Dynamic IP address allocation system and method

• US 6,687,252 B1
• Filed: 06/12/2000
• Issued: 02/03/2004
• Est. Priority Date: 06/12/2000
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Cobo, Miguel, Tran, Hung, Bertrand, Jean-Francois, Hasan, Suhail
• Primary Examiner(s): CANGIALOSI, SALVATORE A
• Application Number:
  US09/592,096
• Time in Patent Office: 1,331 Days
• Field of Search: 370/329, 370/352, 370/401, 370/409, 370/437, 709/245
• US Class Current: 370/401
• CPC Class Codes: H04L 61/5061 Pools of addresses
• CPC Class Codes: H04W 76/10 Connection setup
• CPC Class Codes: H04W 8/26 Network addressing or numbering for mobility support
• CPC Class Codes: H04W 80/04 Network layer protocols, e.g. mobile IP [Internet Protocol]

Abstract

In a General Packet Radio Service (GPRS) network, a system and method of dynamically allocating an Internet Protocol (IP) address to a mobile terminal (MT) operating in the network. A Gateway GPRS Service Node (GGSN) requests IP addresses over the Gi interface from a Radius server in an IP-based network. A Conditional PDP Address (CPA) parameter is stored in the MT'"'"'s Home Location Register (HLR) as part of the user subscriber data, and is passed to the GGSN during the GPRS Attach procedure. The CPA parameter indicates whether the subscriber is entitled to a backup IP address in case of failure to obtain one over the Gi interface, and whether the MT is a user of a real-time application. A timer in the GGSN sets a maximum time period (Ti) that the GGSN will wait for a response from the server, and a counter (Ni) sets the maximum number of requests that are sent. A Network Access Server (NAS) in the GGSN sends a request for an IP address from the GGSN to the server, and determines whether Ti expires without receiving a response from the server. If no response is received, the GGSN allocates an IP address. A public IP address is allocated only if the MT is a user of a real-time application. Otherwise, a private IP address is allocated.

Claims

1. A method of dynamically allocating an Internet Protocol (IP) address to a mobile terminal operating in a General Packet Radio Service (GPRS) network, said GPRS network having a Serving GPRS Service Node (SGSN) serving the mobile terminal and a Gateway GPRS Service Node (GGSN) connecting the GPRS network to a server that allocates IP addresses in an IP-based network, said method comprising the steps of:

setting on a counter in the GGSN, a maximum number (Ni) of requests for an IP address that are to be sent from the GGSN to the server;

setting on a timer in the GGSN, a maximum time period (Ti) that the GGSN will wait for a response from the server after each request for an IP address is sent;

sending a sequence of requests for an IP address from the GGSN to the server, with each request being separated from the previous request by time period Ti, said sequence being halted if a response is received from the server within time period Ti after one of the requests is sent;

receiving in the GGSN, a response from the server that includes an IP address for the mobile terminal within time period Ti after one of the requests is sent; and

sending the IP address from the GGSN to the mobile terminal.

2. The method of claim 1 wherein the step of sending a sequence of requests for an IP address from the GGSN to the server includes unicasting each of the requests in the sequence from the GGSN to a different server.

3. The method of claim 1 wherein the step of sending a sequence of requests for an IP address from the GGSN to the server includes sending a sequence of requests from the GGSN to a Radius server.

4. The method of claim 1 wherein the step of sending a sequence of requests for an IP address from the GGSN to the server includes sending a sequence of requests from the GGSN to a Dynamic Host Configuration Protocol (DHCP) server.

5. The method of claim 1 further comprising the steps of:

determining that the GGSN did not receive a response from the server within time period Ti after a last request was sent; and

allocating an IP address from an internal pool in the GGSN.

6. The method of claim 1 further comprising updating timers in the GPRS network to reflect actual response times experienced by the GGSN when requesting IP addresses from the server.

7. The method of claim 6 wherein the step of updating timers in the GPRS network includes the steps of:

collecting statistics by the GGSN on the actual response time to receive responses from the server, how often time period Ti is exceeded, and how many requests are sent before a response is received;

determining by the GGSN an average number of requests (Nr) required to receive a response from the server, and an average time (Tr) to receive a response;

calculating by the GGSN a new setting for a T3 timer in the SGSN; and

sending the new setting for the T3 timer from the GGSN to the SGSN.

