ANGKOR: A Real-time Remote Classroom on Research and Education Networks◆招待論文◆ANGKOR:A Real-time Remote Classroom on
Research and Education Networks
ANGKOR : 学術研究ネットワークにおける
リアルタイム遠隔教室
Kanchana Kanchanasut
Professor, Computer Science, School of Engineering and Technology
Director, Internet Education and Research Laboratory (IntERLab), Asian Institute of Technology
カンチャナ カンチャナスット
アジア工科大学工学部教授、IntERLab 所長

Jean-François Bertholon
Professor, Faculté de Médecine, Université Pierre et Marie Curie, Paris 6
ジャン・フランソワ ベートロン
ピエール＆マリー・キュリー大学（パリ第６大学）医学部教授

Jean-François Vibert
Professor, Faculté de Médecine, Université Pierre et Marie Curie, Paris 6
ジャン・フランソワ ヴィベー
ピエール＆マリー・キュリー大学（パリ第６大学）医学部教授

In this paper, we describe our experiences from a collaborative project, called ANGKOR. We
conducted real-life experiments on setting up remote teaching and learning in medical sciences, which
comprises of rich media contents with mandatory interactive sessions. Remote teaching experiments
were conducted from the School of Medicine, University of Pierre et Marie Curie (UPMC) in France
to the University of Health Sciences in Cambodia (UHSC). The network being used for the project
poses a real technical challenge, where a combination of very high speed connectivity from France toJapan with relatively low speed satellite Internet from Japan to Cambodia. Rich multimedia content
for medical lessons is sent using digital video transport system, or DVTS, from UPMC. Three maintechnical contributions from this project include the use of IP multicast in heterogeneous environment;
the real-time media stream frame reductions and the provisions for mobile classrooms. Based upon our
experimental results from this project, we propose a framework for a remote classroom system overheterogeneous network environment.
本稿では、ANGKOR プロジェクトにおける成果を解説する。本プロジェクトでは、リッチメディ
アと双方向のインタラクティブセッションを用いて、遠隔地からの医学教育を実施した。この遠隔医学教育実験は、フランスの University of Pierre et Marie Curie (UPMC) 医学部と、カンボジアの the University of Health Sciences in Cambodia (UHSC) の間で行った。この実験では、利超広帯
域回線と狭帯域回線を通してビデオ画像を送信するという技術的な試みを行った。フランス〜日
本間は超広帯域回線を、日本〜カンボジア間は衛星を用いた狭帯域回線を利用し、医学教育用リッチメディアコンテンツを DVTS を用いて送信した。また、様々な受講環境における IP マルチキャ
ストの利用、リアルタイムなビデオフレーム数間引き技術を用いた狭帯域ネットワークへのスト
リーム配信、携帯端末を用いた移動教室環境の整備といった点について、技術的検証を行った。
本プロジェクトによる実験の結果、様々な受講環境下での遠隔教育環境構築の手法を提案できた。
Keywords: Medical education, Real-time classroom, IPv6, IP multicast, VDO streaming

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1 Introduction

classrooms over long distance network using IP

A request from the University of Healthmulticast, problems encountered and experiences.

Sciences Cambodia (UHSC) was made through the

As an outcome from the project a real-time distant

University Pierre et Marie Curie (UPMC)’s Officeclassroom model is being proposed in Section 4of International Affairs to develop distance teaching

to maintain sufficient IP multicast deployment for

during the first, second and third medical cycles

efficiency while a mixture of multicast and unicast

on some subjects of medical education that are notas well as IPv4 and IPv6 can be adopted to reducecovered locally at UHSC. UHSC is the only French

deployment complexity. Section 5 surveys somespeaking medical university in Cambodia, a country

related works, and Section 6 contains a summary andurgently in need of qualified medical manpower, thus

discussion.

their request was given a serious consideration by
UPMC; a feasible technical and economical solution
made by some faculty members in the UPMC School

