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From nyquist.uwaterloo.ca!owpurbo Tue Jul 20 11:45:13 1993
Date: Tue, 20 Jul 93 14:12:59 -0400
From: owpurbo@nyquist.uwaterloo.ca
To: amcgee@netcom.com
Subject: Information Infra-structure to Sustain Current Growth in Indonesia
Status: RO
THE BUILDING OF INFORMATION INFRA-STRUCTURE
TO SUSTAIN THE CURRENT GROWTH IN INDONESIA
Onno W. Purbo
Inter University Center on Microelectronics
Institute of Technology Bandung
Bandung 40135, INDONESIA
FAX: (62)-22-438-338
E-mail: indogtw!paume!onno@uunet.uu.net
ABSTRACT
A five years experience in building a wireless WAN in
Indonesia will be described. Some of the basic ideas are
actually coming from CIDA's funded CoSy project to Indonesia
in 1987-1988. Ways to strengthen the strategic elements,
namely, man-power, knowledge and hardware/software
resources, is explained. An alternative physical layer using
a low cost packet radio technology with possibilities to
interconnect the high-speed LANs into a WAN is presented.
This approach enables the Indonesian universities and
government research institutions to reverse engineering and
to build the TCP/IP WAN and packet radio technology which in
turn supports us to build a self-sustainable and self-
financing wireless WAN required to transfer of information,
knowledge and science needed to sustain a bottom-up
technological and social development in Indonesia.
INTRODUCTION
Although, CIDA's funded CoSy project to assist the
Indonesian scholars have been completed in 1988, the spirit to
use computer medium to inseminate the development in Indonesia
has been carried by several Indonesian CoSy participants (of
which the author happens to be one of them) to implement a more
practical system with the current situation in Indonesia.
In this paper, we report on our five years effort to build a
wireless wide area computer network (WAN) infra-structure needed
to sustain the current growth in Indonesia. Electronic
conferences / mailing lists are used as a strategic medium to
support the transfer of knowledge needed to built the required
man-power for building the WAN. This development is partly
motivated by the exposure of some of the Indonesian staff members
to the CoSy at University of Guelph under CIDA funded project
back in 1987.
Electronics conference, such as, CoSy at University of
Guelph, has many advantages, such as:
1. It provides a medium for fast exchange of information
among the users of the electronics conferences. This in
turn enables a quick transfer of knowledge and
technology to support bottom-up development.
2. The users can participate into on-going discussions at
any time.
CoSy at University of Guelph (back in 1987) as an electronic
conferencing system has two major disadvantages:
1. It is very centralized. All participants have to logon
to the system to participate in the electronic
conferences.
2. It relies heavily on phone or public packet switching
network (PSN).
Wide Area computer Network (WAN) is a crucial infra-
structure to support a solid flow of information as well as
distribution of knowledge and science. The existence of wireless
WAN in Indonesia, which in turn enables a solid flow of
information, permits us to move forward from grass-root level by
elevating the capabilities of our man-power to support a bottom-
up sustainable technological and social development in Indonesia.
There are currently many WAN's in operation in Indonesia.
Many commercial sites, such as, computer vendors, oil companies
and some NGO's, have their own WAN and connected to international
network such as InterNet or PeaceNet. Dedicated and leased lines
are normally used to establish these networks. It is ashamed that
universities and government research institutions, from which the
man-power required to sustain the development in Indonesia are
prepared, have very little support from the government in
establishing our own WAN knowingly that establishing a solid flow
of information is crucial to prepare a knowledgable man-power to
1
sustain the country's continuing development. Aside from this un-
supportive environment, several committed staff members from
several universities and government research institutions manage
to built our own wireless WAN using radio (low cost packet radio
technology) as our primary physical link - with minimal support
from the government and external resources.
Why wireless WAN? Wireless WAN can be established using less
expensive equipments and very decentralized in nature. Thus, it
can be initiated without having to rely on a single authority /
company to provide the equipments / services. This situation is
very favourable for the end-users as well as the supporting
industries. Furthermore, in the long run, a wireless WAN leads to
a lower overhead cost than leased dedicated lines. Moreover, the
software (including the source code) and the hardware are readily
available in public domain. This in turn enables us to reverse
engineering the software and hardware which leads to a low-cost
investment in building our own wireless WAN infra-structure
without having to depend financially and technologically on
external sources (Purbo, 1992).
