Network Types

Network Types

There are two types of networks:

• Local Area Network (LAN) is a network typically contained wholly within a single site and entirely owned and controlled by a single organisation.

• Wide Area Network (WAN) is a network that spreads over a geographically large area. It is characterized by its dependence on Public Telecommunications Providers for either dial-up or dedicated services.

In addition to these traditional two there is another type of network called MAN.

• Metropolitan Area Network (MAN) is a large network usually spanning a university or a city. It typically uses wireless infrastructure or optical fiber connections to link its sites. 

Introduction 3 - Modems

Introduction...

  3. Modems

Modem is the shorter form for MOdulator/DEModulator. It connects a computer to a phone line. A modem converts digital signals (a stream of bits) to analogue signals ( a continuous wave) which is the format used in telephone lines. That analogue signal is sent through the telephone lines.

Figure 1.4 shows how external modems are used with computers to send and receive data over the telephone network. There are internal modems that fit to an expansion slot on the motherboard. Modems have different transmission speeds, measured in bits per second (bps), or in baud.

Figure 1.4: Modems converting digital bit streams to analogue signals and vice versa

Image Credit: CPE Wiki

Introduction 2 - Network Interface Cards

Introduction...

  2. Network Interface Cards

The network interface card (NIC) is installed in an expansion slot of the computer. This card (Figure 1.2) connects the computer to a network, and contains information on the computer's location and also instructions for sending and receiving data over the network.

It adds a serial port to the computer and the port connects directly to a network. NIC converts the computers' low power signals to high power signals that can be transmitted over the network. NIC's speed is measured in megabits per second (Mbps).

Figure 1.2: Network Interface Card (NIC)