Influence of the Distribution of TCRTP Multiplexed Flows on VoIP Conversation Quality
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This document describes an experiment to evaluate the impact of different Tunneling Compressed RTP (TCRTP) multiplexing schemes on voice quality over IP (VoIP) under varying network conditions. The experiment multiplexed VoIP packets using TCRTP tunnels with different numbers of flows and measured the resulting voice quality using the R-factor metric. With a high-capacity router buffer, all TCRTP schemes showed step-like quality degradation as background traffic increased. With a time-limited buffer, smaller tunnels led to smoother quality decline. More flows per tunnel reduced overhead and allowed higher background traffic levels before quality dropped.
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Influence of the Distribution of TCRTP Multiplexed Flows on VoIP Conversation Quality
- 1. Presentación Jose Saldana Jenifer Murillo Julián Fernández Navajas G RUPO DE T ECNOLOGÍAS DE LAS COMUNICACIONES CPS - University of Zaragoza, Spain José Ruiz Mas Eduardo Viruete Navarro José I. Aznar
- 3. 3 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS 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 CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 4. 4 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS RTP packet overhead IP header UDP header RTP header Sample Sample 20 bytes 8 bytes 12 bytes 10 bytes 10 bytes VoIP packet with 2 G.729a samples Efficiency: 33% for IPv4 CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 5. 5 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS 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. CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 6. 6 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS Increasing the number of samples Improvement 2: More samples in a single packet. If different flows share the same path (voice trunking) CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 7. 7 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS Increasing the number of samples CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 8. 8 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS TCRTP: Tunneling Multiplexed Compressed RTP (RFC 4170) IP header UDP header RTP header IP header Sample Sample IP header L2TP RH PPP PPPMux Sample UDP header Sample RH PPPMux RTP header Sample Sample Sample Sample RH PPPMux IP header Sample UDP header RTP header Sample Sample Sample Real scale - Header compression: ECRTP (40 to 5 bytes) - Multiplexing: PPPMux - Tunneling: L2TPv3 Reducing overhead, bandwidth saving CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 9. 9 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS TCRTP: Tunneling Multiplexed Compressed RTP (RFC 4170) IP header UDP header RTP header IP header Sample Sample IP header L2TP RH PPP PPPMux Sample UDP header Sample RH PPPMux RTP header Sample Sample Sample Sample RH PPPMux IP header Sample UDP header RTP header Sample Sample Sample Real scale - Header compression: ECRTP (40 to 5 bytes) - Multiplexing: PPPMux - Tunneling: L2TPv3 Reducing overhead, bandwidth saving CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 10. 10 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS TCRTP: Tunneling Multiplexed Compressed RTP (RFC 4170) IP header UDP header RTP header IP header Sample Sample IP header L2TP RH PPP PPPMux Sample UDP header Sample RH PPPMux RTP header Sample Sample Sample Sample RH PPPMux IP header Sample UDP header RTP header Sample Sample Sample Real scale - Header compression: ECRTP (40 to 5 bytes) - Multiplexing: PPPMux - Tunneling: L2TPv3 Reducing overhead, bandwidth saving CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 11. 11 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS TCRTP: Tunneling Multiplexed Compressed RTP (RFC 4170) IP header UDP header RTP header IP header Sample Sample IP header L2TP RH PPP PPPMux Sample UDP header Sample RH PPPMux RTP header Sample Sample Sample Sample RH PPPMux IP header Sample UDP header RTP header Sample Sample Sample Real scale - Header compression: ECRTP (40 to 5 bytes) - Multiplexing: PPPMux - Tunneling: L2TPv3 Reducing overhead, bandwidth saving CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 12. 12 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS TCRTP: Tunneling Multiplexed Compressed RTP IP header UDP header RTP header IP header Sample Sample IP header L2TP RH PPP PPPMux Sample UDP header Sample RH PPPMux RTP header Sample Sample Sample Sample RH IP header Sample UDP header RTP header Sample Sample Sample PPPMux Real scale Disadvantages: - New added delays (small) - Processing charge Increasing packet size: Good or bad? CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 13. 