AN OVERVIEW OF THE IMPLEMENTATION OF TCP/IP PACKET RADIO WIDE AREA NETWORK IN INDONESIA

Onno W. Purbo, Aulia Khusnul Arif, Arman Hazairin
Basuki, Ichwan F. Agus, Yudhi Prasetyo
Computer Network Research Group
Inter University Center on Microelectronics
Institute of Technology Bandung
Bandung 40132, Indonesia
FAX: 62-22 214-417
yc1dav@itbgtw.itb.ac.id, aulia@itbgtw.itb.ac.id
arman@hme.ee.itb.ac.id, basuki@itbgtw.itb.ac.id
iwan@itbgtw.itb.ac.id, prasetyo@itbgtw.itb.ac.id

Utoro Sastrokusumo
Telecommunication Laboratory
Department of Electrical Engineering
Institute of Technology Bandung
Bandung 40132, Indonesia
FAX: 62-22 250-2260
utoro@radar.ee.itb.ac.id

ABSTRACT
	In this report, the implementation of TCP/IP-based packet radio technology to integrate various universities and institutions into the first Indonesia's national InterNet Wide Area Network (WAN) will be described. Various efforts include TCP/IP software development, HDLC X.25 card, various modems (PSK, AFSK, GMSK and high speed MSK) will be presented. In addition, various advanced networking experiment mostly via satellite will be reported.

INTRODUCTION
	Started in 1991-1992 as a need to build a low cost computer network among universities and research institutions in Indonesia, TCP/IP packet radio-based computer network is now the largest TCP/IP Wide Area Network (WAN) ever implemented in Indonesia connecting a large number of institutions. The rapid development is not possible without the generous assistance from many institutions within Indonesia as well as foreign organizations. To name a few, we have to acknowledge generous assistance from:

  •	German Aerospace Research Establishment (DLR) sponsored JASIPAKTA.
  •	Canadian International Development Agency (CIDA) funded Eastern Indonesia University Development Project (EIUDP).
  •	United Nations Development Programme (UNDP) funded Sustainable Development Network (SDN)
  •	Australian International Development Aid Bureau (AIDAB) funded Indonesia Australia University Project.
  •	IPTEK-NET funded by The Indonesian National Research Council (DRN).

There are too many institutions and individuals to be acknowledged.
	In this report, the current status of the network in the last three years, direction of growth as well as overview of various research works to enhance the operation of the network will be described.

NETWORK STATUS IN AUGUST 1994

Figure 1. Indonesia Network Topology (August 1994)
	Figure 1 shows the network topology of the Indonesian computer network as of August 1994. It shows clearly that most of the long distance traffic is carried over packet radio technology. Packet radio technology is a non-captive market with no monopoly on the provider side and, thus, gives more advantages to the users due to its competitiveness as well as availability.
	The network status summary can be described as follows. In november 1994, a total of 68 major nodes are in operation with 46 (68%) of which are located in Bandung; the rest (32%) are spread all over Indonesia including Jakarta. Interestingly, most of the nodes (80%) are using the low cost packet radio technology to form a WAN, the rest (20%) mostly in Jakarta are using dial-up UUCP / TCP/IP to reach the InterNet gateway at IPTEK-NET Jakarta. Nearly none of the node is using the Indonesian commercial packet switching network (SKDP) to reach IPTEK-NET gateway. In addition to the active nodes, there are currently at least 56 nodes are preparing their equipments and human resources to join the network. The estimated total user is 2869 users with 72.6% are at universities, 16.0% in research institutions, 3.7% NGO, 3.1% in government institutes, and 4.6% commercial/industries. Approximately 58.2% of total users reside in Bandung (48.3% are users of ITB). Major applications are 4 major electronic mailing lists, 14 major newsgroups & Gopher servers. For international links, we currently rely on the subsidized 64Kbps Sprint-Net link from the National Technology Assessment Agency in Jakarta to Sprint-Net in the US. Since most of the implementations rely on the low cost packet radio technology, it enables a rapid expansion of the network. The rapid expansion of the network can be clearly observed as a comparison that in early 1993, only five (5) institutions are connected to the network.
	To sustain the rapid grow of the network has forced us in Indonesia to be able to make most of the equipment ourselves. In the next section, our effort to build most of the equipment to install the network in Indonesia will be described. Some of the prototypes, such as, a simple AFSK 1200bps modem, are currently under mass-production. These initial efforts have in turn speed up the network expansion.

