Patent ID: 8724500

Claim:
A method of duplicate address detection (DAD) proxy, the method comprising: obtaining a DAD-neighbor solicitation (DAD-NS) message, the DAD-NS message comprising address information sent by a subscriber and access location information corresponding to the address information, wherein the address information comprises at least an IP address to be detected and a link layer address; comparing an obtained DAD-NS message with locally stored DAD information, and adding the DAD-NS message to the locally stored DAD information when it is determined, according to a comparison result, that the IP address to be detected is not duplicate; when it cannot be determined, according to a comparison result, whether the IP address to be detected is duplicate or not, initiating, according to the address information comprised in the locally stored DAD information after comparison, an unreachability detection to the IP address to be detected to determine whether the IP address to be detected is duplicate, wherein the DAD information comprises address information and access location information of at least one subscriber; wherein when it cannot be determined, according to a comparison result, whether the IP address to be detected is duplicate or not, the initiating, according to the address information comprised in the locally stored DAD information after comparison, an unreachability detection to the IP address to be detected to determine whether the IP address to be detected is duplicate comprises: if the comparison result indicates that the IP address to be detected and the access location information comprised in the obtained DAD-NS message are the same as those comprised in the DAD information, but the link layer address is different, or if the comparison result indicates that the IP address to be detected comprised in the obtained DAD-NS message is the same as that comprised in the DAD information, but the access location information and the link layer address are different, or if the comparison result indicates that the link layer address and the IP address to be detected that are comprised in the obtained DAD-NS message are the same as those comprised in the DAD information, but the access location information is different, initiating, according to the address information comprised in the locally stored DAD information after comparison, the unreachability detection to the IP address to be detected to determine whether the IP address to be detected is duplicate; if the unreachability detection succeeds, determining that the IP address to be detected is duplicate and sending a DAD-neighbor advertisement (DAD-NA) message to the subscriber; if the unreachability detection fails, determining that the IP address to be detected is not duplicate.