System and method for communicating packetized data over a channel bank

• US 6,678,282 B2
• Filed: 04/20/1998
• Issued: 01/13/2004
• Est. Priority Date: 10/23/1996
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Sharper, Craig Alan, Sachs, Nadia
• Primary Examiner(s): TON, DANG T
• Application Number:
  US09/063,340
• Publication Number:
  US 20030137992A1
• Time in Patent Office: 2,094 Days
• Field of Search: 370/442, 370/443, 370/444, 370/447, 370/458, 370/459, 370/360, 370/375, 370/376, 370/357, 370/353, 370/389, 370/433, 370/468, 370/537, 370/538, 370/351, 370/352, 370/396.1, 370/395.52, 370/395.61, 370/395.42, 370/395.41, 370/395.5, 370/395.65, 370/395.63, 370/395.64, 370/431, 370/347, 370/461, 370/462, 370/465, 370/467, 370/503
• US Class Current: 370/442
• CPC Class Codes: H04J 3/1682 Allocation of channels according to the instantaneous demands of the users, e.g. concentrated multiplexers, statistical multiplexers
• CPC Class Codes: H04J 3/247 ATM or packet multiplexing

Abstract

An apparatus for communicating packetized data over a communications link using a channel bank having a time division multiplexing addressing scheme, the communications link having a predetermined format for data transmitted over the communications link including a framing bit and a frame period defined by the framing bit, is provided wherein the apparatus comprises a plurality of channel units for generating packetized data, each piece of packetized data having a packet period corresponding to a sufficient amount of time to communicate the packetized data over the communications link, a system for allocating the communication link to a channel unit that is currently sending data over the communications link for the packet period, a system for skipping the framing bit when communicating said packetized data if the framing bit occurs during the packet period, a system for determining a next sender of packetized data over the communications link, the determining system being distributed over the plurality of channel units so that each channel unit independently determines whether it is the next sender, and a system for allocating the communications link to the channel unit that is the next sender of packetized data after said packet period so that the time division multiplexing addressing scheme of the channel bank is ignored, and the channel bank is communicating packetized data. A method for communicating packetized data over a channel bank is also disclosed.

Claims

1. An apparatus for communicating packetized data over a communications link using a channel bank having a time division multiplexing addressing scheme, comprising:

a plurality of channel units each generating packetized data; and

contention circuitry incorporated into the channel bank that ignores time slot boundaries in the time division multiplexing addressing scheme while enabling a packetized data protocol in the channel units for communicating packetized data over the communications link independently of the time slot boundaries.

2. An apparatus according to claim 1 wherein each one of the channel units communicates with the contention circuitry for sending packetized data over the communications link.

3. An apparatus according to claim 1 wherein the channel bank includes common equipment that uses TDM signaling for assigning fixed timeslots to the channel units, each one of the channel units including a portion of the contention circuitry that receives but ignores the TDM signaling when sending packetized data.

4. An apparatus according to claim 3 wherein the TDM signaling includes a framing bit that is skipped by the contention circuitry in the channel units when communicating the packetized data.

5. An apparatus according to claim 1 wherein the contention circuitry includes a contention bus including a signaling bus normally used for voice communications within the channel bank but alternatively used by the contention circuitry for resolving contention among the channel units vying to send packetized data over the communications links.

6. An apparatus according to claim 5 wherein the channel bank comprises a D4 channel bank having a TA bus, a TB bus and a TPAM bus, and wherein the signaling bus comprises one of the buses in the D4 channel bank.

7. An apparatus according to claim 1 wherein the packetized data is in a frame relay format.

8. An apparatus according to claim 1 wherein the contention circuitry provides a plurality of contention periods for assigning a next sender of packetized data over the communications link.

9. An apparatus according to claim 8 wherein the channel units generate contention signals that are compared by the contention circuitry to determine which of the channel units to assign as the next sender.

10. An apparatus according to claim 9 wherein the contention signals include a priority value used by the contention circuitry to determine which of the channel units to assign as the next sender.

11. An apparatus for communicating packetized data over a communications link using a channel bank having a time division multiplexing addressing scheme, comprising:

a plurality of channel units each generating packetized data; and

contention circuitry incorporated into the channel bank that ignores the time division multiplexing addressing scheme while enabling a packetized data protocol in the channel units for communicating packetized data over the communications link,

the contention circuitry providing a plurality of contention periods for assigning a next sender of packetized data over the communications link and the channel units generating contention signals that are compared by the contention circuitry to determine which of the channel units to assign as the next sender,

the contention signals including a priority value used by the contention circuitry to determine which of the channel units to assign as the next sender and a fairness value for preventing a channel unit that has sent packetized data using a particular priority value from sending additional data at that same particular priority value until the other channel units have also had a chance to send data at that particular priority value.

12. An apparatus according to claim 11 wherein the contention signals include a current sender signal indicating which of the channel units is the current sender of packetized data, a next sender signal indicating which of the channel units is the next sender of packetized data, and a slot signal indicating a slot address associated with the channel units.

