1 / 18

Improvements in Core-Stateless Fair Queueing (CSFQ)

Improvements in Core-Stateless Fair Queueing (CSFQ). Ling Huang U.C. Berkeley cml.me.berkeley.edu/~hlion. Achievements. Analyze the limitation of current approach Failure to work with congestion avoidance algorithm. H eavy depen d ence on the estimation algorithms

olaf
Download Presentation

Improvements in Core-Stateless Fair Queueing (CSFQ)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Improvements in Core-Stateless Fair Queueing (CSFQ) Ling Huang U.C. Berkeley cml.me.berkeley.edu/~hlion

  2. Achievements • Analyze the limitation of current approach • Failure to work with congestion avoidance algorithm. • Heavy dependence on the estimation algorithms • Estimation has big deviation when many flows startup simultaneously and during bursty traffic. • Achieve three improvements • Achieving fair share when working with congestion avoidance algorithm. • Application of high order Low-Pass-Filter (LPF) in flow arrival rate estimation. • Application of control-theory in fair share estimation.

  3. Algorithm of CSFQ • Edge routers put flow state in packet‘s header. • Core routers estimate fair share and drop. incoming packets with probability of • A flow should get bandwidth. • Core router updates fair share  as follows: if (A > C) new = old * C / F else new = max (ri), where ri active flows Combining fair share computation and probabilistic dropping to approximate fair queueing!

  4. Improv.1: CSFQ working with TCP Vegas • CSFQ get fare share to incoming flows, but • Not accurately approximate delay properties of Fair Queueing. • Incompatible with congestion avoidance mechanisms. Fig 1. CSFQ work with TCP Reno Fig 2. CSFQ work with TCP Vegas

  5. Improv. 1: CSFQ working with TCP Vegas • High priority queue in core router • Flows whose rates are less than their fare share go into high priority queue and get service first. • Restores fairness when work with TCP Vegas. Fig 3. CSFQ + Priority Queue Fig 4. CSFQ + Priority Queue work with TCP Reno work with TCP Vegas

  6. Improv. 2: LPF in arrival rate estimation • Current Approach employ 1st order Low-Pass-Filter: • Better properties from 2nd order Low-Pass-Filter: • Fast response to burst traffic. • Estimation result more smooth.

  7. Improv. 2: LPF in arrival rate estimation • Fast response to burst traffic Input singal Output of 1st order LPF Output of 2nd order LPF Followings are the same Fig 5. Response to pulse signal

  8. Improv. 2: LPF in arrival rate estimation • Rate estimation for arrival traffic Fig 6. Estimation of arrival rate for UDP(1Mbps) Fig 7. Estimation of arrival rate for TCP (0.5Mbps)

  9. Improv. 2: LPF in arrival rate estimation • Results of 2nd Low-Pass-Filter in CSFQ • Service allocated to flows more fare. Fig 8. CSFQ + Priority Queue + 2nd LPF Fig 9. CSFQ + Priority Queue + 2nd LPF work with TCP Reno work with TCP Vegas

  10. R Q Q0 Cs Improv. 3: Applying control theory in CSFQ Flow 1 Flow n • Picture: Traffic model • faucet and Exponential Average Exponential Average Arrival Rate Arrival Rate Packet Dropper R Estimating accepting rate Q0 Cs Q Observer Fig 10. Architecture of CSFQ scheduling: the same model as that in a water reservation system

  11. R Q Q0 Cs Improv. 3: Applying control theory in CSFQ • Dynamic equation: using queue occupancy information to compute arrival rate. R: the aggregate accepted traffic during one update interval. Cs: the output link capacity. Q: the buffer occupancy at current time. Q0:equilibrium point that we want the buffer occupancy to be.

  12. Improv. 3: Applying control theory in CSFQ • Use queue occupancy information to predict the next allowed accepting rate: flow and congestion control. • Allocate the allowed accepting rate to the incoming flows, fair share is the unique solution of equation:

  13. Improv. 3: Applying control theory in CSFQ • Results Fig 11. CSFQ + control theory Fig 12. CSFQ + control theory work with TCP work with TCP Reno

  14. Improv. 3: Applying control theory in CSFQ • Results (cont.) Fig 13. CSFQ + control theory work with TCP Vega Possible reason: priority queue confusing control system with buffer length. Fig 14. Average throughput by a TCP sharing a link of capacity 10 Mbps with (n-1) UDP flows. ( Import from [Hoon-Tong’00] )

  15. Improv. 3: Applying control theory in CSFQ • Conclusion: control theory produce stable and robust system. • Without the the estimation of aggregate arrival rate and accepted traffic. • Compute fare share continuously. • Exhibit good transient and steady behavior. • Achieve high utilization.

  16. Summary • Three improvements in CSFQ • High priority helps CSFQ achieve fair share when working with congestion avoidance algorithm. • High order Low-Pass-Filter (LPF) helps improve fair share rate. • Control-theory produce robust and highly utilized system. • CS268 is a productive class • Paper review and lecture let me know every aspect of network. • Class project help me go deep into algorithm of resource allocation and packet scheduling. • Work hard, you get achievement!

  17. CSFQ work with TCP RenogCSFQ + Priority Queue work with TCP Reno CSFQ + Priority Queue + 2nd LPF CSFQ + control theory work with TCP Reno work with TCP Reno

  18. CSFQ work with TCP VegasCSFQ + Priority Queue work with TCP Vegas CSFQ + Priority Queue + 2nd LPF CSFQ + control theory work with TCP Vegas work with TCP Vegas

More Related