2 ANGKOR: a next generation Internet
for remote medical science classroom
projectof Medicine who have to travel long distances at high

The ANGKOR Project (or Next Generation

costs to deliver lectures in overseas French speaking

Internet for Remote Medical Science Classroom)

institutions.

is a collaboration led by the Faculty of Medicine of

had to be sought out. A similar request was also

Medical science distance education provides

the University Pierre et Marie Curie (FMPMC),

students with specialized education not available

France, and the Asian Institute of Technology (AIT),in their own schools, which as up to now, been

Thailand, funded in part by ICT-Asia project ofprovided by foreign specialists who need to travel

the French Ministry of Foreign Affairs. It involves

to provide the courses consuming both time andactive participations and support of several research

travel expenses. In response to the requests for longand education networks, namely, RAP (Réseau

distance education above, the ANGKOR Project

Académique Parisien), Renater (Réseau National

was launched as a collaborative research project, tode pour la Technologie l’Enseignement et laexperiment on the deployment aspects of IP multicast

Recherche)1*, GEANT2 2*,TEIN2 3*, APAN-JP 4*,and thefor real-time classrooms. The project was set up

Asian Interconnection Initiative, or AI 3, satellite test

to explore the technical as well as the educational

bed5* of the WIDE Project, Japan. Other members

issues raised by the use of the Internet for educationof the ANGKOR Project include the School onover a long distance in real-time with interactions.

Internet Asia (SOI Asia)6*, which conducts real-time

Its long term objective or ultimate aim is to be ableclassrooms in many countries in Southeast Asia. SOI-

to share ongoing classes being offered at UPMC on

Asia lectures are delivered over the satellite Internet

local high speed network with those students withtest bed run by the AI 3 Project whose coverage

low speed network at remote sites, such as at UHSC,

reaches UHSC, providing 13 Mbps unidirectional

simultaneously using IP multicast.

downlink.

T h e p a p e r i s o r g a n i z e d w i t h t h e p r oject

The ANGKOR Project has been applying highdescription of the ANGKOR in Section 2 with aquality digital video transmission using the Digital

discussion of its design considerations and theVideo Transport System (DVTS) [6] and VClass

conceptual framework. Section 3 describes the

E-Education Platform7* developed by AIT to broadcast

experiments of this project in setting up real-time

lectures with interactive sessions from FMPMC Paris

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ANGKOR: A Real-time Remote Classroom on Research and Education Networks

6 and UHSC. The main tasks in this project are tocooperative and are more prepared to co-ordinate

develop and test some means to distribute lectures

than the normal commercial Internet Service

from a distance over the next generation Internet

Providers (ISPs). Deployment of IP multicast by(IPv6, multimedia and mobile or wireless Internet).

commercial ISP’s has not been common because IP

Next we will explain the design and implementation

multicast is resource intensive on the network, allof ANGKOR classrooms, starting with the require-routers must be supporting IP multicast for nativements.

IP multicast and more importantly inter-ISP coordination is required. However, on research andeducation networks, IP multicast is expected to be

2.1 Distance medical classrooms requirements
Typical medical teaching and learning includes

one of the standard services offered.

rich multimedia contents with interactive sessions(b) Video Streaming.

Since our main focus iswith high quality video and audio, thus we need toin the field of medicine, where distance learning is

consider the following requirements:

becoming increasingly important, high quality video
streams should flow seamlessly with as little delay

We assume that ouras possible. The current techniques of broadcasting

long distance classroom is intended to bring lectureson the Internet are generally sufficient for traditionalfrom France with rich networks to developing

lectures but it cannot handle the delivery of highcountries with limited bandwidth and connectivity.

quality video images needed for broadcasting

Ultimately, medical lectures from the lecture rooms

medical lectures with detailed images from radiology,

should be shareable, at the same time, among local

scanner, histology, anatomical pathology and frommedical schools and by those at the remote sites.

surgical demonstration. For medical education, theWith this assumption, we have to deal with drasticallyuse of Digital Video (DV) format [1] or even higher

different network scenarios upon which our distancequality video stream has thus become essential.

teaching and learning is expected to operate and is

The Digital Video Transport System (DVTS) can

expected to reach as many classes around the world

accommodate these requirements while providing

as possible simultaneously.

full NTSC/PAL quality without encoding delay using(a) Communication Model.