13. A method for communicating packetized data over a communications link using a channel bank having a time division multiplexing addressing scheme, comprising:

generating packetized data during packet periods using channel units in the channel bank;

assigning one of the channel units as a current sender of packetized data over the communications link;

assigning one of the channel units as a next sender of packetized data over the communications link; and

ignoring fixed time slots in the time division multiplexing addressing scheme in the channel bank while enabling the current sender to use a packetized data protocol that transmits the packetized data over the communications link without using the fixed time slots in the time division multiplexing addressing scheme.

14. A method according to claim 13 wherein ignoring the time division multiplexing addressing scheme comprises skipping a framing bit in the time division multiplexing addressing scheme if the framing bit occurs during one of the packet periods.

15. A method according to claim 14 including using a signaling bus normally used in the channel bank for voice communications to determine the next sender of packetized data over the communications link.

16. A method according to claim 15 wherein the channel bank comprises a D4 channel bank having a TA bus, a TB bus and a TPAM bus, and wherein using the signaling bus comprises selecting the signaling bus from one of the buses in the D4 channel bank.

17. A method according to claim 13 wherein the packetized data is in a frame relay format.

18. A method according to claim 13 wherein assigning the next sender comprises:

generating a plurality of contention signals from the channel units;

sending the contention signals over a contention bus; and

comparing the contention signals to determine the next sender.

19. A method according to claim 13 wherein the contention signals include priority signals that assign priorities to the packetized data transmitted by the channel units.

25. A method according to claim 13 including retaining the communications by the current sender of packetized data if no next sender of packetized data has been determined.

20. A method for communicating packetized data over a communications link using a channel bank having a time division multiplexing addressing scheme, comprising:

generating packetized data during packet periods using channel units in the channel bank;

assigning one of the channel units as a current sender of packetized data over the communications link;

assigning one of the channel units as a next sender of packetized data over the communications link;

ignoring the time division multiplexing addressing scheme in the channel bank while enabling the current sender to use a packetized data protocol to communicate the packetized data over the communications link; and

generating a fairness signal that prevents the channel units from sending packetized data at a particular priority after previously sending data at that particular priority until the other channel units have had a chance to send packetized data at that particular priority.

21. A method according to claim 20 including resetting the fairness signal once all of the channel units have had a chance to send packetized data at that particular priority.

22. A method according to claim 21 including resetting the fairness signal for one of the channel units for a particular priority when another one of the channel units becomes the next sender at that particular priority.

23. A method according to claim 22 including determining the next sender by selecting one of the channel units having a same priority as the other channel units but that has a different fairness signal for that priority.

24. A method according to claim 23 wherein the contention signals include a current sender signal identifying one of the channel units as the current sender of packetized data, a next sender signal indicating one of the channel units as the next sender of packetized data, and a slot signal indicating slot addresses for the channel units within the channel bank.

26. An electronic storage medium containing a software program for operating in a channel bank, the channel bank having a time division multiplexing addressing scheme for communicating over a communications link, the software program comprising:

program code for generating packetized data during packet periods from channel units in the channel bank;

program code for assigning the communications link to one of the channel units as a current sender of packetized data over the communications link;

program code for assigning one of the channel units as a next sender of packetized data over the communications link; and

program code for ignoring fixed time slots in the time division multiplexing addressing scheme in the channel bank while enabling the channel units to use a packetized data protocol that transfers the packetized data over the communications link independently of the fixed time slots.

27. An electronic storage medium according to claim 26 wherein the program code that ignores the time division multiplexing addressing scheme skips a framing bit in the time division multiplexing addressing scheme when communicating the packetized data if the framing bit occurs during one of the packet periods.

28. An electronic storage medium according to claim 26 including program code that uses a signaling bus normally used for voice communications in the channel bank to determine the next sender of packetized data over the communications link.

29. An electronic storage medium according to claim 28 wherein the channel bank comprises a D4 channel bank having a TA bus, a TB bus, and a TPAM bus, and the program code selects the signaling bus from one of the buses in the D4 channel bank.

30. An electronic storage medium according to claim 26 wherein the packetized data is in a frame relay format.

31. An electronic storage medium according to claim 26 wherein the program code determines the next sender as follows:

generating a plurality of contention signals from the channel units;

sending the contention signals over a contention bus; and

comparing the contention signals to determine the next sender.

32. An electronic storage medium according to claim 26 including program code for assigning priorities to the packetized data transmitted by the channel units.

33. An electronic storage medium according to claim 26 including program code that generates a fairness signal that prevents the channel units from sending packetized data at a particular priority after previously sending data at that particular priority until the other channel units have also had a chance to send packetized data at that particular priority.

34. An electronic storage medium according to claim 33 including program code that resets the fairness signal once all of the channel units have had a chance to send packetized data at that particular priority.

35. An electronic storage medium according to claim 34 including program code that resets the fairness signal for one of the channel units for a particular priority when another one of the channel units becomes the next sender at that particular priority.

