comparison and analysis of fifo, pq, and wfq disciplines ... › ~ljilja › ensc427 › spring11...

ENSC 427

Communication Networks Final Project Demo – Spring 2011

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Comparison and analysis of FIFO, PQ, and WFQ Disciplines in OPNET

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Introduction and Motivation • Queuing methods are used to handle network resources

• Real-time applications such as voice and video conferencing are

especially susceptible to delays and packet losses

• The Quality of Service (QoS) network devices must employ proper queuing methods to differentiate among arriving packets

• Queuing disciplines are implemented in routers

• We seek to provide an answer to the question:

• What is the best queuing discipline to use for a given application?

ENSC 427 – Communication Networks – Final Project Professor: Ljiljana Trajković

Comparison and analysis of queuing disciplines in OPNET

• Focus on:

▫ FIFO First-in, First Out

▫ PQ Priority Queuing

▫ WFQ Weighted Fair Queuing

• Apply each queuing method towards:

▫ FTP

▫ Voice

▫ Video Conferencing

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Overview

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Global and Object statistics collected and analyzed

Overview

Statistics for Object Statistics

Point-to-point

Average Queuing Delay ->

Throughput ->

Utilization ->

Statistics for Global Statistics

FTP

Traffic Sent

Traffic Received

VoIP

End-to-End Delay

Jitter

Mean Opinion Score

Packet Delay Variation

Traffic Sent

Traffic Received

Video Conferencing

End-to-End Delay

Packet Delay Variation

Traffic Sent

Traffic Received

IP Traffic Dropped


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OPNET Implementation

Scenario 1

Scenario 2

Scenario 3

Queuing discipline

First-in, First-out Queuing

Priority Queuing

Weighted Fair Queuing

Simulation Time 5 minutes 5 minutes 5 minutes

Applications

considered

FTP

VoIP

Video Conferencing

FTP

VoIP

Video Conferencing

FTP

VoIP

Video Conferencing

Scenarios and applications considered

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OPNET Implementation • Network Topology

• Campus network 10 x 10 km

• 5 workstations

• 2 routers

• 1 Ethernet server

• Application, Profile, and QoS

Definitions

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Application Definition Attributes

Application Name

FTP

VoIP

Video Conferencing

Description

High Load

PCM Quality Speech

Low Resolution Video

Type of Service (ToS)

Best Effort (0)

Interactive Voice (6)

Streaming Multimedia (4)

OPNET Implementation

Application Attributes

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FTP

Simulation Results –Traffic Sent

• Traffic sent in bytes/s

• Application : FTP

• FIFO and WFQ show reasonable traffic sent

• PQ worst queuing discipline for FTP traffic with respect to traffic sent

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FTP

Simulation Results –Traffic Received • Traffic received in bytes/s

• Application : FTP

• WFQ shows more traffic

received than FIFO over the long run

• PQ worst queuing discipline for FTP traffic, no traffic is received

• FTP Packets given lowest priority

• FTP traffic not sensitive to jitter, delay

Voice

Simulation Results – End-to-End Delay

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• Time taken for packets to be transmitted from source to destination.

• Application : Voice

• ETE in voice and video should be small to provide natural conversation

• FIFO shows most ETE Delay (~ 2 sec)

• PQ and WFQ have lower ETE delay(~ 0.063 sec)

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Voice

Simulation Results - Jitter


• Jitter is the variation in ETE Delay


• Jitter should be minimized especially in real time applications

• FIFO shows most jitter

• PQ and WFQ show less jitter than FIFO

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Voice

Simulation Results – MOS Value • Mean Opinion Score

defines the perceived voice quality

• MOS scale : 1-5 • 1: Bad • 2: Poor • 3: Fair • 4: Good • 5: Excellent

• FIFO shows bad perceived

audio quality

• PQ and WFQ in between fair and good perceived audio quality

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• PDV is a measure of the difference in ETE

• Ignores lost packets


• PDV should be minimized especially in real time applications

• FIFO shows most PDV

• PQ and WFQ show less PDV than FIFO

Voice

Simulation Results – Packet Delay Variation

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Voice

Simulation Results – Traffic Received

• Voice Traffic received in bytes/s

• Traffic received roughly equal initially

• Degree of loss increases over time

• FIFO queuing results in fewer bytes received

• PQ and WFQ result in more traffic received

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Simulation Results – IP Traffic Dropped


• IP traffic dropped packets/sec

• Drop in IP Traffic results due to insufficient queue space

• PQ and WFQ shows less drop in IP packets

• FIFO shows most drop

• Drop should be minimized, especially in real-time applications

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Video Conferencing

Simulation Results – End-to-End Delay • ETE delay (s)

• WFQ shows highest

ETE because it transmits packets from all applications fairly

• FIFO shows no preference for packets sent, shows better ETE Delay than WFQ

• PQ shows smallest ETE, it is the best queuing choice for video conferencing with respect to ETE Delay

