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Aggregate Traffic Performance with Active Queue Management and Drop from Tail

Aggregate Traffic Performance with Active Queue Management and Drop from Tail. Christophe Diot, Gianluca Iannaccone, Martin May Sprint ATL, Universit à di Pisa, Activia www.sprintlabs.com. Active Queue Management. queue. average. instantaneous. drop size. function. sharp. RED.

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Aggregate Traffic Performance with Active Queue Management and Drop from Tail

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  1. Aggregate Traffic Performance with Active Queue Management and Drop from Tail Christophe Diot, Gianluca Iannaccone, Martin May Sprint ATL, Universitàdi Pisa, Activia www.sprintlabs.com

  2. Active Queue Management queue average instantaneous drop size function sharp RED Drop from Tail smooth Gentle Gentle RED RED Instantaneous

  3. Original RED 1 max-p min-tresh max-tresh buffer size

  4. Revised RED 1 max-p min-tresh max-tresh buffer size

  5. Gentle RED 1 max-p min-tresh max-tresh buffer size 2 max-tresh

  6. Testbed with CISCO routers (7500) with Dummynet We use “recommended” RED and GRED parameters Heterogeneous delays (120 to 180 ms) Experiments

  7. 16 to 256 TCP connections sharing the bottleneck. Experimental traffic generated by Chariot long-lived TCP connections. more “realistic” traffic mix: 90% short lived TCP connections (up to 20 packets) 10 % long lived TCP connections 1Mbps UDP in both cases Traffic characteristics

  8. Testbed (CISCO routers) 7500 7500 10 Megs

  9. Testbed (Dummynet) 7500 7500 10 Megs Dummy net 100 Megs

  10. What is Dummynet? application dummynet network

  11. Aggregate goodput through a router TCP and UDP loss rate Consecutive losses Queuing behavior Metrics observed

  12. Aggregate goodput (long-lived TCP)

  13. 256 short and long lived TCP connections

  14. Consecutive packet losses (long lived)

  15. …if we use “optimal” RED parameters

  16. Consecutive packet losses (realistic traffic mix)

  17. Queuing behavior (256 long lived connections)

  18. Queuing behavior (256 connections, realistic mix)

  19. No significant difference on goodput, TCP losses and UDP losses. On consecutive losses, clear advantage to GRED and GRED-I. “gentle” modification solves many RED problems. Oscillations: no clear winner. Traffic seems to be the determining factor. In summary ...

  20. Not clear there is an advantage in deploying RED, GRED, or GRED-I. Maybe GRED-I is an option if one can find a “universal” exponential dropping function. ECN will work with any scheme. Not clear the solution is in the AQM space. From the ISP standpoint ...

  21. GRED-I with exponential dropping function 1 buffer size

  22. Not only feasible … easy at the edges! www.agere.com (an example) vendors support from 64k to 200k flows Really fair everybody gets what he/she paid for local signaling (end host to CPE) About Fair Queuing ...

  23. Number of flows on an OC-3 link

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