Which BGP feature provides fast convergence?

BGP PIC pre-computes and pre-installs backup next-hop entries into the Forwarding Information Base (FIB) at the time the primary path is installed, so when a primary path fails the data plane can immediately switch to the backup path independent of BGP control plane reconvergence. This reduces failover time from several seconds down to sub-second or millisecond ranges for all affected prefixes simultaneously.

BGP-EVPN is a control plane solution for Ethernet VPN services and data center overlay networks and does not provide a general-purpose fast convergence mechanism for IP routing.

BGP FlowSpec is used to distribute traffic filtering and traffic engineering rules to routers for purposes such as DDoS mitigation and is not related to convergence speed.

BGP-LS distributes network topology and traffic engineering link-state information to external controllers such as path computation elements and does not accelerate BGP route failover.