Patent ID: 8533779

Claim:
A method for preventing IP address from unexpected dispersion when using point-to-point protocol, the method comprising: starting and initializing a PPP session; performing a PPP LCP negotiation between a terminal of customers and the PPP session, in which times of successful PPP LCP negotiation in PPP LCP negotiation phase is limited, wherein the times of successful PPP LCP negotiation refers to the times that a PPP LCP state machine enters an “OPENED” state; if the times of the successful PPP LCP negotiation exceeds an allowed maximum times of successful PPP LCP negotiation, activating the PPP session termination procedure, wherein performing a PPP LCP negotiation between a terminal of customers and the PPP session includes: determining whether LCP negotiation is successful; adding 1 to the count of successful LCP negotiation if the LCP negotiation is determined to be successful; otherwise, terminating the PPP session; and determining whether the count of successful LCP negotiation exceeds an allowed maximum times so that the PPP authentication could be activated if not or the PPP session could be activated if so; performing a PPP authentication, in order to assign a IP address from the AAA client only once, sending an authentication request to a AAA client only once by checking, before sending the authentication request, whether the authentication request has ever been sent to the AAA client; performing a PPP IPCP negotiation between the PPP and the terminal of customers, in which an accounting-start request is sent only once by checking, before sending the accounting-start request, whether the accounting-start request has ever been sent, and limiting times of successful PPP IPCP negotiation, wherein the times of successful PPP IPCP negotiation refers to the times that a PPP IPCP state machine enters an “OPENED” state; if the times of the successful PPP IPCP negotiation exceeds an allowed maximum times of successful PPP IPCP negotiation, activating the PPP session termination procedure, wherein performing the PPP IPCP negotiation between the PPP and the terminal of customers includes: activating the IPCP negotiation procedure; determining whether the IPCP negotiation is successful or not; adding 1 to the count of successful IPCP negotiation if the IPCP negotiation is determined to be successful; determine whether the count of successful IPCP negotiation exceeds an allowed maximum times or not; checking a sending accounting-start request flag if the count of successful IPCP negotiation does not exceed the allowed maximum times; otherwise, terminating the PPP session; determining whether a sending accounting-start request has been already sent; and setting “SENT” for the sending accounting-start request flag at first and sends accounting-start request to the AAA client if the sending accounting-start request has not been sent; otherwise, not proceeding with any process; activating the PPP session termination procedure and releasing the IP address after the PPP session is terminated.