Method and apparatus for loop breaking in a data bus

• US 7,389,371 B2
• Filed: 03/19/2007
• Issued: 06/17/2008
• Est. Priority Date: 11/05/1999
• Status: Expired due to Fees

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Whitby-Strevens, Colin, Hauck, Jerrold Von
• Primary Examiner(s): Myers; Paul R.
• Application Number:
  US11/725,711
• Publication Number:
  US 20070255871A1
• Time in Patent Office: 456 Days
• Field of Search: 710/104, 709/251, 709/221, 370/256, 370/222
• US Class Current: 710/104
• CPC Class Codes: G06F 13/426 using an embedded synchronisation, e.g. Firewire bus, Fibre Channel bus, SSA bus
• CPC Class Codes: H04L 12/40078 Bus configuration home automation networks H04L12/2803; arrangements for maintenance or administration H04L41/00
• CPC Class Codes: H04L 12/40117 Interconnection of audio or video/imaging devices home automation networks H04L12/2803; bitstream network arrangements specially adapted for distribution of digital video signals H04N7/24
• CPC Class Codes: H04L 12/40123 Interconnection of computers and peripherals printer information exchange with computer G06F3/1293
• CPC Class Codes: H04L 12/6418 Hybrid transport
• CPC Class Codes: H04L 43/50 Testing arrangements

Abstract

A method and apparatus is disclosed for preventing loops in a full-duplex bus The method has the acts of: selecting at least two candidates to join said bus; establishing a dominant candidate from one of the candidates; testing for loops in said bus; and joining said dominant candidate is no loop is found in said bus. Alternate embodiments are shown that utilize unique identifiers to facilitate candidate selection and to establish dominance on the bus.

Claims

1. A method of operating a high-speed data bus comprising at least two nodes, said bus and nodes forming a loop, the method comprising:

determining whether said at least two nodes comprise the same type of node; and

if said determining indicates the same type of node, breaking said loop between any of said at least two nodes.

2. The method of claim 1, wherein said high-speed bus comprises a serial protocol bus, and said at least two nodes comprise IEEE-1394b-compliant devices.

3. The method of claim 1, wherein said at least two nodes comprises at least first, second, and third nodes all of the same type, and said breaking comprises breaking between either said first and second nodes, or said second an third nodes.

4. The method of claim 1, wherein said at least two nodes comprises at least first, second, and third nodes, said first node and second node being of a first type, and said third node being of a second type;

and

wherein said breaking comprises breaking between said first and second nodes and not between said second and third nodes.

5. A method of loop breaking in a high-speed serialized bus with a plurality of nodes of a first type and at least one node of a second type, the operation of said at least one node being adversely affected by breaking said loop between said at least one node and another node immediately proximate thereto within said loop, the method comprising:

identifying at least two of said first type of node of said plurality that are logically adjacent to one another within said loop; and

breaking said loop between said at least two nodes before breaking said loop at any other location.

6. The method of claim 5, further comprising prohibiting breaking said loop immediately proximate said at least one node.

7. A computerized device for use with a high-speed data bus comprising at least two nodes, said bus and nodes forming a loop, the apparatus comprising:

first apparatus adapted to determine whether said at least two nodes comprise the same type of node; and

second apparatus adapted to, if said determination indicates the same type of node, break said loop between any of said at least two nodes.

8. The device of claim 7, wherein said device comprises one of said at least two nodes.

9. The device of claim 7, wherein said high-speed bus comprises a serial protocol bus, and said at least two nodes comprise IEEE-1394b-compliant devices.

10. The device of claim 7, wherein said at least two nodes comprises at least first, second, and third nodes all of the same type, and said second apparatus is configured to cause breakage of said loop between either said first and second nodes, or said second an third nodes.

11. The device of claim 7, wherein said at least two nodes comprises at least first, second, and third nodes, said first node and second node being of a first type, and said third node being of a second type;

and

wherein said second apparatus is configured to cause breakage of said loop between said first and second nodes and not between said second and third nodes.

12. A loop-breaking device for use with a high-speed data bus, the bus comprising a plurality of nodes, said plurality comprising:

(i) at least one of a first type of node being in communication with the device without any other nodes interposed therebetween; and

(ii) at least one of a second type of node;

wherein said bus and nodes form a loop, and the device comprises computer program apparatus adapted to;

detect said loop; and

selectively break said loop between said device and said at least one node of said first type.

13. The device of claim 12, wherein said high-speed bus comprises a serial protocol bus, and said first type of node comprises an IEEE-1394b-compliant device.

14. The device of claim 12, wherein said device and said at least one of a first type of node comprise the same type of device.

15. The device of claim 14, wherein said same type of device comprises a device which is substantially unaffected by an immediately proximate loop break.

16. The device of claim 14, wherein said device comprises an embedded physical layer controller.

17. The device of claim 16, wherein said computer program apparatus comprises part of said physical layer controller.

18. A computerized device adapted for loop breaking in a high-speed serialized bus having a plurality of nodes, comprising:

processing apparatus; and

a computer program adapted to run on said processing apparatus, said computer program adapted to, when executed by said processing apparatus;

identify at least two of a particular type of node of said plurality; and

break said loop selectively between said at least two nodes.

19. The device of claim 18, wherein said computerized device comprises one of said at least two of a particular type of node.

20. The device of claim 18, wherein said identification of at least two of a particular type of node comprises identification of at least two IEEE-1394b-compliant nodes.

