Method and apparatus for allocating and obtaining IP address

摘要

A switch sends an authentication request message to a client at intervals of a preset duration. A response message sent by the client is received. The response message carries authentication information of a user carried on the client. An authentication message is sent to a server according to the response message. An authentication reply message sent by the server is received. The authentication reply message carries information about an authentication domain authorized by the server to the user. It is determined, according to the authentication reply message, whether the authentication domain of the user is changed. If the authentication domain of the user is changed, an authentication domain change message is sent to the client according to the authentication reply message, so that the client obtains an IP address again.