Intelligent Grouping of TCP Flows for Coordinated Congestion Management
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Transcript of Intelligent Grouping of TCP Flows for Coordinated Congestion Management
Intelligent Grouping of TCP Flows for Coordinated Congestion Management
Venkatesh PrabhakarRajeev Gopalakrishna
Hoi Chang
Motivation and Goals
To coordinate TCP flows and make them more reactive to current network states
MotivationMotivation
GoalsGoals To dynamically identify and group flows with common points of congestion
To coordinate the congestion control for each group in a network friendly manner
Coordinated Congestion Management
NeedNeed Provide fairness among flows Better utilize network bandwidth
MechanismsMechanisms Group related flows together Make the flows in a group react to
congestion in a similar manner
Real traces of PING RTTs
Ping from the CS Dept:• Flow 50: www.umass.edu• Flow 55: www.cs.umass.edu• Flow 40: www.mit.edu
Ping from the home PC thru AOL:• Flows 40, 50, and 55: same flows• Flows 10, 20, 25, and 30: web sites in California
Related work TCP-Int TCP-Ensemble TCP Fast Start Congestion Manager (CM)
DrawbackDrawbackCan only coordinate flows between the sameend hosts.
Our approachOur approachCoordinate flows that share common points ofcongestion.
Intelligent grouping of TCP flows
TCP process startsTCP process starts
No grouping of flowsNo grouping of flows
Coordinate flows on a group basis Coordinate flows on a group basis
End of correlation period reachedEnd of correlation period reached
Correlate RTTs of flowsCorrelate RTTs of flows
Regroup flows based on pastRegroup flows based on pastand current correlationshipsand current correlationships
• Dynamically Dynamically group/regroup group/regroup flows based on their flows based on their (dynamic) RTT (dynamic) RTT correlationshipcorrelationship
• Coordinate flows on a Coordinate flows on a
groupgroup basisbasis
Correlating different TCP flows
RTTsof twodiff.TCPflows
Time
...
current correlation time periodprev. period
RTTsofflowRED
RTTs of flow BLUE
x
xx
x
Correlation formula:Correlation formula:
correlation coeff: r = SR,B/(SR,B SR,B)where Su,v = (u - u’)(v - v’)
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.
Simulation
Source
Destination 1
Destination 2
Congestion sink
3Mb 5ms
10Mb 5ms
6Mb 5ms
6Mb 5ms
Major bottleneck at 1st hop
Another bottleneck bet’n router and dest2
2nd bottleneck starts 50 sec later
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.