13 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS 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. CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 14. 14 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS Buffer size and buffer policies - We will compare - High-capacity buffer - Time-limited buffer (80 ms) IP network . . . MUX RTP CCNC January 9-11, 2011. Las Vegas DEMUX RTP multiplexing . . . RTP Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 15. 15 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS High capacity buffer - 1Mbps shared. 15 flows R factor 15 RTP 85 15 TCRTP 80 R 75 70 65 60 400 450 500 550 600 650 700 750 800 850 900 950 1000 background traffic (kbps) CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 16. 16 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS High capacity buffer - 1Mbps shared. 15 flows R factor 15 RTP 85 15 TCRTP 80 75 R Step-like graphs. When the bandwidth is not enough, the quality falls 70 65 60 400 450 500 550 600 650 700 750 800 850 900 950 1000 background traffic (kbps) CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 17. 17 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS High capacity buffer - 1Mbps shared. 15 flows R factor 15 RTP 85 15 TCRTP 80 75 R Bandwidth saving allows a bigger amount of background traffic 70 Native RTP Packet size: 60 bytes 432 kbps 65 TCRTP Packet size: 550 bytes 172 kbps 60 400 450 500 550 600 650 700 750 800 850 900 950 1000 background traffic (kbps) CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 18. 18 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS Time-limited buffer - 1Mbps shared. 20 flows 20 RTP R-factor 82 20 TCRTP 80 78 Effect of Bandwidth saving 76 R-factor 74 72 70 68 66 64 62 60 400 450 500 550 600 650 700 750 800 850 900 950 1000 background traffic (kbps) CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 19. 19 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS Time-limited buffer - 1Mbps shared. 20 flows 20 RTP R-factor 82 20 TCRTP 80 78 76 R-factor 74 Non step-like graphs. The bigger the packet size, the bigger the slope 72 70 68 66 64 62 60 400 450 500 550 600 650 700 750 800 850 900 950 1000 background traffic (kbps) CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 20. 20 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS Time-limited buffer - 1Mbps shared. 20 flows 20 RTP R-factor 82 20 TCRTP 80 78 TCRTP Packet size: 550 bytes 225 kbps 76 R-factor 74 72 70 68 Native RTP Packet size: 60 bytes 576 kbps 66 64 62 60 400 450 500 550 600 650 700 750 800 850 900 950 1000 background traffic (kbps) CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 21. 21 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS Time-limited buffer - Is it better to use only one tunnel or to group calls into a number of tunnels? R factor 20 RTP 85 20 TCRTP 2x10 TCRTP 80 75 R 70 65 60 55 50 400 450 500 550 600 650 700 750 800 850 900 950 1000 background traffic (kbps) CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 22. 22 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS 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 2 tunnels of 20 flows 4 tunnels of 10 flows CCNC January 9-11, 2011. Las Vegas 5 tunnels of 8 flows 8 tunnels of 5 flows 40 RTP flows Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 24. 24 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS General Scheme - Use of a testbed Real Traffic in a testbed Offline post-processing Buffer policies VoIP Network delays + Dejitter buffer Background Router Traffic Generation CCNC January 9-11, 2011. Las Vegas Traffic Capture Traffic Trace Final Results Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 25. 25 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS 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. CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 27. 27 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS High capacity buffer 1x40 TCRTP R-factor 2x20 TCRTP 82 4x10 TCRTP 80 5x8 TCRTP 78 8x5 TCRTP R-factor 76 74 72 70 68 66 64 62 1200 1300 1400 1500 1600 1700 1800 1900 2000 background traffic (kbps) CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 28. 28 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS High capacity buffer 1x40 TCRTP R-factor 2x20 TCRTP 82 4x10 TCRTP 80 5x8 TCRTP 78 8x5 TCRTP R-factor 76 74 72 Step-like graphs 70 68 66 64 62 1200 1300 1400 1500 1600 1700 1800 1900 2000 background traffic (kbps) CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 29. 