In this paper, we will report on our five years experience
in building wireless WAN among the universities and government
research institutions in Indonesia. Strategic elements in the
development of wireless WAN will be discussed. The TCP/IP
computer network architecture used will be briefly reviewed.
Current connectivities of our universities and research
institution will be shown. Furthermore, our current strategies to
move forward will be briefly described. We hope this report will
give a valuable input for other developing countries in building
their own WAN infra-structure.
KEY ELEMENTS IN BUILDING WAN IN INDONESIAN
There are basically three strategic elements in building the
computer network in Indonesia, namely:
1. Knowledgable & committed man-power.
2. Access and the development of knowledge in computer
network.
3. Ability to build and assembled the required hardware /
software.
Among these elements, the existence of a group of knowledgable
and committed people (man-power) is the most crucial component to
assure the ability of the Indonesian people in building their own
network without having to rely heavily on external resources. In
this section, we will focus on our experience in building of the
knowledgable and committed man-power (historical perspective).
Experience learned from CIDA's funded CoSy project in 1987-
1988 indicates that computer medium can be served as a useful
medium in transferring technology as well as in motivating people
to learn from others and, in turn, increase their self-
motivation.
Five years, after the completion of CIDA's funded CoSy
2
project in Indonesia, an exposure to such rare opportunity in
1987 has prompted some of the Indonesian scholars aboard who were
studying towards their graduate degree to start several
Indonesian mailing lists using their computer account at schools.
The first known Indonesian electronic mailing list is located at
University of California Berkeley in the US with address
<indonesians@janus.berkeley.edu> established around 1987-1988. It
is now still in operation and is mainly used for general
discussions. Subsequently, many Indonesian mailing lists
including a newsgroup soc.culture.indonesia in USENET have been
established in InterNet some of which have attracted participants
from various Canadian NGOs and institutions such as McGill
Indonesia Project, EMDI and WUSC. Among these Indonesian
electronic discussion groups, there are two major mailing lists
established with purpose solely to support the technological and
social development in Indonesia, namely:
1. PAU-Mikro-net <pau-mikro@ee.umanitoba.ca>
(established in 1990 with total member of around 200)
2. the Indonesia Development Study <ids@suvm.bitnet>
(established in 1991 with total member of around 350)
The Indonesia Development Study (IDS) is currently dealing
with various general issues in Indonesia's development in a more
global sense. The member of IDS are coming from many backgrounds
with majority in social and economics sciences. Several people
from international organizations including EMDI and McGill
Indonesia Project join the IDS mailing list.
Different from IDS, PAU-Mikro-net is specifically working on
a more narrow subject in building the computer network in
Indonesia as well as various microelectronics and computer
science aspects. Consequently, the majority of the members in
PAU-Mikro-net have engineering background. Similar to IDS,
several staff members from Western Universities, such as
University of Wisconsin, and several international NGO's, are
also joining the PAU-Mikro-net. PAU-Mikro-net is more unique in
nature as compared to other Indonesian mailing lists in InterNet.
PAU-Mikro-net interchanges ideas as well as performing real tasks
directly with participants in Indonesia, namely, at UI (Jakarta);
ITB (Bandung); STT-Telkom (Bandung); LAPAN (Jakarta); INKOM-LIPI
(Bandung); Ministry of Environment (Jakarta); Ministry of Foreign
Affair (Jakarta) and BPPT (Jakarta), via computer network. The
Paguyuban TCP/IP is currently active in discussing various issues
regarding the development of computer network in Indonesia in
PAU-Mikro-net. The international E-mail connection between
Indonesia and the InterNet is currently provided by the Center
for Computer Science at UI in Jakarta.
In terms of helping building the information infra-structure
in Indonesia, the discussions in PAU-Mikro-net serve several
purposes, such as:
1. Transfer of knowledge by means of consultations for any
3
problems encountered in implementing the technology in
Indonesia.
2. Feed-back and report of the current network expansion
in Indonesia.
3. Finding an alternative international routes and funding
for Indonesia. This is mainly motivated by our
expensive PSN.
4. Keeping the spirit of our colleagues in Indonesia in
building the computer network. This is very crucial as
nearly all of us are currently doing this as a
volunteer apart from our daily jobs. Most of us agree
to keep this voluntarily basis of our institution to
reduce the bureaucracy (which usually slow the
progress).
These purposes have been served very nicely at PAU-Mikro-Net
mainly because most of the members abroad have access to InterNet
which enable them to find the required information. Furthermore,
prior to the implementation of certain methods / concepts
precaution can be provided by monitoring newsgroup / other
InterNet mailing lists. Thus, in concept, this is actually a
transfer of technology process.
