Buffer-based traffic measurement system and method for nominal bit rate (NBR) service

• US 6,167,030 A
• Filed: 03/20/1997
• Issued: 12/26/2000
• Est. Priority Date: 03/20/1997
• Status: Expired due to Fees

• Current Assignee: Nokia Telecommunications Oy (Nokia Corporation)
• Original Assignee: Nokia Telecommunications Oy (Nokia Corporation)
• Inventors: Ruutu, Jussi Pekka Olavi, Kilkki, Matti Kalevi, Saranka, Sari Irene
• Primary Examiner(s): Nguyen, Chau
• Assistant Examiner(s): LEE, CHI HO A
• Application Number:
  US08/821,363
• Time in Patent Office: 1,377 Days
• Field of Search: 370/229, 370/230, 370/231, 370/232, 370/233, 370/234, 370/236, 370/235, 370/239, 370/412, 370/395, 370/397, 370/391, 370/400, 370/444, 370/410, 370/455, 370/465, 370/468
• US Class Current: 370/236
• CPC Class Codes: H04L 2012/5614 User Network Interface
• CPC Class Codes: H04L 2012/5651 Priority, marking, classes
• CPC Class Codes: H04L 2012/5682 Threshold; Watermark
• CPC Class Codes: H04Q 11/0478 Provisions for broadband connections

Abstract

A system and method for controlling the cell priority of cells transmitted from a cell source to network destinations across a network connection is provided. Each of the cells transmitted is registered in a measurement buffer upon being output from the cell source. The registered cells in the measurement buffer are discharged at a discharge rate corresponding to the current occupancy level of the measurement buffer. Cell priority values are generated by correlating the current buffer occupancy level to one of a plurality of predetermined buffer occupancy ranges to determine which occupancy range coincides with the current occupancy level. The generated cell priority values are loaded into cells transmitted from the cell source for use by the network connection.

Claims

1. A method of adjusting a transmission rate of information cells transmitted over a network connection, comprising:

transmitting a measurement cell to a measurement buffer substantially contemporaneously with respect to each transmission of an information cell to the network connection;

regulating an occupancy level of the measurement buffer;

generating a cell priority value in response to the occupancy level of the measurement buffer, the cell priority value indicating a probability of information cell acceptance at a node of the network connection; and

assigning the cell priority value to information cells being transmitted to the network connection.

2. The method of claim 1, wherein generating the cell priority value further comprises determining the occupancy level of the measurement buffer.

3. The method of claim 1, wherein regulating the occupancy level of the measurement buffer further comprises increasing a discharge rate of the measurement buffer in response to an increase in the occupancy level of the measurement buffer and decreasing the discharge rate of the measurement buffer in response to a decrease in the occupancy level of the measurement buffer.

4. The method of claim 1, wherein generating the cell priority value further comprises decreasing the cell priority value in response to an increase in the occupancy level of the measurement buffer and increasing the cell priority value in response to a decrease in the occupancy level of the measurement buffer.

8. The method of claim 1, wherein the network connection comprises a nominal bit rate connection.

5. The method of claim 5, wherein the measurement buffer is arranged to include a plurality of buffer occupancy ranges, and generating the cell priority value further comprises generating the cell priority value that varies relative to the occupancy level falling within a particular one of the plurality of buffer occupancy ranges.

6. The method of claim 5, wherein regulating the occupancy level of the measurement buffer further comprises increasing a discharge rate of the measurement buffer in response to the occupancy level increasing from a current buffer occupancy range to a higher buffer occupancy range, and decreasing the discharge rate of the measurement buffer in response to the occupancy level decreasing from the current buffer occupancy range to a lower buffer occupancy range.

7. The method of claim 5, wherein generating the cell priority value further comprises decreasing the cell priority value in response to the occupancy level increasing from a current buffer occupancy range to a higher buffer occupancy range, and increasing the cell priority value in response to the occupancy level decreasing from the current buffer occupancy range to a lower buffer occupancy range.

9. A method of adjusting a transmission rate of information cells transmitted over a network connection, comprising:

transmitting a measurement cell to a measurement buffer substantially contemporaneously with respect to transmission of an information cell to the network connection, the measurement buffer configured to include a plurality of buffer occupancy ranges;

discharging measurement cells from the measurement buffer at a discharge rate that varies relative to a current occupancy level of the measurement buffer falling within a particular range of the plurality of buffer occupancy ranges;

generating a cell priority value having a magnitude that varies relative to the current occupancy level of the measurement buffer falling within the particular buffer occupancy range, the cell priority value indicating a probability of information cell acceptance at a node of the network connection; and

assigning the cell priority value to information cells being transmitted to the network connection.

