Presentación · CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP 4 RTP packet overhead VoIP packet with 2 G.729a samples

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University of Zaragoza

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University of Zaragoza

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Presentación

Jose Saldana

Jenifer Murillo

Julián Fernández Navajas

José Ruiz Mas

Eduardo Viruete Navarro

José I. Aznar

O M U N I C A C I O N E S

TRUPO DE

CECNOLOGÍAS

GDE LAS

CPS - University of Zaragoza, Spain

INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS

Index

CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP

3

Introduction

The use of Internet for multimedia transmission is growing as bandwidth increases.

Services with hard real-time

requirements:

- VoIP: Voice over IP

- Videoconferencing

- Online Gaming



4

RTP packet overhead

VoIP packet with 2 G.729a samples

Efficiency: 33% for IPv4

IP header UDP header RTP header Sample Sample

8 bytes20 bytes 12 bytes 10 bytes 10 bytes



5

Two possible improvements Improvement 1: RTP compression schemes:

- CRTP: RFC 2508, February 1999

- ECRTP: RFC 3545, July 2003: Enhanced CRTP for scenarios with packet loss, packet reordering and long delays.

- ROHCv2: RFC 5225, April 2008

They use the repeatability of IP/UDP/RTP headers to compress them.

Problem: Only hop-by-hop. Solution: tunneling.



6

Increasing the number of samples

Improvement 2: More samples in a single packet. If different flows share the same path (voice trunking)



7

Increasing the number of samples



8

IP header UDP header RTP header

IP header L2TP

Sample Sample IP header UDP header RTP header Sample Sample IP header UDP header RTP header Sample Sample

RH Sample Sample RH Sample Sample RH Sample Sample

PPP PPPMux PPPMux PPPMux

TCRTP: Tunneling Multiplexed Compressed RTP

(RFC 4170)

- Header compression: ECRTP (40 to 5 bytes)

- Multiplexing: PPPMux

- Tunneling: L2TPv3

Reducing overhead, bandwidth saving

Real scale



9


IP header L2TP





(RFC 4170)



- Tunneling: L2TPv3


Real scale



10


IP header L2TP





(RFC 4170)



- Tunneling: L2TPv3


Real scale



11


IP header L2TP





(RFC 4170)

Real scale



- Tunneling: L2TPv3




12

Disadvantages:

- New added delays (small)

- Processing charge

Increasing packet size: Good or bad?

Real scale


IP header L2TP







13

Influence of the router

- Packet loss can be modified with the change of packet size, depending on the policy of the router’s buffer.

- The amount and size distribution of background traffic will affect the real-time traffic.

- We will use R-factor for comparatives. Takes into account delay and packet loss.



14

Buffer size and buffer policies - We will compare

- High-capacity buffer

- Time-limited buffer (80 ms)

IP network

MUX DEMUX .

.

.

.

.

.

RTP RTP multiplexing RTP



15

High capacity buffer - 1Mbps shared. 15 flows

60

65

70

75

80

85

400 450 500 550 600 650 700 750 800 850 900 950 1000

R

background traffic (kbps)

R factor15 RTP

15 TCRTP



16


60

65

70

75

80

85

400 450 500 550 600 650 700 750 800 850 900 950 1000

R


R factor15 RTP

15 TCRTP


Step-like graphs. When the bandwidth is not enough, the quality falls


17


60

65

70

75

80

85

400 450 500 550 600 650 700 750 800 850 900 950 1000

R


R factor15 RTP

15 TCRTP


Bandwidth saving allows a bigger amount of background traffic

TCRTP Packet size: 550 bytes 172 kbps

Native RTP Packet size: 60 bytes 432 kbps


18

Time-limited buffer - 1Mbps shared. 20 flows

60

62

64

66

68

70

72

74

76

78

80

82

400 450 500 550 600 650 700 750 800 850 900 950 1000

R-f

acto

r


R-factor20 RTP

20 TCRTP


Effect of Bandwidth saving


19


60

62

64

66

68

70

72

74

76

78

80

82

400 450 500 550 600 650 700 750 800 850 900 950 1000

R-f

acto

r


R-factor20 RTP

20 TCRTP


Non step-like graphs. The bigger the packet size, the bigger the slope


20


60

62

64

66

68

70

72

74

76

78

80

82

400 450 500 550 600 650 700 750 800 850 900 950 1000

R-f

acto

r


R-factor20 RTP

20 TCRTP


Native RTP Packet size: 60 bytes 576 kbps

TCRTP Packet size: 550 bytes 225 kbps


21

Time-limited buffer - Is it better to use only one tunnel or to

group calls into a number of tunnels?

50

55

60

65

70

75

80

85

400 450 500 550 600 650 700 750 800 850 900 950 1000

R


R factor

20 RTP

20 TCRTP

2x10 TCRTP



22

Motivation of this work

- Study the influence of different TCRTP multiplexing schemes on the perceived quality, depending on buffer policies.

- We will use 40 RTP flows sharing the same path, but divided on:

- l tunnels of k flows (l x k = 40)

- 1 tunnel of 40 flows 5 tunnels of 8 flows

- 2 tunnels of 20 flows 8 tunnels of 5 flows

- 4 tunnels of 10 flows 40 RTP flows



Index


24

General Scheme - Use of a testbed

Traffic

Generation

RouterTraffic

Capture

Real Traffic in a testbed

Network

delays

+

Dejitter

buffer

Offline post-processing

Traffic

Trace

Final

Results

VoIP

Background

Buffer

policies



25

Traffic generation - Background traffic

- 50% 40 bytes

- 10% 576 bytes

- 40% 1500 bytes

- Only UDP, in order to avoid flow control: always the same background traffic.