8. The method of claim 7 wherein the step of updating timers in the GPRS network also includes sending by the GGSN the new setting for the T3 timer to any SGSN in the GPRS network from which an MT is attempting to obtain an IP address.

9. A method of dynamically allocating an Internet Protocol (IP) address to a mobile terminal operating in a General Packet Radio Service (GPRS) network, said GPRS network having a Serving GPRS Service Node (SGSN) serving the mobile terminal and a Gateway GPRS Service Node (GGSN) connecting the GPRS network to a server that allocates IP addresses in an IP-based network, said method comprising the steps of:

receiving in the GGSN, information regarding whether the mobile terminal is authorized to receive a backup IP address if an IP address cannot be obtained from the server, and whether the mobile terminal is a user of a real-time application;

setting on a timer in the GGSN, a maximum time period (Ti) that the GGSN will wait for a response from the server after a request for an IP address is sent from the GGSN to the server;

sending a request for an IP address from the GGSN to the server;

determining that time period Ti expired without receiving in the GGSN, a response from the server that includes an IP address for the mobile terminal;

determining from the information in the GGSN whether the mobile terminal is authorized to receive a backup IP address;

upon determining that the mobile terminal is authorized to receive a backup IP address, determining from the information in the GGSN whether the mobile terminal is a user of a real-time application;

sending a public IP address from the GGSN to the mobile terminal upon determining that the mobile terminal is a user of a real-time application; and

sending a private IP address from the GGSN to the mobile terminal upon determining that the mobile terminal is not a user of a real-time application.

10. A method of dynamically allocating an Internet Protocol (IP) address to a mobile terminal operating in a General Packet Radio Service (GPRS) network, said GPRS network having a Serving GPRS Service Node (SGSN) serving the mobile terminal and a Gateway GPRS Service Node (GGSN) connecting the GPRS network to a server that allocates IP addresses in an IP-based network, said method comprising the steps of:

setting on a counter in the GGSN, a maximum number (Ni) of requests for an IP address that are to be sent from the GGSN to the server;

setting on a timer in the GGSN, a maximum time period (Ti) that the GGSN will wait for a response from the server after each request for an IP address is sent;

sending a sequence of requests for an IP address from the GGSN to the server, with each request being separated from the previous request by time period Ti, said sequence being halted if a response is received from the server within time period Ti after one of the requests is sent;

determining that time period Ti expired following a last request in the sequence of Ni requests without receiving in the GGSN, a response from the server that includes an IP address for the mobile terminal;

determining from the information in the GGSN whether the mobile terminal is authorized to receive a backup IP address;

upon determining that the mobile terminal is authorized to receive a backup IP address, determining from the information in the GGSN whether the mobile terminal is a user of a real-time application;

sending a public IP address from the GGSN to the mobile terminal upon determining that the mobile terminal is a user of a real-time application; and

sending a private IP address from the GGSN to the mobile terminal upon determining that the mobile terminal is not a user of a real-time application.

11. In a General Packet Radio Service (GPRS) network, a Gateway GPRS Service Node (GGSN) for dynamically allocating an Internet Protocol (IP) address to a mobile terminal operating in the GPRS network, said GPRS network including a Serving GPRS Service Node (SGSN) serving the mobile terminal, and said GGSN connecting the GPRS network to a server that allocates IP addresses in an IP-based network, said GGSN comprising:

a counter for setting a maximum number (Ni) of requests for an IP address that are to be sent from the GGSN to the server;

a timer for setting a maximum time period (Ti) that the GGSN will wait for a response from the server after each request for an IP address is sent;

a Network Access Server (NAS) that includes;

means for sending a sequence of requests for an IP address from the GGSN to the server, with each request being separated from the previous request by time period Ti, said sequence being halted if a response is received from the server within time period Ti after one of the requests is sent; and

means for receiving a response from the server that includes an IP address for the mobile terminal; and

means for sending the IP address from the GGSN to the mobile terminal.

