Network device which maintains a list of device addresses

• US 6,021,429 A
• Filed: 11/18/1996
• Issued: 02/01/2000
• Est. Priority Date: 11/18/1996
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Information Systems Incorporated (Canon Inc.)
• Inventors: Danknick, Dan
• Primary Examiner(s): Asta, Frank J.
• Assistant Examiner(s): Thompson, Marc D.
• Application Number:
  US08/749,629
• Time in Patent Office: 1,170 Days
• Field of Search: 395/200.53, 395/200.54, 395/200.38, 395/200.39, 395/200.48, 395/200.67, 395/200.75, 395/200.79, 395/200.8, 395/200.83, 395/823 , 395/824, 395/828, 395/829, 395/835, 395/840, 395/200.52, 709/218, 709/219, 709/208, 709/209, 709/223, 709/224, 709/247, 709/249, 709/250, 709/253, 710/3, 710/4, 710/8, 710/9
• US Class Current: 709/208
• CPC Class Codes: H04L 61/00 Network arrangements, protocols or services for addressing or naming
• CPC Class Codes: H04L 61/45 Network directories; Name-to-address mapping

Abstract

A method controls a network device on a local area network (LAN) to operate as a list manager which maintains a list of device addresses for the LAN, and to operate as a slave which provides a device address of the network device to a list manager. The method comprises the steps of determining whether a list manager is operating on the LAN, controlling the network device to operate as a slave on the LAN when the determining step determines that a list manager is operating on the LAN, and controlling the network device to operate as the list manager for the LAN when the determining step determines that no list manager is operating on the LAN.

Claims

1. A method of controlling a network device on a local area network (LAN) in which plural different network devices communicate over the LAN by transmitting broadcast packets that are not addressed to any one particular network device and by transmitting addressed packets that are addressed to a network device corresponding to a device address contained therein, the network device being controlled to operate as a list manager which maintains a list of device addresses for the LAN, and being controlled to operate as a slave which provides a device address of the network device to a list manager, the method comprising the steps of:

determining whether a list manager is operating on the LAN by transmitting a broadcast packet from the network device to request a list manager and by waiting for a response for a predetermined period of time after the broadcast packet has been transmitted, said determining step determining that no list manager is operating on the LAN if a response to the broadcast packet is not received by the network device after the predetermined period of time, and determining that a list manager is operating on the LAN if a response to the broadcast packet is received by the network device within the predetermined period of time;

controlling the network device to operate as a slave on the LAN when the determining step determines that a list manager is operating on the LAN, including controlling the network device to transmit an addressed packet to the list manager that includes the device address of the network device; and

controlling the network device to operate as the list manager for the LAN when the determining step determines that no list manager is operating on the LAN, including controlling the network device to maintain a list of device addresses and to respond to a requestor'"'"'s request for device addresses by transmitting an addressed packet containing device addresses to the requestor.

2. A method according to claim 1, wherein the step of controlling the network device to operate as the list manager comprises designating the network device as the list manager by storing a device address of the network device in a list of device addresses on the network device.

3. A method according to claim 2, wherein when the network device is controlled to operate as the list manager, the method further comprises the steps of:

monitoring the LAN via the network device for a request for a list manager broadcasted over the LAN; and

responding to a request for a list manager on the LAN by broadcasting a response to the request from the network device, the response identifying the network device as the list manager.

4. A method according to claim 3, further comprising the steps of:

receiving, in the network device, a device address from the LAN; and

storing the device address in the list of device addresses on the network device, the storing step storing the list of device address in a memory on the network device.

5. A method according to claim 1, wherein when the network device is controlled to operate as the list manager, the method further comprises:

a second determining step for determining whether a second list manager is operating on the LAN; and

in a case that a second list manager is operating on the LAN, a resolving step for resolving contention between the second list manager and the network device designated as list manager.

6. A method according to claim 5, where the second determining step comprises the steps of:

broadcasting a request for a list manager over the LAN from the network device; and

receiving, in the network device, a response to the request for a list manager from the second list manager.

7. A method according to claim 6, wherein the resolving step comprises:

a third determining step for determining which of the second list manager and the network device operating as list manager has a higher device address; and

a designating step for designating a device having the higher device address as sole list manager for the LAN.

8. A method according to claim 7, wherein the response received from the second list manager includes a device address of the second list manager;

and

wherein the third determining step comprises comparing the device address of the second list manager to the device address of the network device operating as list manager in order to determine the higher device address.

9. A method according to claim 7, wherein the designating step comprises the step of broadcasting, over the LAN and from the network device having the higher device address, a command to a device having a lower device address to discontinue maintaining a list of device addresses.

