Network Bandwidth Regulation

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Network Bandwidth Regulation
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Outline

• Bandwidth Regulation Model
• Goals and Approaches
• Overall Scheme
• Cedars Local Regulation
• NetMngers Global Regulation
• Future Work

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Bandwidth Regulation Model
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Goals

• Controlled use of bandwidth
• Not monopolizing network
• Why not TCP?
• TCP congestion control does not distinguish
  between user process and Condor process
• We want to give more bandwidth to user process

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Approaches

• Focus on mechanism
• No change to existing Cedar interface
• Cedar network layer of condor
• Compatibility issue
• Simple manager implementation

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Overall Scheme
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Overall Scheme
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Overall Scheme
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Overall Scheme
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Overall Scheme
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Overall Scheme
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Cedars Local Regulation

• Bandwidth Allocation
• Bandwidth Regulation
• Congestion Detection Control

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Bandwidth Allocation

• (window, maxBytes, maxPercent)
• Do not send, in any case, more than maxBytes
  bytes during window sec
• If congestion occurs, back off to maxPercent of
  what you could send at the time of congestion

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Bandwidth Regulation

• Moderate level of short burst is allowed
• Cant saved too much bandwidth for later use
• When (100M, 100sec, 80) is given
• Can send up to 10M(gt 6M) during 6sec
• Cant send 90M during 25sec, even if only 10M has
  been sent during 75sec

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Congestion Detection Control

• Detection
• Measure time taken to send a packet
• Check the number of bytes sent by TCP
• Control
• Back off to the given percent in allocation
• Remain backed off for a while
• Gradually try more bandwidth

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NetMngers Global Regulation

• Bandwidth (Re)Allocation
• Congestion Control

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Bandwidth (Re)Allocation

• Even distribution of bandwidth among Condor
  connections
• Periodic polling of network usage and condition
• Reallocation occurs when
• Extra bandwidth needed new connection
• Free bandwidth found close report, less usage
• Congestion reported

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Congestion Control

• If any of Cedar reports congestion, NetMnger
  backs off every Cedar sharing the network
• If every Cedar reports No congestion, NetMnger
  gives the original bandwidth to each Cedar

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Further Work

• The study of relationship to TCPs congestion
  control
• Congestion Avoidance
• E.g TCP Vegas mechanism

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Thank You

• sschang_at_cs.wisc.edu