Method and apparatus for shaping traffice for a SIMA network

• US 6,549,514 B1
• Filed: 07/07/1998
• Issued: 04/15/2003
• Est. Priority Date: 07/07/1998
• Status: Expired due to Fees

• Current Assignee: Nokia Telecommunications Oy (Nokia Corporation)
• Original Assignee: Nokia Corporation
• Inventors: Kilkki, Kalevi, Ruutu, Jussi
• Primary Examiner(s): Hsu, Alpus H.
• Assistant Examiner(s): Qureshi, Afsar M.
• Application Number:
  US09/111,023
• Time in Patent Office: 1,743 Days
• Field of Search: 370/229, 370/230, 370/231, 370/233, 370/235, 370/236, 370/232, 370/252, 370/253, 370/391, 370/389, 370/395, 370/416
• US Class Current: 370/231
• CPC Class Codes: H04L 12/5602 Bandwidth control in ATM Networks, e.g. leaky bucket
• CPC Class Codes: H04L 2012/5614 User Network Interface
• CPC Class Codes: H04L 2012/5635 Backpressure, e.g. for ABR
• CPC Class Codes: H04L 2012/568 Load balancing, smoothing or shaping
• CPC Class Codes: H04Q 11/0478 Provisions for broadband connections

Abstract

A SIMA Traffic Shaper (STS) and method is disclosed for use between the customer equipment and the SIMA access node to shape the transmitted traffic so that the cells will receive as good priority as possible in the access node. The STS includes an input device for receiving cells from a traffic source, a buffering device, coupled to the input, for holding the cells until instructed to send the cells; and a calculation unit, operatively coupled to the buffer processor, for calculating a send time for sending cells held by the buffering device. The buffering device further includes a buffer and a transmission unit, wherein the buffer holds the cells and the transmission unit sends the cell forward according to the send time received from the calculation unit. A monitoring unit is included for monitoring the input device and the buffering device to obtain loading information regarding the network. The calculation unit calculates the send time based upon a nominal bit rate, a maximum delay, the loading information provided by the monitoring unit and a monitoring principle. The monitoring principle may be based solely upon a number of segments containing cells in the buffer or on the loading information.

Claims

1. A traffic shaper for a network, comprising:

an input device for receiving cells from a traffic source;

a buffering device, coupled to the input, for holding the cells until instructed to send the cells; and

a calculation unit, operatively coupled to the buffer processor, for calculating a send time for sending cells held by the buffering device, wherein the send time optimizes a transmission interval between successive cells to obtain a maximum priority level, the transmission interval between successive cells being based on instantaneous bit rate at the arrival time of a j_th cell, a nominal bit rate and a link rate.

2. The traffic shaper of claim 1 wherein the buffering device further comprises a buffer and a transmission unit, the buffer holding the cells and the transmission unit sending the cell forward according to the send time received from the calculation unit.

3. The traffic shaper of claim 2 further comprising a monitoring unit for monitoring the input device and the buffering device to obtain loading information regarding the network.

4. The traffic shaper of claim 3 wherein the calculation unit calculates the send time based upon the nominal bit rate, a maximum delay, the loading information provided by the monitoring unit and a monitoring principle.

5. The traffic shaper of claim 4 wherein the buffer comprises segments for holding the cells, and wherein the monitoring principle is based solely upon a number of segments containing cells in the buffer.

6. The traffic shaper of claim 5 wherein the calculation unit determines a transmission rate for sending the cells, the transmission rate being equal to:

$\frac{\sqrt{2}<br><br>\mathrm{NBR}}{2^{k-4}}$

where k is the number of a segment up to which the buffer is filled and NBR is the nominal bit rate.

7. The traffic shaper of claim 6 wherein the maximum delay is:

$D_{\max }^{*}<br><br>\left(y\right)=\frac{X·<br><br>\underset{k=0}{\overset{7}{\sum <br><br>}}<br><br>\text{\hspace{1em}<br><br>}<br><br>y<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(k\right)·<br><br>N<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(k\right)}{C_{\mathrm{link}}},$

where y is the number of cells in a segment, C_link is the link rate, k is the number of a segment up to which the buffer is filled and N(k) is the priority level, and wherein D*_max(y)≦

D_max.

