1 measurements of the congestion responsiveness of windows streaming media james nichols, mark...
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Measurements of the Congestion Responsiveness of
Windows Streaming MediaJames Nichols, Mark Claypool, Robert Kinicki and Mingzhe Li
Computer Science DepartmentWorcester Polytechnic Institute
Massachusetts, USA
NOSSDAV 2004 - Kinsale, County Cork, Ireland
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Network Impact of Streaming MediaNetwork Impact of Streaming Media
• Streaming Media has specific bitrate and timing requirements.
• Flows unresponsive to congestion can cause unfairness and contribute to congestion collapse.
• Streaming Media applications rely on the application layer to provide adaptability to available capacity
• Windows Streaming Media (WSM) uses Intelligent Streaming
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MethodologyMethodology
•Construct testbed
•Create/adapt tools
•Encode content
•Systematic control
•Examine SBR clip
•Range of SBR clips
•MBR clips
•Vary loss and latency
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Single Bitrate Clip ExperimentSingle Bitrate Clip Experiment
• Hypothesis: SBR clips are unresponsive to congestion
• Latency: 45 ms• Induced loss: 0%• Bottleneck capacity: 725 Kbps• Start a TCP flow through the link• 10 Seconds later stream a WSM clip• Measure achieved bitrates and loss rates
for each flow
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340 Kbps Clip - Bottleneck Capacity 725 Kbps340 Kbps Clip - Bottleneck Capacity 725 Kbps
< 0.001 packet lossAfter 15 seconds
TCP-Friendly?
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548 Kbps Clip - Bottleneck Capacity 725 Kbps548 Kbps Clip - Bottleneck Capacity 725 Kbps
~ 0.003 packet loss for WSM~ 0.006 packet loss for TCP
after 15 seconds
NotTCP-
Friendly!
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1128 Kbps Clip - Bottleneck Capacity 725 Kbps1128 Kbps Clip - Bottleneck Capacity 725 Kbps
ResponsiveTo
Capacity?
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SBR Clips - Bottleneck Capacity 725 KbpsBuffering Period
SBR Clips - Bottleneck Capacity 725 KbpsBuffering Period
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SBR Clips - Bottleneck Capacity 725 KbpsPlayout Period
SBR Clips - Bottleneck Capacity 725 KbpsPlayout Period
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Multiple Bitrate ClipsMultiple Bitrate Clips
• Hypothesis: Multiple Bitrates make WSM more responsive to congestion
• Same experiment as before, but with different encoded content
• Vary network capacity: 250, 725, 1500 Kbps
• Created two sets of 10 multiple bitrate clips• Experiments with lots of other MBR clips
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Multiple Bitrate ContentMultiple Bitrate Content
• First set of clips (adding lower):• 1128 Kbps• 1128-764 Kbps• 1128-764-548 Kbps• …• 1128-764-548-340-282-148-109-58-43-
28 Kbps
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Multiple Bitrate ClipsMultiple Bitrate Clips
Buffering Playout
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Additional experimentsAdditional experiments
• Not enough time to discuss all the results
• Different bottleneck capacities• Vary loss rate and latencies• Also looked at other network level
metrics: interarrival times, and burst lengths.
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ConclusionsConclusions
• WSM is not CBR• Buffering period
• Not TCP-friendly• Responds to capacity
• Chooses highest rate less than capacity• Otherwise, lowest rate available
• Performance depends upon encoding
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Future WorkFuture Work
• Run the same experiments with other streaming technologies: RealVideo and Quicktime
• Examine the effects of different content types
• Build NS simulation model of streaming media for use in future research
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Measurements of the Congestion Responsiveness of
Windows Streaming MediaJames Nichols, Mark Claypool, Robert Kinicki and Mingzhe Li
http://perform.wpi.edu
NOSSDAV 2004 - Kinsale, County Cork, Ireland