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Congestion Control for
Streaming Media
Jae Won Chung
Ph.D. Dissertation
Committee:
Prof. Mark Claypool, WPIProf. Robert Kinicki, WPIProf. Craig Wills, WPIProf. Kevin Jeffay, UNC-Chapel Hill
04/09/23
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Ph.D. Dissertation
Internet Congestion Control (CC)Internet Congestion Control (CC)
Queue
ReceiverOutbound LinkRouterInbound Link
Receiver
TCP
TCP
ACK
ACK
Queue
ReceiverOutbound LinkRouterInbound Link
Receiver
TCP
TCP
ACK
ACK
Queue
ReceiverOutbound LinkRouterInbound Link
Receiver
TCP
TCP
ACK
Drop!!!
Queue
ReceiverOutbound LinkRouterInbound Link
Receiver
TCP
TCP
Little Support From The Router– Packet Drop: Implicit Congestion Signal
TCP Congestion Avoidance– Respond to Congestion Signal
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Ph.D. Dissertation
Efficient Congestion Control FeedbackEfficient Congestion Control Feedback
Queue
ReceiverOutbound LinkRouterInbound Link
Receiver
TCP
TCP Active Queue Management (AQM)
Congestion
Mark ECN Bit
Explicit Congestion Notification (ECN)
ACK
Queue
ReceiverOutbound LinkRouterInbound Link
Receiver
TCP
TCP Active Queue Management (AQM)
Active Queue Management (AQM)– Low Delay & High Utilization– Reduce Packet Loss
• Reduce Queue Overflow• Explicit Congestion Notification (ECN)
– Stability and Configuration Issue
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Ph.D. Dissertation
Queue
ReceiverOutbound LinkRouterInbound Link
Sink
AQM
UDP
TCP
Bandwidth Usage ControlBandwidth Usage Control
Queue
ReceiverOutbound LinkRouterInbound Link
Sink
AQM
Forced Drop
UDP
TCP
Bandwidth Control Mechanism– Protect network and fairness– Extend AQM Feature– Scalability Issue
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Ph.D. Dissertation
Receiver
Efficient Bandwidth Usage ControlEfficient Bandwidth Usage Control
Queue
ReceiverOutbound LinkRouterInbound Link
AQMTCP
TCP-FriendlyTransportProtocol
TCP-Friendly Transport Protocol– Average throughput does not exceed that of conforming TCP flow under the same network condition– Application-Friendly also?
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Ph.D. Dissertation
OutlineOutline
Internet Congestion Control Problem Statement The Crimson Architecture Aggregate Rate Control Summary
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Ph.D. Dissertation
Problem StatementProblem Statement
The Internet does not provide a streaming-friendly transport protocol (TCP is streaming-unfriendly).– TCP API hides network information.– TCP’s reliable in-order delivery service incurs extra delays.
The Internet stability is vulnerable to misbehaving high-bandwidth UDP streams.– Streaming media applications often use UDP without a
proper congestion control mechanism.– Internet video has potentially high demand for bandwidth.– ISPs provide broadband Internet connections ( 3 Mbps).
The Internet does not guarantee low transmission delays required by streaming media applications.– Large queuing delays at IP routers in congestion.
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Ph.D. Dissertation
The Crimson ArchitectureThe Crimson Architecture
Bandwidth Controller
Bandwidth Controller
InIn FilteredFiltered
Best-Delay-EffortProtection
Active Queue Management (IP Router)
Congestion Controller
Congestion Controller
OutOut
dropdrop dropdropSFG ARC
Multimedia
Transport
Protocol
Multimedia
Transport
Protocol
TCPTCP
UDPUDP
TCPTCP
MTPMTP
UDPUDP
Multimedia
Transport
Protocol
Multimedia
Transport
Protocol
TCPTCP
UDPUDP
UDPUDP
MTPMTP
TCPTCP
MTP: Multimedia Transport Protocol SFG: Stochastic Fairness Guardian ARC: Aggregate Rate Controller
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Contributions (1 of 2)Contributions (1 of 2) Internet measurement study
– Compare commercial Internet TCP & UDP video streams– Characterize streaming transport protocol requirements.
• [Chung+, 2003] Packet Video Workshop (PV)• [Chung+, 2004] Kluwer Multimedia Tools and Applications
Multimedia Transport Protocol (MTP)– Modify TCP (Reno in NS) not to retransmit.– Add streaming-friendly API.
• [Chung+, 2000] SCS Euromedia Conference
Goddard streaming media client and server– Design and implement a realistic streaming application in
Network Simulator (NS).– Simulates bandwidth estimation, media scaling and playout.
