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Example Applications needing Advanced Services

Explore the benefits, issues, and quality of Voice over IP (VoIP) in this focused workshop. Learn about QoS approaches and testing techniques using the VIPER automated environment.

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Example Applications needing Advanced Services

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  1. Example Applications needing Advanced Services Campus Focused Workshop on Advanced Networks Atlanta, GA

  2. Voice over IP Environment for Research (VIPER) Chakravarthy K Sannedhi Electrical & Computer Engineering

  3. VoIP: Benefits • Data traffic growing rapidly • Multiple parallel networks are expensive • VoIP Enables convergence of voice & data networks • Low-cost and flat-rate pricing possible • IP is compatible with most modern network technologies & topologies

  4. VoIP: Issues • Delay • too much can cause “real time” voice interaction to become useless • Jitter • small amounts can be “fixed” by jitter buffers, but end-to-end delay suffers • Packet loss • creates “big gaps” in received (reconstructed) voice

  5. VoIP: QoS approaches • Bandwidth allocation • Necessary, but not sufficient • Prioritization of the voice traffic • Necessary, but not sufficient • Different techniques have different effects on voice as well as “other traffic” • QoS Techniques • DiffServ • IntServ • Traffic Shaping

  6. VoIP: Quality Testing • Objective Testing • Necessary, but not terribly useful • Objective measures often correlate poorly with human perception (even when perceptual models are used) • Subjective Testing • Necessary, but prone to error and interpretation • Time consuming, particularly in context of network-dependent error mechanisms • General idea … VIPER • Automated environment to configure various network-based parameters which affect voice QoS • Enables collecting of subjective test data

  7. VIPER Architecture

  8. VIPER Architecture

  9. Voice Database MySQL Database Call Generator Test taker’s data collector Web Interface Noise Generator Script Loader Script Database VIPER Architecture

  10. QoS Techniques Tested • IntServ (RSVP) • DiffServ (EF and AF) • Label Switching (MPLS) • Traffic Shaping (CAR, GTS, etc.)

  11. Best Effort • No QoS • First In First Out • Still the voice is marked with EF • 1.1

  12. RSVP • IntServ Technique • Sender sends the PATH message which contains TSpec • Receiver sends RESV which includes Flowspec • 75% of the bandwidth to voice • 1.4

  13. Weighted Fair Queuing • Schedules interactive traffic to the front of the queue • Applies weights to identified traffic flows • Shares the remaining bandwidth between the high bandwidth flows • 3.6

  14. Custom Queuing • Services the traffic in round robin basis • Voice was given maximum queue limit and maximum byte count • 1.2

  15. Priority Queuing • Suitable for interfaces with less than 2.048 Mbps bandwidth • Voice is placed in the High priority queue • Injustice to traffics that are other than in High priority queue • 1.2

  16. Class Based WFQ • Traffic is placed in different classes • Simultaneous handling of the traffic • 10 % of bandwidth to voice • 4.4

  17. CBWFQ with LLQ • Brings strict priority queuing to CBWFQ • Preferential treatment for the voice • Not effective on Frame Relay networks • 3.6

  18. Committed Access Rate • Traffic Shaping technique • Voice packets are given the nice burst range with a good amount of tolerance • Lowers the Jitter • 1.4

  19. IP RTP Priority with WFQ • Useful for slow speed links with speeds less than 1.544 Mbps • Voice packets are identified by the UDP port range • Voice was given 60 Kbps of bandwidth along with the application of fair queuing • 3.9

  20. IP RTP Priority with RSVP • Voice is identified by its UDP port range • 75% of the bandwidth to the voice • 1.5

  21. QoS (in extremecongestion) PMOS Missed Calls (%) Confidence (95%) Best Effort 1.1 26.9 1.1  0.14 WFQ 3.6 0 3.6  0.27 RSVP only 1.4 7.7 1.4  0.28 IPRTP + EF 1.4 19.2 1.4  0.28 IPRTP + WFQ 3.9 0 3.9  0.27 RSVP + IPRTP 1.5 15.4 1.5  0.28 CQ + EF 1.2 7.7 1.2  0.19 PQ + EF 1.2 19.2 1.2o.19 CBWFQ + LLQ + EF 3.6 0 3.6  0.27 CBWFQ + EF 4.4 0 4.4  0.22 CAR + EF 1.4 0 1.4  0.36 VIPER pMOS results

  22. Acknowledgements • Jill Gemmill – Assistant Director, Department of Academic Computing, UAB • Stan McClellan – Associate Professor, Electrical & Computer Engineering. UAB

  23. References • Red Hat Linux - http://www.redhat.com • Iperf - http://dast.nlanr.net/Projects/Iperf • MySQL - http://www.mysql.com • PHP - http://www.php.net • Cisco - http://www.cisco.com • Expect - http://expect.nist.gov • Vgetty - http://alpha.greenie.net/vgetty

  24. Web Resources for the Project • http://www.dpo.uab.edu/~kalyan/proreport.html

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