Within a five years experience, it has been proven that
written medium (electronic or a more conventional paper medium)
is essential to be able to transfer the knowledge needed to build
the committed man-power. In 1987-1989, prior to the establishment
of Indonesian electronic mailing lists in the InterNet, most of
the attempts to transfer of knowledge and to increase self-
motivation were done using written paper medium, such as,
newspaper, magazine. In 1990-1991, as above mentioned, we started
using electronic computer medium to perform these tasks as well
as real tasks to help and to coordinate the building of computer
network in Indonesia. This effort in turn leads to the
establishment of an informal consortium of committed staff
members of the Indonesian universities and government research
institutions known as "Paguyuban TCP/IP". Paguyuban TCP/IP is an
informal consortium of about 30-50 committed Indonesian staff
members (both in Indonesia and abroad) with a single objective to
build the computer network in Indonesia. The informal nature of
this consortium enables us to surpass the bureaucracy commonly
found in many Indonesian institutions / government offices and,
thus, enables us to accelerate the building of the network.
Before we proceed with a more detail description of the
current state of the wireless WAN in Indonesia. A brief review of
the architecture of TCP/IP computer network and its attempts to
adopt the technology in Indonesia will be presented in the next
section.
THE ADOPTION OF TCP/IP WAN IN INDONESIA
In this section, a brief overview of the TCP/IP computer
network and our attempts to adopt the technology will be
reported. First, the overview of the TCP/IP WAN technology will
4
be described. Subsequently, we will describe our attempts to
adopt the technology and to transfer the technology to our local
industries in Indonesia to sustain the current growth of the
computer network.
A simple network architecture is used in the implementation
of TCP/IP-based computer network (see Fig. 1). It consists of
five protocol layers. These layers, in terms of its functionality
(from the lowest to the highest level) are physical layer, link
layer, network layer, transport layer and application layer.
There is no need for an end user to understand how these layers
interacts to use the computer network. InterNet Protocol (IP)
(Postel, 1981) and Transport Control Protocol (TCP) (Postel,
1981) are used in network and transport layer, respectively. This
leads to the term TCP/IP-network in referring to this
architecture.
The physical and link layer protocols used in a computer
network may vary depending on the form of the network. In most
high-speed Local Area Network (LAN)s, 10Mbps Ethernet or Token
Ring physical layer, the IEEE 802 link layer protocol (Stallings,
1987) is normally used. To form a Wide Area Network, commercial
Packet Switching Network (PSN) or even ISDN may be used with
various link layer protocol such as CCITT X.25 (CCITT). The
interconnection of various physical and link layer protocols in
various LAN / WAN to form a nation wide or even worldwide
computer network is transparent to the users by using InterNet
Protocol (IP) in TCP/IP-based WAN. The TCP/IP-based WAN has
currently emerged into the largest worldwide computer network
known as InterNet.
We use mostly PC-based TCP/IP routers and switches to
minimize the overhead costs. TCP/IP protocol is implemented in
KA9Q Network Operating System (NOS) originally develop in the
amateur radio (Karn, 1985), (Karn, 1988). NOS is running on PC
with both source and executable code available in public domain
for non-commercial purposes. We have managed to reverse
engineering the NOS software for our purposes. The use of TCP/IP
protocol enables us to merge various high-speed LANs into WAN
over radio as well as leased line. We retain the current policy
in distributing NOS software that is "public domain" provided
with the source code and manual. This is a very important
contribution to sustain the growth of the computer network.
Packet radio as physical layer is of interest especially due
to its nature which allows more flexibility for the end user to
build their network without having to depend on external sources
as well as to reduce the overhead costs. Let us now review some
of the alternative configurations of packet radio technology.
These configurations are currently being pursued into mass
production lines to support further expansion of our wireless WAN
in Indonesia. Aside from the radio and the microcomputer, the
typical configuration of packet radio station can be classified
into:
1. 1200 bps AFSK modems connected directly to PC's serial
5
port.
2. PC add-on Terminal Node Controller (TNC) with AFSK
modems.
3. High-speed 56 Kbps packet radio systems.
In the first configuration, a 1200 bps AFSK modem is
connected directly to PC's serial port. This configuration is
primarily intended to provide an end user with a lowest possible
cost hardware necessary to become a part of the packet radio
network. Typical cost to built such AFSK modem is in the range of
US$20-$40. We are currently working very closely with several
NGO's in transferring the knowledge in building this lowest cost
solution to the small industries in Indonesia. We hope to see the
first shipment of the generation of low cost modem in 1994.