HOME MADE PHYSICAL LAYER
	In this section, we would like to review our effort to build the required physical layer locally in Indonesia. Some of these prototypes developed in Indonesia are:

   •	A simple AFSK modem 1200bps - it currently under mass-production in Indonesia.
   •	Microprocessor based AX.25 Packet Assembly Disassembly (PADS) also known as Terminal Node Controller (TNC).
   •	A 1200bps PSK modem.
   •	FSK and GMSK 9600bps modem.
   •	AX.25 HDLC card for high speed (up to 256Kbps) packet radio systems.
   •	High-speed 64Kbps modems for packet radio network.
   •	Radio and transverter for packet radio systems.

	The simple AFSK 1200bps modem is currently based on a low cost TCM3105. Using these types of modem, the PADS is performed in the computer using software approach. All the software is available at no cost for non-commercial usage. Although, this approach enables us to create the network at low cost, it consumes a significant amount of CPU time to run the network. Thus, a hardware approach should be considered for a dedicated packet radio node. This is done using a microprocessor based Terminal Node Controller. Several local manufacturer is currently producing the modem to support the rapid development of the network.
	In addition to the 1200bps AFSK modem, we are currently working on 1200bps Phase Shift Keying (PSK) modem. It is basically a Quadrature Phase Shift Keying (QPSK) technology.
	We are currently working to develop a microprocessor-based PADS to be used in packet radio network environment. It is based on the amateur radio Terminal Node Controller (TNC). A 8 bit Z80 microprocessor, which can be obtained at a cost of US$1.00/each, is used as the main CPU of the PADS. A TCM3105-based AFSK Bell 202 1200bps modem can be included in the system as necessary. The data from computer can be fed into the TNC at a data-rate up to 38.4Kbps. The output data-rate can be programmed from 300bps up to 19.2Kbps.
	To anticipate the traffic overload in the network, we have been working on FSK and GMSK 9600bps packet radio modems. The FSK modem is using a fairly straight-forward method by burning the FSK signal into the EPROM. The output data from the EPROM is then fed into an ADC to be converted into an analog signal, which then injected into the VCO in the PLL circuit. The detection process is using a conventional tracking system. For GMSK 9600bps system, we are using a commercially available GMSK chip from MX.COM.
	As part of our effort to build a 64Kbps high-speed packet radio back-bone, we are currently working on:

   •	AX.25 HDLC card for high speed (up to 256Kbps) packet radio systems.
   •	High-speed 64Kbps modems for packet radio network.
   •	Radio and transverter for packet radio systems.

Figure 2. Packet Interface Card
	The High Level Data Link Controller (HDLC) card is based on the Zilog 8530 Serial Communication Controller chip. The card is designed to work on PC-based computer. It has two communication port. In the design, port A is set for Direct Memory Access (DMA) operation for high speed up-to 250Kbps operation. Port B is designed to be used with interrupt driven mode, and, thus, the speed is very limited to low speed 1200bps. The block diagram of the Packet Interface card is shown in Fig. 2. A throughput of the order of 30 times of the conventional 1200bps system can be achieved at 250Kbps. Figure 3 shows the typical performance of ping application at various speed with different packet length. In Figure 4, the typical throughput for File Transfer Protocol is shown. The current status of the card is in beta test phase and will be in production line hopefully by the end of 1994.

Figure 3. Typical PING performance
	A minimum shift keying (MSK) modem is currently developed for 64Kbps modem. A state machine of the MSK will be implemented in the an EPROM which will then be converted into analog signal through an ADC. The I and Q signals coming out from the ADC will then be injected into the balance modulator with 90o shift in the 28MHz local oscillator injection. The output is a 28MHz modulated MSK. The demodulator is constructed by using a conventional FM receiver module, such as, MC3359. The output signal from the quadrature modulator is then sampled by a PLL unit to extract the data clock which then used to extract the data stream.

