Transporting multiprotocol datagrams

1. A method of transporting multi-protocol datagrams over a point to point protocol (PPP) link through an asynchronous transport network, comprising the steps of:

encapsulating multi-protocol datagrams into payloads of asynchronous transport network mini-cells, each mini-cell having a header in addition to a payload, the header including a channel identifier (CID) field;

for each mini-cell, associating a PPP identifier of the datagram being encapsulated therein with the CID field of the mini-cell by inserting a PPP identifier into the CID field of the mini-cell;

assembling said mini-cells into transport packets; and

transporting said packets over said point to point link through the asynchronous transport network.

2. A method as claimed in claim 1 , wherein said PPP identifier identifies a PPP session.

3. A method as claimed in claim 1 , wherein said PPP identifier identifies at least one PPP protocol within a PPP session.

4. A method as claimed in claim 1 , wherein the PPP identifier identifies at least one session within a protocol of a PPP session.

5. A method as claimed in claim 1 , wherein the PPP identifier of a multi-protocol datagram comprises two octets, a most significant octet and a least significant octet, and the method includes the step of inserting only the least significant octet of the PPP identifier into the CID field of a mini-cell.

6. A method as claimed in claim 5 , wherein it includes the step of inserting the most significant octet of the PPP identifier in a first byte of the mini-cell payload adjacent the header and to indicating the presence of said most significant octet in said first byte of the mini-cell payload by making a value of a least significant bit (LSB) of the least significant octet to be “1”.

7. A method as claimed in claim 6 , wherein a LSB of the most significant octet of the PPP identifier is utilised as a bit parity check for error detection.

8. A method as claimed in claim 1 , wherein the step of associating a PPP identifier with the CID field of a mini-cell comprises assigning a pre-allocated PPP identifier number to a respective mini-cell CID value and inserting the CID value into the CID field of the mini-cell.

9. A method as claimed in claim 8 , wherein the step of assigning a pre-allocated PPP identifier number to a CID value and inserting said CID value into the CID field of a mini-cell includes obtaining the CID value corresponding to a pre-allocated PPP identifier number from a preconfigured table containing a list of pre-allocated PPP identifiers numbers and corresponding CID values.

10. A method as claimed in claim 8 , wherein the step of assigning a pre-allocated PPP identifier number to a CID value and inserting said CID value in the CID field of a mini-cell comprises assigning said pre-allocated PPP identifier number to said CID value on set-up of a PPP link, said assignment being carried out by a management function.

11. A method as claimed in claim 1 , wherein the asynchronous transport network is an asynchronous transport mode (ATM) network and the mini-cells are ATM adaptation layer 2 (AAL2) mini-cells.

12. A method as claimed in claim 11 , wherein it includes the step of mapping a PPP session to a single AAL2 channel.

13. A method as claimed in claim 11 , wherein it includes the step of mapping at least one protocol of a PPP session to an AAL2 channel.

14. A method as claimed in claim 11 , wherein it includes the step of mapping at least one session of a specified PPP protocol to an AAL2 channel.

15. A method as claimed in claim 11 , wherein it includes the step of mapping several PPP sessions to a same AAL2 channel.

16. A method as claimed in claim 11 , wherein it includes the step of mapping several protocols from different PPP sessions to a same AAL2 channel.

17. A method as claimed in claim 16 , wherein the several protocols from different PPP sessions comprise the same protocol from each of the different PPP sessions.

18. A method as claimed in claim 11 , wherein it includes the step of mapping at least one session of a specified PPP protocol of several PPP sessions to a same AAL2 channel.

19. A method as claimed in claim 11 wherein it includes a mapping step, said mapping step comprising a combination of any of:

mapping a PPP session to a single AAL2 channel;

mapping at least one protocol of a PPP session to an AAL2 channel;

mapping at least one session of a specified PPP protocol to an AAL2 channel;

mapping several PPP sessions to a same AAL2 channel;

mapping several protocols from different PPP sessions to a same AAL2 channel; and

mapping at least one session of a specified PPP protocol of several PPP sessions to a same AAL2 channel;

wherein said AAL2 channels comprise an ATM virtual circuit connection (VCC).

20. A method as claimed in any one of claims 11 to 19 , wherein it includes the step of scheduling transport of ATM mini-cells of said AAL2 channels according to the type of PPP datagrams encapsulated in the mini-cells being transported in respective AAL2 channels.

