Which two design solutions ensure sub 50 msec of the convergence time after a link failure in the network? (Choose two)

BFD accelerates failure detection but is only a detection mechanism; the actual convergence speed still depends on the reaction of the routing protocol, which alone does not guarantee sub-50ms restoration.

Ti-LFA (Topology Independent Loop-Free Alternate) pre-computes guaranteed loop-free backup paths for every protected prefix, enabling immediate sub-50ms traffic rerouting the moment a failure is detected without any routing protocol reconvergence delay.

Reducing the BGP scan timer improves BGP convergence speed but does not provide pre-computed local repair, so restoration times typically remain well above 50ms.

MPLS Fast Reroute pre-installs backup LSPs (bypass or detour tunnels) in the forwarding plane so that the headend LSR can locally repair the path within milliseconds of a link failure, well within the 50ms threshold.

IGP fast hellos shorten failure detection time but do not install pre-computed backup paths, meaning the network must still wait for full SPF recalculation and RIB/FIB updates before traffic is restored.