Mike Whitehead
University of Dundee
Email: M.J.Whitehead@Dundee.ac.uk
We need to explain some of the jargon:
FaTMAN is the Fife & Tayside Metropolitan Area Network.
(The stylistic oddity of the lower case "a" was started by FaTMAN to try to avoid it being thought to refer to obese males). Other MANs in Scotland have adopted similar titles with similar styles:
Do Fife & Tayside count as a Metropolis?
Fortunately, the Concise Oxford Dictionary gives the definition
" Metropolis n. ... a centre of activity ".
This is perfectly fitted to our current requirements.
The usual rule of thumb is that LANs are very fast, MANs are quite fast, and WANs are slower. But FaTMAN and the Interconnections between then now give us faster MANs and WANs than most of our LANs. This just shows that we are living in a world of change.
The purpose of MANs is to link together LANs and campus network and to link to other MANs and/or to the Internet
But this is supposed to be a technology talk so we need to mention that FaTMAN uses ATM.
First what does ATM stand for? It does not stand for:
ATM stands for Asynchronous Transfer Mode
Asynchronous just means that messages are transferred without being synchronised - i.e. they can be sent when they are ready. The name and the technical details are not relevant to our purpose.
... but the technology is vital.
ATM is used because it is designed to be scaleable and multi-service
1. Scaleable - because it can run at several different speeds.
So, you set up an ATM network. When the network becomes busy and overloaded you just buy a faster ATM switch. This uses the same technology and the same core network - no need to change all your equipment.
This is in contrast to Ethernet where the speed of operation is a fixed part of the design so you cannot just run it at a higher speed in the way you can with ATM.
ATM has a simple design - based on hardware switches.
ATM is appropriate to LAN, MAN & WAN. You can use it within your department, within the campus and it can be used as the foundation of JANET.
2. The second major feature of ATM is its Multi-service nature. This means that it can carry a variety of services. Unlike its predecessors, it was not designed specifically for data or for voice or for video. They each have special characteristics and ATM is designed to provide adequate transmission for each - a compromise. As an example, video needs data delivered precisely on time or the pictures break up. Audio is even worse. But computer files can arrive in fits and starts without any problems.
The final advantage of ATM is that there is no alternative: ATM is the only widely accepted system that enables comprehensive modern networks to be created.
So why this concern with speed and "multi-service capability".
For FaTMAN, ATM operates at 155Mbps. This is over 1 million times faster than the old teletype - which lives on in virtual form to display the football results each week. A good reading speed?
This table shows some examples of speeds of various networks from the old teletypes (mechanical devices from the 1960s), through ISDN to ATM. ISDN is the Integrated Services Digital Network (another term where the name is no more meaningful than the acronym). It is used extensively for video conferencing. ISDN2 refers to the equivalent of two telephone lines (to use it you pay approximately the price of two normal telephone calls). ISDN6 refers to the equivalent of six telephone lines (to use it you pay approximately the price of six normal telephone calls).
Teletype = 110
X.25 PAD lines = 9 600 9.6Kbps times 2
Home MODEM link = 28 800 28.8Kbps times 2
ISDN line = 64 000 64Kbps times 2
ISDN-2 = 128 000 128Kbps times 2
ISDN-6 = 384 000 384Kbps times 2
Ethernet = 10 000 000 10Mbps shared
FDDI = 100 000 000 100Mbps shared
ATM = 155 000 000 155Mbps times 2
ATM = 622 000 000 622Mbps times 2
As an example, Ethernet which operates at 10 million bits per second can carry approximately one book per second. This is based on the following calculations:
1 book
= 200 pages
* 50 lines
* 100 characters
* 8 bits per character (i.e. 8 bits per Byte)
= 200 * 50 * 100 * 8 bits
= 8 000 000bps
= 10Mbps (roughly Ethernet speed)
For comparison, video requires much greater capacity. For transmission over the network it is compressed then transmitted and then decompressed before being displayed at the far end.
There is a limit to the amount of compression you can do - if you go beyond a certain point you lose some of the quality of the picture. At first you lose some detail. Eventually, you get jerky pictures if there is not sufficient capacity to transmit sufficient details.
At present, ISDN2 at128Kbps gives barely adequate quality
ISDN6 at 384K gives pretty reasonable quality.
At 2Mbps quality is getting closer to camcorder standard.
By 10Mbps, quality is almost getting to broadcast TV standards.
Now let us see what FaTMAN looks like in practice.
We put an ATM switch at each site. These are connected by 155Mbps ATM. This provides a wide channel between the Universities. It operates over fibre optic cable rented from ScottishTelecom.
Our first step was to use some of the capacity between sites to interconnect the campus LANs. This provides higher speeds than SuperJANET but still leaves some spare capacity....
... which can be used for video, etc.
I have shown a couple of video connections but you can add as many as you need subject to the available bandwidth.
Now let us see how this affects your computers connected to the network.
It is the strongly held belief of all your network staff that you never know you are using a network. We hide it all from you .. until things go wrong or until you don't give us enough money. So you will almost certainly have used FaTMAN already, just like you have used the Internet.
I think of all your PCs, Macs and workstations as part of your campus network, part of JANET and part of the Internet. The Internet is just the collection of interconnected networks around the world - it is not something identifiable as a special bit of wire somewhere in New York. So FaTMAN is part of the modern Internet - if you like, it is a component of the long heralded Information Superhighway.