10. The method of claim 9, wherein the magnitude of the cell priority value decreases in response to a decrease in the discharge rate of measurement cells from the measurement buffer, and the magnitude of the cell priority value increases in response to an increase in the discharge rate of measurement cells from the measurement buffer.

11. The method of claim 9, wherein generating the cell priority value further comprises decreasing the magnitude of the cell priority value in response to the occupancy level of the measurement buffer increasing from the particular buffer occupancy range to a higher buffer occupancy range, and increasing the magnitude of the cell priority value in response to the occupancy level of the measurement buffer decreasing from the particular buffer occupancy range to a lower buffer occupancy range.

12. The method of claim 9, wherein the time to discharge the measurement cells from the measurement buffer remains substantially constant in a change from one cell priority value to the next.

15. The method of claim 9, wherein the network connection comprises a nominal bit rate connection.

13. A method of adjusting a transmission rate of information cells transmitted over a network connection, comprising:

transmitting a measurement cell to a measurement buffer substantially contemporaneously with respect to transmission of an information cell to the network connection, the measurement buffer configured to include a plurality of buffer occupancy ranges;

discharging measurement cells from the measurement buffer at a discharge rate that varies relative to a current occupancy level of the measurement buffer falling within a particular range of the plurality of buffer occupancy ranges;

generating a cell priority value having a magnitude that varies relative to the current occupancy level of the measurement buffer falling within the particular buffer occupancy range, the cell priority value indicating a probability of information cell acceptance at a node of the network connection;

assigning the cell priority value to information cells being transmitted to the network connection; and

wherein each of the buffer occupancy ranges includes substantially the same number of cell storage locations, and a duration of time required to fill each of the buffer occupancy ranges increases exponentially as the current buffer occupancy level increases from the particular buffer occupancy range to a higher buffer occupancy range.

14. A method of adjusting a transmission rate of information cells transmitted over a network connection, comprising:

transmitting a measurement cell to a measurement buffer substantially contemporaneously with respect to transmission of an information cell to the network connection, the measurement buffer configured to include a plurality of buffer occupancy ranges;

discharging measurement cells from the measurement buffer at a discharge rate that varies relative to a current occupancy level of the measurement buffer falling within a particular range of the plurality of buffer occupancy ranges;

generating a cell priority value having a magnitude that varies relative to the current occupancy level of the measurement buffer falling within the particular buffer occupancy range, the cell priority value indicating a probability of information cell acceptance at a node of the network connection; and

wherein each of the buffer occupancy ranges includes an exponentially larger number of cell storage locations than a preceding buffer occupancy range, and a duration of time required to fill each of the buffer occupancy ranges is substantially the same as the time required to fill other ones of the buffer occupancy ranges.

16. A system for adjusting a transmission rate of information cells transmitted over a network connection, comprising:

a source unit that transmits the information cells to the network connection;

a measurement buffer that receives measurement cells from the source unit, the source unit transmitting a measurement cell to the measurement buffer substantially contemporaneously with each information cell transmission;

a detector that detects an occupancy level of the measurement buffer, the detector producing an occupancy level signal indicative of a current occupancy level of the measurement buffer;

an output enable circuit, coupled to the detector, that controls a discharge rate of measurement cells from the measurement buffer in response to the occupancy level signal; and

an encoder that encodes a priority value in each of the information cells, being transmitted over the network connection, the priority value indicating a probability of information cell acceptance at a node of the network connection and having a magnitude that, varies in response to the current occupancy level of the measurement buffer.

17. The system of claim 16, wherein the detector produces the occupancy level signal that varies relative to the current occupancy level of the measurement buffer.

18. The system of claim 16, wherein the measurement buffer is arranged to include a plurality of buffer occupancy ranges demarcated by a corresponding plurality of threshold values, and the detector produces the occupancy level signal that varies relative to detection of a particular one of the plurality of threshold values.

19. The system of claim 16, wherein the output enable circuit increases the discharge rate of measurement cells from the measurement buffer in response to an increase in the occupancy level of the measurement buffer, and decreases the discharge rate of measurement cells from the measurement buffer in response to a decrease in the occupancy level of the measurement buffer.

20. The system of claim 16, wherein the encoder encodes a priority value of a decreasing magnitude in response to an increase in the occupancy level of the measurement buffer, and encodes a priority value of an increasing magnitude in response to a decrease in the occupancy level of the measurement buffer.

21. A method for controlling a cell priority for cells transmitted from a network source unit to one or more network destination units across a network connection, comprising:

registering each of the cells transmitted from the network source unit in a measurement buffer;

discharging the registered cells in the measurement buffer at a discharge rate corresponding to a current buffer occupancy level of the measurement buffer;

generating a cell priority value correlating to one of a plurality of predetermined buffer occupancy ranges which coincides with the current buffer occupancy level wherein the priority value indicates a probability of information cell acceptance at a node of the network connection; and

loading the cell priority value into the cells being transmitted from the network source unit to the one or more network destination units across the network connection.