The choice of multicast, or one-to-many communi-

bandwidth up to 33 Mbps with 30 frames per second.

cation model, became obvious as opposed to unicast

DVTS is an IETF standard protocol (IETF RFC 1394)

in order to reach a large number of remote classes

that allows sending a DV stream over the Internetor receivers with better bandwidth utilization. For

directly from standard digital video cameras. Thereeffective teaching and learning over very longare open source implementations of DVTS available

distances, we have to be concerned over minimizing

for both Windows and Linux.

delay, packet loss and jitters of bandwidth greedy[3]

lecture streams, thus IP multicast

DVTS is an attractive choice; as it does notwith multicast

require special equipments, except a commerciallyrouting are handled by the routers fairs better thanavailable DV video camera connected to a PC withapplication layer multicast (ALM)[2].

an IEEE1394 interface. It has been commonly used
for telemedicine [7] where images from an operating

Our solution is therefore to adopt IP multicast
crossing over many research and education networks

theater can be fed directly as DV streams to DVTS.

with heterogeneous environment. However,(c) Interactive Sessions.

these research and education networks are more

Student participations

or interactive sessions for medical lectures are

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an important component of medical teaching andthe source. It was therefore decided that the source

learning where discussions are strongly encouraged.

sends the video in DV format at full rate (30 framesWith the resource consuming DVTS streams, weper second) using DVTS to all its subscribers overneed to adopt a more economical conversational

IP multicast and find a solution for those lower

system, which may not be of high quality but

ends to be able to view the lectures with sufficientnevertheless sufficient in terms of the audio andquality.Our solution is to introduce a relay to be

low quality video streams. Such interaction is to beplaced on the multicast tree at the critical point

provided by a chatroom, a shared whiteboard as wellwhere the bandwidth reduction is needed. This relay

as a small group video conference system provided byis called DVrelay [8] which was developed by our

the VClass system. VClass was developed by a teamproject member from the Internet Education andat the Internet Education and Research Laboratory

Research Laboratory (intERLab) of AIT. DVrelay

at AIT, a member of our ANGKOR project, using

is a modification of DVTS where a frame-dropping

the Session Initiation Protocol (IETF RFC 3261) tomodule was added, as shown in Figure 1; to randomly

handle users’mobility, hence each remote class candrop frames until the output bandwidth requirementchange its locations without having to reconfigure.

is achieved.
For the ANGKOR Project environment, FMPMC,

2.2 Real-time and remote classrooms in the ANGKOR
project

as a member of RENATER, has a gigabit connectivity

Our proposed system is organized as in Figure

subsequently to its international pan-European

1; the source of the broadcast stream comes from

GEANT2 network with gigabit connectivity to Japanthe main lecture theater where the stream gets sent

through the TEIN2 network; while from Japan toover a multicast channel to a number of subscribers.

Cambodia, a 13 Mbps unidirectional satellite link run

Each subscriber may be on different networks withby AI3 is available. All these networks support IPv6

different network capacity thus they may not be

multicast. In order to satisfy subscribers with lower

able to receive the video with the original stream

bandwidth like UHSC, a DVrelay can be placed inquality; some subscribers who are on the highJapan to reduce the bandwidth from 30 Mbps to 5 or 6

bandwidth network can receive the high bandwidth

Mbps. Though a reduction to 1 or 2 Mbps is feasible,

stream while those at the lower ends may not. If thethe output stream risks quality downgrade especiallysource delivers video stream with low bandwidth

when the original video contains movements andin order to satisfy the lower ends, the higher ends

or when packet loss occur on the network. DVrelay

would unnecessarily loose the opportunity to view

reduces the bandwidth requirements by dropping thehigh quality video that could have been sent fromframes on the DVTS stream thus reducing the frameto the national network RENATER via RAP and