The Interconnection of the four Scottish MANs is a very important part of this development. And it heralds a model for the replacement of SuperJANET due in March next year.
We are very lucky in Scotland to have a forward looking funding council (SHEFC), supportive Principals and a company - ScottishTelecom - which has been willing to sell us fibre optic cable services. England has neither the same sums nor the same willingness from suppliers and so are generally getting less adequate connections than are we in Scotland.
But there is more to the future than high bandwidth and multi-service networks... It is not just about network speeds and technologies. Computer networking is changing as
...New applications are developed
But the WWW is perhaps the most startling
It has grown from nothing a couple of years ago to be the thing.
When people talked about "The Internet" in the old days, they often meant "the NEWS service"
Nowadays, they mean "The Web"
And the World Wide Web is changing in a revolutionary way....
Java seems to be the hottest word around at the moment. It's new and it's lively.
Java is special because it is designed to run on many computers - such as Apple Macs, UNIX workstations and PCs. It is Platform Independent
Java can be delivered over the network.
It is these two features which have enabled the explosive growth of the WWW. This has succeeded by using a fairly simple system which can be run on almost any computer in the world. The same principle of preparing ONE web page which can be displayed on ANY computer ANYWHERE in the world applies to Java.
So Java heralds a paradigm shift which could have significant implications for teaching.
Java enables "Applets" to be created. These are small applications. Instead of loading a massive application like Word for Windows, you could load a word-processor with only the basic functions. Then - when you want to do a spell check - you could just load a suitable applet over the network.
No longer need you load "bloatware" onto your computer".
No longer do you need to be a skilled system administrator just to have a PC on your desk
Instead you use what you need, when you need it. The Applets run on your own computer but they are not stored on your hard disk.
While Java is the herald of this revolution it may not win the battle for supremacy. But it does have astounding momentum. Considering that Java was only announced a year ago it is amazingly well entrenched already - having been adopted by many major manufacturers - inc. Microsoft - even though it is not their product.
It is Object Oriented. This helps to ensure that the programs are accurate. It also enables programs to be written once but used in a variety of circumstances. You take an existing "object" and modify its behaviour.
I may need to reassure you that Java is secure. Its designers considered problems like viruses and have ruled them out.
Let us just mention Platform Independence once more. Java will run on all these computers but - on an IBM compatible PC you have to use Win 95, Win NT etc.. There are inadequacies in Win 3.x which mean it cannot run Java.
The principle of Java programming is clear:
First option is to make your pages move with animations written in Java.
But it is the ability of Java to make the Web to become properly interactive which is vital.
You can make far more use of the web to involve visitors in your web pages. e.g. students could use the pages to explore models. This might mean they type in numbers and see the effects of these parameters - e.g. controlling a nuclear power plant - or it could mean that they take their exams on the web.
Java makes this much easier.
The benefits of Java means that you should try to use it for all new client applications.
Not everyone wants to become Java programmers. Java is not easy to use - but developments are helping. JavaScript is one example - it provides a reasonably simple way to develop applications for the Web. Java itself is much more flexible. But you will be able use Java based facilities to provide enhancements (such as interactivity) for your Web pages. People will write Java Applets which you can exploit without having to learn Java.
Use Java & Web for all student work
You could consider using the WWW to present courses.
It is not only the ability of students to read material when they want to. Books have done this for years.
The key thing about the opportunities provided by Java is the ability to go beyond books and include truly interactive material.
So if the Web and Java allow you to prepare material for your students why stop at local students? The Web is global. This means that U Wisconsin could teach students in Broughty Ferry as readily as you and me. This may not help for the "maturational market" where the students start off as spotty first years and end up as professionals with learning, skill and experience. When you update your lecture notes each year, why not sell these changes to last years students as part of an update course? This is already being done by Stanford and others.
Books gave increased power to students. The Web has even greater potential.
We could at last be seeing a new information age - changing the face of computing, networking and teaching & learning. Learning throughout life - controlled by the learner not the teacher.
Books started off as individually produced and carefully guarded sources of wisdom for the elite
Volume printing has produced books for everyone
The Web is like a book - globally available information at an affordable price.
But books are not interactive
So we have correspondence courses. Slow and cumbersome.
The Internet brings new levels of interactivity
Components of this change are:
Video conferencing over the Internet - personal interaction on a global scale.
Time for some conclusions:
FaTMAN is not just tabout increased bandwidth
Many new services will have significant impact on what we do: examples include video conferencing and electronic libraries.
Before concluding, I would like to that Mairead Kirby for her work in setting up the network for the day.
I would also like to thank Bruce Mitchell and Moira Grainger of the University of St Andrews. They acted as lead site for the FaTMAN installation and we would not be where we are now without their efforts.
Other talks will show you some exciting and innovative use of networks.
So, my message is: Expand your Network Support Teams and give them a pay rise.....
Because, more than ever before, ..
This talk was given at a meeting to promote awareness of the Use of Metropolitan Area Networks. The meeting was organised by LTDI - the Learning and Technology Dissemination Initiative in conjunction with the FaTMAN Consortium members.
West Park Conference Centre
Perth Road
Dundee
Tuesday 21st May 1996