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Video Conferencing

Simulation Results – Packet Delay Variation • PDV is a measure of the

difference in ETE, it ignores lost packets

• Application : Video

• PDV should be minimized especially in real time applications

• WFQ shows most PDV

• FIFO better choice than WFQ

• PQ is best choice for video with respect to PDV

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Video Conferencing

Simulation Results – Traffic Received • Video Traffic received in

bytes/s

• PQ results show it is worst queuing technique for video with respect to traffic received

• FIFO better choice than PQ but has only 1 queue and no priority given to video packets

• WFQ chosen as best queuing discipline because it prioritizes packets

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Point-to-Point: Router A -> Router B

Simulation Results – Average Queuing Delay

• Average Queuing Delay in (s)

• FIFO shows worst Average Queuing Delay

• PQ results show it is much better as compared with FIFO

• WFQ chosen as best queuing discipline in regard to the Average Queuing Delay

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• Throughput (packets/s) is the average number of packets received and transmitted by receiver and transmitter channels per second

• FIFO shows worst Throughput

• PQ results show it is much better as compared with FIFO

• WFQ chosen as best queuing discipline with regard to Throughput


Point-to-Point: Router A -> Router B

Simulation Results – Throughput

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Comparison of Results Obtained

Ranking

System

Equivalent

Numerical Value

Good 1

Worse 2

Worst 3

Ranking System Employed

Statistics

Collected

Scenario

1: FIFO

Scenario

2: PQ

Scenario

3: WFQ

Best Queuing

Discipline

IP Packets

Dropped

3 2 1 WFQ

Average Queuing

Delay

2 1 1 WFQ or PQ

Utilization 1 1 1 FIFO, WFQ, or

PQ

Throughput 3 2 1 WFQ

Comparison of Collected Statistics, part 1

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Comparison of Results Obtained

Application Statistics

Collected

Scenario

1:

FIFO

Scenario

2: PQ

Scenario 3:

WFQ

Best Queuing

Discipline

FTP Traffic Sent 2 3 1 WFQ

Traffic Received 2 3 1 WFQ

Voice

End-to-End Delay 2 1 1 WFQ or PQ

Jitter 3 1 2 PQ

Mean Opinion Score 3 1 2 PQ

Packet Delay

Variation

2 1 1 WFQ or PQ

Traffic Sent 1 1 1 FIFO, WFQ, or

PQ

Traffic Received 3 1 2 PQ

Video

Conferencing

End-to-End Delay 2 1 3 PQ

Packet Delay

Variation

2 1 3 PQ

Traffic Sent 1 1 1 FIFO, WFQ, or

PQ

Traffic Received 2 3 1 WFQ

Comparison of Collected Statistics, part 2

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Conclusion


• Voice Applications: • Best: Priority Queues • Worst: FIFO

• Video Applications:

• Best: Weighted Fair Queues • Worst: Priority Queues

• FTP Applications:

• Best: Weighted Fair Queues • Worst: Priority Queues

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Future Work

• Should study effects of other Queuing Disciplines such as DWRR, Custom Queues, SPQ, and SFQ

• Should study effects of Random-Early Drop (RED) and Drop-tail Policy

• Should consider various other applications such as online gaming.

• Should consider different voice and video qualities to better understand and justify best type of Queue to choose

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References


[1] S.P. Morgan. "Queueing Disciplines and Passive Congestion Control in Byte-Stream Networks." in INFOCOM '89 Proc. 8th Annu. Joint Conference IEEE Computer and Communications Societies, 1989, pp. 1097-1106. [2] L.G. Widjaja and I. Widjaja. Communication Networks. New York, NY: McGraw-Hill, 2004, pp. 539- 547. [3] K. James, and R. Keith. "Scheduling and Policing Mechanisms.” http://www3.gdin.edu.cn/jpkc/dzxnw/jsjkj/chapter6/6-6.htm [Apr. 3, 2011]. [4] B. Dekeris, T. Adomkus, and A. Budnikas. "Analysis of QoS Assurance using Weighted Fair Queueing (WQF) Scheduling Discipline with Low Latency Queue (LLQ)." in 28th Int. Conf. Information Technology Interfaces, 2006, pp. 507-512. [5] P. Calyam et al. "Impact of Router Queuing Disciplines on Multimedia QoE in IPTV Deployments." in QoMEx 2009 Int. Workshop Quality of Multimedia Experience, 2009, pp. 92-97. [6] S. Minseok, C. Naehyuck, and S. Heonshik. "A New Queue Discipline for Various Delay and Jitter Requirements in Real-Time Packet- Switched Networks." in Proc. 7th Int. Conf. Real-Time Computing Systems and Applications, 2000, pp. 191-198. [7] Z. Ni, X. Lu, and D. Liu. "Simulation of Queuing Systems with Different Queuing Disciplines Based on Anylogic." in Int. Conf. Electronic Commerce and Business Intelligence, 2009, pp.164-167. [8] T. Velmurugan, H. Chandra, and S. Balaji. "Comparison of Queuing Disciplines for Differentiated Services Using OPNET." In ARTCom ’09 Int. Conf. Advances in Recent Technologies in Communication and Computing, 2009, pp.744-746.

comparison and analysis of fifo, pq, and wfq disciplines ... › ~ljilja › ensc427 › spring11...

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