Slide1: Distance Learning over ADSL Heinrich J. Stüttgen NEC Europe Ltd. Computer & Communication Research Laboratories Adenauerplatz 6, D 69115 Heidelberg - Germany Tel.: +49 6221 905110 Fax: +49 6221 9051155 Email: stuttgen@ccrle.nec.de


Content: Content NEC C&C Research Laboratories in Europe Internet Trends and Requirements Internet Application Trends Network Infrastructure Trends Requirements of Distance Learning SAMoA - A Server Architecture for Multicast in ATM/xDSL Networks Gateway Solution MC over PVC MC over SVC Outlook


NEC Corporation: NEC Corporation Nippon Electric Company established in 1899 worldwide: revenue of 40 Billion US$ 152 000 employees selling in 159 countries main product areas: computers and peripherals semiconductor devices telecommunication equipment


Worldwide Research in NEC: Worldwide Research in NEC CCRL Bonn CCRL Berlin CCRL Heidelberg NEC Res.Institute CCRL Princeton CCRL San Jose Central Res.Labs


Mode of Operation: Mode of Operation software architectures and prototypes for next generation communication services integrated research&development to reduce „time to market“ application requirement driven approach Networking Research architecture and prototypes network research partners Field Trials verify new technology in „real-live“ environments with user partners Multimedia Applications requirements demos application oriented partners


Computer & Communication Research Laboratories Berlin and Heidelberg: Computer & Communication Research Laboratories Berlin and Heidelberg Heidelberg CCRL focus: multimedia communication over broadband access networks based on Internet protocols first applications: Multimedia-Tele-Learning Internet Telephony Berlin CCRL focus: network & service management for multimedia services software technology (mobile agents) for management of telecommunication networks


Heidelberg Research Areas: Heidelberg Research Areas


CCRL-HD Structure: CCRL-HD Structure


Slide9: Internet Trends and Requirements


Internet Services & Applications: Today: Internet Services & Applications: Today Do you use ....? ... % answered “yes”


Internet Application Trends: Internet Application Trends Drivers Information seeking: hardware, software, books/magazines, travel, music on demand, job opportunities, investment choices Inhibitors connection speed remains most cited problem, download times for multimedia-data, bandwidth, 10,3% do have modems > 14,4 kbps lack of appropriate tools and technologies for multimedia group communication connection cost too high, i.e. charges for telephone and ISP (“always on paradigm”?) Trends mobility - access at any time, any where, to any kind integrated services, distributed cooperative work, conferencing Tele-commuting, Tele-teaching


Network Infrastructure Trends: Network Infrastructure Trends current access networks can not cope with growing IP-traffic! voice-band modems and ISDN do not provide enough bandwidth for advanced multimedia applications the trend goes towards broadband access technologies such as xDSL or HFC!


Slide13: Network Domains - A Provider View Customer Premises Regional Broadband Network Central Office ONU ONU Acces Node ONU: Optical Network Unit ATU: ADSL Termination Unit ISP Content Provider Corporate Network Internet Wide Area Network Multimedia Server Backbone ONU


Multimedia in Residential BB : Multimedia in Residential BB Background residential broadband access networks are currently being deployed technology of choice in Europe is on ATM/xDSL (vs. ATM/HFC) intended use is a „Full Service Access Network“ (FSAN) AND high-speed Internet access current ADSL/HFC usage is very restricted - mainly higher speed Internet access for existing applications existing applications may not justify the added cost Distance Learning over ADSL - Why? desirable as a home-service for professionals & consumers continuous education is of growing importance for professionals DL applications are under developments for the last 6-8 years DL combines most aspects of multimedia applications, in particular: Live and stored, QoS, groups, collaborative work,....


Distance Learning Evolution: Distance Learning Evolution MC Router MC Router Today Tomorrow MC Router MC Router ADSL-based Access Network Campus Campus Campus Home


Distance Learning Requirements: Distance Learning Requirements high quality audio/video distribution teacher to students isochronous unidirectional 384kbps - 1.4 Mbps educational video material from server asynchronous: unidirectional <= 1.4 Mbps) 1 to n (multicast) - semi-reliable student interactions A/V conferencing: isochronous with 64 - 128 kbps n to n, semi-reliable whiteboard/lecture board, including animations bursty data traffic: asynchronous with 64 - 128 kbps n to n, reliable, asymmetric on-line testing asynchronous with 64 - 128 kbps 1 to n reliable, asymmetric security


Distance Learning over ADSL Issues: Distance Learning over ADSL Issues Bandwith requirments of DL scenario can be satisfied by ADSL technology good integrated audio/video(QoS) support needed (rudimentary) DL applications exist (Mbone,....), but need to be adapted and integrated most components of a sophisticated distance learning scenario require multicasting semi-reliable datagram service for A/V streams reliable multicast for whiteboard, etc.... Not only 1 root to n leaves but also “leaf-to-leaf” solution needed for scalable, unreliable & reliable “leaf-to-leaf” IP multicast over ADSL


Server Architecture for Multicasting over ATM/xDSL: Server Architecture for Multicasting over ATM/xDSL A.Banch, T.Dietz, M.Gabrysch, B.Lange H.J.Stüttgen SAMoA -


Slide19: Introduction to IP-Multicasting IP- Unicast Host C Host B Host D Host U Host A


Slide20: Multicast in ATM based Access Networks IP-multicast was designed for shared medium LANs connected via fixed point-to-point WAN links Problem for non-broadcast networks such as ATM Different solutions were suggested to solve these problems (MARS/MCS, LANE,..) Which is the right solution for ATM/xDSL based networks?