- Different rates to saturate the access router: 2Mbps.



Index


27

High capacity buffer

62

64

66

68

70

72

74

76

78

80

82

1200 1300 1400 1500 1600 1700 1800 1900 2000

R-f

acto

r


R-factor1x40 TCRTP

2x20 TCRTP

4x10 TCRTP

5x8 TCRTP

8x5 TCRTP



28


62

64

66

68

70

72

74

76

78

80

82

1200 1300 1400 1500 1600 1700 1800 1900 2000

R-f

acto

r


R-factor1x40 TCRTP

2x20 TCRTP

4x10 TCRTP

5x8 TCRTP

8x5 TCRTP


Step-like graphs


29


62

64

66

68

70

72

74

76

78

80

82

1200 1300 1400 1500 1600 1700 1800 1900 2000

R-f

acto

r


R-factor1x40 TCRTP

2x20 TCRTP

4x10 TCRTP

5x8 TCRTP

8x5 TCRTP


The bigger the bandwidth saving, the better the behaviour


30

Time-limited buffer

46

50

54

58

62

66

70

74

78

82

1200 1300 1400 1500 1600 1700 1800 1900 2000

R-f

acto

r


R-factor1x40 TCRTP

2x20 TCRTP

4x10 TCRTP

5x8 TCRTP

8x5 TCRTP

No mux



31

Time-limited buffer

46

50

54

58

62

66

70

74

78

82

1200 1300 1400 1500 1600 1700 1800 1900 2000

R-f

acto

r


R-factor1x40 TCRTP

2x20 TCRTP

4x10 TCRTP

5x8 TCRTP

8x5 TCRTP

No mux


The graphs present a slope


32

Time-limited buffer

46

50

54

58

62

66

70

74

78

82

1200 1300 1400 1500 1600 1700 1800 1900 2000

R-f

acto

r


R-factor1x40 TCRTP

2x20 TCRTP

4x10 TCRTP

5x8 TCRTP

8x5 TCRTP

No mux


Not ordered by the bandwidth saving

4th


33

Time-limited buffer

46

50

54

58

62

66

70

74

78

82

1200 1300 1400 1500 1600 1700 1800 1900 2000

R-f

acto

r


R-factor1x40 TCRTP

2x20 TCRTP

4x10 TCRTP

5x8 TCRTP

8x5 TCRTP

No mux


Not ordered by the bandwidth saving

1st


34

Time-limited buffer

0

2

4

6

8

10

12

14

1200 1300 1400 1500 1600 1700 1800 1900 2000

Pac

ket

Loss

(%

)


Percentage of Background Traffic Packet Loss1x40 TCRTP

2x20 TCRTP

4x10 TCRTP

5x8 TCRTP

8x5 TCRTP


Ordered by bandwidth saving


Index


36

Asymptotic bandwidth relationship

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

X

k

Bandwidth Saving X for p = 0.95 S=10 bytes

Xrh S=10

S=20 bytes

Xrh=20

S=30 bytes

Xrh S=30


BW compressed/BW native


37

Asymptotic bandwidth relationship

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

X

k

Bandwidth Saving X for p = 0.95 S=10 bytes

Xrh S=10

S=20 bytes

Xrh=20

S=30 bytes

Xrh S=30


BW compressed/BW native

Bandwidth saving increase


38

Linear packet size increase

0

100

200

300

400

500

600

700

800

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

byte

s

k

Packet sizeRTP S=10 bytes

RTP S=20 bytes

RTP S=30 bytes

TCRTP S=10 bytes

TCRTP S=20 bytes

TCRTP S=30bytes



39


0

100

200

300

400

500

600

700

800

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

byte

s

k

Packet sizeRTP S=10 bytes

RTP S=20 bytes

RTP S=30 bytes

TCRTP S=10 bytes

TCRTP S=20 bytes

TCRTP S=30bytes


Packet size increase


40


0

200

400

600

800

1000

1200

0 200 400 600 800 1000 1200

Pa

cke

t siz

e (

byte

s)

Bandwidth (kbps)

Packet size vs Bandwidth 1x40

2x20

4x10

5x8

8x5

40 RTP

1 tunnel of 40 flows

2 tunnels of 20 flows




40 native RTP flows



41


0

200

400

600

800

1000

1200

0 200 400 600 800 1000 1200

Pa

cke

t siz

e (

byte

s)

Bandwidth (kbps)

Packet size vs Bandwidth 1x40

2x20

4x10

5x8

8x5

40 RTP

Packet size increase

Bandwidth decrease



42

Conclusions - The decision of the number of tunnels has

an influence on R-factor.

- The buffer policy has to be taken into account in order to take the correct decision. Previous measurements.

- The increase of packet size may increase packet loss, so it could be better to have a number of tunnels.

- Asymptotic behaviour.


Presentación

Jose Saldana

Jenifer Murillo

Julián Fernández Navajas

José Ruiz Mas

Eduardo Viruete Navarro

José I. Aznar

O M U N I C A C I O N E S

TRUPO DE

CECNOLOGÍAS

GDE LAS

CPS - University of Zaragoza, Spain View publication statsView publication stats

https://www.researchgate.net/publication/245229809

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Presentación · CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP 4 RTP packet overhead VoIP packet with 2 G.729a samples