Post on 29-Dec-2015
transcript
Example Applications needing Example Applications needing Advanced ServicesAdvanced Services
Campus Focused Workshop on Advanced Networks
Atlanta, GA
Voice over IP Environment for Voice over IP Environment for Research (VIPER)Research (VIPER)
Chakravarthy K Sannedhi
Electrical & Computer Engineering
VoIP: BenefitsVoIP: 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: IssuesVoIP: 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 approachesVoIP: 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 TestingVoIP: 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
Web Interface
Call Generator Test taker’s data collector
Noise Generator Script Loader
Voice Database
Script Database
MySQL Database
VIPER ArchitectureVIPER Architecture
QoS Techniques TestedQoS Techniques Tested
IntServ (RSVP)DiffServ (EF and AF)Label Switching (MPLS)Traffic Shaping (CAR, GTS, etc.)
RSVPRSVP
IntServ TechniqueSender sends the PATH message which
contains TSpecReceiver sends RESV which includes
Flowspec75% of the bandwidth to voice1.4
Weighted Fair QueuingWeighted Fair Queuing
Schedules interactive traffic to the front of the queue
Applies weights to identified traffic flowsShares the remaining bandwidth between
the high bandwidth flows3.6
Custom QueuingCustom Queuing
Services the traffic in round robin basisVoice was given maximum queue limit and
maximum byte count1.2
Priority QueuingPriority Queuing
Suitable for interfaces with less than 2.048 Mbps bandwidth
Voice is placed in the High priority queueInjustice to traffics that are other than in
High priority queue1.2
Class Based WFQClass Based WFQ
Traffic is placed in different classesSimultaneous handling of the traffic10 % of bandwidth to voice4.4
CBWFQ with LLQCBWFQ with LLQ
Brings strict priority queuing to CBWFQPreferential treatment for the voiceNot effective on Frame Relay networks3.6
Committed Access RateCommitted Access Rate
Traffic Shaping techniqueVoice packets are given the nice burst range
with a good amount of toleranceLowers the Jitter1.4
IP RTP Priority with WFQIP 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 RSVPIP RTP Priority with RSVP
Voice is identified by its UDP port range75% of the bandwidth to the voice 1.5
VIPER pMOS resultsVIPER pMOS resultsQoS (in extreme congestion) 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 19.21.2 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
AcknowledgementsAcknowledgements
Jill Gemmill – Assistant Director, Department of Academic Computing, UAB
Stan McClellan – Associate Professor, Electrical & Computer Engineering. UAB
ReferencesReferences
Red Hat Linux - http://www.redhat.comIperf - http://dast.nlanr.net/Projects/IperfMySQL - http://www.mysql.comPHP - http://www.php.netCisco - http://www.cisco.comExpect - http://expect.nist.govVgetty - http://alpha.greenie.net/vgetty