Time-based grooming and degrooming methods with common time reference for optical networks

• US 7,170,906 B2
• Filed: 09/21/2001
• Issued: 01/30/2007
• Est. Priority Date: 07/22/1998
• Status: Expired due to Fees

• Current Assignee: Synchrodyne Networks Incorporated
• Original Assignee: Synchrodyne Networks Incorporated
• Inventors: Ofek, Yoram, Baldi, Mario
• Primary Examiner(s): Ngo, Ricky Q.
• Assistant Examiner(s): CHANG, RICHARD K
• Application Number:
  US09/961,081
• Publication Number:
  US 20020051468A1
• Time in Patent Office: 1,957 Days
• Field of Search: 370/498, 370/503, 370/535, 370/537, 370/464, 370/458
• US Class Current: 370/498
• CPC Class Codes: H04J 2203/0082 Interaction of SDH with non-ATM protocols
• CPC Class Codes: H04J 2203/0083 Support of the IP protocol
• CPC Class Codes: H04J 3/0644 External master-clock
• CPC Class Codes: H04J 3/0685 Clock or time synchronisation in a node; Intranode synchronisation
• CPC Class Codes: H04L 12/6418 Hybrid transport
• CPC Class Codes: H04L 2012/5624 Path aspects, e.g. path bundling
• CPC Class Codes: H04L 2012/5674 Synchronisation, timing recovery or alignment
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/22 Traffic shaping
• CPC Class Codes: H04L 47/28 in relation to timing considerations
• CPC Class Codes: H04L 47/283 in response to processing delays, e.g. caused by jitter or round trip time [RTT]
• CPC Class Codes: H04L 49/254 Centralised controller, i.e. arbitration or scheduling
• CPC Class Codes: H04L 49/30 Peripheral units, e.g. input or output ports
• CPC Class Codes: H04L 49/3009 Header conversion, routing tables or routing tags
• CPC Class Codes: H04L 49/3063 Pipelined operation
• CPC Class Codes: H04L 49/55 Prevention, detection or correction of errors
• CPC Class Codes: H04L 69/28 Timers or timing mechanisms used in protocols
• CPC Class Codes: H04L 9/40 Network security protocols
• CPC Class Codes: H04Q 11/0062 Network aspects
• CPC Class Codes: H04Q 11/0478 Provisions for broadband connections
• CPC Class Codes: H04Q 2011/0033 : using time division switching
• CPC Class Codes: H04Q 2011/0045 : Synchronisation

Abstract

Time-based grooming and degrooming methods and systems of data units that utilize a common time reference is disclosed. Time is divided into a plurality of contiguous periodic time frames with a plurality of time frame durations. The system and method enable the grooming and switching of data units from a plurality of low speed links into one or more high-speed links. The system and method further enable the grooming and switching of data units from one or more high-speed links into a plurality of low speed links. The plurality of data units that are contained in each of the time frames are forwarded in a pipelined manner through the network switches. The system operates with high-speed wavelength division multiplexing (WDM) links, i.e., with multiple lambdas. The outcome of this method is called fractional lambda grooming.

Claims

1. A grooming system, comprising a plurality of input channels, and at least one output channel, the system comprising:

a Common Time Reference (CTR), divided into a plurality of contiguous time frames (TFs), wherein the time frames have a plurality of predefined time durations;

wherein each of the input channels are associated with respective time frames grouped according to a respective common time cycle;

wherein the at least one output channel is associated with respective time frames grouped according to a respective common time cycle;

wherein each of the time frames provides for transfer of a plurality of data units;

first means for mapping the time frames from the respective subset of the time frames associated with the respective ones of the input channels for each of the plurality of the data units;

second means for mapping each of the time frames associated with the at least one output channel, from a respective subset of the time frames for respective ones of the input channels, to provide a defined delay between the respective time frames associated with the transfer of each of the data units from the respective input channel, to the respective at least one output channel.

2. The system as in claim 1, wherein the common cycles have a common duration.

3. The system as in claim 1, wherein the common cycles for each of the channels are time offset relative to the respective common cycles for the other ones of the channels.

4. The system as in claim 1, wherein the common cycles for each of the channels are aligned relative to the CTR.

5. The system as in claim 1, wherein the common cycles for each of the channels are time offset relative to the CTR.

6. The system as in claim 1, wherein the mapping reoccurs periodically for each of the common cycles.

7. The system as in claim 1, wherein each of the time frames for the output channel is comprised of at least one sub-time frame;

wherein each of the input channel time frames is mapped into a respective one of the output channel sub-time frames.

8. The system as in claim 1, wherein each of the time frames for the input channels and the output channels is comprised of at least one sub-time frame;

wherein each of the input channel sub-time frames is mapped into a respective one of the output channel sub-time frames.

