8_2_6

Activity 1 - READ

What is a network? A computer network is a number of computers linked together to allow them to share resources. Networked computers can share hardware, software and data.

Most computer networks have at least one server. A server is a powerful computer that provides one or more services to a network and its users. For example, file storage and email.

There are two main types of network:

Local Area Network (LAN)

Covers a small area such as one site or building, eg a school or a college.

Wide Area Network (WAN)

Covers a large geographical area. Most WANs are made from several LANs connected together. An example of a WAN is The Internet.

Networks are connected using structures known as Topologies.

The most common network topologies are Bus, Star, Ring and Mesh. The names are linked closely to their structure. You can see basic interpretations of these topologies in the image.

Networks can be:

• Wired (connected only through hard wiring)
• Wireless (connected only through wireless technology)
• Mixed (a mixture of both wired and wireless)

Activity 2 - READ

The client-server relationship

Networks share resources using a central server. A relationship is established between the client (workstation) and the server.

The connection is known as a 3-way handshake.

The client says "Can we synchronize?"

The server says "I acknowledge that you want to synchronize"

The client says "I acknowledge your acknowledgment"

Once the 3-way handshake has taken place, communication can happen and data can be sent.

Activity 3

Research the advantages and disadvantages of these four network topologies:

• Bus
• Star
• Mesh
• Ring

Design an ideal computer room. Think about:

• The network topology
• The type of connection
• The added extras (printers etc.)
• The room layout

Justify your design giving reasons for the connections chosen.

Act out the different topologies in the school playground. Use short pieces of string as wired connections and time the class sending data from the server to the user.

Record the timings and use the scores to evaluate different topologies.