Afrik-ITers may be interested in this article which was distributed over a new mailing list called
'linux without borders.'
The article deals with setting up wireless LAN networks in universities (using Linux).
The new list deals with using Linux in resource-poor situations where people more often than not
share computers with others. (FYI: Linux is a particularly good operating system when it comes to
handling multiple users on a single computer)
To subscribe, send E-mail to: [log in to unmask] with the following line in the body of the message:
Program Officer, Bellanet International Secretariat
[log in to unmask]
From: Enrique Canessa <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: March 12, 1999 8:42 AM
Subject: Wireless Networking in Africa
:Draft of Article appeared in "Linux Journal", Dec 1998.
: WIRELESS NETWORKING IN AFRICA
: F. Postogna, C. Fonda, E. Canessa, G.O. Ajayi and S. Radicella
: The Abdus Salam International Centre for Theoretical Physics,
: Trieste 34100, Italy - E-mail: [log in to unmask]
: Global connectivity in Africa is in an early stage due to installation
:costs, insufficient basic infrastructures, low quality of available
:telecommunication services and limited financial support. The application
:of wireless technology then might become an effective choice to overcome
:some of these problems, at least within reduced areas and even if the
:transmission speed could be lower than the one achieved by wired networks.
: Within an University campus, it is easier to install a radio link system
:than to dig around and place cables or expensive optical fibres.
:Furthermore, radio installations are easier to protect from external
:natural phenomena such as flood, landslide, etc. At a first glance,
:wireless LANs look more expensive than wired LANs, but, in the long term,
:they have lower maintenance costs and are also relatively easy to
:configure. The use of Linux and standard radiocommunication technologies,
:in conjunction with the many Linux software applications, facilitates even
:more this task.
: With this picture in mind, the "Programme of Training and System
:Development on Networking and Radiocommunications" started in 1995 at The
:Abdus Salam ICTP, Trieste, Italy. Since then, the objective of this
:Programme has been to provide technical assistance and training to
:academic and scientific institutions in developing countries in need to
:establish small area computer networks, and their connection to the
:Internet, either directly or through national networks. Briefly described
:here are our experiences of wireless networking with Linux in Africa.
: The Abdus Salam ICTP in Trieste, Italy, and Obafemi Awolowo University
:(OAU) of Ile-Ife in Nigeria, agreed to collaborate in the establishment
:and future evolution of a Pilot Educational and Research Computer Network
:at OAU. Such a network, based principally on PC computers running Linux,
:today provides connectivity between several Faculties and Departments on
: The training of technical staff on the hardware (PCs, cabling, radio
:techniques) and software (network and system administration) took place
:initially in Trieste. The developmental and simulation work was completed
:in four months, ending in January 1996, when all the necessary equipment
:was sent to OAU. The system was installed in April 1996. At this time
:some staff of other Nigerian Universities came to Ile-Ife in order to
:benefit from this exercise and meet Linux for the first time. Besides
:getting acquainted with the new technology, this experience led to further
:connections to the OAUNET. The campus network has been in operation since
:June 1996 without major problems being highly beneficial for the academic
:life of the University.
: THE FIRST CAMPUS NETWORK
: As shown in the diagram of Fig.1, the wireless campus network (OAUNET)
:was planned on the basis of a radio system in the UHF band, initially
:involving three separate buildings with the capacity to rapidly being
:extended to other University structures. The wireless link uses a Spread
:Spectrum Direct Sequence technique providing data transmission at 2Mbps.
:The so-called "Spread Spectrum" is a digital coding method in which the
:signal is transformed or "spread" so that it cannot be received by any
:receiver except the designated one which understands the transmitted
:signal code. It minimizes interference to other users and normally does
:not require an operation license in the ISM (International Scientific and
:Medical Band), depending of the regulation adopted by the country.
: Inside each building an Ethernet 10-BASE 2 cabling structure is installed
:in order to keep the initial costs as low as possible (no hubs, less
:cable) and to ensure the local availability of spares (BNC), etc. In each
:of these buildings, a Linux PC acts as "Faculty Server" and provides mail
:services for the local users and does routing to the backbone. This type
:of strategy has been selected to keep the user generated traffic local,
:and so reduce the access to the main backbone. All services are TCP/IP
:based to keep the system as standard as possible with Internet protocols,
:avoiding future modifications when a full connectivity might be provided
:to the University.
: The academic network gateway and the main mailhost are located at the
:Department of Computer Science of the University. Due to national
:regulations and to the lack of a permanent connection to Internet, the
:gateway is linked to the Internet on a dial-up base (uucp) using an
:International Direct Dialing line to the ICTP computer network in Trieste,
:Italy. Software was developed by OAU staff with some assistance from ICTP
:to refine over the basic uucp mail transfer: a custom sendmail delivery
:program batches mail in intermediate-sized, BSMTP formatted files; these
:files are compressed as much as possible before being transferred over
:uucp. To cope with telephone line instabilities, a uucp relay was placed
:in Lagos: the uucp configuration takes cares of selecting either path,
:choosing automatically the one that works.