9. The system as in claim 1, wherein the data units from each of the plurality of the input channels for the respective subset are combined in a predefined order with the data units from other ones of the plurality of the input channels for the respective subset.

10. The system as in claim 1, wherein the data units are at least one of a byte, a word, a packet, and an ATM cell.

11. The system as in claim 1, wherein a time stamp is associated with selected ones of the time frames, and

wherein the time stamps are derived responsive to the CTR.

12. The system as in claim 1, wherein each one of the input channels and the output channels is at least one of an optical channel, a wavelength division multiplexing channel, a fiber channel, and a SONET optical channel:

OC-1 to OC-192.

13. The system as in claim 1, wherein the second means for mapping combines at least one of the following:

two time frames of selected ones of the input channels into one time frame of a selected one of the output channels, four time frames of selected ones of the input channels into one time frame of a selected one of the output channels, eight time frames of selected ones of the input channels into one time frame of a selected one of the output channels, and sixteen time frames of selected ones of the input channels into one time frame of a selected one of the output channels.

14. The system as in claim 1, wherein the second means for mapping combines at least one of the following:

selected parts of two time frames of selected ones of the input channels into one time frame of a selected one of the output channels, selected parts of four time frames of selected ones of the input channels into one time frame of a selected one of the output channels, selected parts of eight time frames of selected ones of the input channels into one time frame of a selected one of the output channels, and selected parts of sixteen time frames of selected ones of the input channels into one time frame of a selected one of the output channels.

51. The system as in claim 1, further comprising:

a degrooming subsystem comprising;

a plurality of degrooming subsystems, each degrooming subsystem comprising a plurality of output channels, and at least one input channel;

a Common Time Reference (CTR), divided into a plurality of contiguous time frames (TFs), wherein the time frames have a plurality of predefined time durations; and

wherein each of the time frames is associated with transfer of up to a plurality of data units;

first means for mapping a scheduling of transfer of selected ones of the data units for each respective one of the time frames from a respective input channel to at least one time frame associated with at least one of the output channels from at least one of the plurality of degrooming subsystems;

second means for mapping a scheduling for transfer of respective selected ones of the data units for each respective one of the time frames from the respective input channel to at least one time frame of at least one of the output channels from the plurality of degrooming subsystems, to provide a defined delay between the transfer of the respective data unit from the respective input channel to the respective output channel;

wherein the time frames for each of the output channels from the plurality of degrooming subsystems are grouped according to a respective common cycle;

wherein the time frames for each of the input channels from the plurality of degrooming subsystems are grouped according to a respective common cycle.

52. The system as in claim 1, wherein each of the input channels has at least one of a plurality of associated bit rates.

53. The system as in claim 1, further comprising:

a plurality of switches interconnected by selected ones of the plurality of input channels and the plurality of output channels,

wherein the CTR is coupled to the plurality of switches,

wherein the first means for mapping is associated with a first switch,

wherein the second means for mapping is associated with a second switch;

wherein the defined delay is between the transfer of a respective data unit between the first switch and the second switch.

15. A grooming system, comprising:

a plurality of grooming subsystems, each grooming subsystem comprising;

at least one output channel and a plurality of input channels each associated with a plurality of channel bit rates,

a Common Time Reference (CTR), divided into a plurality of contiguous time Frames (TFs), wherein the time frames have a plurality of predefined time durations;

means for mapping a scheduling of transfer of data units from a respective subset of the time frames for the respective ones of the input channels to a respective one of the time frames for each of the output channels to provide a defined time delay between transfer of each of the respective data units from the respective input channel to the respective output channel, wherein the time frames for each of the input channels from the plurality of grooming subsystems are grouped according to a respective common cycle;

wherein the time frames for each of the output channels from the plurality of grooming subsystems are grouped according to a respective common cycle of a plurality of common cycles; and

wherein all the common cycles have a common duration and are associated with respective ones of the input channels and the output channels from the plurality of grooming subsystems.

16. The system as in claim 15, wherein the common cycles for each of the channels are time offset relative to the respective common cycles for the other ones of the channels.

17. The system as in claim 15, wherein the output channels from a first plurality of the grooming subsystems are coupled to the input channels of a first separate one of the grooming subsystems, to provide a first grooming output.

18. The system as in claim 17, wherein the output channels from a second plurality of the grooming subsystems are coupled to the input channels of a second separate one of the grooming subsystems, to provide a second grooming output;

wherein the system is further comprised of a third grooming subsystem, wherein the first and second grooming outputs are coupled to the input channels of the third grooming subsystem.

19. The system as in claim 15, wherein each one of the input channels and the output channels is at least one of an optical channel, a wavelength division multiplexing channel, a fiber channel, a SONET optical channel:

OC-1 to OC-192.