10. A method according to claim 1, wherein the determining step comprises the step of repeating the broadcasting and waiting steps a predetermined number of times;

wherein the determining step determines that no list manager is operating on the LAN if a response to the request broadcasted over the LAN is not received by the network device after the repeating step broadcasts and waits the predetermined number of times; and

wherein the determining step determines that a list manager is operating on the LAN if a response to the request broadcasted over the LAN is received by the network device in response to the repeating step.

11. A method according to claim 10, wherein when the determining step determines that a list manager is operating on the LAN, the method further comprises the step of re-broadcasting the request for the list manager periodically via the network device in order to determine whether the list manager is still operating.

12. A method according to claim 11, wherein a response from the list manager to the request broadcasted over the LAN includes a call-back time period;

and

wherein the re-broadcasting step re-broadcasts the request for the list manager at a frequency corresponding to the call-back time period provided by the list manager.

13. A method according to claim 12, wherein the call-back time period increases proportionally to an increase in a number of device addresses in the list of device addresses maintained by the list manager.

14. A method according to claim 11, wherein the request for the list manager broadcasted over the LAN comprises a request for a list manager operating on the LAN to identify itself and a response from the list manager includes a device address of the list manager;

and

wherein, the method further comprises the steps of;

storing the device address of the list manager in a memory on the network device; and

determining, after each re-broadcast of the request by the re-broadcasting step, whether a new list manager is operating on the LAN by comparing a stored device address of the list manager to a device address provided in response to a re-broadcasted request.

15. A method according to claim 14, wherein if it is determined that a new list manager is operating on the LAN, the method further comprises the step of providing the device address of the network device to the new list manager.

46. A method according to claim 1, wherein the list of device addresses includes device addresses and corresponding device identification information for each device address.

47. A method according to claim 1, wherein the list of device addresses includes an expiration time for each device address, and wherein when the network device is controlled to operate as a list manager, the network device monitors expiration times and queries a device after expiration times have expired so as to obtain an updated device address.

48. A method according to claim 1, wherein the step of controlling the network device to operate as the list manager comprises the steps of:

receiving a broadcast request from a requester over the LAN, the broadcast request requesting a list manager;

responding to the broadcast request by providing the device address of the network device;

receiving an addressed packet from the requester requesting a list of device addresses; and

transmitting to the requester an addressed packet containing device addresses.

16. A network device on a local area network (LAN) in which plural different network devices communicate over the LAN by transmitting broadcast packets that are not addressed to any one particular network device and by transmitting addressed packets that are addressed to a network device corresponding to a device address contained therein, the network device being controlled, the network device operating as a list manager for the LAN by maintaining a list of device addresses for the LAN, and operating as a slave on the LAN by providing a device address to another device on the LAN operating as the list manager, the network device comprising:

a memory which stores a device address of the network device and process steps for execution by a processor, and which can store the list of device addresses for the LAN;

a LAN interface which interfaces to the LAN, over which communications including broadcast packets and addressed packets are transmitted to and received from the LAN; and

a processor which executes the process steps stored in the memory (1) to determine whether a list manager is operating on the LAN by transmitting a broadcast packet from the network device to request a list manager and by waiting for a response for a predetermined period of time after the broadcast packet has been transmitted, said determining step determining that no list manager is operating on the LAN if a response to the broadcast packet is not received by the network device after the predetermined period of time, and determining that a list manager is operating on the LAN if a response to the broadcast packet is received by the network device within the predetermined period of time, (2) to control the network device to operate as a slave on the LAN when the processor determines that a list manager is operating on the LAN, including controlling the network device to transmit an addressed packet to the list manager that includes the device address of the network device, and (3) to control the network device to operate as the list manager for the LAN when the processor determines that no list manager is operating on the LAN, including controlling the network device to maintain a list of device addresses and to respond to a requestor'"'"'s request for device addresses by transmitting an addressed packet containing device addresses to the requestor.

17. A network device according to claim 16, wherein the processor controls the network device to operate as the list manager by storing the device address of the network device in a list of device addresses in the memory.

18. A network device according to claim 17, wherein when the processor controls the network device to operate as the list manager, the processor executes process steps stored in the memory to monitor the LAN via the LAN interface for a request for a list manager broadcasted over the LAN, and to respond to a request for a list manager on the LAN by broadcasting a response to the request via the LAN interface, the response identifying the network device as the list manager.

19. A network device according to claim 18, wherein the processor executes process steps stored in the memory to receive, via the LAN interface, a device address from the LAN, and to store the device address in the list of device addresses in the memory.

20. A network device according to claim 16, wherein when the processor controls the network device to operate as the list manager, the processor executes process steps stored in the memory to determine whether a second list manager is operating on the LAN, and in a case that a second list manager is operating on the LAN, to resolve contention between the second list manager and the network device designated as list manager.