Figure 1 DVrelay is simply a DVTS with frame dropping

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ANGKOR: A Real-time Remote Classroom on Research and Education Networks

rates without affecting the original frame contents.

for the ANGKOR Project represents a real technicalThe quality of still images remains mostly without

challenge; since we use the combination of a link at

degradation while video with movements may suffervery high speed (2 Gbps) from France to Japan (RAP,

from frames dropping in DVrelay. To optimize the

RENATER, GEANT2 and TEIN2), with a satellite

performance, DVrelay performs additional motion

downlink rate relatively low (13 Mbps satellite link)detection[4]and adjusts the frame dropping rates such

between Japan and Cambodia. With this environment,that when there are a lot of movements detected,

FMPMC streams video using DVTS at 30 Mbps to

DVrelay will avoid the frame dropping as much as

all subscribers with IP multicast. As the video stream

possible and it would increase the frame dropping

arrives at AI3 in Japan, the DVrelay located in AI3

rates as much as possible when little movement

receives the stream then drop some video frames

was detected or still images detected on the input

to reduce the bandwidth into 6Mbps, and relay thevideo. The audio stream is kept as originally sent byvideo stream to the remote class UHSC in Cambodia

DVSend component of DVTS.

using AI 3 satellite link test bed. As the stream is

In our environment for the ANGKOR Project,using IP multicast, other receivers on the AI3 satellite

a remote real-time class is thus organized using

link test bed can receive the stream as well, and they

IP multicast with DVrelay machines placed on the

can join the class by signing up to the VClass.

multicast path between the lecture theater and the

The schools of medicine and pharmacy of thereceiver site where the bandwidth reduction must be

UHSC in Cambodia are equipped with computer

performed, as shown in Figure 2. The network usedrooms for the students with a sufficient number of

Figure 2 The research and education networks used for the ANGKOR Project where all of them except AI3
can accommodate DVTS at 33 Mbps. A DVrelay is placed at AI3 to reduce the bandwidth to 6 Mbps.

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multi-media computers networked at 100 Mbs as

reduction and motion detection to reduce stream

well as a lecture hall fitted with video projection.

to 5Mbps when sending to the AI 3 satellite

A multicast downstream of the lectures can belink both in IPv6 unicast and multicast.

organized in the local campus of UHSC reaching

IntERLab could monitor the end results as AIT-

more classes, if necessary, within the campus LAN.

IntERLab also has a receiving station for the

DVTS streaming as described above allows a one-way

AI3 testbed. Experimental results are displayed

broadcast to a large number of remote classrooms

in Appendix 1; the quality of the video stream

simultaneously in real-time. It allows the transmission

captured at AIT, at 5 Mbps with no packet loss, isof image and sound without compression and without

shown in (picture 1) while in (picture 2) there isloss of quality. In order to provide an interactive

some small, less than 5% packet loss.

AIT-

session, we extended VClass to provide real-time

3. We did experiments on the use of VClass toclass interaction with instant messaging, chat, video

initiate DVTS, sender and receiver, as well as

conferencing via webcam, whiteboard or slideshow,

other two-way communication tools such as

and email. With such environment, we were able tochat, video conference, messaging, shareddeliver a rich educational content, in real-time (ninewhiteboard and shared files. The possibility

hours of the Master one neurophysiopathology

of student audio-video feedback from UHSC

course of the FMPMC), in uncompressed DV format

using the VClass video conferencing systemusing the DVTS through a DVrelay which narrowed

on IPv4 using a 256kbps ADSL connection was

down the bandwidth for a unidirectional (UDL) on

tested. Appendix 1 also includes another picture

JCSAT satellite. The lecture streams were channeledshowing an interactive session on VClass (picture

to the satellite ground station in UHSC with minimum3); an image of the lecture stream as captured

deterioration or degradation.

by another camera at the remote classroom
site at UHSC was sent back to the lecturer at

3 Experiments on the ANGKOR project

UPMC for viewing during the discussions.