For advanced packet radio applications, e.g., dedicated
TCP/IP operations, the PC computing power should be freed to
perform higher-level networking tasks. This can be done in the
second option by leaving lower level protocol operations to a
dedicated hardware. This configuration is process to be produced
in mass production in Indonesia by Prof. Iskandar Alisyahbana
group from ITB.
As the network grows to interlink various high-speed LANs
into WAN, it is most likely that the long-distance packet
switching backbone nodes will experiencing a heavy traffic which
might create network congestion. Work is currently underway to
investigate the use of a high-speed PC add-on card connected to a
56 Kbps packet radio high-speed modem for high-speed packet radio
backbone. It is interesting to note that the commercial packet
switching network (PSN) in Indonesia operates at top speed of
only 9600 bps.
Please note that the packet radio technology is especially
used to link regional and long distance networks. Within a
building or campus complex, a high-speed LAN would be a better
investment. Furthermore, TCP/IP protocol allows us to integrate
these two different technologies (LAN and packet radio
technology) into a single WAN which transparent to end-users.
Since most of the alternative configurations are currently being
produced in Indonesia, the expansion of the wireless WAN can be
done at low cost without having to depend on external sources.
IMPLEMENTATION OF WIRELESS WAN IN INDONESIA
In this section, the actual implementation of packet radio
technology in our WAN will be presented. The wireless WAN is
currently in operation (and keep expanding) to connect:
1. University of Indonesia (UI) in Jakarta.
2. Institute of Technology Bandung (ITB) in Bandung.
3. National Aerospace Institute (LAPAN) in Jakarta and Bogor.
4. Agency for the Assessment and Application of Technology
(BPPT) in Jakarta.
5. School of the Telecommunication Agency (STT-Telkom) in
Bandung.
6
6. The Indonesian Science Institute (P3INKOM-LIPI) in Bandung.
7. The Ministry of Environment in Jakarta.
8. The Ministry of Foreign Affair in Jakarta.
Several other institutions (such as University of Gadjah Mada in
Jogyakarta, University of Parahiyangan in Bandung, University of
Satya Watjana in Salatiga, University of Brawidjaja in Malang)
are currently preparing their man-power and equipments to join
the network. All of these activities are initiated by the
committed staff members of each institution without any direct
intervention from the top government policy-makers. It is to say
that the nature of the development is bottom-up approach.
Since TCP/IP protocol is used in the network, the nature of
our network is fairly similar to InterNet. The discussions in
PAU-Mikro-net is forwarded using E-mail (SMTP) (Postel, 1982) and
news (NNTP) (Kantor, 1986) to various hosts in Jakarta, Bandung
and Bogor. Indonesia has just recently becoming part of InterNet
with top domain ".id".
Figure 2 shows a simplified topology of our current packet
radio network in Indonesia. VHF and UHF links are used to
interconnect the high-speed LAN at ITB, UI, BPPT, LAPAN, STT-
Telkom and P3INKOM-LIPI. The operational speed used in the VHF
and UHF links is currently 1200 bps and 9600 bps. However, works
are currently underway to increase the regional packet radio
speed to 56 Kbps. The wireless WAN is currently coexist with some
of the (expensive) UUCP links used mainly as back-up links.
Furthermore, it appears most of the institutions are more
favourable towards the wireless technology which would be a low-
cost investment in the long run. In Figure 2, it is shown some of
our international links currently in operation. These links are
primarily using our commercial packet switching network (PSN),
i.e.:
1. TCP/IP link to University of Aachen in Germany.
2. UUCP link to UUNET in the US.
Through these two international links, we are currently able to
communicate to our international counter part. Unfortunately, the
Indonesian PSN is known to be one of the expensive PSN in the
world. Work is currently performed to use alternative routes to
get a lower cost international connection. In the next section,
attempts to use VITASAT to connect our packet radio network in
Indonesia to international InterNet network work will be
described in more detail.
LOW EARTH ORBIT VITASAT SATELLITE
At the time this manuscript is written, an experiment to
interchange messages between North America (InterNet) and
Indonesia via VITASAT (Volunteers In Technical Assistance
SATellite) has been successfully underway for several months.
