TOK

Computer Networks are used by billions of people all over the world, with both positive and negative consequences.

Should we hold people responsible for the technologies they create?

Objectives - Topic 3

Students will be able to:

  • 3.1.1 identify different types of network
  • 3.1.2 outline the importance of standards in the construction of networks.
  • 3.1.3 describe how communication over networks is broken down into different layers.
  • 3.1.4 identify the technologies required to provide a VPN.
  • 3.1.5 evaluate the use of a VPN.

protocols

A (network) protocol is an established set of rules which devices must follow in order to communicate across a network.

Some examples of protocols are:

  • http, https : for communicating on the Internet
  • smtp: for sending and receiving email
  • tcp: for creating data packets to be transmitted

Peer-to-Peer Networks

 

Client/Server networks are extremely popular.

However, there is another popular network type that allows devices to share resources: peer-to-peer (p2p)

In this kind of network, every device is a client and every device is a server! There is no central server. It is known as a decentralised network.

network fundametals

crash course

A Local Area Network (LAN) is a network of devices connected together by cables and/or wifi in a relatively small geographical area eg a school or an office building.

Their main aim is to communcate and share files.

Task

Watch the video and answer the questions on the question sheet.

In order to communicate on a network, devices need to follow a eg:

  • HTTP - HyperText Transfer Protocol: to communicate on the Internet
  • TCP - Transfer Control Protocol: to communicate on a network eg a LAN
  • SMTP - Simple Mail Transfer Protocol: to send and receive emails

But what if the files that a device requires are on someone else's device and that device is turned off?

The solution to this is to have a special computer called a server which stores files and resources that other devices can request when needed.

These other devices can be considered clients, requesting information from the server.

Most servers have to be on 24 hours a day, 365 days a year!

LAN ISSUES

Ethernet cable offers faster transmission than wifi. Also, physical objects like walls may cause interference with a wifi signal.

Also, it is hard to break into a cabled network unless you are in the building and devices don't have some kind of security measure eg password protection.

However, if you are within range of the wifi signal, you can attempt to join the network. A wireless network is considered less secure than a cabled network and, as the above image shows, connecting a wireless network to a wired network will make the wired network vulnerable to an attack!

Network Interface Cards (NIC)

Did you know that your device has a NIC?! This allows your device to join a network. It has a special address coded into it - it is unique and called the MAC (Media Access Control) address.

Your MAC address is needed so that when you send messages across the network, other devices know where the message came from.

A NIC can require a cable to attach it to a network or it can be a wireless NIC, for example in your smartphone!

So, the next time you connect to the Internet, don't forget that your NIC is a very NICE thing to have!

Food For Thought

The Internet is global and would never work without agreed-upon protocols for the transmission, routing and receiving of data. Imagine if each sub-network on the Internet used a different set of rules for the sending and receiving of data?! It would be chaos!

The Internet is considered reliable because it is fault-tolerant - if one route breaks, another can be used.

So, enjoy it while this scenario remains!

Projects