The DVTS and VClass transmission tests wereThis demonstrates an acceptable quality of the

conducted from the Department of Informationtransmission by comparing the original image

and Communication Technologies for Education

quality (large DVTS display on the right hand

(DPMTICE) laboratory located in FMPMC in Paris

screen) and the quality of the DVTS stream atwith high speed Gigabit IPv4 and IPv6 multicast

the remote classroom (in small display on theconnectivity. A series of experiments was started atleft screen) reflected back to UPMC screen via

beginning of June 2006 with the following steps:

VClass.

1. Setting up and assessing the transmission quality

From our series of fifteen experiments conductedof full-rate DVTS between FMPMC (France),

during 2006-2007, including a successful demon-

Keio-SFC (Japan) and IntERLab (Thailand) both

stration at a medical meeting at UHSC where wein unicast and multicast, with IPv4 and IPv6, withtransmitted DVTS streams from UPMC studio toand without DVrelay.

UHSC lecture hall in October 2006, we can summarize

2. Setting up and assessing the transmission quality

our valuable experiences and learning as follows:of DVTS between UPMC, Keio-SFC, and UHSC
through the DVrelay system that uses frame

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ANGKOR: A Real-time Remote Classroom on Research and Education Networks

Evenmeeting at UHSC, Cambodia. Packet losses appeared

though IP multicast has been defined almost two

to degrade not only the video precision and thedecades ago, it has not been widely deployed on

pedagogic impact of the video but also results inmost commercial networks due to additional costs

scratchy sound at times.

and co-ordinations required. On most research

Packet losses.

Deployment complexity of IP multicast.

Quality of distant teaching andand education networks, IP multicast is morelearning depends heavily on the quality of the video

readily available but not all research and education

and audio transmissions which in turn suffers when

network do provide native IP multicast. From ourpacket losses occur. It was found that apart fromexperiments, it was found that the operation of IP

satellite transmission losses, which occasionally affectMulticast was not stable particularly for inter-domain

the quality of the output, it was necessary to ensure

IPv6 multicast; tunneling had to be applied wheneverthat bandwidth reservation or the network operators

failures occur. Tunneling is known to compromisemust properly assign prioritized traffic flow.

the efficiency gains of IP multicast with tunneling

Pedagogy.

In our environment, the receiving

gateways and tunneling packets. Most of the failuresinstitution has very little educational option opened

were due to changes in the network configurations,to them because they lack the human expertise inwhich need proper co-ordination among network

teaching the courses themselves. Though distance

operators of the various networks.

teaching offer them less appealing class interactions,

It was found that DVrelay should

the students have no other choice when come toadopt constant bit rates rather than variable but

specialized courses which cannot be offered byrates to avoid peak traffic on the narrow links. This

their own institution, such as the case of UHSC.

was discovered after unexpected 20% packet loss kept

Technical failures and interruptions do affect theoccurring on DVTS streams between Keio-SFC topedagogical impact of distance classes substantially;

AIT (and UHSC) while IPv6 multicast was proven to

supplementary technologies and pedagogy must be

work successful from UPMC to all the intermediateprovided. Archived lecture materials appear to be a

DVrelay.

3

networks and within the AI . It was later found thatvaluable resource for the students for subsequent

such a big loss occurred due to peak traffic of thereviews as well as opportunities for tutorials or post-

VDO stream sent with variable bit rates thus we

lecture live question and answering sessions.

modified DVrelay’s bandwidth reduction algorithm
adopting constant bit rates for its output streams.

