Network Hardware (Cambridge International IGCSE ICT)

Router

Spec point — 4.1.1

What is a router?

• The router is responsible for routing data packets between different networks
• An example of data the router can direct is, sending internet traffic to the correct destination/devices in your home network
• The router connects networks together, local area networks (LAN) to the wider internet which is a type of wide area network (WAN)
• The router can manage and prioritise data traffic, which can help to keep connections stable
• The router will assign IP addresses to the devices on the network

What are data packets?

• Data packets are small 'chunks' of data that make up a larger piece of data that has been broken down so that is can transmitted over the internet
• Data can include anything from text, images, audio, video, animations, etc, or any combination of these
• A data packet consists of:

What is an IP address?

• An IP (Internet Protocol) address is a unique identifier given to devices which communicate over the Internet (WAN)
• IP addresses are dynamic, they can change
• IP addresses make it possible to deliver data to the right device
• A device connecting to a network will be given an IP address, if it moves to a different network then the IP address will change

IPv4

• Internet Protocol version 4 is represented as 4 blocks of denary numbers between 0 and 255, separated by full stops
• Each block is one byte (8 bits), each address is 4 bytes (32 bits)

• IPv4 provides over 4 billion unique addresses(2³²), however, with over 7 billion people and countless devices per person, a solution was needed

IPv6

• Internet Protocol version 6 is represented as 8 blocks of 4 hexadecimal digits, separated by colons
• Each block is 2 bytes (16 bits), each address is 16 bytes (128 bits)

• IPv6 could provide over one billion unique addresses for every person on the planet (2¹²⁸)

Network Interface Card (NIC)

What is a network interface card (NIC)?

• The Network Interface Card (NIC) is required for a computer to connect to a network
• A NIC can be both wired and wireless and allows your computer to send and receive data over a network

Hub

What is a hub?

• A hub is a networking device which is used to connect multiple devices in a network
• Hubs are "dumb" devices that pass on anything received on one connection to all other connections
• All data is sent to all devices, this can lead to network inefficiencies and security issues

Switch

What is a switch?

• A network switch is a device that connects multiple devices on a network together
• Unlike a hub, a switch only sends data to the device it was intended for, which improves network efficiency
• This is done by a switch ****having a lookup table
• When a switch receives a** data packet, it examines the destination MAC address** of the packet and looks up that address in the lookup table
• Once it has found the matching MAC address it will then forward the data packet to the corresponding device

What is a MAC address?

• A MAC (Media Access Control) address is a unique identifier given to devices which communicate over a local area network (LAN)
• MAC addresses are static, they can never change
• MAC addresses make it possible for switches to efficiently forward data to the intended recipient
• Any device that contains a Network Interface Card (NIC) has a MAC address assigned during manufacturing
• A device connecting to a local network already has a MAC address, if it moves to a different network then the MAC address will stay the same

• A MAC address is represented as 12 hexadecimal digits (48 bits), usually grouped in pairs
• The first three pairs are the manufacturer ID number (OUI) and the last three pairs are the serial number of the network interface card (NIC)
• There are enough unique MAC addresses for roughly 281 trillion devices

Bridge

What is a bridge?

• A network bridge is a device used to connect two local area networks(LANs) together to create one larger network
• Unlike a switch/hub, bridges only connect local area networks together

Worked Example Explain the difference between a switch and a hub regarding data forwarding capabilities.

[2]

Answer

Final answer: A switch forwards data packets based on the destination MAC address and only sends data to the intended device [1]

Final answer: A hub broadcasts incoming data packets to all connected devices [1]