VITASAT is a polar Low Earth Orbit (LEO) satellite with apogee
around 900 km above the Earth especially design for carrying
7
digital information using packet radio technology (Davidoff,
1990). VHF 139 MHz band and UHF 440 MHz band are used for up-link
and down-link frequencies which enables a simple satellite ground
station to access this satellite.
A simplified topology of our experiment to exchange messages
between Indonesia and InterNet via VITASAT is shown in Fig. 3. We
currently have two VITASAT ground stations in operation in
Indonesia, namely, ITBJKT in Jakarta and ITBBDG in Bandung.
Messages from ITBJKT or ITBBDG will be carried by VITASAT to the
US. A VITANET station in the US will then download the message
and delivered to UUNET in the US East coast to deliver to the
intended InterNet destinations. At least three additional VITASAT
ground stations in Indonesia (one in Jakarta and two others in
east Indonesia) will be installed by the end of 1993. Prof.
Iskandar Alisyahbana group at Electrical Engineering Department
ITB is currently working to built low cost VITASAT ground station
for used in Indonesia. To give a ball-park figure of VITASAT
ground station, excluding the PC, a VITASAT ground station can be
obtained at around $1000-$2000. The equipments is very easy to
find in the market and to install as it is originally based on
Microsat / PACSAT design from the amateur radio (Davidoff, 1990).
This approach has significant advantages in terms of
overhead cost as compared to the previous approach using
commercial PSN for international connection. Furthermore, it
allows remote areas in many part of Indonesia (or the world if
you wish) to communicate with the more "civilized" world and
exchanging information to assist the development in the remote
regions. This can be done without having to rely on any
commercial services which is a favourable approach for the end-
user to sustain and to expand network at the lowest possible
costs. Cooperation and coordination between Prof. Iskandar
Alisyahbana's group and our packet radio network is currently
underway to integrate the existing packet radio network of
"Paguyuban TCP/IP" into VITANET to communicate to InterNet.
STRATEGIES TO MOVE FORWARD
In the previous sections, we have reported the history and
the "state-of-the art" of our wireless computer network in
Indonesia. In this section, we will briefly described our
strategies in sustaining the growth of the computer network in
Indonesia. We are currently focusing our work on three aspects,
i.e.:
1. Strategies in building our man-power.
2. Strategies in mastering the knowledge in computer
network.
3. Strategies in developing the required small industries
to support the required hardware.
To perform these strategies, we are not relying on any
authorities in the government of Indonesia to execute our
projects. All of these projects are performed by committed man-
8
power in Paguyuban TCP/IP using a bottom-up approach. However,
with the current political situation in Indonesia, as most of the
ministers have engineering background, our tasks would be much
easier.
Building the required man-power is our major effort. It is
currently done mainly through informal meetings, discussions,
mailing lists as well as through articles in the mass media in
Indonesia. In a more formal stage, the staff members at ITB (in
Bandung) and UI (in Jakarta) are currently employing several
students to work in building / learning the computer network as
part of their final projects. Most of the members of Paguyuban
TCP/IP is currently doing free consultation jobs to help others
who want to initiate their institutions to integrate into our
packet radio network. All of these efforts are trying to increase
the awareness and self-motivation in building the computer
network.
Several members of the Paguyuban TCP/IP is currently
learning in-depth on various practical methods in TCP/IP computer
network. The references for these works are mainly from the
freely available Request For Comments (RFC) documents available
via FTP from various sites in InterNet. A book on TCP/IP network
is currently being written in Indonesian language. In addition,
at least, 3 members are currently active in programming the
TCP/IP software on PC. All of these activities are performed in
attempts to master the TCP/IP technology to be able to develop
our own technology.
Our last point, the development of the small industries to
produce the required hardware to support the development of
packet radio WAN. It is currently in a very early stage of
development. Most of the works are currently concentrated in
creating a network between Paguyuban TCP/IP and various NGO's,
Development Studies group in several universities (such as ITB
and University Satya Watjana) to discuss the best way in
approaching the small industries in Indonesia. Several contact
persons have been found within NGO's and Development Studies
Group in Indonesia who are willing to help us in approaching the
small industries.
We are going to concentrate our effort to rely on the small
industries as our primary base to support the development of
computer network in Indonesia. We believe through the small
industries, it would be easier for us to reach the lower income
family and to increase their knowledge as well as their earning.
We hope, this approach will in turn benefit not only the small
industries but also the whole nation.
SUMMARY
In this paper, an experience in building a self-sustainable
computer network in Indonesia
using a low-cost packet radio technology has been presented.