: STICKING TO LINUX
: Previous in-house experiences with the Unix system (SunOS and SunSolaris)
:led us to test, within the Project, the commercial Solaris 2.4 (x86
:version) and Linux. While this version of Solaris required specific
:hardware components to function on the available (486) PCs, Linux was
:found more flexible in terms of hardware compatibility and low memory
:requirements. On top of that, the possibility of having high quality free
:compilers and software applications, motivated us to continue using Linux
:to the present. Only two years ago the alternative Windows NT was just
:starting to be popular around the world, so this possibility was not then
:considered. At that time, Linux was also unknown in the Nigerian academic
:world. The main operating systems available there were MS-DOS & Windows
: The Linux distribution chosen was the Slackware distribution. Though more
:difficult to install than other distributions, right from the first trials
:the system configuration (start-up scripts, etc) was easier to locate,
:understand, manage and, most importantly, it was easy to teach. After a
:whole cycle of Linux setup experiences and training, autonomous management
:of all aspects has became a reality. Part of the system installed at the
:OAU is shown in the Picture.
: CAMPUS WIRELESS CONNECTIVITY
: In order to achieve campus wireless connectivity, the requirements needed
:from the system administrator point of view were to have a network working
:all day and night long with the least possible human intervention, as well
:as to have a reasonable throughput (bandwidth). The technology adopted to
:do this job was, as mentioned above, Spread Spectrum.
: The first attempts were implemented using Direct Sequence Spread Spectrum
:card which is supported by the Linux kernel. Most recently an alternative
:Spread Spectrum equipment that does not require the Linux kernel support
:is being tested, not because of Linux unreliability, but because this new
:equipment instead of being an ISA card to plug in a PC, has an Ethernet
:interface. This configuration makes the installation of a wireless link
:much easier and flexible, because you can place the radio unit very close
:to the antenna (keeping attenuation very low) and connect it to the PC
:using a UTP cable. In the case on an ISA card the RF output is at the rear
:side of the PC and from there the antenna is connected. But due to the
:small output power and the attenuation of the cable it is not advisable to
:use more that 10m of coax. This new equipment uses a different spreading
:method called frequency hopping and provide a higher bandwidth.
: The possibility of using packet radio technologies, which are very well
:supported and documented under Linux (AX-25 HOW-TO), were analyzed at the
:beginning of the Project. However, due to the specific training required,
:the implementation of this technology was postponed. An advantage of the
:present Spread Spectrum installation, running since two years without
:major interventions, is that it is almost plug, play and go.
: The local network is in fact stable and does not suffer from failure of
:primary main power supply, because of the standby generator availability
:and UPS facilities. The number of registered users of the network
:increased from 150 in early August 1996 to about 290 in September 1996,
:with a number over 600 now.
: ON-LINE SERVICES
: Campus-wide services such as e-mail and FTP, WWW, NFS are today available
:within the OAUNET. As anticipated, connection to the rest of the world is
:done on a dial-up line so that only e-mail exchange is provided freely to
:the local users. There is not limitation in the amount and size of the
:information being transferred on the campus.
: Some of the communication applications like TALK or WRITE become important
:due to the poor performances of the local PABX. For example, after the
:take off of the network, people that used to walk in order to speak with
:an administrative officer or a colleague are now enjoying the relax of a
:TALK between two building located a few kilometers apart. To reduce
:bandwidth usage only "text" based conferences tools are being
:implemented. Hopefully, voice over IP will be also experimented in the
: All of these new communication tools are certainly providing a
:revolutionary change in the local academic life.
: NEXT STEPS
: The next phase of the wireless network requires the installation of other
:Internet services on the OAUNET. For example, arrangements are being made
:to provide connectivity to the Library and other Faculties such as
: The success of the Ife experience stimulated cooperation with other
:Nigerian Universities. A large program of cooperation with the National
:Universities Commission for the establishment of a national academic
:network started in 1996 and it is still going on. Linux is one of the
:technical basis of this activity; on the other hand, the most interesting
:applications of radio till now have been in individual Universities. Among
:these, is the Bayero University (Kano) which decided to built up a link on
:a larger distance to connect the new campus with the old Campus of the
:University (about 9 Km). This connection is implemented using a
:commercial wireless equipment and two Linux machines as routers, with one
:of them as the whole university mail server and uucp gateway.
: Following these results a series of additional proposals have been
:received at our headquarter in Trieste. The first of these new projects
:is being carried out in Ghana and collaboration with countries such as
:Democratic Republic of Congo, Ivory Cost and Morocco will start soon.
: No doubt, these initial experiences with Linux in Africa are a proof of
:the success and reliability of Linux.
: This Programme is partially supported by the United Nations University
:(UNU). Swisscomm has donated microwave links and several measurement
:instruments and equipment that constitute the foundation for the
:establishment of a laboratory which is being utilized for practical
:exercises in the framework of the Programme and the concrete field
:Our appreciation also goes to Dr A. Nobile, one of the coordinators of the
:Programme, and Dr. E. Ekuwem, Mr. A. Maggi and C.E. Onime who are actively
:participating in this Project.