Congestion Control forStreaming Media

Jae Won Chung

Ph.D. Dissertation

Committee:Prof. Mark Claypool, WPIProf. Robert Kinicki, WPIProf. Craig Wills, WPIProf. Kevin Jeffay, UNC-Chapel Hill

04/22/23

2

Ph.D. Dissertation

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 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 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 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

Outline

Internet Congestion Control Problem Statement The Crimson Architecture Aggregate Rate Control Summary

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Ph.D. Dissertation

Problem 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 Architecture

Bandwidth Controller

In Filtered

Best-Delay-EffortProtection

Active Queue Management (IP Router)

Congestion Controller

Out

drop dropSFG ARC

Multimedia

Transport

Protocol

TCP

UDP

TCP

MTP

UDP

Multimedia

Transport

Protocol

TCP

UDP

UDP

MTP

TCP

MTP: Multimedia Transport Protocol SFG: Stochastic Fairness Guardian ARC: Aggregate Rate Controller

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Ph.D. Dissertation

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) 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

Outline

Internet Congestion Control Problem Statement The Crimson Architecture Aggregate Rate Control Summary

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Ph.D. Dissertation

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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Ph.D. Dissertation

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 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 Model

2

22

( )2( )

N

CsN

CP s e

s

( ) ?C s p N w

ARC TCP + Delay

1

1

( ) d sC s

s s

0( ) ( )p Nw t q t q d C

0

0

0

limt

N w q Nw d Cp

tN w q Nw d C

d

.

(Hollot+, 2001)

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Ph.D. Dissertation

TCP-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 60g

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 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

4ˆˆ

minmax

max

NanddC

ˆ,N

1 2ˆ secmax or

ˆmaxSystem RTT ()

Number of flows (N)minN

N

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Ph.D. Dissertation

Evaluation 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– PI

q0 = 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 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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Ph.D. Dissertation

Web Flash Crowd: Queue Dynamics

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Ph.D. Dissertation

Web Flash Crowd: Data Losses

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Ph.D. Dissertation

Light 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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Ph.D. Dissertation

Light Traffic Load: Queue Dynamics

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Ph.D. Dissertation

Light Traffic Load: Throughput

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Ph.D. Dissertation

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

Outline

Internet Congestion Control Problem Statement The Crimson Architecture Aggregate Rate Control Summary

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Ph.D. Dissertation

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) 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?

Congestion Control forStreaming Media

Jae Won Chung

Ph.D. Dissertation

Committee:Prof. Mark Claypool, WPIProf. Robert Kinicki, WPIProf. Craig Wills, WPIProf. Kevin Jeffay, UNC-Chapel Hill