29 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS High capacity buffer 1x40 TCRTP R-factor 2x20 TCRTP 82 4x10 TCRTP 80 5x8 TCRTP 78 8x5 TCRTP R-factor 76 74 72 The bigger the bandwidth saving, the better the behaviour 70 68 66 64 62 1200 1300 1400 1500 1600 1700 1800 1900 2000 background traffic (kbps) CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 30. 30 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS Time-limited buffer R-factor 1x40 TCRTP 82 2x20 TCRTP 78 4x10 TCRTP 5x8 TCRTP 74 8x5 TCRTP No mux R-factor 70 66 62 58 54 50 46 1200 1300 1400 1500 1600 1700 1800 1900 2000 background traffic (kbps) CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 31. 31 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS Time-limited buffer R-factor 1x40 TCRTP 82 2x20 TCRTP 78 4x10 TCRTP 5x8 TCRTP 74 8x5 TCRTP No mux R-factor 70 66 The graphs present a slope 62 58 54 50 46 1200 1300 1400 1500 1600 1700 1800 1900 2000 background traffic (kbps) CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 32. 32 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS Time-limited buffer R-factor 4th 82 1x40 TCRTP 2x20 TCRTP 78 4x10 TCRTP 5x8 TCRTP 74 8x5 TCRTP No mux R-factor 70 66 Not ordered by the bandwidth saving 62 58 54 50 46 1200 1300 1400 1500 1600 1700 1800 1900 2000 background traffic (kbps) CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 33. 33 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS Time-limited buffer R-factor 1x40 TCRTP 82 1st 78 4x10 TCRTP 5x8 TCRTP 74 8x5 TCRTP No mux R-factor 70 66 2x20 TCRTP Not ordered by the bandwidth saving 62 58 54 50 46 1200 1300 1400 1500 1600 1700 1800 1900 2000 background traffic (kbps) CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 34. 34 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS Time-limited buffer 1x40 TCRTP 14 Percentage of Background Traffic Packet Loss 2x20 TCRTP 4x10 TCRTP Packet Loss (%) 12 5x8 TCRTP 8x5 TCRTP 10 8 Ordered by bandwidth saving 6 4 2 0 1200 1300 1400 1500 1600 1700 1800 1900 2000 background traffic (kbps) CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 36. 36 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS Asymptotic bandwidth relationship Bandwidth Saving X for p = 0.95 BW compressed/BW native S=10 bytes Xrh S=10 S=20 bytes 0,9 Xrh=20 S=30 bytes 0,8 Xrh S=30 X 0,7 0,6 0,5 0,4 0,3 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 k CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 37. 37 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS Asymptotic bandwidth relationship Bandwidth Saving X for p = 0.95 BW compressed/BW native S=10 bytes Xrh S=10 S=20 bytes 0,9 Xrh=20 S=30 bytes 0,8 Xrh S=30 X 0,7 Bandwidth saving increase 0,6 0,5 0,4 0,3 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 k CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 38. 38 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS Linear packet size increase Packet size RTP S=10 bytes 800 RTP S=20 bytes RTP S=30 bytes TCRTP S=10 bytes 700 TCRTP S=20 bytes TCRTP S=30bytes 600 bytes 500 400 300 200 100 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 k CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 39. 39 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS Linear packet size increase Packet size RTP S=10 bytes 800 RTP S=20 bytes RTP S=30 bytes TCRTP S=10 bytes 700 Packet size increase TCRTP S=20 bytes TCRTP S=30bytes 600 bytes 500 400 300 200 100 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 k CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 40. 40 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS Linear packet size increase Packet size vs Bandwidth 1x40 1200 2x20 1 tunnel of 40 flows 4x10 1000 5x8 8x5 40 RTP Packet size (bytes) 800 2 tunnels of 20 flows 600 4 tunnels of 10 flows 400 5 tunnels of 8 flows 200 40 native RTP flows 8 tunnels of 5 flows 0 0 200 400 600 800 1000 1200 Bandwidth (kbps) CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 41. 41 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS Linear packet size increase Packet size vs Bandwidth 1x40 Bandwidth decrease 2x20 1200 1000 5x8 8x5 Packet size increase 800 Packet size (bytes) 4x10 40 RTP 600 400 200 0 0 200 400 600 800 1000 1200 Bandwidth (kbps) CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 42. 42 INTRODUCTION MEASUREMENTS RESULTS DISCUSSION CONCLUSIONS 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. CCNC January 9-11, 2011. Las Vegas Influence of the Distribution of TCRTP Multiplexed flows on VoIP
- 43. Presentación Jose Saldana Jenifer Murillo Julián Fernández Navajas G RUPO DE T ECNOLOGÍAS DE LAS COMUNICACIONES CPS - University of Zaragoza, Spain José Ruiz Mas Eduardo Viruete Navarro José I. Aznar