Abstract: A communication network constructed by a plurality of packet transfer apparatuses each having a function of autonomously setting routing information in a routing table. Each of the packet transfer apparatuses has a function of setting routing information designated by a management apparatus into a routing table and places priority on the routing information designated by the management apparatus over the routing information autonomously set, thereby to transferring received packets from a user who has reserved a bandwidth through an optimum route in which the bandwidth can be guaranteed.

Abstract: In an Internet roaming service, an amount of user information transferred between an authentication server of an uncontracted company which a user does not have a contract with and an authentication server of a contracted company which the user has a contract with is reduced, thereby a load applied on a backbone is reduced. When a user makes connection to the uncontracted company, the authentication server of the uncontracted company registers the user information of the user with a user information table out of the user information received from the user and the information contained in an authentication response received from the contracted company. When the user makes a connection request again to the access server of the uncontracted company, the authentication server of the uncontracted company performs authentication for the uncontracted user by using the information registered with the user information table of its own server.