36. An electronic storage medium according to claim 26 including program code that determines the next sender by selecting one of the channel units having a same priority as the other channel units but that has a different fairness signal for that priority.

37. An electronic storage medium according to claim 26 including program code that generates a current sender signal indicating one of the channel units as the current sender of packetized data, a next sender signal indicating one of the channel units as the next sender of packetized data, priority signals indicating particular priorities for packetized data to be communicated by the channel units, and slot signals indicating slot addresses for the channel units within the channel bank.

38. An electronic storage medium according to claim 26 including program code that retains the communications link by the current sender of packetized data if no next sender of packetized data has been determined.

39. An apparatus for communicating packetized data over a communications link, comprising:

a plurality of channel units generating packetized data and assigning priority values to the packetized data, the channel units also generating fairness signals indicating whether the channel units have previously sent packetized data at that particular priority value;

a contention circuit that allocates one of the channel units as a current sender of packetized data and assigns one of the channel units as a next sender of packetized data, the contention circuit assigning the next sender based on the priority values assigned by the channel units to the packetized data and also based on the fairness signals generated by the channel units, the contention circuit allocating the communication link to the next sender after said current sender has finished sending packetized data.

40. An apparatus according to claim 39 wherein the channel units are given slot assignments and the contention circuit allocates the next sender according to the slot assignments.

41. An apparatus according to claim 39 wherein the channel units set their fairness signals for a particular priority value once that channel unit has sent packetized data at that particular priority value.

42. An apparatus according to claim 41 wherein the channel units reset their fairness signals once all of the channel units have had a chance to send packetized data at that particular priority value.

43. An apparatus according to claim 42 wherein the contention circuit selects the next sender from channel units having the same priority value and a reset fairness bit for that priority value.

44. An apparatus according to claim 39 wherein the channel units are part of a channel bank that provides a time division multiplexing addressing scheme for communicating over the communications link and the contention circuitry ignores the time division multiplexing addressing scheme used in the channel bank while enabling the channel units to use a packetized data protocol to communicate packetized data over the communications link.

45. An apparatus according to claim 44 wherein the contention circuitry ignores the time division multiplexing addressing scheme by skipping a framing bit in the addressing scheme if the framing bit occurs when one of the channel banks is sending packetized data.

46. An electronic storage medium containing a software program for communicating packetized data over a communications link, the software program comprising:

program code for generating packetized data from channel units and assigning priority values to the packetized data, the program code also generating fairness signals indicating whether the channel units have previously sent packetized data at a particular priority value;

contention program code that allocates one of the channel units as a current sender of packetized data and assigns one of the channel units as a next sender of packetized data, the contention program code assigning the next sender based on the priority values assigned by the channel units to the packetized data and also based on the fairness signals generated by the channel units, the contention circuit allocating the communication link to the next sender after the current sender has finished sending packetized data.

47. An electronic storage medium according to claim 46 including program code that gives the channel units slot assignments and assigns the next sender according to the slot assignments.

48. An electronic storage medium according to claim 46 including program code that sets the fairness signals for particular priority values once the channel unit have sent packetized data at those particular priority values.

49. An electronic storage medium according to claim 46 including program code that resets the fairness signals for a particular priority value after all of the channel units having packetized data to send at that particular priority value have sent packetized data at that particular priority value.

50. An electronic storage medium according to claim 46 wherein the contention program code selects the next sender from channel units having the same priority value and a reset fairness bit for that priority value.

51. An electronic storage medium according to claim 46 wherein the channel units are part of a channel bank that provides a time division multiplexing addressing scheme for communicating over the communications link and the contention program code ignores the time division multiplexing addressing scheme used in the channel bank while enabling the channel units to use a packetized data protocol to communicate packetized data over the communications link.

52. An electronic storage medium according to claim 51 wherein the contention program code ignores the time division multiplexing addressing scheme by skipping a framing bit in the addressing scheme if the framing bit occurs when one of the channel banks is sending packetized data.

53. An apparatus for communicating packetized data over a communications link, comprising:

means for generating packetized data from channel units and assigning priority values to the packetized data, the program code also generating fairness signals indicating whether the channel units have previously sent packetized data at a particular priority value;

means for allocating one of the channel units as a current sender of packetized data and assigning one of the channel units as a next sender of packetized data,

means for assigning the next sender based on the priority values assigned by the channel units to the packetized data and also based on the fairness signals generated by the channel units; and

means for allocating the communication link to the next sender after the current sender has finished sending packetized data.

54. An apparatus according to claim 53 including means for giving the channel units slot assignments and assigning the next sender according to the slot assignments.

55. An apparatus according to claim 53 including means for setting the fairness signals for particular priority values once the channel unit have sent packetized data at those particular priority values.

56. An apparatus according to claim 53 including means for resetting the fairness signals for a particular priority value after all of the channel units having packetized data to send at that particular priority value have sent packetized data at that particular priority value.

57. An apparatus according to claim 53 including means for selecting the next sender from channel units having the same priority value and resetting the fairness signals for that priority value.