1. Quality of Service for Real-Time Network Management Debbie Greenstreet Product Management Director Texas Instruments

2. Agenda Overview of VoIP QOS QOS system level elements QOS measurement metrics QOS monitoring techniques Solutions

3. VoIP Quality Monitoring What happens if it doesn’t sound good…. –Telephony tools support production lab testing –LAN, packet network tools don’t capture voice QOS problems Result hurts: –Market penetration –Network Manager’s ability to support –Carrier’s ability to assure quality –Manufacturer’s ability to defend products

4. Gateway Packet Network PSTN Office Network GatewayPBX Gateway PBX Phone PC IP phone PC Call server NMS BB modem Phone EP P VoIP System Elements Router

5. Causes of Degradation - Implementation End point Implementation - Delay – processing, accumulation - Echo – robust canceller design - Jitter – proper buffer sizing - Packet loss – jitter buffer sizing System Implementation - Delay – network performance - Echo – proper loss plan, cancellation - Jitter – network behavior - Packet loss – network performance

6. Causes of Degradation – Operational System Operation –Outages, failures Infrastructure: switch, router, bridge, etc VoIP elements: call server, SIP server, gateways, terminal endpoints. System Performance –Increase in traffic Affects delay, jitter, loss –Increase in system complexity Changes delay, potential for failure

7. Quality Degradation: Delay, Jitter Variations in Packet Inter-arrival Rate  Changes in Network Load  Variations in Routing Paths  Variable queuing delays Playout Buffer Gateway Product Packet Network Delay guideline: ITU-T G.114

8. Quality Degradation: Packet Loss, Out of Order 6 54 3 2 1 Playout Buffer Gateway Product Packet Network Lost Potential Causes of Lost Packets:  Network Congestion/Performance  Network Architecture  Improper Jitter Buffer Size  Software Not Designed for Peak Load Potential Causes of Packet Reordering:  Network Congestion/Performance  Network Architecture

9. Gateway Packet Network PSTN Office Network GatewayPBX Gateway PBX Phone PC IP phone PC Call server NMS BB modem Phone EP P Quality Vulnerabilities Router

10. VoIP QOS Metrics - Implementation MOS (Mean Opinion Score): - Subjective measurement of voice quality - Group rates 1 – 5 PSQM - ITU-T P.861 (Perceptual Speech Quality Measurement): - Automated scoring system - Designed for circuit-switched network

11. VoIP QOS Metrics – System level PAMS (Perceptual Analysis and Measurement System): –Intrusive speech quality assessment tool –End to End degradation analysis of injected signal PESQ - ITU–T P.862: –Recent standard for assessing voice quality –Adds to PSQM and PAMS algorithms

12. Existing QOS Related Standards ITU-T –G.107: E-Model network design guide –G.114:Delay guidelines –P.800: Subjective MOS techniques –P.862: PESQ, replaces P.861 (PSQM) –P.562:Call-clarity Index (CCI) non-invasive measurements to estimate conversational quality

13. Monitoring Options Active Monitoring –Intrusive –Metrics calculation on “test” calls Passive Monitoring –Non-Intrusive –Metrics calculation on live calls

14. Active Monitoring QoS Monitoring Station Simulated traffic Reporting protocol Simulated VoIP traffic injected Endpoints are PCs or servers

15. Active Monitoring VQT Call Server/SIP Proxy Switch Analog RTP SIP IP Phone Phone Gateway Pre-recorded audio injected, compared to receive

16. Gateway Packet Network PSTN Office Network Gateway PBX Gateway PBX Phone PC IP phone PC Call server NMS BB modem Phone SIM EP SIM Reports SIM traffic Active Monitoring

17. Passive Monitoring Options Port Mirroring Switch IP Phone Probe Switch/Router Inline Insertion Probe IP Phone Phone Switch Gateway Phone Gateway

18. Other Measurement Tools E Model: R-Factor –“R” = Ro - Is - Id - Ie + A –“Mouth to ear”, 0 – 100 rating RTCP –IETF RFC 3550 – significant change to RTP, mostly RTCP –Use to report far end performance

19. RTCP XR Extended Reports VoIP Metrics Block –Packet loss and discard –Physical level signal metrics Signal level Noise level RERL – Residual Echo Return Loss –Call Quality Metrics User and Network R Factor MOS – LQ (listening quality) MOS – CQ (conversational quality) Gap Threshold Receiver configuration

20. Passive Monitoring - Embedded Solutions QoS Domain QoS Domain Jitter Buffer Emulator VoIP End-Point QOS Monitor Embedded Software IP Network CODEC Embedded Software CODEC IP Network

21. New QOS Measurement Standards IETF –RTCP Reporting Extensions (XR) –SIP using RTCP ITU –Extensions to Megaco, H.323 –P.VTQ, P.SEAM, P.AAM –G.113 TIA –VoIP CPE Performance Management requirements ETSI –TS 101 329-5 Annex E

22. Gateway Packet Network PSTN Office Network Gateway PBX Gateway PBX Phone PC IP phone PC Call server NMS BB modem Phone EP SIM EP SIM Reports RTP Passive Monitoring

23. QOS Management System Central QoS Manager Console VoIP Network Packet monitoring RTCP SNMP ALARM

24. Summary Comprehensive QOS monitoring and management required for VoIP Techniques and standards exist VoIP equipment needs to include monitoring and measurement elements QOS management tools need to be deployed