Henning Schulzrinne Dept. of Computer Science Columbia University New York, New York

Transcription

1 IRT lab 1 Henning Schulzrinne Dept. of Computer Science Columbia University New York, New York schulzrinne@cs.columbia.edu April 25, 1999

2 IRT lab 2 IRT Members: Full-Time PhD Students Student CU IRT research topic Jonathan Lennox F1994 S1997 call processing language Wenyu Jiang F1995 F1998 Internet QOS measurements Xin Wang F1996 F1996 multicast, QOS, pricing Maria Papadopouli F1996 F1997 ad-hoc networks Fatima Al-Garawi F1997 F1997 distance learning Weibin Zhao F1997 F1997 directory services April 25, 1999

3 IRT lab 3 IRT Members: Part-Time PhD students Student employer research topic Lisa Amini IBM video on demand Mandis Beigi IBM resource reservation Ethen. Bommaiah Bell Labs media on demand Ashutosh Dutta Telcordia MarconiNet Christopher Kang Bell Atlantic signaling translation Santosh Krishnan Bell Labs scheduling, QOS Ping Pan Bell Labs resource reservation Jonathan Rosenberg Bell Labs Internet telephony April 25, 1999

4 IRT lab 4 IRT Members: Masters Students and Visitors Gautam Nair 1999 Internet telephony Xiaotao Wu SIP implementation Jianqi Yin BUPT, Beijing Internet telephony Elin Wedlund Ericsson, Sweden mobility Tony Eyers U. Wollongong 1999 signaling performance April 25, 1999

5 IRT lab 5 Research Topics network infrastructure scalable resource reservation protocols QOS measurements and management adaptive services and pricing Internet telephony (VoIP) signaling: SIP, translation to ISUP/H.323/MGCP VoIP services and service creation e*phone applications civil society computing Internet TV and radio distance learning April 25, 1999

6 IRT lab 6 QoS Measurement and Management packet delay and loss characteristics in the Internet inter-domain QoS Monitoring and fault location study of user behavior in IP telephony Wenyu Jiang April 25, 1999

7 IRT lab 7 One-way End-to-End Packet Delay Measurement Measurement without clock synchronization: cannot precisely measure absolute value of delay but sufficient for analyzing delay variation (jitter) need to compensate for clock drift for long measurements Combining traditional telephone network and IP network: reasonably precise in measuring absolute value of delay requires special telephone-audio converters Using GPS as globally synchronized time source: best precision but requires special (expensive) GPS equipment Wenyu Jiang April 25, 1999

8 IRT lab 8 Modeling Packet Delay and Loss Correlation packet losses are correlated; can be described with n-state Gilbert model delay and loss are correlated: P[d_n>a] P[d_n>a d_n-1>a] probability delay (sec) Wenyu Jiang April 25, 1999

9 IRT lab 9 Prediction of User-Perceived Quality short-term QoS statistics such as loss rate are essential to quality prediction. first-order statistics such as average loss rate do not capture user-perceived quality: e.g., burst losses vs. random losses FEC or low bit-rate redundancy, coupled with error concealment, further improves (and complicates) measure of user-perceived quality. signaling performance also needed Wenyu Jiang April 25, 1999

10 IRT lab 10 Inter-Domain QoS Monitoring and Fault Location SNMP statistics provide per-host information difficult to pinpoint the source of trouble in a large network use (extended) RTCP statistics for e2e quality monitoring hierarchy of monitoring stations aggregate across multimedia sessions Wenyu Jiang April 25, 1999

11 IRT lab 11 User Behavior in IP Telephony will user behavior change from PSTN to IP Telephony? call attempt and retries? speech s on-off pattern feature usage: time-of-day forwarding, filtering, voice/ ,... user trade-offs: quality vs. cost test bed at Columbia University planned Wenyu Jiang April 25, 1999

12 IRT lab 12 Pricing Adaptive Multimedia Services pricing schemes that consider the holding cost, usage cost, and congestion cost as well as supports differential quality and advance reservation in the Internet. develop a network infrastructure that supports dynamic resource negotiation and pricing across Internet domains and users RNAP Xin Wang April 25, 1999

13 IRT lab 13 S2 S1 RNAP Architecture HRN NRN NRN NRN B HRN B2 B B3 B B1 B7 Access Network RNAP messages Intra-domain Messages B4 B5 Transit Network Access Network HRN 00 11R2 HRN 00 11R1 S1 HRN B3 B B B1 B2 B5 Access Network Transit Network Access Network B6 HRN R1 RNAP messages Xin Wang April 25, 1999

14 IRT lab 14 Adaptive Multimedia Services design an incentive-compatible adaptation framework that optimizes user satisfication and network revenue, minimizes connection rejections. cross-media adaptation scheme to optimize system wide performance; designing test methods for user utility functions for different tasks Audio MNA Video MNA WhiteBoard MNA ISC Reservation Agent HRN RNB RNAP NRN Internet Xin Wang April 25, 1999