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Ph.D. Dissertation
Contributions (2 of 2)Contributions (2 of 2) Stochastic Fairness guardian (SFG)
– Design a lightweight bandwidth controller (statistical packet filter) that limits misbehaving high-bandwidth UDP traffic.• [Chung+, 2000] NOSSDAV• [Chung+, 2000] ACM Multimedia• [Chung+, 2002] IEEE Symposium on Computers and Comm.
Aggregate Rate Controller (ARC)– Design a congestion controller that minimizes queuing
delay while achieving high link utilization.– Provide complete and practical configuration guidelines.
• [Chung+, 2003] Network Computing and Applications• [Chung+, 2004] ACM SIGCOMM, (Poster)
Integration of the Crimson components– Evaluate Goddard over MTP with the Crimson (SFG+ARC).
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Ph.D. Dissertation
OutlineOutline
Internet Congestion Control Problem Statement The Crimson Architecture Aggregate Rate Control Summary
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Ph.D. Dissertation
Random Early Detection (RED)Random Early Detection (RED)
RED (Floyd+, 1993) : 1G AQM congestion controller– Uses a low pass filter on the queue length to detect and
compute congestion notification probability (p). RED configuration problems
– Lack of configuration guidelines Queue law (Firoiu+, 2000; Chung+, 2003)
– Stability margin is small (Hollot+, 2001) Gentle extension, self-configuring RED (add-hoc approaches).
Proportional Integral (PI) AQM Controllers: Apply control engineering paradigm to design AQM– Large stability margin and prompt response.– AVQ (Kunniyur+, 2001),– PI (Hollot+, 2001) and REM (Athuraliya+, 2001)
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Aggregate Rate Control (ARC)Aggregate Rate Control (ARC)
Problem with current PI-based congestion controllers– Difficult to configure PI controller for a time-delay system.– Incomplete stability analysis: measurement epoch.– Queue sample-based control information acquisition
Induce control noise when link is not fully utilized. Aggregated Rate Controller (ARC)
– Parameter reduced PI controller for TCP System Ease the control parameter configuration.
– Complete stability analysis Practical configuration guidelines &
recommendations.– Rate-based control information acquisition
Noise reduction + flexible configuration Minimized queuing delay.
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Ph.D. Dissertation
Rate-Based Implementation of PIRate-Based Implementation of PI
1: p p + (b (dC (q – q0)));
C : link capacity : target utilization (C0/C)q0 : target queue lengthd : measurement interval : virtual queue control const. : queue control const.
1: p p + (b (dC (q – q0)));
ARC Algorithm
p : notification probability q : queue lengthb : bytes received this epoch
Every d seconds:
2: b 0;
Every packet arrival:
3: if (uniform (0,1) p)
4: if (mark (packet) == false) {
5: drop (packet);
6: return;
7: }
8: b b + sizeof (packet);
9: if (enqueue (packet) == false) drop (packet);
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Ph.D. Dissertation
TCP-ARC Feedback Control ModelTCP-ARC Feedback Control Model
2
22
( )2( )
N
CsN
C
P s es
( ) ?C s p N w
ARC TCP + Delay
1
1
( )d s
C ss s
0( ) ( )p Nw t q t q d C
0
0
0
limt
N w q Nw d Cp
t
N w q Nw d Cd
.
(Hollot+, 2001)
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Ph.D. Dissertation
TCP-ARC Stability ConditionsTCP-ARC Stability Conditions
Slope = 20 dB/decade
40 dB/decade
60 dB/decade
40 dB/decade
90
180
0
p180
gp
rad/sec
rad/sec
(dB)
(deg)
g
0
3 3C
3(1+)
4dN 2
1
2C2N
1+
Tp=
( , )
( )d
6
30 60
g
p
and
Select /d such that
Given System Boundaryˆ :
:
upper bound RTT
N lower bound N
Bode Stability Analysis
( , ) 6
150 ( ( )) 120
g
p
dd
dd
and
TCP-ARC Stable Operating Range
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Ph.D. Dissertation
ARC Configuration GuidelinesARC Configuration Guidelines
Configure ARC ( /d ) for your average case lower boundary ( ) condition.
Set the measurement interval ( d ) close to the maximum expected system RTT ( ).
Check to see if the chosen meets the minimum stability condition. 2
3 2 2
4ˆ
ˆmin
maxmax
Nandd
C
ˆ,N
1 2ˆ secmax or
ˆmaxSystem RTT ()
Number of flows (N)minN
N
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Ph.D. Dissertation
Evaluation of ARCEvaluation of ARC
Evaluate ARC with other PI-based AQM congestion controllers (AVQ and PI) and Drop-Tail– Over a wide range of realistic traffic mixes and loads.– Show two simulation study results in this presentation.
