Method and system for dynamically updating ARP cache tables in an ad hoc network

• US 20050007962A1
• Filed: 07/09/2004
• Published: 01/13/2005
• Est. Priority Date: 07/10/2003
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd. (Samsung Group)
• Original Assignee: Samsung Electronics Co. Ltd. (Samsung Group)
• Inventors: Mun, Byung-in, Nam, Sang-su, Kim, Min-soo
• Granted Patent: US 7,492,772 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: H04L 61/10 of different types
• CPC Class Codes: H04L 61/5046 Resolving address allocation conflicts; Testing of addresses testing when self-assigning an address H04L61/5092
• CPC Class Codes: H04L 61/5092 by self-assignment, e.g. picking addresses at random and testing if they are already in use
• CPC Class Codes: H04W 8/26 Network addressing or numbering for mobility support
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks

Abstract

A method and system for dynamically updating information registered in ARP cache tables of other terminals in a case where a protocol address of a terminal existing in an ad hoc network changes. The method includes detecting whether protocol addresses of terminals are duplicated and changing the protocol addresses of some of the terminals having the duplicate protocol addresses; by a terminal whose protocol address has changed, transmitting information on the previously used protocol address and its own hardware address to neighboring terminals; updating the address information tables in accordance with the received information; by a terminal whose protocol address has not changed among the terminals having the duplicate protocol addresses, transmitting its own address information to the neighboring terminals; and by the neighboring terminals that has received the address information in the fourth step, updating the address information tables in accordance with the received information.

Claims

1. A method for dynamically updating address information tables in an ad hoc network, comprising:

detecting whether protocol addresses of terminals are duplicated and changing the protocol addresses of at least one of the terminals having the duplicate protocol addresses from a previously used protocol address to a new currently used protocol address;

by a terminal whose protocol address has changed, transmitting information on the previously used protocol address and transmitting a hardware address of the terminal whose protocol address has changed, to neighboring terminals; and

by the neighboring terminals that have received the address information, updating the address information tables in accordance with the received information.

2. The method as claimed in claim 1, wherein transmitting information on the previously used protocol address and transmitting a hardware address of the terminal whose protocol address has changed, to neighboring terminals is performed when the terminal whose protocol address has changed sends back to one of the neighboring terminals a data packet received from the one of the neighboring terminals.

3. The method as claimed in claim 1, wherein updating the address information tables in accordance with the received information comprises:

by each of the neighboring terminals that have received the address information, searching for an entry having the same protocol address as the protocol address information from the address information tables; and

deleting the entry when a hardware address in the entry is identical to the hardware address information.

4. The method as claimed in claim 1, wherein updating the address information tables in accordance with the received information further comprises after the entry has been deleted, adding a new entry having correct protocol and hardware addresses of the transmitting terminal to the address information tables.

5. The method as claimed in claim 1, wherein a selective Unsolicited Address Resolution Protocol (UnARP) packet is used to transmit the information on the protocol and hardware addresses, and wherein the selective UnARP packet comprises a source hardware address field in which a (Media Access Control (MAC) address of the transmitting terminal is written, a source protocol address field in which the previously used protocol address is written, a destination hardware address field which is left empty, and a destination protocol address field in which a broadcast address is written.

14. The method as claimed in claim 1, wherein the address information tables are ARP cache tables of the terminals.

6. A method for dynamically updating address information tables in an ad hoc network, comprising:

detecting whether protocol addresses of terminals are duplicated and changing the protocol addresses of at least one of the terminals having the duplicate protocol addresses from a previously used protocol address to a new currently used protocol address;

by a terminal whose protocol address has not changed among the terminals having the duplicate protocol addresses, transmitting an address information of the terminal whose protocol address has not changed, to neighboring terminals; and

by the neighboring terminals that have received the address information, updating the address information tables in accordance with the received information.

7. The method as claimed in claim 6, wherein a gratuitous Address Resolution Protocol (ARP) packet is used to transmit the address information, and wherein the gratuitous ARP packet comprises a source hardware address field in which a MAC address of the transmitting terminal is written, a source protocol address field in which the protocol address of the transmitting terminal is written, a destination hardware address field which is left empty, and a destination protocol address field in which the protocol address of the transmitting terminal is written.

