Method and apparatus for handoff of a connection between network devices

• US 6,522,880 B1
• Filed: 02/28/2000
• Issued: 02/18/2003
• Est. Priority Date: 02/28/2000
• Status: Expired due to Fees

• Current Assignee: UTStarcom Incorporated (UTStarcom Holdings Corp.)
• Original Assignee: 3Com Corporation (HP Inc.)
• Inventors: Senthilnathan, Janakiraman, Verma, Rohit
• Primary Examiner(s): Trost, William
• Assistant Examiner(s): Yun, Eugene
• Application Number:
  US09/514,709
• Time in Patent Office: 1,086 Days
• Field of Search: 456/436, 456/437, 456/410, 456/524, 456/525, 370/331, 370/332
• US Class Current: 455/436
• CPC Class Codes: H04L 61/00 Network arrangements, protocols or services for addressing or naming
• CPC Class Codes: H04L 9/40 Network security protocols
• CPC Class Codes: H04W 36/0019 adapted for mobile IP [MIP]
• CPC Class Codes: H04W 80/04 Network layer protocols, e.g. mobile IP [Internet Protocol]

Abstract

A method and system are shown for handing off a communication stream between a mobile node and a communication endpoint from a first connection initiator to a second connection initiator while maintaining call state for the communication stream. The first connection initiator establishes a first connection to the communication endpoint in response to receiving a first connection request from the mobile node that includes a client identifier value for the mobile node. When the first connection initiator detects loss of communication with the mobile node, it sends a call-disconnect-notify (CDN) message having a cause code set to a handoff value to the connection endpoint. The connection endpoint, in response to the CDN message, stores call information for the first connection along with the mobile node'"'"'s client identifier value. The first connection initiator also broadcasts a user-moved message that includes the mobile node'"'"'s client identifier value and the first connection initiator'"'"'s call information for the first connection. The second connection initiator, upon receiving the user-moved message, stores the first connection initiator'"'"'s call information from the message along with the mobile node'"'"'s client identifier value. When the second connection initiator receives a second connection request from the mobile node having the mobile node'"'"'s client identifier value, it retrieves the call information from the user-moved message using the client identifier value and sends a tunnel-handoff-request message, which includes the client identifier value, to the connection endpoint. The connection endpoint retrieves its call information for the first connection using the client identifier value and sends a tunnel-handoff-response message to the second connection initiator. The second connection initiator and the connection endpoint then resume the communication stream using the call information for the first connection.

Claims

1. A method for handing off a communication stream in a communications system, the method comprising the steps of:

receiving a first connection request from a client, where the first connection request includes a client identifier value for the client;

responsive to the first connection request, establishing a first connection from a first connection initiator to a connection endpoint;

sensing loss of communication between the client and the first connection initiator and, responsive thereto, transmitting a disconnect message to the connection endpoint, where the disconnect message includes a predetermined handoff code;

responsive to receiving the disconnect message having the handoff code, storing a first set of call information for the first connection from the connection endpoint along with the client identifier value;

broadcasting a user moved message from the first connection initiator, where the user moved message includes the client identifier value and a second set of call information for the first connection from the first connection initiator;

receiving the user moved message in a second connection initiator and, responsive thereto, storing the second set of call information included with the user moved message along with the client identifier value;

receiving a second connection request from the client at the second connection initiator, where the second connection request includes the client identifier value;

retrieving the second set of call information using the identifier value for the client;

sending a handoff request message to the connection endpoint, where the handoff request message includes the client identifier value from the second connection request;

responsive to the handoff request message, retrieving the first set of call information from using the identifier value for the client; and

establishing a second connection from the second connection initiator, where the second initiator uses the second set of call information, to the connection endpoint, where the connection endpoint uses the first set of call information.

2. The method of claim 1, where the step of retrieving the second set of call information includes querying a database local to the second connection initiator.

3. The method of claim 1, where the step of retrieving the second set of call information includes querying a database remote from the second connection initiator.

4. The method of claim 3, where the database is accessed through an Authentication, Authorization and Accounting (AAA) server.

5. The method of claim 1, where the client identifier value is a Mobile Identification Number (MIN).

6. The method of claim 1, where the step of broadcasting a user moved message further comprises multicasting the user moved message to a predetermined group address.

7. The method of claim 1, where the first set of call information comprises call state information from the connection endpoint for the first connection and the second set of call information comprises call state information from the first connection initiator for the first connection.

8. The method of claim 7, where the call state information from the connection endpoint and the call state information from the first connection initiator each include a number of packets sent parameter and a number of packets received parameter.

9. A computer readable medium having stored therein instructions for causing a central processing unit to execute the method of claim 1.

10. A network communication system, the system comprising:

a first connection initiator device coupled to a network, having a first network address, and configured to communicate with a mobile client broadcasting within a first service area of the first connection initiator, the first connection initiator being further configured to receive a first connection request from the mobile client that includes a client identifier value for the mobile client and, responsive to the first connection request, obtain a second network address corresponding to the client identifier value and establish a first connection between the first and second network addresses, the first connection initiator being further configured to detect that the mobile client has left the first service area and, responsive thereto, transmit a disconnect message having a predetermined handoff code to the second network address and transmit a user moved message to a predetermined network broadcast address, where the user moved message includes a first set of call state information from the first connection initiator that pertains to the first connection;

a connection endpoint device coupled to the network, having the second network address, and configured to establish the first connection between the first and second network addresses, the connection endpoint being further configured to receive the disconnect message having the predetermined handoff code and, responsive thereto, store a second set of call state information from the connection endpoint that pertains to the first connection along with the client identifier value, and the connection endpoint being still further configured to receive a handoff request message from a third network address, where the handoff request message contains the client identifier value, and, responsive thereto, retrieve the second set of call state information and establish a second connection between the second and third network addresses using the second set of call state information; and

a second connection initiator device coupled to the network, having the third network address, the second connection initiator being configured to receive the user moved message transmitted to the predetermined network broadcast address and store the first set of call state information along with the client identifier value, the second connection initiator being further configured to communicate with the mobile client broadcasting within a second service area of the second connection initiator, receive a second connection request from the mobile client that includes the client identifier value, and, responsive thereto, retrieve the first set of call state information, send the tunnel handoff request message to the second network address, and establish the second connection between the second and third network addresses using the first set of call state information.

11. The network communication system of claim 10, where the first network initiator device is further configured to obtain the second network address corresponding to the client identifier value by querying a database using the client identifier value.

12. The network communication system of claim 11, where the database is local to the first network initiator device.

13. The network communication system of claim 12, where the database is accessible through a AAA server coupled to the network.

14. The network communication system of claim 10, where the client identifier value further comprises a Mobile Identification Number (MIN).

15. The network communication system of claim 10, where the predetermined network broadcast address further comprises a multicast address associated with all devices coupled to a subnetwork of the network, where the first and second connection initiator devices are both coupled to the subnetwork.

16. The network communication system of claim 10, where the first and second sets of call state information each include a number of packets sent parameter and a number of packets received parameter.

17. The network communication system of claim 10, where the first and second sets of call state information each include the second network address.

18. The network communication system of claim 10, where the first and second connections each further comprise a point-to-point connection.