21. A method as claimed in claim 11 wherein it includes a mapping step, said mapping step comprising one of:

mapping a PPP session to a single ATM virtual channel connection (VCC);

mapping at least one protocol of a PPP session to an ATM VCC;

mapping at least one session of a specified PPP protocol to an ATM VCC mapping several PPP sessions to a same ATM VCC;

mapping several protocols from different PPP sessions to a same ATM VCC; and

mapping at least one session of a specified PPP protocol of several PPP sessions to a same ATM VCC.

22. A method as claimed 11 , wherein it includes the step of multiplexing mini-cells into an ATM virtual channel connection (VCC).

23. A method as claimed in claim 22 , wherein said step of multiplexing mini-cells into an ATM virtual channel connection (VCC) includes multiplexing mini-cells encapsulating PPP datagrams and mini-cells encapsulating non-PPP datagrams into the ATM VCC.

24. A method as claimed in claim 23 , wherein said PPP traffic data comprises voice traffic data.

25. A method as claimed in claim 11 , wherein the multi-protocol datagrams are encapsulated into mini-cells of variable lengths.

26. A method as claimed in claim 11 , wherein multi-protocol datagrams comprising delay sensitive traffic are encapsulated into mini-cells comprising a first channel of an ATM virtual circuit (VC) and datagrams comprising delay insensitive traffic are encapsulated into mini-cells comprising a second channel of said ATM VC.

27. A method as claimed in claim 11 , wherein said step of assembling mini-ells into transport packets comprises assembling mini-cells into ATM packets.

28. A method as claimed in claim 11 , wherein said step of assembling mini-cells into transport packets comprises assembling mini-cells directly into MPEG-TS frames.

29. A method as claimed in claim 11 , wherein said step of assembling mini-cells into transport packets comprises assembling mini-cells directly into TDMA time slots.

30. A method as claimed in claim 1 , wherein it includes the step of encoding a flag in a user to user information (UUI) field of a mini-cell to indicate whether an encapsulated datagram extends into a payload of a next mini-cell.

31. A method as claimed in claim 1 , wherein the step of encapsulating a datagram in a mini-cell includes inserting the PPP identifier, a payload of the datagram and an optional trailer into the payload of the mini-cell.

32. A method of encapsulating point to point protocol (PPP) datagrams into payloads of asynchronous transport network mini-cells, each mini-cell having a header in addition to a payload, the header including a channel identifier (CID) field, the method comprising the steps of:

encapsulating the PPP datagrams into the payloads of the asynchronous transport network mini-cells;

for each mini-cell, associating a PPP identifier of the datagram being encapsulated therein with the CID field of the mini-cell by inserting a PPP identifier into the CID field of the mini-cell; and

assembling said mini-cells into transport packets.

33. A method as claimed in claim 32 , wherein said PPP identifier identifies a PPP session.

34. A method as claimed in claim 32 , wherein said PPP identifier identifies at least one PPP protocol within a PPP session.

35. A method as claimed in claim 32 , wherein the PPP identifier identifies at least one session within a protocol of a PPP session.

36. A method as claimed in claim 32 , wherein the PPP identifier of a multi-protocol datagram comprises two octets, a most significant octet and a least significant octet, and the method includes the step of inserting only the least significant octet of the PPP identifier into the CID field of a mini-cell.

37. A method as claimed in claim 36 , wherein it includes the step of inserting the most significant octet of the PPP identifier in a first byte of the mini-ell payload adjacent the header and to indicating the presence of said most significant octet in said first byte of the mini-cell payload by making a value of a least significant bit (LSB) of the least significant octet to be “1”.

38. A method as claimed in claim 37 , wherein a LSB of the most significant octet of the PPP identifier is utilised as a bit parity check for error detection.

39. A method as claimed in claim 32 , wherein the step of associating a PPP identifier with the CID field of a mini-cell comprises assigning a pre-allocated PPP identifier number to a respective mini-cell CID value and inserting the CID value into the CID field of the mini-cell.

40. A method as claimed in claim 39 , wherein the step of assigning a pre-allocated PPP identifier number to a CID value and inserting said CID value into the CID field of a mini-cell includes obtaining the CID value corresponding to a pre-allocated PPP identifier number from a pre-configured table containing a list of pre-allocated PPP identifiers numbers and corresponding CID values.

41. A method as claimed in claim 39 , wherein the step of assigning a pre-allocated PPP identifier number to a CID value and inserting said CID value in the CID field of a mini-cell comprises assigning said pre-allocated PPP identifier number to said CID value on set-up of a PPP link, said assignment being carried out by a management function.

42. A method as claimed in claim 32 , wherein the asynchronous transport network is an asynchronous transport mode (ATM) network and the mini-cells are ATM adaptation layer 2 (AAL2) mini-cells.