15 IRT lab 15 IP Multicast and Network Reliability performance analysis of different multicast protocols (DVMRP, MOSPF, CBT, PIM-DM, PIM-SM) failure tests of routing protocols PIM-DM and PIM-SM implementation of multicast protocols (PIM-DM, PIM-SM) in Opnet environment. Xin Wang April 25, 1999

16 IRT lab 16 Internet Telephony SIP development: developing the SIP specification and various extensions for supporting IP telephony: call control, QoS, and PSTN interoperation. SIP implementation: implementing a SIP server: full proxy, redirect, and registrar, with support for policy, and programmability. IP telephony service creation: SIP CGI for service creation; implement Call Processing Language (CPL) Jonathan Rosenberg April 25, 1999

17 IRT lab 17 Internet Telephony FEC: integration of FEC and adaptive playout buffer algorithms. RTP: sampling algorithms for group membership tables in RTP; conformance tests for verifying RTCP implementation correctness. Presence: protocols and architectures (based on SIP) for presence and instant messaging. Jonathan Rosenberg April 25, 1999

18 IRT lab 18 Integrating packet FEC into adaptive voice playout buffers playout buffer: trade loss ( %) for delay ( ms) sender receiver (n, k) FEC: add n k additional packets for total of n 0.25 Exp-avg Optimal Trace Trace Application Loss Rate Average Playout Delay Network Loss Rate 0.02 Exp-avg Optimal Network Loss Rate Jonathan Rosenberg April 25, 1999

19 IRT lab 19 FEC: Virtual Delay virtual delay = min(arrival, recovery) departure playout delay α σ if loss < target loss, α α + δ recover lost and late packets 20% loss: application loss/5, delay * 2 Jonathan Rosenberg April 25, 1999

20 IRT lab 20 Application Loss Rate Exp-avg Exp-avg Ext Exp-avg vs. Its Extension Network Loss Rate Average Playout Delay (sec) Exp-avg vs. Its Extension 0.02 Exp-avg 0 Exp-avg Ext Network Loss Rate Application Loss Rate Spk-det Spk-det Ext Spk-det vs. Its Extension Network Loss Rate Average Playout Delay (sec) Spk-det vs. Its Extension Spk-det Spk-det Ext Network Loss Rate Application Loss Rate Window Window Ext Window vs. Its Extension Network Loss Rate Average Playout Delay (sec) Window vs. Its Extension Window Window Ext Network Loss Rate Jonathan Rosenberg April 25, 1999

21 IRT lab 21 New Playout Algorithm: Delayed Optimal after talkspurt, one knows optimal delay use optimal combination for next talkspurt D i = αd i 1 +(1 α)d opt user perception function: minimal delay that achieves loss target Jonathan Rosenberg April 25, 1999

22 IRT lab 22 New Playout Algorithm: Analytical assume independent loss p, delayed randomly d compute playout probability tabulate delay distribution histogram at end of talkspurt, find matching playout delay for target loss rate Jonathan Rosenberg April 25, 1999

23 IRT lab 23 Call Processing Language for Internet Telephony enable Internet telephony features: call forwarding user location call filtering and many other features... let users control and customize features help from provider not needed simple, safe scripting language Jonathan Lennox April 25, 1999

24 IRT lab 24 Call String-switch field: from match: otherwise Call Processing Language location url: example.com location url: voic . example.com merge: clear proxy timeout: 10s redirect busy timeout failure no loops or variables safe execution easily created in graphical environment XML-based easy to parse Jonathan Lennox April 25, 1999

25 IRT lab 25 RTP and SIP Implementations Columbia/Elemedia RTP library Columbia SIP proxy/redirect/registration server sipd user registration forking proxy capability: one call, many destinations sip-cgi: interface to scripting languages security mechanisms for authentication caller preferences RTP and SIP Implementations April 25, 1999

26 IRT lab 26 E*phone: An Internet Phone Appliance phone = $49.99; PC > $600 (GPF included) Ethernet phone no PBX for switching DSP for voice coding limited memory (512 kb SRAM!) minimal real-time OS (threads, signals) implemented minimal IP stack (IP/UDP/RTP, DHCP, SIP) no TCP, no DNS MP3 radio? interface to the real world: alarms, measurements,... Jianqi Yin April 25, 1999

27 IRT lab 27 Jianqi Yin April 25, 1999

28 IRT lab 28 VoIP Signaling Translation and Gateways H.323 Decoder identify the packets that contain signaling informations in Q.931, H and H.245; decode the signaling packets coded in Packed Encoding Rules (PER) X.691 Christopher Kang April 25, 1999

29 IRT lab 29 SIP, ISUP and H.323 Gateways SIP H.323 gateway: 1. identify SIP requests and headers for H.323 signaling messages; 2. develop of SIP in-call control messages if necessary; 3. build SIP H.323 gateway SS7 SIP gateway: ISUP-to-SIP handoff & SIP bridging map SIP requests SS7 ISDN User Part (ISUP) implement prototype gateway Christopher Kang April 25, 1999

