Which ip verify unicast source reachable-via interface configuration prevents RPF from dropping packets when a route lookup fails even though the prefix exists in the routing table?

The ip verify unicast source reachable-via any command configures Unicast Reverse Path Forwarding (uRPF) to check if a packet's source IP address exists in the routing table, regardless of the ingress interface. This prevents RPF from dropping packets if the route lookup fails on the specific ingress interface, as long as a route to the source exists elsewhere in the routing table. ip verify unicast source reachable-via l2-src checks the Layer 2 source address, which is not relevant to IP RPF. ip verify unicast source reachable-via allow-default permits packets if a default route is the only match, but doesn't override the ingress interface check for specific routes. ip verify unicast source reachable-via rx strictly checks if the route to the source IP is reachable via the receiving interface, which is the default behavior and would still drop packets if the route exists but not via the ingress interface.