8. The traffic shaper of claim 4 wherein the buffer comprises segments for holding the cells, and wherein the monitoring principle is based on the loading information.

9. A traffic shaper for a network, comprising:

an input device for receiving cells from a traffic source;

a buffering device, coupled to the input, for holding the cells until instructed to send the cells, wherein the buffering device further comprises a buffer and a transmission unit, the buffer holding the cells and the transmission unit sending the cell forward according to the send time received from the calculation unit, and wherein the buffering device comprises segments for holding the cells, and wherein the monitoring principle is based on the loading information;

a calculation unit, operatively coupled to the buffer processor, for calculating a send time for sending cells held by the buffering device, wherein the calculation unit calculates the send time based upon a nominal bit rate, a maximum delay, the loading information provided by the monitoring unit and a monitoring principle, and wherein the calculation unit calculates a transmission interval between successive cells based on instantaneous bit rate at the arrival time of a j_th cell, the nominal bit rate and the link rate; and

a monitoring unit for monitoring the input device and the buffering device to obtain loading information regarding the network.

10. The traffic shaper of claim 9 wherein the transmission interval between successive cells is calculated to:

$N^{*}<br><br>\left(j\right)=\frac{C_{\mathrm{link}}}{\mathrm{IBR}<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(j\right)}$

where IBR(j) is the instantaneous bit rate of the j_th cell, NBR is the nominal bit rate and C_link is the link rate.

11. The traffic shaper of claim 10 wherein the calculating unit calculates a list of optimum transmission intervals for a plurality of priority levels and selects a final transmission interval based on the loading information such that N_m(j) is equal to the largest N(k) smaller than or equal to N*(j), where N_m(j) is the final transmission interval, N(k) is the transmission interval for priority level k, and N*(j) is the transmission interval for the j_th cell.

12. The traffic shaper of claim 11 wherein the list of optimum transmission interval for each priority level k is calculated according to:

$N<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(k\right)=\mathrm{Int}<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(\frac{C_{\mathrm{link}}·<br><br>2^{k-4}}{\sqrt{2}·<br><br>\mathrm{NBR}}\right)+1.$

13. The traffic shaper of claim 12 wherein the calculating unit further calculates a transmission interval N_d(j) that takes into account the maximum delay according to:

$N_d<br><br>\left(j\right)=\min <br><br>\text{\hspace{1em}<br><br>}<br><br>\left(\mathrm{int}<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(\frac{C_{\mathrm{link}}·<br><br>D_{\max }}{X·<br><br>M<br><br>\left(j\right)}\right),N_d<br><br>\left(j-1\right)\right),$

where X is the fixed cell size in bits, M(j) is the number of cells in the buffer at the arrival or j^th cell, D_max is the maximum delay and C_link is the link rate.

14. The traffic shaper of claim 13 wherein the calculating unit selects the smaller of N_m(j) and N_d(j) as a send time and sends the send time to the transmission unit.

15. A network, comprising:

a traffic source for issuing cells;

an access node providing an interface to a SIMA network; and

a traffic shaper, functioning between the traffic source and the access node, the traffic shaper comprising;

an input device for receiving cells from a traffic source;

a buffering device, coupled to the input, for holding the cells until instructed to send the cells; and

a calculation unit, operatively coupled to the buffer processor, for calculating a send time for sending cells held by the buffering device, wherein the send time optimizes a transmission interval between successive cells to obtain a maximum priority level, the transmission interval between successive cells being based on instantaneous bit rate at the arrival time of a j_th cell, a nominal bit rate and a link rate.

16. The network of claim 15 wherein the buffering device further comprises a buffer and a transmission unit, the buffer holding the cells and the transmission unit sending the cell forward according to the send time received from the calculation unit.

17. The network of claim 16 further comprising a monitoring unit for monitoring the input device and the buffering device to obtain loading information regarding the network.

18. The network of claim 17 wherein the calculation unit calculates the send time based upon a nominal bit rate, a maximum delay, the loading information provided by the monitoring unit and a monitoring principle.