From our experiences, it was found that theInteractive sessions. Bidirectional communication

setting up of a successful long distance classes

was introduced with the use of IntERLab’s mobile

requires stable support from the network operators

VClass with very small webcam 328 x 244 pixels

from end-to-end; and that the co-operations among

video images (H.263). It was found that the audio

network operators in the heterogeneous research

quality and echoes were problematic. The use ofand education networks appears to be the key

echo cancellation microphone was found to fix thiscomponent for success. Most technical problems

problem and hence recommended.

we have found in our experiments were mainly due

Though DVrelay leaves the DVTS

to configuration mismatches. This could be due

audio stream untouched, we have found that DVTS

to the fact that, unlike unicast, multicast has notaudio do suffer from packet loss when we tested

been deployed widely so it has not been regularly

sending didactic hepatic surgery video to a surgeonssupported or routinely checked by the network

DVTS audio.

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operators even on research and education networks.

minimal backbone, in term of the number of nodes,

In such condition, deployment of multicast cannot bein order to reduce the support of the NOC engineers

smooth without a strong support from the network

as much as possible. Native IPv6 multicast is efficient

operation community.

but it should be adopted on the common backbone
connecting many as many neighboring networks

4 A real-time remote classroom networkmodel

as possible. The backbone IPv6 multicast must be

The ANGKOR Project has given us a muchwhile it is not compulsory for the remaining networks

clearer picture of how real-time classrooms can be

to provide IPv6 multicast. Streaming channels are

realized on a semi-autonomous and heterogeneous

managed or routed via DVrelays whose main task is

network environment. We identified that the mostto forward streams within its network to the common

important factor to the success of the ANGKOR

multicast backbone to efficiently deliver the streams

classroom is based upon the network operation

to the wider community through the backbone. In

support. In order to realize a real-time classroom

this was, only the core NOCs have to routinely checkfor a day-to-day operation, such dependencies on

the operation of their multicast setup and provide

the network operation team must be reduced to a

emergency trouble shooting when necessary.

maintained and guaranteed to work on 24/7 basis,bare minimum, namely reducing the deployment

Our proposed real-time classroom network thus

complexity of IP multicast.

comprises a common area or domain, which connects

The set up of distance classrooms should

to all members, networks, as shown in Figure 3. Eachbe scalable to be economical and the classrooms

connecting network set up a gateway with a DVrelay

must be real-time with many possible types ofwhose function is not only to adjust the bandwidthcommunication channels: multicast (one-to-manybut also to convert multicast to/from unicast and IPv4

and many-to-many) and unicast (one-to-one) enabling

to/from IPv6 streams. These gateways uniformly

one-to-one or multipoint conferencing/meetings.

send out IPv6 multicast streams to the common pool,

We have found that native IPv6 multicast, though

for example TEIN2 AS24490 in Figure 3, while theefficient in bandwidth utilization and consuming lesscommon pool is expected to have IPv6 multicast

host processing power, it needs heavy co-operations

operational all the time. Gateways are placed infrom and co-ordination among all the network

any neighboring networks, within which no native

operation centers (NOC) involved. End-to-end NOC

IPv6 multicast is necessarily supported. Our overlay

support for each distance classroom set up appears to

network is not an application level multicast (ALM)

be unrealistic for a day-to-day operation, let alone theoverlay network as it does not perform multicasting

scalability issue.

at the application layer; it is simply a patchwork of

We can view our heterogeneous network as a setdifferent network environments using the nativeof networks connecting to one another either directly

communication protocol (IPv4 vs IPv6 and unicat vsor indirectly. The core backbone of the network has

multicast) for DV streaming. As shown in Figure 3,

to be identified which connects all member networks,a real-time class may consist of a path of DVrelaysin the same way as a minimum spanning tree, andon the overlay network with a combination of native

is to be maintained by the network engineers such

IPv4/IPv6 and multicast/unicast depending on thethat native IPv6 multicast is guaranteed. The core oravailable underlying networks.

backbone should, as far as possible, be confined to aThis proposed model has been adopted for