43. A method as claimed in claim 42 , wherein it includes the step of mapping a PPP session to a single AAL2 channel.

44. A method as claimed in claim 42 , wherein It Includes the step of mapping at least one protocol of a PPP session to an AAL2 channel.

45. A method as claimed in claim 42 , wherein it includes the step of mapping at least one session of a specified PPP protocol to an AAL2 channel.

46. A method as claimed in claim 42 , wherein it includes the step of mapping several PPP sessions to a same AAL2 channel.

47. A method as claimed in claim 42 , wherein it includes the step of mapping several protocols from different PPP sessions to a same AAL2 channel.

48. A method as claimed in claim 47 , wherein the several protocols from different PPP sessions comprise the same protocol from each of the different PPP sessions.

49. A method as claimed in claim 42 , wherein It Includes the step of mapping at least one session of a specified PPP protocol of several PPP sessions to a same AAL2 channel.

50. A method as claimed in claim 42 wherein It includes a mapping step, said mapping step comprising a combination of any of:

mapping a PPP session to a single AAL2 channel;

mapping at least one protocol of a PPP session to an AAL2 channel;

mapping at least one session of a specified PPP protocol to an AAL2 channel;

mapping several PPP sessions to a same AAL2 channel;

mapping several protocols from different PPP sessions to a same AAL2 channel; and

mapping at least one session of a specified PPP protocol of several PPP sessions to a same AAL2 channel;

wherein said AAL2 channels comprise an ATM virtual circuit connection (VCC).

51. A method as claimed in any one of claims 42 to 50 , wherein it includes the step of scheduling transport of ATM mini-cells of said AAL2 channels according to the type of PPP datagrams encapsulated in the mini-cells being transported in respective AAL2 channels.

52. A method as claimed in claim 42 wherein it includes a mapping step, said mapping step comprising one of:

mapping a PPP session to a single ATM virtual channel connection (VCC);

mapping at least one protocol of a PPP session to an ATM VCC;

mapping at least one session of a specified PPP protocol to an ATM VCC

mapping several PPP sessions to a same ATM VCC;

mapping several protocols from different PPP sessions to a same ATM VCC; and

mapping at least one session of a specified PPP protocol of several PPP sessions to a same ATM VCC.

53. A method as claimed 42 , wherein it includes the step of multiplexing mini-cells into an ATM virtual channel connection (VCC).

54. A method as claimed in claim 53 , wherein said step of multiplexing mini-cells into an ATM virtual channel connection (VCC) includes multiplexing mini-ells encapsulating PPP datagrams and mini-cells encapsulating non-PPP datagrams into the ATM VCC.

55. A method as claimed in claim 54 , wherein said PPP traffic data comprises voice traffic data.

56. A method as claimed in claim 42 , wherein the multi-protocol datagrams are encapsulated into mini-cells of variable lengths.

57. A method as claimed in claim 42 , wherein multi-protocol datagrams comprising delay sensitive traffic are encapsulated into mini-cells comprising a first channel of an ATM virtual circuit (VC) and datagrams comprising delay insensitive traffic are encapsulated into mini-cells comprising a second channel of said ATM VC.

58. A method as claimed in claim 42 , wherein said step of assembling mini-cells into transport packets comprises assembling mini-cells into ATM packets.

59. A method as claimed in claim 32 , wherein It Includes the step of encoding a flag in a user to user information (UUI) field of a mini-cell to indicate whether an encapsulated datagram extends into a payload of a next mini-cell.

60. A method as claimed in claim 32 , wherein the step of encapsulating a datagram in a mini cell includes inserting the PPP identifier, a payload of the datagram and an optional trailer into the payload of the mini-cell.

61. Apparatus for transporting multi-protocol datagrams over a point to point protocol (PPP) link through an asynchronous transport network, comprising:

encapsulating means arranged to encapsulate multi-protocol datagrams into payloads of asynchronous transport network mini-cells, each mini-cell having a header in addition to a payload, the header including a channel identifier (CID) field;

associating means arranged to associate a PPP identifier of a datagram being encapsulated into a mini-cell with the CID field of the mini-cell by inserting a PPP identifier into the CID field of the mini-cell;

assembling means arranged to assemble said mini-cells into transport packets; and

transporting means arranged to transport said packets over said point to point link through the asynchronous transport network.

62. A transport apparatus as claimed in claim 61 , wherein the associating means is arranged to insert only a least significant octet of a two octet PPP identifier into the CID field of a mini-cell.

63. A transport apparatus as claimed in claim 62 , wherein the associating means is arranged to insert a most significant octet of the PPP identifier in a first byte of the mini-cell payload adjacent the header and to indicating the presence of said most significant octet in said first byte of the mini-cell payload by making a value of a least significant bit (LSB) of the least significant octet to be “1”.