12. The GGSN of claim 11 wherein the means for sending a sequence of requests for an IP address from the GGSN to the server includes means for unicasting each of the requests in the sequence from the GGSN to a different server.

13. The GGSN of claim 11 wherein the means for sending a sequence of requests for an IP address from the GGSN to the server includes a Radius client for sending a sequence of requests from the GGSN to a Radius server.

14. The GGSN of claim 11 wherein the means for sending a sequence of requests for an IP address from the GGSN to the server includes a Dynamic Host Configuration Protocol (DHCP) client for sending a sequence of requests from the GGSN to a DHCP server.

15. In a General Packet Radio Service (GPRS) network having a Serving GPRS Service Node (SGSN) serving a mobile terminal operating in the GPRS network, and a Gateway GPRS Service Node (GGSN) connecting the GPRS network to a server that allocates IP addresses in an IP-based network, a system for dynamically allocating an Internet Protocol (IP) address to the mobile terminal, said system comprising:

a Home Location Register (HLR) that stores information regarding whether the mobile terminal is authorized to receive a backup IP address if an IP address cannot be obtained from the server, and whether the mobile terminal is a user of a real-time application;

means for sending the information to the GGSN,

a timer in the GGSN for setting a maximum time period (Ti) that the GGSN will wait for a response from the server after a request for an IP address is sent from the GGSN to the server;

a Network Access Server (NAS) in the GGSN that includes;

means for sending a request for an IP address from the GGSN to the server; and

means for determining that time period Ti expired without receiving a response from the server that includes an IP address for the mobile terminal;

means in the GGSN for determining from the information in the GGSN whether the mobile terminal is authorized to receive a backup IP address, and if so, determining from the information in the GGSN whether the mobile terminal is a user of a real-time application;

means for sending a public IP address from the GGSN to the mobile terminal upon determining that the mobile terminal is a user of a real-time application; and

means for sending a private IP address from the GGSN to the mobile terminal upon determining that the mobile terminal is not a user of a real-time application.

16. A system for dynamically allocating an IP address to a mobile terminal operating in an access network, said system comprising:

a Network Access Server (NAS) connecting the access network to a server that allocates IP addresses in an Internet Protocol (IP)-based network, said NAS including;

means for sending a request for an IP address to the server; and

means for receiving an IP address from the server; and

an Authorization, Authentication, and Accounting (AAA) server that stores information regarding whether the mobile terminal is authorized to receive a backup IP address if an IP address cannot be obtained from the server, and whether the mobile terminal is a user of a real-time application;

means for sending a public IP address from the NAS to the mobile terminal upon determining that the mobile terminal is a user of a real-time application; and

means for sending a private IP address from the NAS to the mobile terminal upon determining that the mobile terminal is not a user of a real-time application.

17. In a General Packet Radio Service (GPRS) network, a method in a Gateway GPRS Service Node (GGSN) for dynamically allocating Internet Protocol (IP) addresses to mobile terminals operating in the GPRS network, said GGSN connecting the GPRS network to a plurality of servers that allocate IP addresses in an IP-based network, said method comprising the steps of:

obtaining a first IP address for a first mobile terminal from a first server;

obtaining a second IP address for a second mobile terminal from a second server;

determining whether the first IP address and the second IP address are duplicate IP addresses;

releasing the second IP address upon determining that the first IP address and the second IP address are duplicate IP addresses; and

obtaining a third IP address for the second mobile terminal that is not the same as the first IP address.

18. In a General Packet Radio Service (GPRS) network, a method of dynamically setting up a Layer 2 Tunneling Protocol (L2TP) tunnel from a Gateway GPRS Service Node (GGSN) to a Virtual Private Network (VPN), said method comprising the steps of:

sending a predetermined number (Ni) of requests for an Internet Protocol (IP) address from the GGSN to a server, each of the requests being separated by time (Ti);

determining that time period Ti expired following a last request in the sequence of Ni requests without receiving in the GGSN, a response from the server that includes an IP address for the mobile terminal; and

examining by the GGSN, an Access Point Name (APN) to deduce tunnel endpoint parameters for setting up the L2TP tunnel.