8. A method for dynamically updating address information tables in an ad hoc network, comprising:

detecting whether protocol addresses of terminals are duplicated and changing the protocol addresses of at least one of the terminals having the duplicate protocol addresses from a previously used protocol address to a new currently used protocol address;

by a terminal whose protocol address has changed, transmitting information on the previously used protocol address and transmitting a hardware address of the terminal those protocol address has changed, to neighboring terminals;

by the neighboring terminals that have received the address information, updating the address information tables in accordance with the received information;

by a terminal whose protocol address has not changed among the terminals having the duplicate protocol addresses, transmitting its own address information to the neighboring terminals; and

by the neighboring terminals that have received the address information in the fourth step, updating the address information tables in accordance with the received information.

9. The method as claimed in claim 8, wherein transmitting information on the previously used protocol address and transmitting a hardware address of the terminal those protocol address has changed, to neighboring terminals is performed when the terminal whose protocol address has changed sends back to one of the neighboring terminals a data packet received from the one of the neighboring terminals.

10. The method as claimed in claim 8, wherein updating the address information tables in accordance with the received information further comprises:

by each of the neighboring terminals that have received the address information, searching for an entry having the same protocol address as the protocol address information from the address information tables; and

deleting the entry when a hardware address in the entry is identical to the hardware address information.

11. The method as claimed in claim 8, wherein updating the address information tables in accordance with the received information comprises, after the entry has been deleted, adding a new entry having correct protocol and hardware addresses of the transmitting terminal to the address information tables.

12. The method as claimed in claim 8, wherein a selective UnARP packet is used to transmit the information on the protocol and hardware addresses, and wherein the selective UnARP packet comprises a source hardware address field in which a MAC address of the transmitting terminal is written, a source protocol address field in which the previously used protocol address is written, a destination hardware address field which is left empty, and a destination protocol address field in which a broadcast address is written.

13. The method as claimed in claim 8, wherein a gratuitous ARP packet is used to transmit the address information, and wherein the gratuitous ARP packet comprises a source hardware address field in which a MAC address of the transmitting terminal is written, a source protocol address field in which the protocol address of the transmitting terminal is written, a destination hardware address field which is left empty, and a destination protocol address field in which the protocol address of the transmitting terminal is written.

15. A system for dynamically updating address information tables in an ad hoc network, comprising:

a first terminal whose protocol address is changed from a previously used protocol address to a new currently used protocol address using an automatic address assignment function on the ad hoc network when the protocol address thereof is duplicated; and

neighboring terminals located within positions where the neighboring terminals can communicate directly with the first terminal,

wherein the first terminal transmits information on the previously used protocol address and its own hardware address, and the neighboring terminals update the address information tables in accordance with the received information.

16. The system as claimed in claim 15, wherein transmission of the address information to neighboring terminals by the first terminal is performed where the first terminal whose address has changed transmits a data packet received from one terminal among the neighboring terminals again to the one terminal

17. The system as claimed in claim 15, wherein a selective UnARP packet is used to transmit the address information, and wherein the selective UnARP packet comprises a source hardware address field in which a MAC address of the first terminal is written, a source protocol address field in which the previously used protocol address is written, a destination hardware address field which is left empty, and a destination protocol address field in which a broadcast address is written.

18. The system as claimed in claim 15, further comprising a second terminal whose protocol address has not changed even when the protocol address is duplicated between the terminals,

wherein the second terminal transmits its own address information to terminals located within positions where the terminals can communicate directly with the second terminal.

19. The system as claimed in claim 18, wherein a gratuitous ARP packet is used to transmit the address information, and wherein the gratuitous ARP packet comprises a source hardware address field in which a MAC address of the second terminal is written, a source protocol address field in which the protocol address of the second terminal is written, a destination hardware address field which is left empty, and a destination protocol address field in which the protocol address of the second terminal is written.

20. The system as claimed in claims 15, wherein the address information tables are ARP cache tables of the terminals.