System Administration Guide: IP Services

Comparison With IPv4

The IPv6 neighbor discovery protocol corresponds to a combination of the IPv4 protocols Address Resolution Protocol (ARP), ICMP Router Discovery, and ICMP Redirect. IPv4 does not have a generally agreed on protocol or mechanism for neighbor unreachability detection. However, host requirements do specify some possible algorithms for dead gateway detection. Dead gateway detection is a subset of the problems that neighbor unreachability detection solves.

The neighbor discovery protocol provides a multitude of improvements over the IPv4 set of protocols.