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Example Applications needing Advanced Services. Campus Focused Workshop on Advanced Networks Atlanta, GA. Voice over IP Environment for Research (VIPER). Chakravarthy K Sannedhi Electrical & Computer Engineering. VoIP: Benefits. Data traffic growing rapidly
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Example Applications needing Advanced Services Campus Focused Workshop on Advanced Networks Atlanta, GA
Voice over IP Environment for Research (VIPER) Chakravarthy K Sannedhi Electrical & Computer Engineering
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
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
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
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
Voice Database MySQL Database Call Generator Test taker’s data collector Web Interface Noise Generator Script Loader Script Database VIPER Architecture
QoS Techniques Tested • IntServ (RSVP) • DiffServ (EF and AF) • Label Switching (MPLS) • Traffic Shaping (CAR, GTS, etc.)
Best Effort • No QoS • First In First Out • Still the voice is marked with EF • 1.1
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
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
Custom Queuing • Services the traffic in round robin basis • Voice was given maximum queue limit and maximum byte count • 1.2
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
Class Based WFQ • Traffic is placed in different classes • Simultaneous handling of the traffic • 10 % of bandwidth to voice • 4.4
CBWFQ with LLQ • Brings strict priority queuing to CBWFQ • Preferential treatment for the voice • Not effective on Frame Relay networks • 3.6
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
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
IP RTP Priority with RSVP • Voice is identified by its UDP port range • 75% of the bandwidth to the voice • 1.5
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 1.2o.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
Acknowledgements • Jill Gemmill – Assistant Director, Department of Academic Computing, UAB • Stan McClellan – Associate Professor, Electrical & Computer Engineering. UAB
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
Web Resources for the Project • http://www.dpo.uab.edu/~kalyan/proreport.html