5.1 Neighbor Discovery Operation

Answer 1

ND provides address resolution, router discovery, and redirection services for IPv6 using ICMPv6. ICMPv6 ND uses five ICMPv6 messages to perform these services:

Neighbor solicitation messages
Neighbor advertisement messages
Router solicitation messages
Router advertisement messages
Redirect message
Neighbor solicitation and neighbor advertisement messages are used for device-to-device messaging such as address resolution (similar to ARP for IPv4). Devices include both host computers and routers.

Router solicitation and router advertisement messages are for messaging between devices and routers. Typically router discovery is used for dynamic address allocation and stateless address autoconfiguration (SLAAC).

Note: The fifth ICMPv6 ND message is a redirect message which is used for better next-hop selection.