19. The network of claim 18 wherein the buffer comprises segments for holding the cells, and wherein the monitoring principle is based solely upon a number of segments containing cells in the buffer.

20. The network of claim 19 wherein the calculation unit determines a transmission rate for sending the cells, the transmission rate being equal to:

$\frac{\sqrt{2}<br><br>\mathrm{NBR}}{2^{k-4}}$

where k is the number of a segment up to which the buffer is filled and NBR is the nominal bit rate.

21. The network of claim 20 wherein the maximum delay is:

$D_{\max }^{*}<br><br>\left(y\right)=\frac{X·<br><br>\underset{k=0}{\overset{7}{\sum <br><br>}}<br><br>\text{\hspace{1em}<br><br>}<br><br>y<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(k\right)·<br><br>N<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(k\right)}{C_{\mathrm{link}}},$

where y is the number of cells in a segment, C_link is the link rate, k is the number of a segment up to which the buffer is filled and N(k) is the priority level, and wherein D*_max(y)≦

D_max.

22. The network of claim 18 wherein the buffer comprises segments for holding the cells, and wherein the monitoring principle is based on the loading information.

23. A network comprising:

a traffic source for issuing cells;

an access node providing an interface to a SIMA network; and

a traffic shaper, functioning between the traffic source and the access node, the traffic shaper comprising;

an input device for receiving cells from a traffic source;

a buffering device, coupled to the input, for holding the cells until instructed to send the cells, wherein the buffering device further comprises a buffer and a transmission unit, the buffer holding the cells and the transmission unit sending the cell forward according to the send time received from the calculation unit, wherein the buffering device further comprises segments for holding the cells, and wherein the monitoring principle is based on the loading information;

a calculation unit, operatively coupled to the buffer processor, for calculating a send time for sending cells held by the buffering device, wherein the calculation unit calculates the send time based upon a nominal bit rate, a maximum delay, the loading information provided by the monitoring unit and a monitoring principle, wherein the calculation unit calculates a transmission interval between successive cells based on instantaneous bit rate at the arrival time of a j_th cell, the nominal bit rate and the link rate; and

a monitoring unit for monitoring the input device and the buffering device to obtain loading information regarding the network.

24. The network of claim 23 wherein the transmission interval between successive cells is calculated according to:

$N^{*}<br><br>\left(j\right)=\frac{C_{\mathrm{link}}}{\mathrm{IBR}<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(j\right)}$

where IBR(j) is the instantaneous bit rate of the j_th cell, NBR is the nominal bit rate and C_link is the link rate.

25. The network of claim 24 wherein the calculating unit calculates a list of optimum transmission intervals for a plurality of priority levels and selects a final transmission interval based on the loading information such that N_m(j) is equal to the largest N(k) smaller than or equal to N*(j), where N_m(j) is the final transmission interval, N(k) is the transmission interval for priority level k, and N*(j) is the transmission interval for the j_th cell.

26. The network of claim 25 wherein the list of optimum transmission interval for each priority level k is calculated according to:

$N<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(k\right)=\mathrm{Int}<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(\frac{C_{\mathrm{link}}·<br><br>2^{k-4}}{\sqrt{2}·<br><br>\mathrm{NBR}}\right)+1.$

27. The network of claim 26 wherein the calculating unit further calculates a transmission interval N_d(j) that takes into account the maximum delay according to:

$N_d<br><br>\left(j\right)=\min <br><br>\text{\hspace{1em}<br><br>}<br><br>\left(\mathrm{int}<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(\frac{C_{\mathrm{link}}·<br><br>D_{\max }}{X·<br><br>M<br><br>\left(j\right)}\right),N_d<br><br>\left(j-1\right)\right),$

where X is the fixed cell size in bits, M(j) is the number of cells in the buffer at the arrival or j^th cell, D_max is the maximum delay and C_link is the link rate.

28. The network of claim 27 wherein the calculating unit selects the smaller of N_m(j) and N_d(j) as a send time and sends the send time to the transmission unit.

