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Intelligent Grouping of TCP Flows for Coordinated Congestion Management

Intelligent Grouping of TCP Flows for Coordinated Congestion Management. Venkatesh Prabhakar Rajeev Gopalakrishna Hoi Chang. Motivation and Goals. Motivation. To coordinate TCP flows and make them more reactive to current network states. Goals. To dynamically identify and group flows

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Intelligent Grouping of TCP Flows for Coordinated Congestion Management

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  1. Intelligent Grouping of TCP Flows for Coordinated Congestion Management Venkatesh Prabhakar Rajeev Gopalakrishna Hoi Chang

  2. Motivation and Goals Motivation To coordinate TCP flows and make them more reactive to current network states Goals To dynamically identify and group flows with common points of congestion To coordinate the congestion control for each group in a network friendly manner

  3. Coordinated Congestion Management • Need • Provide fairness among flows • Better utilize network bandwidth • Mechanisms • Group related flows together • Make the flows in a group react to congestion in a similar manner

  4. Real traces of PING RTTs • Ping from the home PC thru AOL: • Flows 40, 50, and 55: same flows • Flows 10, 20, 25, and 30: • web sites in California • Ping from the CS Dept: • Flow 50: www.umass.edu • Flow 55: www.cs.umass.edu • Flow 40: www.mit.edu

  5. Related work • TCP-Int • TCP-Ensemble • TCP Fast Start • Congestion Manager (CM) Drawback Can only coordinate flows between the same end hosts. Our approach Coordinate flows that share common points of congestion.

  6. TCP process starts No grouping of flows Coordinate flows on a group basis End of correlation period reached Correlate RTTs of flows Regroup flows based on past and current correlationships Intelligent grouping of TCP flows • Dynamically group/regroup • flows based on their • (dynamic) RTT • correlationship • Coordinate flows on a group • basis

  7. RTTs of two diff. TCP flows ... Time prev. period current correlation time period x x x x Correlating different TCP flows Correlation formula: correlation coeff: r = SR,B/(SR,B SR,B) where Su,v = (u - u’)(v - v’) RTTs of flow RED RTTs of flow BLUE

  8. Coordinating flows within a group • React to available bandwidth • Upon receipt of a fast ack, increase the cwnd of all other flows in the same group based on a threshold scheme. • React to congestion • Upon packet loss for a flow, decrease the cwnd/ssthresh of all other flows in the same group accordingly.

  9. Simulation Congestion sink Destination 1 10Mb 5ms 6Mb 5ms 3Mb 5ms Source 6Mb 5ms Destination 2

  10. Major bottleneck at 1st hop

  11. Another bottleneck bet’n router and dest2

  12. 2nd bottleneck starts 50 sec later

  13. Conclusion • Achieved dynamic grouping of TCP flows which shared common points of congestion. • Achieved fairness among TCP flows in each group by coordinating their congestion control.

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