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ANGKOR: A Real-time Remote Classroom on Research and Education Networks

Figure 3 A real-time classroom model with IPv6 multicast core spans over the Pacific and DVrelays ateach national research and education network gateway to the common TEIN2 core network.

deployment by a digital streaming CanalAVIST 8*

manageable environment for CanalAVIST NOC

project where the common TEIN2 network connects

engineers; in contrast to the end-to-end support

all member national research and education networks

from NOC engineers in the ANGKOR to ensure thein Australia (AU), China (CN), Japan (JP), Korea

that IP multicast is operational. When IP multicast(KR), Malaysia (MY), Philippines (PH), Singapore

is not available, which could be caused by one of the(SG), Thailand (TH), and Vietnam (VN together withconfiguration mismatch at a router on the multicast

the national gateways running DVRelays placed attree, the ANGKOR Project has to drop the native IP

respective point of attachment.

multicast and adopt tunneling while CanalAVIST can

While in the ANGKOR Project, a real-time

make use of DVrelays without tunneling.

class is constructed using network layer IP mulicast

Performance efficiency.

CanalAVIST real-timethroughout, CanalAVIST allows a hybrid model

classrooms are arranged and operated on the native

where a real-time class can be constructed using as

network without tunneling. Whenever multicast isa string of DVRelays which may be connected by a

not available, a native IP unicast can be adopted until

combination of IPv4/IPv6 unicast/multicast in native

when a DVrelay with multicast output is found, thenmode. In the following, we compare our proposed

DVrelay will output a multicast stream. All nativemodel against our IP multicast model of ANGKOR

communication protocols are used without tunneling,in terms of deployment complexity, performancethus achieving better performance efficiency without

efficiency and scalability.

having to modify any router configurations. In
ANGKOR, tunneling is deployed whenever native
By confining IPv6

multicast is not available thus affecting the overall

multicast within the core network, it provides aperformance. However, each DVrelay does impose

Deployment complexity.

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some delays for the frame dropping and motion

for streaming lecture contents to a large number ofdetection activity, which means that only a limited

audiences simultaneously, its limited deployment has

number of DVrelays can be acceptable for a given

made the support operation unstable. DVTS provides

real-time class.

high quality video suitable for delivering distanceIn this model, we can introduce

lectures particularly for medicine. Neverthelessas many core native IP multicast networks in ourlong distance classrooms for medical lectures canmodel linking the rest of the networks together.

never provide lively interaction as in the face-to-Thus the number of simultaneous classrooms is

face classes; supporting archived lectures as well

not limited by the introduction of DVrelay overlay

as organized interactive question and answering orin the model but it is limited by the network or

tutorials should be provided to compensate the loss

bandwidth capacity. Though the distant of the class,of effective teaching and learning environment.

Scalability.

or the number of DVrelays being used in the distantclass set up, depends on the number of DVrelays

From these experiments, we have found that inused to construct the class, which is thus limited by

setting up successful delivery of lectures involves

the acceptable delays. Scalability is subject to thesubstantial support from the network operators due

network capacity.

to the deployment complexity of IP multicast andtunneling. We proposed a new model of distance

5 Related Work

education where we limit native IP multicast to

CanalAVIST and ANGKOR share common

the core or the backbone network and allow for a

objectives with SOI-Asia [5] which is to provide

combination of IPv4/IPv6 and unicast/multicast tohigh quality distance education using the Internet

co-exist in the model. The core or but with extensive

technologies. In SOI-Asia, a 13 Mbps unidirectional

coverage area, like the Asia-Pacific, and also withbroadcast satellite covers Asia region enabling

the ability to support a large number of concurrent

lecture sharing among student sites. IPv6 Multicast

multicast groups.

overlay network is established by UDLR and IPv6

Acknowledgements:

tunnel technologies to create a virtual network
connecting lecturer-site and student-sites on top

We would like to acknowledge the support of theof network heterogeneity. While SOI-Asia mainly

ICT-ASIA project of the French government. We owe

3

focuses on using the AI testbed to disseminate

to all the research and education networks mentioned

3

in the paper for their services and generous technicalnetwork, CanalAVIST and ANGKOR addresses the

support. This project would not have achieved its

delivery of lectures over many peering networks withaims without the team from IntERLab/AIT with M.A.

heterogeneous networking conditions, thus higher

Awal, A. Kuprianov and R. Padilla; the AI3 team with

deployment complexity.

