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.

Originally published in Arusha Times 308

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