The development of computers and telecommunications has led to the growth of university computer networks that are essential in the fields of research, education and university administration. The National Autonomous University of Mexico, one of the largest in the world with a student population of about 350,000 and an academic and administrative population of about 80,000 distributed on 35 campuses throughout the country, has implemented an academic com- puter network that offers the following services:

• Access to very specific or costly computer resources not available in the country through an international satellite link with the NSFTNET,

• Computer and communication resource sharing,

• Access to national and international databases,

• Access to computer programs and applications developed on and off the university campus,

• Access to national and international academic and research communities for information exchange and experience sharing,

• Access to national and international electronic mail services through the BITNET and INTERNET nodes on campus,

• Access to commercial networks such as TELEPAC, INFONET, TYMENET, etc.

Rapid, efficient and trustworthy channels of communication are a must for any institution which generates and disseminates knowledge. Even though wide area networks and satellite links are still a controversial matter in Mexico, their use is constantly increasing to meet our universities changing needs because they improve the quality and quantity of academic research, and provide opportunities for worldwide and national joint academic ventures. These same channels of communication have also permitted us to decentralize administrative procedures. All of this has been made possible by revolutionary developments in the fields of micro-electronics and telecom-munications as the latest in communication technology such as fiber-optic cables, microwave connections and satellite links have been integrated into UNAM'S network.

2. THE SATELLITE LINK

In 1986, we began to analyze possibilities for long distance communication via satellite at the Institute of Astronomy on our Mexico City campus due to the constant need to transmit a great quantity of date between this institute and our installations in Ensenada and San Pedro Martyr in Baja California Norte. At the same time we started making contacts with NSFNET to study the feasibility of establishing contact with supercomputers in the USA also via satellite link. The decision was made to use the Morelos Satellite System for this purpose. Our initial design included three satellite nodes: one at the Institute of Astronomy in Mexico City, another at the Monterrey Institute of Technology and Postgraduate Studies (Instituto Technologic y de Estudios Superiores de Monterrey) and a third at the National Center for Atmospheric Research located in Boulder, Colorado -- this last being where we logged on to the NSFNET. Agreement was reached that this satellite link would be used exclusively for academic purposes and also that the UNAM would permit any national educational institution to make use of this facility. Each institution would pay for its own installation, operating and maintenance costs. In April 1988, the project was expanded to include two additional nodes; one at our research center in Ensenada, and the other at our installations in Cuernavaca, Morelos. Each of these additional nodes would also be connected to the NSFNET via satellite link with Boulder, Colorado. The nodes in our university system have the following characteristics:

• The antenna at the Institute of Astronomy has a diameter of 3.7 meters while the node operates with a power of 4 watts on KU bands at 128 bps with a growth capacity for up to 256 k bps,

• The antenna in Ensenada measures 1.8 meters in diameter: the node operates with a power of 2 watts at 64 k bps,

• The antenna at our facility in Cuernavaca measures 2.4 meters in diameter while the node operates with a power of 2 watts at 64 k bps.

Our international entry node at Boulder Colorado has an antenna which measures 4.6 meters in diameter and operates with a 4 watt power at 128 k bps. Communication protocol between nodes is TCP/IP. It is important to stress that the impact of this satellite link on the academic life of our university has been greatly increased by our own computer networks.

3. UNAM COMPUTER NETWORKS

Our communication needs are not limited to satellite links but also depend on the efficient use of local and wide area networks in Mexico City. Generally, users of computer networks are connected by a local area network to a host computer which may be anything from a workstation to a large mainframe. This, in turn, is connected to other computers or local area networks, with the difference that it is usually designed to transmit great quantities of data long distance at speeds measured in millions of bits per second. Lastly, this backbone network is connected to other large computer systems forming wide area networks.

4. UNAM LOCAL AREA NETWORKS

UNAM ETHERNET and TOKEN-RING local area networks exist at the Instrument Center, the School of Science, the School of Chemistry, the School of Business Administration, the School of Engineering, the School of Psychology, the Institute of Astronomy, the Institute of Nuclear Sciences, the Institute of Geophysical Research, the Institute for Materials Research, the Institute for Research in Applied Mathematics and Systems, the Institute of Engineering, the Administration Building and in our Central Academic Computer and Telecommunications facilities. These LAN, have a great variety or equipment including micros, PS/2, PC, SUN, IBM, HP and VAX and an IBM 4381 in the central academic computer center.

5. BACKBONE NETWORK

Our backbone network uses fiber-optic cables with a transmission speed of 10 to 16 m bps. Who would have thought that conventional metallic wires would one day become obsolete? However, the revolutionary developments in the field of fiber optics have transformed the commu-nication industry. In systems based on fiber-optic principles, light rays are transported on very fine fiber-optic fibers capable of transmitting several thousands of individual telephone conver-sations on one single cable.

The fiber-optic cables used in our backbone network have been protected with a waterproof and rodent-proof jacket. Inside each cable there are four fibers 62.5 by 125 micras. These cables are immersed in poyduct tubes. These tubes, in turn, are generally inserted inside existing tele-phone channels (lines). Occasionally it has been necessary to lay new cables. Reduced dimen-sions and weight together with greatly increased transportation capacity contribute to make fiber-optic cables the best available today for data transmission.

Our backbone network based on either TOKEN-RING or ETHERNET architecture interconnects six local area networks in the following locations:

• The Central Academic Communications and Telecommunications Facilities

• The School of Science

• The Institute of Astronomy

• The School of Nuclear Sciences and the Institute for Geophysical Research

• The Instrument Center

• The Institute for Atmospheric Research and the Central Institute for Scientific and Humanistic Research.

Using modern technology we are now able to connect new locations to our backbone network in periods less than two weeks.

6. FEATURES OF UNAM'S NETWORK (June 1990)

The network has the following features:

• 30 miles of installed fiber-optic cables for high speed date, voice and video

• 38 multistation access units including about 230 token-ring stations at 16 M bps

• 4 ground stations for national and international satellite communications and 10 more at the planning stage

• 3 microwave stations for inter campus high speed voice/data communications

• 50 minicomputers and mainframes connected to the network using their own operating system and TCP/IPP protocol

• 32 Ethernet segments including 100 mainframes, minicomputers and work stations

• A private pbx digital system for 15,000 ports (operational in 1991).

7. HIGHLIGHTS

• Token-ring and Ethernet backbones interconnected via an UNGERMAN BASS card in an IBM 4381 communications processor,

• Beta test of 16 M bps token-ring speed,

• First wold test of a UNYSIS A series mainframe connected to the Ethernet backbone using TCP/IP,

• Low/high voice/data network looking forward to FDDI and to ISDN technologies,

• BITNET node for EDUCOM members,

• INTERNET node for NSFNET.
 

8. CONCLUSION

In the near future it is essential to set up the additional infrastructure necessary to bring our entire academic community together so that we may all exchange ideas, information and experien-ces with our fellow colleagues. UNAM'S network, the first national metropolitan area network (MAN), has been selected as a model for others to imitate.