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On the Enhancement of QoE for IPTV Services through Knowledge Plane Development. Edith Gilon Kris Struyve Tom Van Caenegem. Bart De Vleeschauwer Wim Van de Meerssche Pieter Simoens Filip De Turck Bart Dhoedt Piet Demeester. Overview. Access network challenges
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On the Enhancement of QoE for IPTV Services through Knowledge Plane Development Edith Gilon Kris Struyve Tom Van Caenegem Bart De Vleeschauwer Wim Van de Meerssche Pieter Simoens Filip De Turck Bart Dhoedt Piet Demeester
Overview • Access network challenges • Monitoring Plane & Knowledge Plane • Monitoring in the home network
Access Network Overview Access Network Home Network Access Node Residential Gateway Service Providers Service Edge End Device User
Services & Challenge • Classic best-effort internet services: • Web Surfing, E-mail, File Transfer, … • New services: • VOIP, Broadcast IPTV, Video on Demand, Gaming • Higher Requirements: • Interactivity, Media quality, Zapping Time, Setup Time, Synced Sound, Artifact-free Video • Need for guaranteed Quality of Experience =how the user experiences the service • Influenced by network jitter, delay and loss How can we detect & automatically solve QoE degradation?
Overview • Access network challenges • Monitoring Plane & Knowledge Plane • Monitoring in the home network
QoE decrease detected root cause analysis restorative action MP/KP: Architecture Knowledge Plane Monitor Plane Monitoring data sources
Monitor Plane • Logical layer containing all monitoring tools: • SNMP: • Read & write device parameters • Set traps • IPFIX (or netflow): • Flow statistics • TR-069 • Residential gateway configuration & monitoring • …
Knowledge plane Overview Knowledge Plane Additional info might be needed for accurate fault recovery Diagnosis and Solution Initialize new anomaly detection modules Additional queries over available data Initiate new monitor probes Solution Execution Anomaly Detection Anomaly is detected Solve Problem Monitoring Plane Continuous monitoring e.g. FEC, interleaving, local retransmission, device reconfiguration, warn end-user or network management, … Data Reduction Active: e.g. generate additional ICMP ping requests Passive: e.g. additional threshold in RMON MIB
QoE decrease detected root cause analysis restorative action MP/KP: Example Knowledge Plane Cause known: ADSL-line loss Monitor Plane Loss Detected Loss in Home Network ADSL-line Statistics: loss detected Add FEC to stream
Overview • Access network challenges • Monitoring Plane & Knowledge Plane • Monitoring in the home network
Home Network Monitoring ? Loss, RTT and Jitter monitoring How to monitor? • Limited or no knowledge & control of end-devices • Active monitoring • Passive monitoring From the Access Node
Active Monitoring • Dedicated software • Assumes control of end-devices and end-device software by access network • ICMP-based • Each IP device should support “ping” • Can measure RTT, jitter and loss • Problem: • Firewall • Might be handled differently than other traffic • Large Loss detection overhead! • To detect a packet loss ratio p, you need 10/p packets • Active monitoring isn’t very useful
Passive Monitoring • From in the access network, monitor packets from and to the home network • Use service specific algorithms to derive home network parameters • Use cases: • Broadcast TV using RTP/RTCP • VoD using TCP
RTP/RTCP monitoring • Overview: • RTP/RTCP basics • Jitter Monitoring • Loss Monitoring RTP RTCP Sender Reports RTCP Receiver Reports
RTP/RTCP • RFC 3550: RTP: A Transport Protocol for Real-Time Applications • Two protocols • RTP protocol for data packets • RTCP protocol for control traffic • RTP packets contain data • Sequence number • Timestamps (Sampling instant of first octet in the RTP data packet) • RTCP packets contain control & feedback information
RTCP Messages • SDES, source description items • BYE, end of participation • APP, application specific • SR, Sender Report • RR, Receiver Report ReportBlock
RTP/RTCP loss estimation • Receiver report: • Same calculations can be done on AN,by looking at RTP stream Fraction lost since last RR # Expected - # Received Loss
Access node home network loss detection Access Network Home Network Receiver Reports (loss=A) Calculate: A - B RTP Monitoring on AN (loss=B)
RTP/RTCP interarrival Jitter estimation • Interarrival jitter: variance in interarrival time Sj Si Sk Server Aj Access Node (AN) Ai Ak time Ri Rj End-Device Rk • End-to-end jitter is reported in RR • Do analogous calculations on RTP at AN to determine Server – AN jitter • Compare end-to-end jitter (RR) and Server-AN jitter
TCP monitoring • Overview: • TCP basics • RTT & Jitter Monitoring • Loss Monitoring • Our algorithm: ANTMA TCP
DP 1 ACK 1 TCP: Basics Monitoring Point Receiver Sender A1 1
DP 1 DP 1 ACK 1 TCP: Loss Monitoring Point Receiver Sender Time-out! 1 A1 1
DP 1 DP 2 ACK 1 ACK 2 TCP: Flights Monitoring Point Receiver Sender 2 A1 1 A2
DP 1 ACK 1 TCP Middle Monitoring: RTT & Jitter in home network • RTT is time between seeing a data packet, and seeing its matching ACK • “RTT Jitter” can be derived from RTT • Finding matching ACK is hard when loss & jitter occur: 1 2 3 4 A1 A1 2 3 4 A1 A4 A4 A4 Need smart matching for jitter detection!
TCP Middle Monitoring: Loss in Home Network • Counting retransmissions • Unreliable, as jitter can cause retransmissions • Tests on the internet show difference with loss can be very high • “Smart” counting retransmissions • Assume multiple losses in row are jitter, and ignore them • Bursty loss is seen as jitter!
TCP Middle Monitoring: ANTMA • ANTMA = “Access Network TCP Monitoring Algorithm” • What? • Loss, RTT & Jitter estimations • Measure each TCP connection separately • Monitor only home network part of connection • How? • Passive monitoring of packets on AN (or RGW) • History is evaluated by various rules • Packets are matched with their ACK
DP 1 DP 2 DP 3 DP 4 DP 5 DP 6 ACK 2 ACK 1 ACK 3 ACK 3 ACK 3 TCP Middle Monitoring: ANTMA Example 1 2 3 A1 A2 A3 4 5 6 A3 A3 MP LOST History: 1 2 3 A1 A2 A3 4 5 6 A3 A3 Can match: 1,3 2 3 5,6 6
Conclusion • Monitoring Plane • Monitoring in Acces Network • Monitoring in Home Network • RTP/RTCP • TCP • Knowledge Plane • Detect & Solve QoEdegradations