Figure 4. Typical throughput of FTP
	To use the high-speed 64Kbps systems, the commercially available radio cannot be used due to restriction in the bandwidth. Most commercial radio is designed for audio applications with 20KHz bandwidth. A transverter, which is basically a linear frequency translator, is designed to work with the 64Kbps modem. The bandwidth of the transverter can be easily designed for wide bandwidth operation.

ADVANCED NETWORKING IN INDONESIA
	In addition to the effort to build the equipment in Indonesia, at least there are three major known efforts for advanced networking in Indonesia. These efforts are:

  •	Satellite based 300bps packet radio network via Palapa satellite to integrate at least eleven eastern Indonesian Universities.
  •	International TCP/IP experiment via ETS-V satellite.
  •	Set-up of Low Earth Orbit satellite ground station at ITB.
  •	Initial study to build a low earth orbit satellite.

Interestingly, most of the advanced effort is a satellite-based network.
	Lead by the Indonesian Technology Assessment Agency (BPPT), a Palapa satellite based 300bps packet radio network is currently implemented to integrate the Ministry of Education office to the eastern Indonesia university network. A conventional Terminal Node Controller is used to integrate various Local Area Network to the Palapa ground station. A normal packet radio CSMA access method is used in the network. Satellite channel utilization is low as performance is not the number one concern at this moment.
	An international TCP/IP network experiment via ETS-V satellite has been done by the Microwave Laboratory at the Electrical Engineering Department at ITB via Communication Research Laboratory in Kashima, Japan to communicate with the Computer Center at Tohoku University. A speed of 38.4Kbps SLIP line via ETS-V is used in the experiment. The low thruoghput in the experiment is mainly due to the difficulties in tracking the satellite as the satellite is moving from time to time and, thus, no longer in fully geostationary position. Seven hour experiment per month is not sufficient with many options to be experimented in computer network via satellite.

Figure 5. ITB's satellite ground station
	At the Institute of Technology Bandung, we are currently working on building our own low earth orbit (LEO) satellite ground station. The LEO ground station would be the command and control station of the Indonesian Microsat which is currently being built. The typical set-up of the ground station is shown in Figure 5. The 9600bps packet radio station is very similar with the one we use for terrestrial work, which consists of a PC connected to a TNC with added 9600bps FSK modem. VHF and UHF radio transcveiver is used to access the LEO satellite. A traxbox, which basically a microprocessor based automatic tracking unit, is added into the system to automate the tracking processes. The traxbox is currently being built by the Amateur Radio Club at ITB.
	To gain more access to the satellite knowledge, we at ITB is currently working on the initial phase of the design of the satellite. The satellite will be launch for free by the Ariane Space prior to 1998. The mission objective of the satellite is for scientific and engineering test bed of satellite technology made by the Indonesian. At least telemetery and date communication payload will be incorporated in the microsat.

SOFTWARE DEVELOPMENT EFFORT
	In addition to various hardware development, some works are currently being done in software side. Although most of the software used in the network operation are available in commercial as well as in public domain, some adjustments still need to be performed. The software development effort is ranging from:

  •	Development of software interface between Network Operating System (NOS) TCP/IP packet radio and UUCP network (via telephone line). This software includes the interface for E-mail and news services.
  •	Enhancement of the currect TCP/IP Network Operating System (NOS), such as, capability to handle multiple alias in the E-mail, enhancement in Routing Information Protocol (RIP) routines for properly handling the broadcast RIP.
  •	Software for counting the traffic both E-mail as well as packet.

Most of the software development is currently concentrated at the IUC Microelectronics and the Electrical Engineering Student Society of ITB.

SUMMARY
	In summary, the implementation of TCP/IP-based packet radio technology to integrate various universities and institutions into the first Indonesia's national InterNet Wide Area Network (WAN) is described. The estimated total user in November 1994 is 2869 users with 72.6% are at universities. Various efforts include TCP/IP software development, HDLC X.25 card, various modems (PSK, AFSK, GMSK and high speed MSK) are presented. In addition, various advanced networking experiments, such as, the building of 300bps packet radio via satellite, the development of LEO satellite ground station as well as the effort to design and build a LEO Microsat, is reported.