20. A grooming subsystem, comprising:

a plurality of input channels, and at least one output channel;

a Common Time Reference (CTR), divided into a plurality of contiguous time frames (TFs), wherein the time frames have a plurality of predefined time durations;

wherein each of the time frames is associated with a predefined number of plurality of data units; and

means for mapping for each of the time frames of each of the output channels a predefined subset of the data units from a respective subset of the time frames for a respective subset of the input channels to provide a defined delay between transfer of each of the data units from the respective input channel to the respective output channel.

21. The system as in claim 20,

wherein the mapping of the data units for the time frames of the input channels into the respective time frame of the respective output channel is done in a predefined order.

54. The system as in claim 20, wherein the data units are each at least one of a byte, a word, a packet, and an ATM cell.

55. The system as in claim 20, wherein there are a plurality of grooming subsystems each comprised of a plurality of input channels and a plurality of output channels.

56. The system as in claim 55, wherein the means for mapping is associated with a first grooming subsystem, the system further comprising:

second means for mapping associated with a second grooming subsystem, for mapping for each of the time frames of each of the output channels, a predefined subset of the data units from a respective subset of time frames for a respective subset of input channels, to provide a defined delay between the transfer of the respective data unit from the respective input channel to the respective output channel.

57. The system as in claim 20, further comprising:

second mapping means for associating each of the time frames of each of the output channels with a predefined subset of the data units from a respective subset of the time frames for a respective subset of the input channels, to provide a defined delay between the transfer of the respective data unit from the respective input channel to the respective output channel.

22. A degrooming system, comprising:

a plurality of degrooming subsystems, each degrooming subsystem comprising a plurality of output channels, and at least one input channel;

a Common Time Reference (CTR), divided into a plurality of contiguous time frames (TFs), wherein the time frames have a plurality of predefined time durations; and

wherein each of the time frames provides a plurality of data units;

first means for mapping a scheduling of transfer of selected ones of the data units for each respective one of the time frames, from a respective input channel to at least one time frame associated with the at least one of the output channels from at least one of the plurality of degrooming subsystems;

second means for mapping a scheduling for transfer of data units for each respective one of the time frames from the respective input channel to at least one time frame of at least one of the output channels from the plurality of degrooming subsystems, to provide a defined delay between the transfer of each respective data unit from the respective input channel to the respective output channel;

wherein the time frames for each of the output channels from the plurality of degrooming subsystems are grouped according to a respective common cycle;

wherein the time frames for each of the input channels from the plurality of degrooming subsystems are grouped according to a respective common cycle.

23. The system as in claim 22, wherein the common cycles for each of the channels are time offset relative to the respective common cycles for the other ones of the channels.

24. The system as in claim 22, wherein the mapping reoccurs periodically for each of the common cycles.

25. The system as in claim 22, wherein each of the time frames for the input channel is comprised of at least one sub-time frame;

wherein said input channel sub-time frame is mapped into at least one of the output channel time frames.

26. The system as in claim 22, wherein each of the time frames for the output channels and each of the time frames for the input channels is comprised of at least one sub-time frame;

wherein said input channel sub-time frame is mapped into said output channel sub-time frame.

27. The system as in claim 22,

wherein the mapping of the time frames for the respective ones of the output channels is provided from a respective subset of the input channels;

and

wherein each of the time frames of the output channels receives a subset of data units from the input channel.

28. The system as in claim 22, wherein the data units are at least one of a byte, a word, a packet, an ATM cell.

29. The system as in claim 22, wherein delimiters are provided between data units.

30. The system as in claim 22, wherein delimiters are provided between time frames.

31. The system as in claim 22, wherein a time stamp is associated with selected ones of the time frames, and

wherein the time stamp is derived responsive to the CTR.

32. The system as in claim 22, wherein each of the input channels and output channels is at least one of an optical channel, a wavelength division multiplexing channel, a fiber channel, and a SONET optical channel:

OC-1 to OC-192.

58. The system as in claim 31, wherein the first means for mapping is associated with a first degrooming subsystem, wherein the second means for mapping is associated with a second degrooming subsystem.

33. A grooming method, for use in scheduling transfer of data units with a switching system comprising a plurality of input channels, and at least one of a plurality of output channels, the method comprising:

providing a Common Time Reference (CTR);

dividing the CTR into a plurality of contiguous time frames (TFs), wherein the time frames have a plurality of predefined time durations, wherein a plurality of data units can be transferred within each of the time frames;

mapping a scheduling of transfer of respective selected ones of the data units for each of the input channels, into selected ones of the time frames from a respective subset of the time frames for each respective ones of the input channels; and

mapping a scheduling of transfer of the respective selected data units into respective selected ones of the time frames for each of the output channels, from each of the respective subset of the time frames for the respective ones of the input channels, to provide a defined delay between the transfer of the respective data unit from the respective input channel to the respective output channel.

