Patent ID: 8335852

Claim:
A contact destination information registration method employed in a network system that includes a plurality of nodes and employs a distributed hash table, wherein when registering contact destination information corresponding to a predetermined node address in the distributed hash table, the node first performs a first request operation of looking up a value associated with a key that is a hash value of the node address in the distributed hash table, and, if no value associated with the key is registered in the distributed hash table, registering provisional contact destination information in the distributed hash table so as to be associated with the key and acquiring a first registration time of the provisional contact destination information, but, if any value associated with the key is registered in the distributed hash table, acquiring a second registration time of the value registered, and then performs a second request operation of registering true contact destination information in the distributed hash table so as to be associated with the key, the second request operation including transmitting the true contact destination information and the first or second registration time acquired by the first request operation, wherein the second request is granted if the first or second registration time of the value registered in the distributed hash table so as to be associated with the key after a last update of the distributed hash table coincides with the first or second registration time acquired by the first request operation.