64. A transport apparatus as claimed in claim 61 , wherein the associating mean is arranged to assign a pre-allocated PPP identifier number to a respective mini-cell CID value and to insert the CID value into the CID field of the mini-cell.

65. A transport apparatus as claimed in claim 61 , wherein the asynchronous transport network is an asynchronous transport mode (ATM) network and the mini-cells are ATM adaptation layer 2 (AAL2) mini-ells.

66. A transport apparatus as claimed in claim 65 , wherein it includes scheduling means arranged to schedule transport of ATM mini-cells of said AAL2 channels according to the type of PPP datagrams encapsulated in the mini-cells being transported in respective AAL2 channels.

67. A transport apparatus as claimed 65 , wherein it includes multiplexing means arranged to multiplex a mini-cells into an ATM virtual channel connection (VCC).

68. A transport apparatus as claimed in claim 67 , wherein said multiplexing means is arranged to multiplex mini-cells encapsulating PPP datagrams and mini-cells encapsulating non-PPP datagrams into the ATM VCC.

69. A transport apparatus as claimed in claim 65 , wherein the encapsulating means is arranged to encapsulate datagrams comprising delay sensitive traffic into mini-cells comprising a first channel of an ATM virtual circuit (VC) and encapsulate datagrams comprising delay insensitive traffic into mini-cells comprising a second channel of said ATM VC.

70. A transport apparatus as claimed in claim 65 , wherein said assembling means is arranged to assemble mini-cells into ATM packets.

71. A transport apparatus as claimed in claim 65 , wherein said assembling means is arranged to assemble mini-cells directly into MPEG-TS frames.

72. A transport apparatus as claimed in claim 65 , wherein said assembling means is arranged to assemble mini-cells directly into TDMA time slots.

73. Apparatus for encapsulating point to point protocol (PPP) datagrams into payloads of asynchronous transport network mini-cells, each mini-cell having a header in addition to a payload, the header including a channel identifier (CID) field, the apparatus comprising:

encapsulating means arranged to encapsulate the PPP datagrams into the payloads of the asynchronous transport network mini-cells;

associating means arranged to associate a PPP identifier of a datagram being encapsulated into a mini-cell with the CID field of the mini-cell by inserting a PPP identifier into the CID field of the mini-cell; and

assembling means arranged to assemble said mini-cells into transport packets.

74. An apparatus as claimed in claim 73 , wherein the associating means is arranged to insert only a least significant octet of a two octet PPP identifier into the CID field of a mini-cell.

75. An apparatus as claimed in claim 74 , wherein the associating means is arranged to insert a most significant octet of the PPP identifier in a first byte of the mini-cell payload adjacent the header and to indicating the presence of said most significant octet in said first byte of the mini-cell payload by making a value of a least significant bit (LSB) of the least significant octet to be “1”.

76. An apparatus as claimed in claim 73 , wherein the associating means is arranged to assign a pre-allocated PPP identifier number to a respective mini-cell CID value and to insert the CID value into the CID field of the mini-cell.

77. An apparatus as claimed in claim 73 , wherein the asynchronous transport network is an asynchronous transport mode (ATM) network and the mini-cells are ATM adaptation layer 2 (AAL2) mini-cells.

78. An apparatus as claimed in claim 77 , wherein it includes scheduling means arranged to schedule transport of ATM mini-cells of said AAL2 channels according to the type of PPP datagrams encapsulated in the mini-cells being transported in respective AAL2 channels.

79. An apparatus as claimed 77 , wherein it includes multiplexing means arranged to multiplex mini-cells into an ATM virtual channel connection (VCC).

80. An apparatus as claimed in claim 79 , wherein said multiplexing means is arranged to multiplex mini-cells encapsulating PPP datagrams and mini-cells encapsulating non-PPP datagrams into the ATM VCC.

81. An apparatus as claimed in claim 77 , wherein the encapsulating means is arranged to encapsulate datagrams comprising delay sensitive traffic into mini-cells comprising a first channel of an ATM virtual circuit (VC) and encapsulate datagrams comprising delay insensitive traffic into mini-cells comprising a second channel of said ATM VC.

82. An apparatus as claimed in claim 77 , wherein said assembling means is arranged to assemble mini-cells into ATM packets.

83. An apparatus as claimed in claim 77 , wherein said assembling means is arranged to assemble mini-cells directly into MPEG-TS frames.

84. An apparatus as claimed in claim 77 , wherein said assembling means is arranged to assemble mini-cells directly into TDMA time slots.