This configuration command features an IPv6 Neighbor Discovery (ND) option (called Boot File URL (BFURL) option)

Enabling “Proxy ARP/ND for Single Aggregation (AG) VTEP Campus Deployments without EVPN” allows an aggregation VTEP to proxy reply to a VXLAN-encapsulated ARP request/NS when the ARP/NS target host is remote and the ARP/ND binding is already learned by the AG VTEP.

ARP and IPv6 Neighbor Discovery use a neighbor cache to store neighbor address resolutions. The capacity of the neighbor cache is determined by the resources and capabilities of the device platform. The neighbor cache capacity feature adds a means to specify a per-interface capacity for the neighbor cache. A neighboring device, through misconfiguration or maliciousness, can unfairly use a large number of address resolutions. This feature can help to mitigate this over-utilization.

RFC4191 describes an optional extension to Router Advertisement messages for communicating default router

Nd RA RFC4191