A. MEDDAHI (TERENA Networking Conference 2001, ANTALYA, TURKEY 14~17 May)
1
MEDDAHI Ahmed (Ecole Nouvelle d Ingénieurs en Communication)
E.N.I.CCité Scientifique, rue G. Marconi
59658 Villeneuve d ’Ascq (France)
Tel: +33(0)3-20.33.55.62
Fax: +33(0)3-20.33.55.98
email: [email protected]
* this paper was supported by the European Commission through the VirTEPPE project
« Mobility issues in the context of
distance learning services »*
A. MEDDAHI (TERENA Networking Conference 2001, ANTALYA, TURKEY 14~17 May)
2
CONTENT
• Introduction
• A distance learning tool based on ISDN
• A distance learning tool based on Internet
• Mobility issues
• SIP for providing distance learning services
• Conclusion
A. MEDDAHI (TERENA Networking Conference 2001, ANTALYA, TURKEY 14~17 May)
3
Ecole Nouvelle d’Ingénieurs en CommunicationEcole Nouvelle d’Ingénieurs en Communication
New Communications Engineering InstituteNew Communications Engineering Institute
www.enic.frwww.enic.frwww.enic.frwww.enic.fr
Introduction
A. MEDDAHI (TERENA Networking Conference 2001, ANTALYA, TURKEY 14~17 May)
4
Introduction: Channels / ActivitiesIntroduction: Channels / Activities
• Training for Engineer Degree• Training for Engineer Degree
Initial trainingInitial trainingInitial trainingInitial training 5 years5 years5 years5 years 335 for 2000335 for 2000335 for 2000335 for 2000
““Adult” trainingAdult” training““Adult” trainingAdult” training18 18
months months minimini
18 18 months months
minimini200 for 2000200 for 2000200 for 2000200 for 2000
distant trainingdistant training (for Adult only) (for Adult only)distant trainingdistant training (for Adult only) (for Adult only) 3 years3 years3 years3 years 100 for 2000100 for 2000100 for 2000100 for 2000
• On-site Training On-site Training
• Research / DevelopmentResearch / Development
• Pedagogical EngineeringPedagogical Engineering
• On-site Training On-site Training
• Research / DevelopmentResearch / Development
• Pedagogical EngineeringPedagogical Engineering
On-site training
A. MEDDAHI (TERENA Networking Conference 2001, ANTALYA, TURKEY 14~17 May)
5
Tutelvisio® (a distance learning service based on ISDN)
• « Student » studio:
– Audio/video system (pan-tilt camera) controled by a specific software.
– « Question & Answer » system controled and managed by specific software and hardware.
• « Lecturer » studio:
– Audio/video system controled by a software.
– a « user friendly » GUI for managing the lecture (interactivity, audio and video sources...)
• Softwares and protocols for controling the system and for communication between remote and Local site.
A. MEDDAHI (TERENA Networking Conference 2001, ANTALYA, TURKEY 14~17 May)
6
Tutelvisio® architecture
*
ISDN
Internet
H320System 256 kbs
H320System
MCU
Audio system (microphones, speakers..)
video system(pan/tilt cam.Monitor..)
Audio system
video system
« user-friendly »Soft.Soft.
« Student » studio « Lecturer » studio
T2Audio
Video
Data
A. MEDDAHI (TERENA Networking Conference 2001, ANTALYA, TURKEY 14~17 May)
7
A distance learning application :
Visiocentre GUI A distance learning application :
Visiocentre GUI
A. MEDDAHI (TERENA Networking Conference 2001, ANTALYA, TURKEY 14~17 May)
8
Remarks
• Benefits:– good video/audio quality (CIF/G711) and performances
(throughput up to 768 Kbs) H320 QoS.
• drawbacks:– still some interoperability problems
– difficult to deploy for individual or self training services
– deployment cost
A. MEDDAHI (TERENA Networking Conference 2001, ANTALYA, TURKEY 14~17 May)
9
Tutelnet® (a distance learning tool based on Internet)
*
Internet
Web server (Html+Smil)
(Asynchronous web courses)
Streaming server(live or stored Audio/Video sources)
MCU
Client(lecturer)
Client (student)
« TutelServer® »
A. MEDDAHI (TERENA Networking Conference 2001, ANTALYA, TURKEY 14~17 May)
10
Tutelnet® (components) • WEB SERVER (HTML+SMIL):
– contains Enic web courses for Asynchronous lectures (« Lecture On Demand »)
• STREAMING SERVER:
– stored audio/video lectures for Asynchronous lectures (working with the web server)
– live audio/video lectures for Synchronous lectures
• MCU :
– multipoint videoconferencing for Synchronous lectures
• « TutelSERVER » :
– specific multi-unicast software (JAVA) with enhanced services for Synchronous lectures (live « data » conferencing)
A. MEDDAHI (TERENA Networking Conference 2001, ANTALYA, TURKEY 14~17 May)
11
Components (continue)
• CLIENT:
– client software (student) for accessing to « live » or « stored » lectures
– client software (lecturer) for providing and managing live lectures
» web browser
» streaming client
» H323 client» specific client (tutelbrowser®/tutelcast®)
A. MEDDAHI (TERENA Networking Conference 2001, ANTALYA, TURKEY 14~17 May)
12
Tutelcast® GUI (teacher point of view)
A. MEDDAHI (TERENA Networking Conference 2001, ANTALYA, TURKEY 14~17 May)
13
Tutelbrowser® GUI (student point of view)
A. MEDDAHI (TERENA Networking Conference 2001, ANTALYA, TURKEY 14~17 May)
14
G.U.I (for Voice/Video/Data integration)
A. MEDDAHI (TERENA Networking Conference 2001, ANTALYA, TURKEY 14~17 May)
15
Architecture (tutelnet®/tutelvisio®)
Internet
« CLIENT »(lecturer)
« CLIENT» (student)
ISDN
H320System
256 kbs
H320System
MCUH320
H323/H320Gateway
+GateKeeper
A. MEDDAHI (TERENA Networking Conference 2001, ANTALYA, TURKEY 14~17 May)
16
Remarks
• Still some issues concerning interoperability (H323 systems).
