1. 71 Sidevõrgud IRT 0020 loeng 6 04. okt. 2005 Avo Ots telekommunikatsiooni õppetool, TTÜ raadio- ja sidetehnika inst. avo.ots@ttu.ee

2. 72 Shouldn’t you have some kind of equipment or something? It’s the Quality of the Service, our methods are not always apparent. Q o S

3. 73 The Hidden Costs WAN Over-provisioning LAN Over-provisioning Increased administrative costs Extensive Troubleshooting Unintended PSTN usage Monitoring and measurement Problems grow as network size increases Positive IP Telephony Business Case Negative IP Telephony Business Case Hidden Costs of Convergence

4. 74 Voice not just another IP data application… Enterprise customers have high expectations: –“No tolerance for poor voice, it has to be toll quality” –“Voice goes down – they are on the phone” –“Don’t want to lose business because of QoS” Voice inherently different from most data applications –Intolerant of delays, packet loss and jitter –Performance essential to the delivery of the service –Voice specific application behavior YetAnother Data Application

5. 75 DiffServ Predominant QoS technology in use today Bandwidth allocated per traffic classes (via DSCP) Traffic Classification and Conditioning at edge Per Hop Behavior at interior nodes –Queuing and Dropping according to priority & bandwidth Queuing must be configured for minimum packet delay Easy for endpoints, scales well, CPU intensive DiffServ: –Has no end-to-end network/service view –Limited Call Admission Control Scheme –High priority packets can be dropped when congested –Often difficult to configure and maintain –Doesn’t always guarantee high quality

6. 76 (IntServ) Reserves resources end-to-end to provide service guarantees Uses the RSVP protocol which signals per flow QoS requirements to the network If reservation succeeds, flow has end-to-end guaranteed bandwidth Includes an inherent call admission control mechanism Ideal for real-time traffic such as voice and video Providing benefits similar to circuit switching Not as heavily used due to perceived drawbacks: –Setup times, I.e. post-dial delay –Issues due to per-flow behavior –Amount of state information and overhead

7. 77 IP Solution Easy to Manage Dynamic Pro-active Adaptable Qos Engineering IP Telephony Content Video Multiservice Applications Multiservice Applications Any Infrastructure Any Infrastructure Gateway Router Switch MediaIP Controller Flow Aggregation, QoS/Access Control Traffic Engineering, Forecasting and Optimization MediaIP Director Integrated Services Diffserv (with LLQ) Operations Savings Bandwidth Savings PSTN/ISDN Savings

8. 78 Over-Provisioning Traditional approach for data networks… No mechanism for QoS Is actually best-effort Overprovision where? Expensive Converged Networks: –“Bursty” Traffic –3X to 5X not sufficient –Congestion still occurs 01234 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 Packet Counts Hours Packets Mean Bandwidth Over-Provisioning 2x 3x 4x 5x

9. 79 The Benefits and ROI from QoS Enterprise WAN Network Operations Center IP PBX Legacy PBX PSTN Fewer PSTN Trunks Reduced PSTN Minutes Reduced ISDN Minutes WAN Bandwidth Savings Access Bandwidth Savings Operations Savings

10. 80 384 Kbps Video (30 fps) “I” frame is a full sample of the video “P” and “B” frames use quantization via motion vectors and prediction algorithms “P” and “B” Frames 128–256 Bytes “I” Frame 1024–1518 Bytes “I” Frame 1024–1518 Bytes 15pps 30pps 600Kbps 32Kbps