21. A network device according to claim 20, wherein the processor determines whether a second list manager is operating on the LAN by broadcasting a request for a list manager over the LAN, and receiving a response to the request for a list manager from the second list manager.

22. A network device according to claim 21, wherein the processor resolves contention between the second list manager and the network device designated as list manager by determining which of the second list manager and the network device operating as list manager has a higher device address, and by designating a device having the higher device address as sole list manager for the LAN.

23. A network device according to claim 22, wherein the response received from the second list manager includes a device address of the second list manager;

and

wherein the processor determines which of the second list manager and the network device operating as list manager has a higher device address by comparing the device address of the second list manager to the device address of the network device operating as list manager.

24. A network device according to claim 22, wherein the processor designates a device having the higher device address as sole list manager for the LAN by broadcasting, over the LAN, a command to a device having a lower device address to discontinue maintaining a list of device addresses.

25. A network device according to claim 16, wherein the processor determines whether a list manager is operating on the LAN by repeating the broadcasting and waiting a predetermined number of times;

wherein the processor determines that no list manager is operating on the LAN if a response to the request broadcasted over the LAN is not received by the network device after the processor repeats broadcasting and waiting the predetermined number of times; and

wherein the processor determines that a list manager is operating on the LAN if a response to the request broadcasted over the LAN is received by the network device in response to broadcasting the request for the list manager.

26. A network device according to claim 25, wherein when the processor determines that a list manager is operating on the LAN, the processor executes process steps stored in the memory to re-broadcast the request for the list manager periodically in order to determine whether the list manager is still operating.

27. A network device according to claim 26, wherein a response from the list manager to the request broadcasted over the LAN includes a call-back time period;

and

wherein the processor re-broadcasts the request for the list manager at a frequency corresponding to the call-back time period provided by the list manager.

28. A network device according to claim 27, wherein the call-back time period increases proportionally to an increase in a number of device addresses in the list of device addresses maintained by the list manager.

29. A network device according to claim 26, wherein the request for the list manager broadcasted over the LAN comprises a request for a list manager operating on the LAN to identify itself and a response from the list manager includes a device address of the list manager;

and

wherein the processor executes process steps stored in the memory to store the device address of the list manager in the memory, and to determine, after each re-broadcast of the request by the processor, whether a new list manager is operating on the LAN by comparing a stored device address of the list manager to a device address provided in response to a re-broadcasted request.

30. A network device according to claim 29, wherein if it is determined that a new list manager is operating on the LAN, the processor executes process steps stored in the memory to provide the device address of the network device stored in the memory to the new list manager.

49. A network device according to claim 16, wherein the list of device addresses includes device addresses and corresponding device identification information for each device address.

50. A network device according to claim 16, wherein the list of device addresses includes an expiration time for each device address, and wherein when the network device is controlled to operate as a list manager, the network device monitors expiration times and queries a device after expiration times have expired so as to obtain an updated device address.

51. A network device according to claim 16, wherein the step of controlling the network device to operate as the list manager comprises the steps of:

receiving a broadcast request from a requestor over the LAN, the broadcast request requesting a list manager;

responding to the broadcast request by providing the device address of the network device;

receiving an addressed packet from the requester requesting a list of device addresses; and

transmitting to the requester an addressed packet containing device addresses.

31. Computer-executable process steps stored on a computer-readable medium, the computer-executable process steps to control a network device on a local area network (LAN) in which plural different network devices communicate over the LAN by transmitting broadcast rackets that are not addressed to any one particular network device and by transmitting addressed packets that are addressed to a network device corresponding to a device address contained therein, the network device being controlled to operate as a list manager which maintains a list of device addresses for the LAN, and being controlled to operate as a slave which provides a device address of the network device to a list manager, the computer-executable process steps comprising:

a determining step to determine whether a list manager is operating on the LAN by transmitting a broadcast packet from the network device to request a list manager and by waiting for a response for a predetermined period of time after the broadcast packet has been transmitted, said determining step determining that no list manager is operating on the LAN if a response to the broadcast packet is not received by the network device after the predetermined period of time, and determining that a list manager is operating on the LAN if a response to the broadcast packet is received by the network device within the predetermined period of time;

a controlling step to control the network device to operate as a slave on the LAN when the determining step determines that a list manager is operating on the LAN, including controlling the network device to transmit an addressed packet to the list manager that includes the device address of the network device; and

a controlling step to control the network device to operate as the list manager for the LAN when the determining step determines that no list manager is operating on the LAN, including controlling the network device to maintain a list of device addresses and to respond to a requestor'"'"'s request for device addresses by transmitting an addressed packet containing device addresses to the requestor.

