. An example multi-chassis router is described that includes a primary routing engine and a standby routing engine in each chassis. According to the synchronization gradient, the primary routing engine of a control node updates state information on the standby routing engine of the control node prior to updating the primary routing engines of the other chassis. The primary routing engines of the other chassis update state information in respective standby routing engines prior to updating state information in consumers. If a primary routing engine fails, the corresponding standby routing engine assumes control of the primary routing engine's duties. Upon assuming control, a standby routing engine resumes updating state information without having to resend state information or interrupt packet forwarding.

Abstract: State information is synchronized between a plurality of routing engines in a multi-chassis router according to a synchronization gradient. An example multi-chassis router is described that includes a primary routing engine and a standby routing engine in each chassis. According to the synchronization gradient, the primary routing engine of a control node updates state information on the standby routing engine of the control node prior to updating the primary routing engines of the other chassis. The primary routing engines of the other chassis update state information in respective standby routing engines prior to updating state information in consumers. If a primary routing engine fails, the corresponding standby routing engine assumes control of the primary routing engine's duties. Upon assuming control, a standby routing engine resumes updating state information without having to resend state information or interrupt packet forwarding.

Abstract: In general, techniques are described for flooding VPLS traffic with a network device according to flood groups. The network device resides within a layer 3 (L3) network and includes a control unit that executes a virtual private LAN service (VPLS) protocol that enables a VPLS domain to operate over the L3 network. The network device further includes a plurality of packet forwarding engines, each of which include a plurality of interface cards that receive a layer 2 (L2) message originating from the L2 network. The packet forwarding engines associate the L2 packet with a configurable flood group, wherein the flood group defines criteria to determine which messages to associate to the flood group and indicates a set of the interface cards for forwarding the associated messages. The packet forwarding engines further flood the L2 packet via each interface card indicated by the associated flood group.

Abstract: Techniques are described for synchronizing state information between a plurality of control units. A router, for example, is described that includes a primary control unit and a standby control unit. The primary control unit maintains router resources to ensure operation of the router. To ensure operation, the primary control unit receives state information from the router resources and maintains the state information for consumers, i.e. router resources that require or “consume” state information. Prior to updating the consumers with the state information, the primary control unit synchronizes the state information with the standby control unit. In the event the primary control unit fails, the standby control unit assumes control of the router resources. Upon assuming control, the standby control unit resumes updating the consumers with state information without having to “relearn” state information, e.g., by way of power cycling the router resources to a known state.

Abstract: A forwarding component of a routing node floods copies of a packet to a plurality of next hops associated with the same layer two (L2) network as an interface on which the packet was received. The plurality of next hops excludes a next hop that corresponds to the interface that received the packet. The forwarding component requires that forwarding information installed by a control unit specify the plurality of next hops to which to flood the copies of the packet, and the forwarding component is not capable of deriving the plurality of next hops to which to flood the copies of the packet from a single flooding next hop identifier after the packet is received. Prior to receiving the packet, a flooding next hop control module derives the plurality of next hops based on the flooding next hop and installs the derived next hops into the forwarding information.

Abstract: A multi-chassis network device sends state information to internal consumers within the multi-chassis device via a hierarchical distribution. As one example, a primary master routing engine within a control node of a multi-chassis router forwards state information to local routing engines within other chassis, which in turn distribute the state information to consumers on each chassis. Each local routing engine defers sending acknowledgement to the master routing engine until acknowledgements have been received from all consumers serviced by the local routing engine. Embodiments of the invention may reduce control plane data traffic and convergence times associated with distribution of state updates in the multi-chassis network device.