34. The method as in claim 33, wherein the common cycles have a common duration.

35. The method as in claim 33, wherein the common cycles for each of the channels are time offset relative to the respective common cycles for the other ones of the channels.

36. The method as in claim 33, wherein the common cycles for each of the channels are aligned relative to the CTR.

37. The method as in claim 33, wherein the common cycles for each of the channels are time offset relative to the CTR.

38. The method as in claim 33, further comprising:

providing the mapping for each of the common cycles on a periodically reoccurring basis.

39. The method as in claim 33, wherein each of the time frames for the output channel is comprised of at least one sub-time frame, the method further comprising:

mapping each of the input channel time frames into a respective one of the output channel sub-time frames.

40. The method as in claim 33, wherein each of the time frames for the input channels and the output channels is comprised of at least one sub-time frame, the method further comprising:

mapping each of the input channel sub-time frames into a respective one of the output channel sub-time frames.

41. The method as in claim 33, the method further comprising:

mapping the time frames for respective ones of the input channels provided for each of the data units from a respective subset of the input channels to the respective output channel.

42. The method as in claim 41, further comprising:

combining the data units from each of the plurality of the input channels for the respective subset in a predefined order with the data units from other ones of the plurality of the input channels for the respective subset.

59. The method as in claim 33, further comprising:

grouping the time frames for each of the output channels and the input channels associated according to a respective common cycle; and

associating each of the common cycles with respective ones of plurality of input channels and said at least one of a plurality of the output channels.

43. A grooming method for use with a switching system, comprising a plurality of input channels, and at least one output channel, the method comprising:

providing a Common Time Reference (CTR);

dividing the CTR into a plurality of contiguous time frames (TFs), wherein the time frames have a plurality of predefined time durations, wherein each of the time frames can provide for communications of a predefined number of plurality of data units; and

mapping for each of the time frames of each of the output channels a predefined subset of the data units from a respective subset of the time frames for a respective subset of the input channels, to provide a defined delay between the transfer of each respective one of the plurality of data units from the respective input channel to the respective output channel, wherein the time frames for each of the input channels from the plurality of grooming subsystems are grouped according to a respective common cycle;

wherein the time frames for each of the output channels from the plurality of grooming subsystems are grouped according to a respective common cycle of a plurality of common cycles; and

wherein all the common cycles have a common duration and are associated with respective ones of the input channels and the output channels from the plurality of grooming subsystems.

44. The method as in claim 43,

wherein the data units are at least one of a byte, a word, a packet, an ATM cell.

60. The method as in claim 43, further comprising:

mapping for each of the time frames of each of the output channels, a second predefined subset of the data units from a respective subset of the time frames for a respective subset of the input channels, to provide a defined delay between the transfer of the respective data unit from the respective input channel to the respective output channel.

45. A degrooming method, for use in providing for transfer of a plurality of data units, with a switching system comprised of a plurality of output channels, and at least one input channel, the method comprising:

providing a Common Time Reference (CTR),

dividing the CTR into a plurality of contiguous time frames (TFs), wherein the time frames have a plurality of predefined time durations;

mapping for each respective one of the time frames from the respective input channel, to at least one time frame associated with at least one of the output channels to provide a defined delay between the transfer of the respective data unit from the respective input channel to the respective output channel;

grouping the time frames for each of the output channels and the at least one input channel; and

associating each of the groupings of time frames with a respective common time cycle of a plurality of time cycles, wherein the time frames for each of the input channels are grouped according to a respective common cycle.

46. The method as in claim 45, wherein the common cycles for each of the channels are time offset relative to the respective common cycles for the other ones of the channels.

47. The method as in claim 45, wherein the mapping reoccurs for each of the common cycles on a periodically reoccurring basis.

48. The method as in claim 45, wherein each of the time frames for the input channel is comprised of at least one sub-time frame, the method further comprising:

mapping each of the input channel sub-time frames into at least one of the output channel time frames.

49. The method as in claim 45, wherein each of the time frames for the output channels and the input channels is comprised of at least one sub-time frame, the method further comprising:

mapping each of the input channel sub-time frames is mapped into one of the output channel sub-time frames.

50. The method as in claim 45, wherein each of the time frames provides a plurality of data units, the method further comprising:

mapping the time frames for the respective ones of the output channels from a respective subset of the input channels; and

receiving for each of the time frames of the output channels a subset of data units from the input channel.

61. The method as in claim 45, further comprising:

mapping for each respective one of the time frames from a respective second input channel to at least one time frame of at least one of the output channels, to provide a defined delay between the transfer of the respective data unit from the respective input channel to the respective output channel.