30 IRT lab 30 Social Mobile Computing provision of multimedia applications to mobile wireless users: ad-hoc mobile networks combining different wireless technologies; collaborative multimedia applications: teleconferencing, web browsing, sharing notes, multicast discussion anticipatory caching and prefetching Maria Papadopouli April 25, 1999

31 IRT lab 31 Ad-hoc Wireless Networks Users wish to collaborate by creating a wireless network on the spot, dynamically teleconferencing, news on demand, e-white boards, Current wireless deployment: limited wireless network access to global network, intermittent connectivity, low bit rates, and high end-to-end delays better utilization of the user s local resources to achieve higher data availability and QoS. Maria Papadopouli April 25, 1999

32 IRT lab 32 Resource Sharing of Collaborating Hosts in Wireless Adhoc Network Fixed Cache Wireless WAN Base Station Global Network WAN Home Network G D Base Station Resources: local cache, network connection E A B C F Ad Hoc Network: hosts A,B,C,D,E,F,G Temporal Gateways: (dual home hosts) A,B,E Maria Papadopouli April 25, 1999

33 IRT lab 33 Motivations for Resource Sharing reduction in the transmission of replicated data that belong to shared (collaborative) applications. utilization of temporarily idle connections increase QoS for the shared-data applications financial benefits (e.g., resource renting, bandwidth co-op ) Maria Papadopouli April 25, 1999

34 IRT lab 34 Connection Sharing of Collaborating Hosts in Wireless Adhoc Network Fixed Cache Wireless WAN Base Station Global Network WAN Home Network G D Base Station E (1) (3) A B C F (4) (2) E will act as gateway for f multicast availability as gateways for G (bw, drop. pkt rates) select gateway for f (e.g., host E) multicast request for accessing Internet for flow f Maria Papadopouli April 25, 1999

35 IRT lab 35 Design Properties for the Resource Sharing Protocol sharing takes place on the spot, dynamically lightweight protocol (low complexity and overhead) reduction of the replicated data that users are interested in viewing host selects host-gateway for a flow based on the gateway s bandwidth availability and packet loss rates simply select least loaded gateway load balancing lightweight and secure micro-payment method needed need security and privacy for different types of collaboration Maria Papadopouli April 25, 1999

36 IRT lab 36 Multimedia on Demand Servers heterogeneous network environment admission control, scheduling and QoS guarantees server fault-tolerance and reliability issues storage issues: memory hierarchy and data layout Maria Papadopouli April 25, 1999

37 IRT lab 37 MarconiNet Internet Radio & TV large and small audiences services: automatic insertion of local contents, advertising, media-on-demand services, switching between global and local program anybody can be a potential broadcaster access to any station in the world support for heterogeneous receivers in the local domain pricing structure for the network affiliates hardware dedicated to Internet radio/tv? Ashutosh Dutta April 25, 1999

38 IRT lab 38 MarconiNet hierarchically scoped multicast for scalability components: primary station, local station, Internet clients RTCP to trigger automatic insertion of local contents, commercials RTSP server for media-on-demand application popularity-based spectrum management for bandwidth control extension of SAP/SDR to provide scalable directory structure novel program management at the local station secured distribution of paid programming Java-based user interface Ashutosh Dutta April 25, 1999

39 IRT lab 39 Other Research session control architecture for the next-generation network IP/PPP/SONET, IP/ATM/SONET and IP/WDM issues power management for low-earth orbit satellites under bursty broadband traffic Ashutosh Dutta April 25, 1999

40 IRT lab 40 Interactive Distance Learning CLIC lab + classroom: 40 workstations analog TV production facilities: remote-control cameras, video mixers, wireless microphones,... designed for off-site participation experimented with existing video-conferencing tools (vic/vat, rendezvous, IP/TV) integrate to view lectures off-line participate during class minimal post-processing of lectures cross-platform support variety of networks: modem, ADSL, Internet2 Fatima Al-Garawi April 25, 1999

41 IRT lab 41 Distance Learning develop system to integrate video, slides, web pages and electronic whiteboard: capturing of video, slides and whiteboard; synchronizing audio and video with slides; annotation; interface to electronic whiteboard. query mechanism: off-campus students interact in real time with instructor. Fatima Al-Garawi April 25, 1999

42 IRT lab 42 Service Location Replicated Server Placement measure network distance, bandwidth, delay use BGP4 to collect network distance metric (hop counts) combine distance metric with DNS for replicated server selection Weibin Zhao April 25, 1999

43 IRT lab 43 Project MarketNet (DARPA) use pricing for access and resource control need price advertising and real-time updating location or path-dependent service pricing scheme Service Location Protocol: given service name and some attributes description, provide related servers location local area network service location discovery wide area network service location discovery implementation for SLPv2 completed Weibin Zhao April 25, 1999