How the Internet works
All successful technologies enter our lives with a bang – we
are excited, afraid, suspicious of new technology, but if it proves to be useful
to us it becomes part of our daily existence and we cease to notice it until it
is taken away from us. The internet is approaching this stage.
Many of us hear about the internet for the first time and are
excited by the concepts of cheap, fast worldwide communication (email) and
access to a huge range of information (the web). These technologies are so
useful, and the tools we use to access them so easy to use (once learnt) that we
never have time or inclination to ask how they work. The internet has become so
ubiquitous that we rarely ask what it is or how it works.
What is the Internet?
The internet is in fact a network of other networks. The word
internet describes nothing else but the joining up of many networks into a
single network. All of the individual networks have been set up to serve
individual purposes – businesses have networks so workers can share documents;
universities have networks so students can access the same resources;
governments have networks so different departments can look up the same records.
Computer networks are for sharing information and other resources between
computers and the people who use them. The internet joins together these
networks and thus increases the number of people who have access to the same
information.
How?
When you sit down at a computer in an internet café and log-in
to your Yahoo! email account data is flowing from your computer through its
network card. This links the computer to the local area network (LAN) within the
café. This LAN allows all the computers in the café to communicate with each
other, and use the same resources – the printer, scanner and most importantly
the café’s internet connection. The LAN is made up of cables connected to a
router. Routers are used to connect different networks together. From your
café’s router your login details are sent (either by wireless radio or Ethernet
cables) to a local Internet Service Provider’s network. This network connects
together many LANs allowing them to share resources – email servers, web
proxies, and, once again, connection to a wider network serving a number of
ISPs. Your login details are sent on to a regional network provider. In Tanzania
this connection is usually made via satellite to providers who support ISPs in
many countries. Finally, these regional providers’ networks are connected
together with what is called the internet backbone. The internet backbone is
made up of extremely fast connections set up on a national or international
level by large companies and government agencies. Your login details find
themselves on one of these backbones. They are then sent back down the chain
until they arrive at the computer on the LAN of the company who looks after your
email.
The journey looks like this:
Computer - Café LAN - Tanzanian ISP - African Regional
Provider - Internet Backbone - US Regional Provider - US ISP - Yahoo- LAN -
Yahoo!-Mail Server
Phew! Quite a journey! How do your login details know to take
this long and winding route? There must be so many opportunities for it to take
the wrong turn. The navigation is dealt with by routers. At every - in the
diagram above a router is involved. When you click send, a label is attached to
your details saying where they should go – it is the familiar web address
mail.yahoo.com, converted into terms computers understand – an IP address (eg
216.109.127.60). When your details reach a router it examines the IP address and
sees whether it corresponds to a computer on it’s network. If it does not it
sends the message on to the next network up the chain. Eventually your details
will reach the internet backbone. Here computers called Network Access Points
examine the IP address. Consulting databases known as Internet Registries, the
Network Access Point finds out which Regional Provider’s connection to send the
details. From here on in, routers examining the IP address will know which route
the details should take, and pass them down the chain until they reach the
appropriate computer. The journey then begins again as the list of your email
messages is sent back to you in Arusha. An epic journey which can take less than
a second.
News Flash
Arushan computer users unable or unwilling to fork out for a
new version of Norton Anti Virus each year had only one option – The rather
basic AVG Anti-virus from www.grisoft.com.
That is until now – Computer Associates have recently released their eTrust
software for free download with free updates for a year. Go to
www.my-etrust.com/microsoft/
for details and the download. Not free for ever and probably just a marketing
ploy, but maybe worth a try if AVG isn’t up to your expectations and your Norton
subscription has run out.
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