Before sending a Neighbor Solicitation, an interface MUST join the all-nodes multicast address and the solicited-node multicast address of the tentative address. The former insures that the node receives Neighbor Advertisements from other nodes already using the address; the latter insures that two nodes attempting to use the same address simultaneously detect each other's presence.
To check an address, a node sends DupAddrDetectTransmits Neighbor
Solicitations, each separated by RetransTimer milliseconds. The
solicitation's Target Address is set to the address being checked,
the IP source is set to the unspecified address and the IP
destination is set to the solicited-node multicast address of the
target address.
If after (re)initialization the Neighbor Solicitation is the first message to be sent from an interface the node should delay sending the message.
When more than one node is trying to solicit for the same address at the same time,it helps to void race conditions
In order to improve the robustness of the Duplicate Address Detection algorithm, an interface MUST receive and process datagrams sent to the all-nodes multicast address or solicited-node multicast address of the tentative address while delaying transmission of the initial Neighbor Solicitation.
