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How BGP Prefix Independent Convergence Work?

 
Summary

This section talks about how BGP Prefix Independent Convergence (PIC) improves BGP convergence on network node failures.

BGP PIC creates and stores primary and backup paths for the indirect next hop on the Routing Engine and also provides the indirect next hop route information to the Packet Forwarding Engine. When a network node failure occurs, the Routing Engine signals the Packet Forwarding Engine that an indirect next hop has failed, and that the traffic is rerouted to a pre-calculated equal-cost or backup path without modifying BGP prefixes. Routing the traffic to the destination prefix continues by using the backup path to reduce traffic loss until the global convergence through BGP is resolved.

BGP convergence is applicable to both core and edge network node failures. In the case of BGP PIC Core, adjustments to the forwarding chains are made as a result of node or core link failures. In the case of BGP PIC Edge, adjustments to the forwarding chains are made as a result of edge node or edge link failures.