22. The method of claim 21, further comprising establishing a nominal bit rate for the cells transmitted from the network source unit, and for presetting the cell priority value to a midpoint of a continuum of the priority values.

23. The method of claim 21, wherein registering each of the cells comprises providing a virtual cell in the measurement buffer for each of the cells transmitted from the network source unit.

24. The method of claim 21, wherein providing a virtual cell comprises generating a duplicate cell for each of the cells transmitted from the network source unit and storing the duplicate cell in the measurement buffer.

25. The method of claim 23, wherein providing a virtual cell comprises incrementing a buffer address pointer by one cell amount for each of the cells transmitted from the network source unit.

26. The method of claim 25, wherein discharging the registered cells comprises decrementing the buffer address pointer according to the discharge rate.

27. The method of claim 21, wherein registering each of the cells comprises buffering the cells transmitted from the network source unit in the measurement buffer.

28. The method of claim 21, wherein generating the cell priority value comprises identifying the buffer occupancy range that coincides with the current buffer occupancy level by comparing the current buffer occupancy level to a plurality of threshold values separating the plurality of predetermined buffer occupancy ranges.

29. The method of claim 21, wherein generating a cell priority value comprises encoding the cell priority value into n bits, wherein a number of the predetermined buffer occupancy ranges is less than or equal to 2ⁿ.

30. The method of claim 21, wherein discharging the registered cells comprises regulating the discharge rate by providing one of a plurality of output enable signals to a measurement buffer output, wherein a different one of the plurality of output enable signals is provided for each of the predetermined buffer occupancy ranges.

31. The method of claim 21, wherein discharging the registered cells comprises regulating the discharge rate by providing an output enable signal proportional to the current buffer occupancy level to a measurement buffer output.

32. The method of claim 21, wherein discharging comprises increasing the discharge rate as the current occupancy level increases from a current buffer occupancy range to a higher one of the buffer occupancy ranges, and decreasing the discharge rate as the current occupancy level decreases from the current buffer occupancy range to a lower one of the buffer occupancy ranges.

33. The method of claim 21, wherein the each of the predetermined buffer occupancy ranges includes substantially the same number of cell locations, such that the time required to fill each of the buffer occupancy ranges increases exponentially as the current buffer occupancy range, and the cell priority value, increase.

34. The method of claim 21, wherein each of the predetermined buffer occupancy ranges includes an exponentially larger number of cell locations than a preceding buffer occupancy range, such that the time required to fill each of the buffer occupancy ranges is substantially the same as the time required to fill other ones of the buffer occupancy ranges.

40. The method of claim 21, wherein each of the predetermined buffer occupancy ranges includes a predetermined number of cell locations, and wherein the time required to fill each of the buffer occupancy ranges is dependent on the predetermined number of cell locations in each particular buffer occupancy range.

35. A system for adjusting a transmission rate of information cells transmitted over a network connection, comprising:

a source unit that transmits the information cells to the network connection;

a cell transmission measurement device coupled to the source unit to register an occurrence of each information cell transmission to provide a quantitative cell transmission level;

a detector that detects the cell transmission level of the cell transmission measurement device, the detector producing a cell level signal indicative of a current quantitative cell transmission level of the cell transmission measurement device;

an output enable circuit, coupled to the detector to control a decrementing rate of the quantitative cell transmission level from the cell transmission measurement device in response to the cell level signal; and

an encoder that encodes a priority value in each of the information cells, being transmitted over the network connection, the priority value indicating a probability of information cell acceptance at a node of the network connection and having a magnitude that varies in response to the current quantitative cell transmission level of the cell transmission measurement device.

36. The system of claim 35, wherein the cell transmission measurement device is a buffer capable of storing a virtual cell upon the occurrence of each information cell transmission, and wherein an occupancy level of the buffer corresponds to the quantitative cell transmission level.

37. The system of claim 35, wherein the cell transmission measurement device and the output enable circuit collectively comprise a counter, wherein the quantitative cell transmission level corresponds to a counter value of the counter, and wherein the counter value is incremented upon the occurrence of each information cell transmission, and is decremented at a rate dictated by the cell level signal.

38. The system of claim 37, wherein the decrement rate of the counter value increases as the counter value increases.

39. The system of claim 38, wherein the encoder encodes a priority value in each of the information cells, wherein the priority value has a magnitude corresponding one of a predetermined plurality of ranges of the counter values.