Slide21: Requirements for IP-Multicast over ATM/xDSL Key aspects: Scalability (# of clients, # of groups) Support for dynamic joining and leaving Avoid broadcasting all multicast groups Accounting facilities Others: QoS Implementation effort Smooth PVC ---> SVC migration


Multicast over ATM/xDSL - Approaches: Multicast over ATM/xDSL - Approaches Short-term solution: Multicast Gateway PPP based approach (RAS-Replication) Mid-term solution: Multicast/Broadcast over PVC Long-term solution : MARS/MCS over SVC (RFC 2022)


Short-term Solution 1: Multicast Gateway: Short-term Solution 1: Multicast Gateway Idea server running an application at user space performing MC replication and forwarding according to clients requests. Advantages immediate solution easy implementation multicast, not broadcast Disadvantages ADSL client needs to install special software replication of packets at the application layer (inefficient!) not scalable in terms of number of clients


Short-term Solution 2: Multicast over PPP (I): Short-term Solution 2: Multicast over PPP (I) Customer Premises Regional Broadband Network CO ONU ONU ONU Central Office ONU Wide Area Network ONU RAS/ ISP Internet MC packets Access Node ONU PPP is used!


Multicast over PPP (II): Multicast over PPP (II) Advantages uses existing infrastructures (authentication, accounting) of ISPs PPP has been proposed as access protocol for ADSL networks easy implementation (MC-functionality has to be added to the RAS) real multicast, not broadcast Disadvantages replication of packets at network layer (less efficient as at ATM-level) inefficient use of backbone bandwidth not scalable with respect to number of clients MC-Packet Backbone Access Network RAS(Mrouter) or MC-Gateway Replication performed at the RAS/PPP MC-Gateway ! NSP network (e.g. Mbone) 3 streams in the backbone !


Desirable behavior of future solutions: Desirable behavior of future solutions RAS : Remote Access Server 1 stream in the backbone ! Backbone Access Network RAS (Mrouter) NSP network (e.g. Mbone) MC-Packet Replication performed in the access network Our approach: 1) Multicast over PVCs 2) Multicast over SVCs (MARS/MCS)


Slide27: Mid-term solution: Multicast over PVC (I) Address resolution: MARS Replication/Forwarding: MCS Pt2Pt PVC: Replication done at the network level Pt2mPt PVC to all hosts Replication done at the ATM level Broadcast Tradeoff between replication efficiency and efficient use of access bandwidth


Slide28: MRtr MARS MCS MRtr MARS MCS PP PVC PMP PVC Multicast over PVC (II)


Multicast over PVC (III): Multicast over PVC (III) Advantages can be used in parallel with PPP approach for unicast traffic real multicast flexibility (client has Pt-2-Pt, Pt-2-mPt PVC connection!) more efficient use of backbone bandwidth (MARS/MCS could be used in a SVC ATM backbone!) smooth transition to long-term MARS/MCS solution for SVCs replication of packets at ATM level (Pt-2-mPt option) Disadvantages replication of packets at network layer (multiple Pt-2-Pt option) complex implementation


Long-term Solution: MARS/MCS for SVCs: Long-term Solution: MARS/MCS for SVCs Access MC Router MARS MCS group membership information/updates from the MARS Each client has to be configured with the ATM address of the MARS Client sends join or leave messages to the MARS MARS updates MCS cache for group memberships MCS adds or deletes clients from the PMP SVC for the corresponding MC-group MC-data packets


MARS/MCS for SVCs: MARS/MCS for SVCs Advantages can be used in parallel with PPP approach for unicast traffic real multicast high scalability (in of # of users, groups, backbone bandwidth) most efficient use of backbone bandwidth replication of packets at ATM layer Disadvantages relies on SVC which are currently not available for ADSL based access networks complex implementation due to dynamic set-up of VCs signalling overhead


Comparison of the different approaches: Comparison of the different approaches


Planned Field-Trial: TeleTeaching over ADSL: Planned Field-Trial: TeleTeaching over ADSL Students Home Uni Mannheim University Backbone CO ONU ONU ONU MC Router CO ONU ONU 1 ATM X Switch 1 2 3? 24 1 24 1 24 : : : ATM Backbone of B-Win Aachen ONU


Conclusions and Outlook : Conclusions and Outlook Results IP-Multicast support in the access network is a key requirement for further deployment of broadband access technologies Different approaches possible: Multicast Gateway approach and MC over PPP: poor scalability (# of clients) - short-term solution Multicast over PVC performance below MARS/MCS/SVC - mid-term solution MARS/MCS/SVC - long-term solution Best performance and scalability Needs SVC capable backbone Open Issues Scalability issues of IP-Multicast over ATM/xDSL QoS in IP-Multicasting over ATM Multicast with mobile clients