29. A method of shaping traffic between a traffic source and an access node to a SIMA network, comprising the steps of:

receiving data cells at an input device;

loading the cells into a buffer,

obtaining information regarding the loading of the network via a monitoring device;

calculating a send time of a next cell at a calculation unit based upon a nominal bit rate, a maximum delay and a monitoring principle, wherein the send time optimizes a transmission interval between successive cells to obtain a maximum priority level, the transmission interval between successive cells being based on instantaneous bit rate at the arrival time of a j_th cell, a nominal bit rate and a link rate.

30. The method of claim 29 wherein the monitoring principle is based solely on a buffer occupancy level.

31. The method of claim 30 wherein the step of calculating further comprises the step of determining a transmission rate for sending the cells, the transmission rate being equal to:

$\frac{\sqrt{2}<br><br>\mathrm{NBR}}{2^{k-4}}$

where k is the number of a segment up to which the buffer is filled and NBR is the nominal bit rate.

32. The method of claim 31 wherein the step of calculating further comprises the step of calculating a maximum delay according to:

$D_{\max }^{*}<br><br>\left(y\right)=\frac{X·<br><br>\underset{k=0}{\overset{7}{\sum <br><br>}}<br><br>\text{\hspace{1em}<br><br>}<br><br>y<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(k\right)·<br><br>N<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(k\right)}{C_{\mathrm{link}}},$

where y is the number of cells in a segment, C_link is the link rate, k is the number of a segment up to which the buffer is filled and N(k) is the priority level, and wherein D*_max(y)≦

D_max.

33. The method of claim 29 wherein the monitoring principle is based on a load measurement result.

34. A method of shaping traffic between a traffic source and an access node to a SIMA network, comprising the steps of:

receiving data cells at an input device;

loading the cells into a buffer;

obtaining information regarding the loading of the network via a monitoring device;

calculating a send time of a next cell at a calculation unit based upon a nominal bit rate, a maximum delay and a monitoring principle, wherein the monitoring principle is based on a load measurement result and wherein the step of calculating further comprises the step of calculating a transmission interval between successive cells based on instantaneous bit rate at the arrival time of a j_th cell, the nominal bit rate and the link rate.

35. The method of claim 34 wherein the step of calculating a transmission interval between successive cells further comprises the step of calculating the transmission interval between successive cells according to:

$N^{*}<br><br>\left(j\right)=\frac{C_{\mathrm{link}}}{\mathrm{IBR}<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(j\right)}$

where IBR(j) is the instantaneous bit rate of the j_th cell, NBR is the nominal bit rate and C_link is the link rate.

36. The method of claim 35 wherein the step of calculating further comprises the steps of calculating a list of optimum transmission intervals for a plurality of priority levels and selecting a final transmission interval based on the loading information such that N_m(j) is equal to the largest N(k) smaller than or equal to N*(j), where N_m(j) is the final transmission interval, N(k) is the transmission interval for priority level k, and N*(j) is the transmission interval for the j_th cell.

37. The method of claim 36 wherein the step of calculating the list of optimum transmission interval for each priority level k further comprises the step of calculating an optimum transmission interval for priority level k according to:

$N<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(k\right)=\mathrm{Int}<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(\frac{C_{\mathrm{link}}·<br><br>2^{k-4}}{\sqrt{2}·<br><br>\mathrm{NBR}}\right)+1.$

38. The method of claim 37 wherein the step of calculating further comprises the step of calculating a transmission interval N_d(j) that takes into account the maximum delay according to:

$N_d<br><br>\left(j\right)=\min <br><br>\text{\hspace{1em}<br><br>}<br><br>\left(\mathrm{int}<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(\frac{C_{\mathrm{link}}·<br><br>D_{\max }}{X·<br><br>M<br><br>\left(j\right)}\right),N_d<br><br>\left(j-1\right)\right),$

where X is the fixed cell size in bits, M(j) is the number of cells in the buffer at the arrival or j^th cell, D_max is the maximum delay and C_link is the link rate.

39. The method of claim 38 wherein the step of calculating further comprises the steps of selecting the smaller of N_m(j) and N_d(j) as a send time and