• Strong issues concerning H323 through fire wall( open all UDP and TCP ports >1024).
• Heterogeneity in the access (Adsl, V90 modem, low bit rate modem, …)
• Today « our » Internet is not enough performant for supporting applications requiring interactivity
» pstn access and phone for voice interactivity
» internet only for data conferencing
» streaming server for providing a « picture » of the lecturer
• Problem of servers load need « load sharing/balancing » between multiple servers and install the servers close to the client location.
• Ip address (clients) are dynamic and change very often.
• Control access is needed.
A. MEDDAHI (TERENA Networking Conference 2001, ANTALYA, TURKEY 14~17 May)
17
Mobility in the context of distance learning
• Lecturers may be in their office, lab or « outside », they want to be able to give their lectures from « anywhere »
• Students may be located at school, at home or at job office, they want to be able to access to live lectures or to a « Lecture on Demand » server
• Location of servers and content may change.
• Generaly outside university they have dynamic Ip adress from their ISP (DHCP)
• Ip address translation may occur through NAT.
A. MEDDAHI (TERENA Networking Conference 2001, ANTALYA, TURKEY 14~17 May)
18
SIP Protocol
• A good mean for dynamic ip address and clients mobility issues.
• Fields in SIP headers and « SDP » message body can provide a solution to describe the type of service the client wants to access
» type of lecture and its identifier
» start time
» duration
» ...
• Provide enhanced services
» forking, call forward...
• Can be used independantly of the media stream transfert protocol.
A. MEDDAHI (TERENA Networking Conference 2001, ANTALYA, TURKEY 14~17 May)
19
SIP Protocol (continue)
• RFC 2543 of the IETF MMUSIC Working Group.
• Signaling and call control protocol.
• Text oriented protocol (like Http, Smtp).
• Client/Server oriented protocol.
• Message strucure:» 1 START LINE
» 2 HEADERS
» 3 BLANK LINE
» 4 MESSAGE BODY
A. MEDDAHI (TERENA Networking Conference 2001, ANTALYA, TURKEY 14~17 May)
20
Architecture for Sip (two new servers)
*
Internet
Registar serverdatabase
Sip proxy+
redirect server+
tutelServer®
client
A. MEDDAHI (TERENA Networking Conference 2001, ANTALYA, TURKEY 14~17 May)
21
Different scenarios for distance learning services
Scenario 1: access to a live/asynchronous lecture*
Registar serverdatabase (registar.enic.com)
Sip proxy.enic.fr+
redirect server+
tutelServer®
database request(III) response(IV)
Multi-unicast invite(V)
(VI) data stream
« a45live »@IP1@IP2@IP3@IPn
@IP2@IP3 @IPn
Clients@IP1
REGISTER sip:registar.enic.fr SIP/2.0…subject=...content-type:application/sdp…v=0o=« lecturer ’s name paul »s=« module n° a45live »t=« 2 h »….
(I)
INVITE sip:a45live.enic.fr SIP/2.0…….
(II)
A. MEDDAHI (TERENA Networking Conference 2001, ANTALYA, TURKEY 14~17 May)
22
Different scenarios for distance learning (cont.)
Scenario 2: access to a stored/Asynchronous lecture(Lecture On Demand)
Sip proxy+
redirect server+
tutelServer®
Redirect server database
INVITE sip:a45stored.enic.fr sip/2.0…content-type:application/sdp..O=P=0146532655...
302 movedcontact: <sip:server2.paris.fr>expires: 3600content-type:application/sdp..i=« Login/Pwd »...
« smart load balancing » between servers and access control
A. MEDDAHI (TERENA Networking Conference 2001, ANTALYA, TURKEY 14~17 May)
23
Different scenarios for distance learning (cont.)
Scenario 3: « access » to the lecturer at a clearly defined time (« tutorat »)*
Registar server
Sip proxy+
redirect
INVITE sip:a45tut.enic.fr Fork the request to all possible location
INVITE sip:[email protected]
INVITE sip:[email protected]
INVITE sip:[email protected]
« client »student
A. MEDDAHI (TERENA Networking Conference 2001, ANTALYA, TURKEY 14~17 May)
24
Conclusion
– SIP is not the only alternative H323, Megaco/h248 ...
– Etablishment of users connections goes through sip proxy (it is not mandatory), provides some means for:• acces control• Log/Statistics
– SIP is a « stand alone » protocole so it ’s possible to use it with any other media transfert protocols ( data transfert will be the first step, afterwards audio)
– Minimal configuration is required from the client side.
– Text oriented protocol facilitate understanding and implementation
– Cohabitation and interworking with other signaling protocols (H323,H248…)?
– This solution has to be fully validated.