A.H. Thamrin, P. Basu from SOI-Asia and D. Rado

real-time lectures to their members within one AI

from UHSC.

6 Conclusions
In this paper, we have presented our real-life
experiments on setting up long distance IP multicast
for remote classrooms. It was found that though IP
multicast should provide an efficient mechanism

46

ANGKOR: A Real-time Remote Classroom on Research and Education Networks

Notes
1*
2*
3*
4*
5*
6*
7*
8*

http://www.renater.fr
http://www.geant2.net
http://www.tein2.net
http://www.apan.net
http://www.ai3.net
http://www.soi.wide.ad.jp/soi-asia/
http://www.vclass.net
http://www.canalavist.org

[5]

[6]

[7]

References[1] “Specifications of Consumer-Use Digital VCR’s using 6.3mm
magnetic tape”, HD Digital VCR Conference, 1994.
[2] Y.H. Chu, S.G. Rao and H. Zhang, A Case for End System
Multicast. In Proceedings of ACM SIGMETRICS, June 2000.
[3] S. Deering and D. Cheriton, Multicast Routing in Datagram
Internetworks and Extended LANS. In ACM transactions on
Computer Systems, May 1990.
[4] N. Kamnoonwatana, A. Kuprianov, P. Saengudomlert, T.
Sanguankotchakorn and K. Kanchanasut. DVTS Video
Frame Rate Adjustment Based on Motion Detection. In IEEE

[8]

Computer Society Proceedings of the Second International
Conference on Automated Production of Cross Media Content
for Multi-Channel Distribution, pp.229-235, Leeds, Dec 2006.
S. Mikawa, K. Okawa and J. Murai, Establishment of a
Lecture Environment Using Internet Technology via Satellite
Communication in Asian Countries, in Proceedings of IEEE
Computer Society Symposium on Applications and the Internet
Workshop, saint-w, p.60, Jan 2003.
A. Okawa, K. Kobayashi, K. Sugiura, O. Nakamura and J.
Murai, Design and Implementations of DV based video over
RTP. In Packet Video, May 2000.
Y. Shima, A. Suwa, Y. Gomi, H. Nogawa, H. Nagata and H.
Tanaka, Qualitative and quantitative assessment of video
transmitted by DVTS (digital video transport system) in surgicaltelemedicine. In Journal of Telemedicine and Telecare, Number
3, Vol 13, pp.148-153, 2007.
Y. Tsuchimoto, M. A. Awal, P. Saengudomlert, T. Sanguankotchakorn and K. Kanchanasut Bandwidth Adjustable
DVTS on the Heterogeneous Internet Environment forDistance Learning. In IEEE Computer Society Proceedings ofSAINT2007 Workshop on Educational Challenges to deploy theInternet, Tokyo, Jan 2007.

Appendix: Experimental Results(1) A screen capture of a lecture stream received at 5 Mbps without packet loss from the AI3 satellite testbed.

KEIO SFC JOURNAL Vol.8 No.2 2008

47

特集

アジアにおけるネットワークと遠隔教育(2) A screen capture of the same lecture stream received at 5 Mbps with less than 5% packet loss (as marked)
from the AI3 satellite testbed.

(3) Left hand screen shows ongoing interactive session using VClass; the lower right hand image of the left
screen displayed the Endoscopic lecture stream from UPMC which was received at USHC and sent back to
UPMC using VClass. The original VDO stream being sent by DVTS from UPMC can be viewed on the right hand
laptop.

48