Although packet radio technology is not the state-of-the art
technology, it has been proven to serve quite nicely in enabling
us in Indonesia to build and to reverse engineering packet radio
9
technology which leads to a low cost wireless wide area network.
This in turn enables us to build a self-sustainable and self-
financing wireless wide area computer network to support a solid
transfer of information, knowledge and science needed to have a
bottom-up technological development in Indonesia without having
to rely on external sources.
Three different alternatives for packet radio configuration
have been described. Mass production of the packet radio
technology is being done in Indonesia as a result of our reverse
engineering process. Thus, packet radio technology will
accommodate a wide range of budget and requirements. The use of
TCP/IP protocol in packet radio technology enables us to
interconnect our high-speed LANs into a single WAN. Research
studies are currently underway to increase the speed of our
regional packet radio network to 56Kbps and also to use
alternative international link via VITASAT for a low-cost
connection to InterNet.
The establishment of a group of knowledgable and committed
people is the crucial element to be able to perform such task in
building the computer network in Indonesia. Electronic computer
conferencing system has proven to be an essential medium to
support the transfer of knowledge needed to increase self-
motivation and the knowledge of the required man-power.
Exposure to the tele-conferencing in CIDA's funded CoSy
project has shown its benefit few years after the exposure. It is
shown that the experience learned from CIDA's funded CoSy project
has lead us to use electronic mailing lists and discussion groups
to perform transfer of technology to Indonesia. This in turn
enables us to built and to sustain our own computer network in
Indonesia with minimal support from external sources. Finally,
thank you Canada to expose us to this exiting new information
technology which enable us in Indonesia to help building our
country.
ACKNOWLEDGEMENTS
We wish to thank Ms.Maria Cioni to allow the author to
access CoSy in 1987 (as part of CIDA's funded project). We would
like to thank Prof. Dr. T. Chapman (University of Wisconsin -
Madison), Prof. Dr. Iskandar Alisyahbana (ITB), Dr. Kusmayanto
Kadiman (PIKSI-ITB), Dr. S. Nasserie (ITB), Dr. Adang Suwandi
(ITB), the members of ITB-ARC and the members at PAU-Mikronet for
their valuable comments and encouragements during the course of
the work.
We wish to thank the University of Waterloo - Amateur Radio
Club VE3UOW to allow the author to perform experiments in
TCP/IP-based packet radio network. We wish to thank many amateur
radio fellows, such as Robby Soebiakto YB1BG, Dwi YB0QC, Suryono
YG1QN/N5SNN, Roger VE3RKS.
The financial supports from the Indonesian Government as
well as the Canadian International Development Agency (CIDA)
through the Canadian Bureau of International Education (CBIE) are
greatfully acknowledged.
10
REFERENCES
O.W.PURBO, "An alternative approach to build low cost
TCP/IP-based wide area network in Indonesia," South East
Asia Regional Computer Confederation (SEARCC) '92
conference, Kuala Lumpur, 14 August 1992.
J.POSTEL ed., Internet protocol, RFC 791, September 1981.
J.POSTEL ed., Transmission control protocol, RFC 793, September
1981.
W.STALLINGS, Handbook of computer communications standards: local
network standards, vol. 2, MacMillan Book, 1987.
CCITT Recommendation X.25, Interface between Data Terminal
Equipment (DTE) and Data-Circuit Terminating Equipment (DCE)
for Terminals Operating in the Packet Mode on Public Data
Networks.
PHIL KARN, KA9Q, "Amateur TCP/IP: an update," Proceedings 7th
ARRL Computer Networking Conference, pp. 115-121, 1988.
P.R.KARN, KA9Q, H.E.PRICE, NK6K dan R.J.DIERSING, N5AHD, "Packet
radio in the amateur service," IEEE Journal on Selected
Areas in Communications, vol. SAC-3, pp. 431-439, 1985.
J.POSTEL, Simple mail transfer protocol, RFC 821, August 1982.
B.KANTOR and P.LAPSLEY, Network news transfer protocol, RFC 977,
February 1986.
M.DAVIDOFF, K2UBC, The satellite experimenter's handbook, 2nd
edition, American Radio Relay League, 1990.
11
FIGURE CAPTIONS
Figure 1. TCP/IP based computer network architecture.
Figure 2. A simplified topology of our current TCP/IP packet
radio network in Indonesia as of May 1993.
Figure 3. A simplified topology of the communication experiment
between Indonesia and InterNet via VITASAT as of March
1993.
12