21. The device of claim 18, wherein said selective break of said loop by said program comprises breaking said loop between said at least two nodes preferentially over breaking said loop at any other location.

22. The device of claim 21, wherein said plurality of nodes further comprises at least one other node, and breaking of said loop adjacent said at least one other node renders at least said at least one other node inoperative.

23. The device of claim 21, further comprising detecting the formation of a loop within said bus.

24. The device of claim 23, wherein said plurality of nodes further comprises at least one node of a second type, the operation of said at least one node which would be adversely affected if said break of said loop is performed adjacent thereto;

and

wherein said break of said loop selectively comprises not breaking said loop adjacent said at least one node so as to avoid said adverse effects.

25. A computerized device adapted for loop breaking in a high-speed serialized bus having a plurality of nodes of a first type and at least one node of a second type, the operation of said at least one node being adversely affected by breaking said loop between said at least one node and another node immediately proximate thereto within said loop, the device comprising:

processing apparatus; and

a computer program, said program adapted to, when executed;

identify at least two of said first type of node of said plurality that are logically adjacent to one another within said loop; and

break said loop between said at least two nodes before breaking said loop at any other location.

26. The device of claim 25, wherein said computerized device comprises one of said at least two of said first type of node.

27. The device of claim 25, wherein said program is further adapted to prohibit breaking said loop immediately proximate said at least one node.

28. A computerized device adapted for loop breaking in a high-speed serialized bus, said bus comprising a plurality of nodes, the device comprising:

a processing apparatus; and

at least one computer program, said at least one program adapted to, when executed on said processing apparatus;

identify a location within said loop and between two of said plurality of nodes where no adverse effects will result from said breaking; and

break said loop between said at least two nodes preferentially over another location within said loop.

29. A method of operating a high-speed data bus comprising at least first and second nodes and loop, said first node comprising a different type of node than said second node and being in communication with said loop via said second node, the method comprising breaking the bus between said first and second node so as to sever said loop from said bus;

wherein said first node comprises an IEEE-1394b-compliant node, said second node comprises a hybrid node, and said loop comprises a plurality of IEEE-1394a-compliant nodes.

30. The method of claim 29, wherein said plurality of IEEE-1394a-compliant nodes comprises at least one node which does not have loop-breaking capability.

31. The method of claim 30, wherein said loop comprises only one node that is coupled to said second node.

32. A method of operating a high-speed data bus comprising a plurality of nodes, said plurality comprising:

(i) a plurality of a first type of node, at least two of said plurality of first type of node being in communication with one another without any other nodes interposed therebetween; and

(ii) at least one of a second type of node; and

(iii) at least one of a third type of node, said third type comprising attributes of said first and second types of nodes;

wherein said bus and nodes form a loop, and the method comprises selectively breaking said loop between said at least two nodes.

33. The method of claim 32, wherein said high-speed bus comprises a serial protocol bus, and wherein said at least two nodes comprise IEEE-1394b-compliant devices.

34. The method of claim 32, wherein said plurality of first type of node comprises at least first, second, and third nodes all of the first type, and said breaking comprises breaking between either said first and second nodes, or said second an third nodes.

35. A method of loop breaking in a high-speed serialized bus with a plurality of nodes, comprising:

identifying at least two of a particular type of node of said plurality; and

breaking said loop selectively between said at least two nodes preferentially over breaking said loop at any other location;

wherein said plurality of nodes further comprises at least one other node, and breaking of said loop adjacent to said at least one other node renders at least said at least one other node inoperative.

36. The method of claim 35, wherein said identifying at least two of a particular type of node comprises identifying at least two IEEE-1394b-compliant nodes.

37. The method of claim 35, further comprising detecting the formation of a loop within said bus.

38. The method of claim 37, wherein said plurality of nodes further comprises at least one node of a second type, wherein the operation of said at least one node would be adversely affected if said breaking of said loop is performed adjacent thereto;

and

wherein said breaking said loop selectively comprises not breaking said loop adjacent to said at least one node so as to avoid said adverse effects.

39. A method of loop breaking in a high-speed serialized bus with a plurality of nodes, comprising:

identifying at least two of a particular type of node of said plurality; and

breaking said loop selectively between said at least two nodes preferentially over breaking said loop at any other location; and

detecting the formation of a loop within said bus;

wherein said plurality of nodes further comprises at least one node of a second type, the operation of said at least one node being adversely affected if said breaking of said loop is performed adjacent thereto and

wherein said breaking said loop selectively comprises not breaking said loop adjacent said at least one node so as to avoid said adverse effects.

40. The method of claim 39, wherein said identifying at least two of a particular type of node comprises identifying at least two IEEE-1394b-compliant nodes.

41. The method of claim 39, wherein said plurality of nodes further comprises at least one other node, and breaking of said loop adjacent to said at least one other node renders at least said at least one other node inoperative.

42. An IEEE-1394b-compliant device adapted for operation with a high-speed data bus, the bus comprising at least said device, a hybrid node, and a loop comprising a plurality of IEEE-1394a-compliant nodes, said hybrid node comprising a different type of entity than said device, said device being in communication with said loop via said hybrid node, the device comprising computer program apparatus operative to break the bus between itself and the node.

43. The device of claim 42, wherein said loop further comprises at least one node which does not have loop-breaking capability.

44. The device of claim 42, wherein said device comprises an embedded physical layer controller.

45. The device of claim 44, wherein said computer program apparatus comprises part of said physical layer controller.