TP-Link T1700G-28TQ User Manual page 31

packet header, on the local link. After the source node receives the neighbor advertisement,
the source node and destination node can communicate.
Neighbor advertisement messages are also sent when there is a change in the link-layer
address of a node on a local link.
Address Resolution
The address resolution procedure is as follows:
Node A multicasts an NS message. The source address of the NS message is the IPv6

address of an interface of node A and the destination address is the solicited-node multicast
address of node B. The NS message contains the link-layer address of node A.
After receiving the NS message, node B judges whether the destination address of the

packet corresponds to the solicited-node multicast address. If yes, node B can learn the
link-layer address of node A, and unicasts an NA message containing its link-layer address.
Node A acquires the link-layer address of node B from the NA message.

Neighbor Reachability Detection
After node A acquires the link-layer address of its neighbor node B, node A can verify whether
node B is reachable according to NS and NA messages.
Node A sends an NS message whose destination address is the IPv6 address of node B.

If node A receives an NA message from node B, node A considers that node B is reachable.

Otherwise, node B is unreachable.
Duplicate Address Detection
Neighbor solicitation messages are used in the stateless autoconfiguration process to verify
the uniqueness of unicast IPv6 addresses before the addresses are assigned to an interface.
After node A acquires an IPv6 address, it will perform duplicate address detection (DAD) to
determine whether the address is being used by other nodes (similar to the gratuitous ARP
function of IPv4). DAD is accomplished through NS and NA messages. The DAD procedure is
as follows:
Node A sends an NS message whose source address is the unassigned address :: and

destination address is the corresponding solicited-node multicast address of the IPv6
address to be detected. The NS message contains the IPv6 address.
If node B uses this IPv6 address, node B returns an NA message. The NA message

contains the IPv6 address of node B.
Node A learns that the IPv6 address is being used by node B after receiving the NA

message from node B. Otherwise, node B is not using the IPv6 address and node A can
use it.
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