AQM Configurations– AVQ
= 0.98, = 0.15
– PIq0 = 50, = 1.822 10-5, = 1.81610-5, = 170
– ARC = 0.98, q0 = 0, d = 1 sec, = 1.4210-5
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Ph.D. Dissertation
Web Flash Crowd SimulationWeb Flash Crowd Simulation
C = 10Mbps Q = 500 Kbytes RTLD = [60, 1000] ms Nftp_fw = 25, Nftp_bw = 50 Nweb = 300 (OL=0.25) 1300 (OL=1.10) 300
– + Nweb = + 10 sessions/min (from 100 sec) Nweb = 10 sessions/min (from 6100 sec)– Flash Rate (FIFA World Cup ’98 Data)
Peak Flash Rate: 2M 10M reqs/h in 2 hours– Web session setting (H-Campos+, 2003)
Sizeavg= 5KB, Shape = 1.2, Tavg_think = 7sec (expo) Simulation time = 12100 sec
r1 r2
s
s
s
s
d
d
d
d
Q = 500 pkts
C = 10 Mbps
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Web Flash Crowd: Queue DynamicsWeb Flash Crowd: Queue Dynamics
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Web Flash Crowd: Data LossesWeb Flash Crowd: Data Losses
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Light Traffic Load SimulationLight Traffic Load Simulation
Simulation Objectives:– Compare PI-based AQMs on everyday light traffic load.– Simulate sudden increase in delay (due to routing change).
C = 10Mbps Q = 500 Kbytes Nftp_fw = 5, Nftp_bw = 10 Nweb = 300 sessions RTLD = [100, 500] ms [2200, 2600] ms
– Increase the congested link RTLD 300 ms every 200 secs.– Average RTLD: 300 600 … 2100 2400 (ms)
r1 r2
s
s
s
s
d
d
d
d
Q = 500 pkts
C = 10 Mbps
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Light Traffic Load: Queue DynamicsLight Traffic Load: Queue Dynamics
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Light Traffic Load: ThroughputLight Traffic Load: Throughput
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Summary of ARC Summary of ARC
Minimize queuing delay at IP routers.– Provide best-delay-effort Internet service to support
streaming media and other delay sensitive applications. Practical and complete configuration guidelines and
recommendations.– Ease the controller parameter configuration through the PI
parameter reduction.– Provide configuration guidelines and recommendations that
works for a wide range of traffic condition Robust congestion control performance over wide
range of traffic conditions.– Rate-based control information acquisition.– High (flash crowd) and low (everyday) traffic loads.
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Ph.D. Dissertation
OutlineOutline
Internet Congestion Control Problem Statement The Crimson Architecture Aggregate Rate Control Summary
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Ph.D. Dissertation
Conclusions (1 of 2)Conclusions (1 of 2)
Internet measurement study– Compare Internet TCP and UDP media streams.– Characterize commercial video stream behavors.– Identify streaming unfriendly features of TCP.
Multimedia Transport Protocol (MTP)– TCP-friendly: TCP modification not to retransmit. – API: Streaming-friendly transport protocol.– MTP offers streaming performance comparable to that
provided by UDP, while doing so under a TCP-Friendly rate.
Goddard streaming media client and server– Design and build a realistic streaming application in NS.– Simulates bandwidth estimation, media scaling and playout.
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Ph.D. Dissertation
Conclusions (2 of 2)Conclusions (2 of 2)
Stochastic Fairness guardian (SFG)– Lightweight bandwidth controller that filters misbehaving
high-bandwidth UDP traffic without flow monitoring.– SFG outperforms other statistical traffic filters, and performs
as well as bandwidth controllers using per-flow information.
Aggregate Rate Controller (ARC)– Minimizes queuing delay with high link utilization.– Complete and practical configuration guidelines.– Robust performance over wide range of traffic conditions.
Evaluation of the Crimson network (SFG + ARC)– Goddard over MTP achieves the best stream quality. – SFG controls high-bandwidth UDP Goddard streams.– ARC minimizes the queuing delay.
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Ph.D. Dissertation
Questions?Questions?
Congestion Control for
Streaming Media
Jae Won Chung
Ph.D. Dissertation
Committee:
Prof. Mark Claypool, WPIProf. Robert Kinicki, WPIProf. Craig Wills, WPIProf. Kevin Jeffay, UNC-Chapel Hill