32. Computer-executable process steps according to claim 31, wherein the controlling step controls the network device to operate as the list manager for the LAN by storing a device address of the network device in a list of device addresses on the network device.

33. Computer-executable process steps according to claim 32, wherein when the network device is controlled to operate as the list manager, the computer-executable process steps further comprise:

a monitoring step to monitor the LAN via the network device for a request for a list manager broadcasted over the LAN; and

a responding step to respond to a request for a list manager on the LAN by broadcasting a response to the request from the network device, the response identifying the network device as the list manager.

34. Computer-executable process steps according to claim 33, further comprising:

a receiving step to receive, in the network device, a device address from the LAN; and

a storing step to store the device address in the list of device addresses on the network device, the storing step storing the list of device address in a memory on the network device.

35. Computer-executable process steps according to claim 31, wherein when the network device is controlled to operate as the list manager, the computer-executable process steps further comprise:

a second determining step to determine whether a second list manager is operating on the LAN; and

a resolving step to resolve, in a case that a second list manager is operating on the LAN, contention between the second list manager and the network device designated as list manager.

36. Computer-executable process steps according to claim 35, where the second determining step comprises:

a broadcasting step to broadcast a request for a list manager over the LAN from the network device; and

a receiving step to receive, in the network device, a response to the request for a list manager from the second list manager.

37. Computer-executable process steps according to claim 36, wherein the resolving step comprises:

a third determining step to determine which of the second list manager and the network device operating as list manager has a higher device address; and

a designating step to designate a device having the higher device address as sole list manager for the LAN.

38. Computer-executable process steps according to claim 37, wherein the response received from the second list manager includes a device address of the second list manager;

and

wherein the third determining step comprises a comparing step to compare the device address of the second list manager to the device address of the network device operating as list manager in order to determine the higher device address.

39. Computer-executable process steps according to claim 37, wherein the designating step comprises a broadcasting step to broadcast, over the LAN and from the network device having the higher device address, a command to a device having a lower device address to discontinue maintaining a list of device addresses.

40. Computer-executable process steps according to claim 31, wherein the determining step comprises a repeating step to repeat the broadcasting and waiting steps a predetermined number of times;

wherein the determining step determines that no list manager is operating on the LAN if a response to the request broadcasted over the LAN is not received by the network device after the repeating step broadcasts and waits the predetermined number of times; and

wherein the determining step determines that a list manager is operating on the LAN if a response to the request broadcasted over the LAN is received by the network device in response to the repeating step.

41. Computer-executable process steps according to claim 40, wherein when the determining step determines that a list manager is operating on the LAN, the computer-executable process steps further comprise a re-broadcasting step to re-broadcast the request for the list manager periodically via the network device in order to determine whether the list manager is still operating.

42. Computer-executable process steps according to claim 41, wherein a response from the list manager to the request broadcasted over the LAN includes a call-back time period;

and

wherein the re-broadcasting step re-broadcasts the request for the list manager at a frequency corresponding to the call-back time period provided by the list manager.

43. Computer-executable process steps according to claim 42, wherein the call-back time period increases proportionally to an increase in a number of device addresses in the list of device addresses maintained by the list manager.

44. Computer-executable process steps according to claim 41, wherein the request for the list manager broadcasted over the LAN comprises a request for a list manager operating on the LAN to identify itself and a response from the list manager includes a device address of the list manager;

and

wherein, the computer-executable process steps further comprise;

a storing step to store the device address of the list manager in a memory on the network device; and

a determining step to determine, after each re-broadcast of the request by the re-broadcasting step, whether a new list manager is operating on the LAN by comparing a stored device address of the list manager to a device address provided in response to a re-broadcasted request.

45. Computer-executable process steps according to claim 44, wherein if it is determined that a new list manager is operating on the LAN, the computer-executable process steps further comprise a providing step to provide the device address of the network device to the new list manager.

52. Computer-executable process steps according to claim 31, wherein the list of device addresses includes device addresses and corresponding device identification information for each device address.

53. Computer-executable process steps according to claim 31, wherein the list of device addresses includes an expiration time for each device address, and wherein when the network device is controlled to operate as a list manager, the network device monitors expiration times and queries a device after expiration times have expired so as to obtain an updated device address.

54. Computer-executable process steps according to claim 31, wherein the step of controlling the network device to operate as the list manager comprises the steps of:

receiving a broadcast request from a requester over the LAN, the broadcast request requesting a list manager;

responding to the broadcast request by providing the device address of the network device;

receiving an addressed packet from the requester requesting a list of device addresses; and

transmitting to the requester an addressed packet containing device addresses.