IPv6 Neighbor Discovery
NDP defines five ICMPv6 packet types:
- 路由器请求消息 Router Solicitation (Type 133) Hosts inquire with Router Solicitation messages to locate routers on an attached link. Routers which forward packets not addressed to them generate Router Advertisements immediately upon receipt of this message rather than at their next scheduled time.
- 路由器通告消息 Router Advertisement (Type 134) Routers advertise their presence together with various link and Internet parameters either periodically, or in response to a Router Solicitation message.
- 邻居请求消息 Neighbor Solicitation (Type 135)
- IPv4 ARP requset Neighbor solicitations are used by nodes to determine the link layer address of a neighbor, or to verify that a neighbor is still reachable via a cached link layer address.
- 邻居通告消息 Neighbor Advertisement (Type 136)
- IPv4 ARP response Neighbor advertisements are used by nodes to respond to a Neighbor Solicitation message.
- Redirect (Type 137) Routers may inform hosts of a better first hop router for a destination.