better-behaved multimedia networking keith barber jason ingalsbe joel thibault prof. mark claypool...

Better-Behaved Multimedia Networking

Keith Barber

Jason Ingalsbe

Joel Thibault

Prof. Mark Claypool (Advisor)

April 19, 2001

Issues with Multimedia Traffic

• Basic Internet protocols inappropriate for multimedia– TCP does not provide smooth transmission– UDP takes up too much bandwidth

• Multimedia protocols must be TCP-friendly

Existing Alternatives

• TCP-Friendly Rate Control (TFRC)

• TCP Emulation At Receivers (TEAR)

• MM-Flow

Re-Engineering MM-Flow

• Location of flow control logic– “True” application and transport layers– Receiver decides whether scale value should

change– Sender converts scale values to transmission

rate

• Number of scale values• Weighted average scale

Evaluation Techniques

• Simulation Scenarios– Standard Bottleneck Layout– Standard Delay Layout– Standard Fragile Layout

Standard Bottleneck Layout

Standard Delay Layout

Standard Fragile Layout

Effects of Re-Engineering MM-Flow

• Responsiveness to Congestion

• Fair Share of Bandwidth

• Relative Smoothness

MM-App-Old vs. TCP

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Percent Utilization

TCP MM-App-Old Total

MM-App-Old Average Utilization = 66.0% TCP Average Utilizaton = 32.7%

MM-App-New vs. TCP

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Percent Utilization

TCP MM-App-New Total

MM-App-New Average Utilization = 51.8% TCP Average Utilizaton = 44.5%

Further Evaluation of MM-App-New

• Packet Size

• Number of Scale Values

• Delay

• Fragile Flows

• Weighted Scale Values

TCP-Friendly Flows

• Possible definitions:– Flow uses fair share of bandwidth– Flow responds to congestion– Flow transmission rate less than or equal to

TCP flow transmission rate

• Quantitative measurement is desired

TCP-Friendly Equation

• Implications and Assumptions:– Packet Drop Rate– Measurement Interval Size

pR

BT

*

*3/25.1

TCP-Friendly Results (1 sec.)

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Time (sec)

Ban

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(M

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Actual Bandwidth

TCP-Friendly Bandwidth

TCP-Friendly Results (3 sec.)

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Time (sec)

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Actual Bandwidth

TCP-Friendly Bandwidth

TCP-Friendliness of MM-App-New

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Actual Bandwidth

TCP-Friendly Bandwidth

Fair Bandwidth

TCP-Friendliness of TFRC

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Time (sec)

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Actual Bandwidth

TCP-Friendly Bandwidth

Fair Bandwidth

Multi-Protocol Layout

Multi-Protocol Env. (TCP)

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Time (sec)

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Actual Bandwidth

TCP-Friendly Bandwidth

Fair Bandwidth

Multi-Protocol Env. (TFRC)

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Time (sec)

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Actual Bandwidth

TCP-Friendly Bandwidth

Fair Bandwidth

Multi-Protocol Env. (MM-App-New)

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Time (sec)

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Actual Bandwidth

TCP-Friendly Bandwidth

Fair Bandwidth

Conclusion and Future Work

• MM-Flow is an improvement over original

• Areas for future research:– Increase transmission rate quickly at startup– Decrease fluctuation in transmission rate– Continue examination of TCP-Friendliness

Questions?

http://www.wpi.edu/~jmi725/mqp

http://perform.wpi.edu