Network Hardware (Cambridge (CIE) IGCSE ICT)
Revision Note
Router
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
![router](https://cdn.savemyexams.com/cdn-cgi/image/f=auto,width=3840/https://cdn.savemyexams.com/uploads/2024/03/router.png)
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:
Header | Payload | Trailer |
---|---|---|
Source IP address | Actual data being transported | Additional security information |
Destination IP address | End of packet notification | |
Packet number (1 of 5 etc.) | ||
Error checking (checksums) |
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](https://cdn.savemyexams.com/cdn-cgi/image/f=auto,width=3840/https://cdn.savemyexams.com/uploads/2024/02/ipv4.png)
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](https://cdn.savemyexams.com/cdn-cgi/image/f=auto,width=3840/https://cdn.savemyexams.com/uploads/2024/02/-ipv6.png)
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
![nic-](https://cdn.savemyexams.com/cdn-cgi/image/f=auto,width=3840/https://cdn.savemyexams.com/uploads/2024/03/nic-.png)
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
![switch](https://cdn.savemyexams.com/cdn-cgi/image/f=auto,width=3840/https://cdn.savemyexams.com/uploads/2024/03/switch.png)
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
![mac-address-1](https://cdn.savemyexams.com/cdn-cgi/image/f=auto,width=3840/https://cdn.savemyexams.com/uploads/2024/02/mac-address-1.png)
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
![2-1-networks-common-network-devices-04](https://cdn.savemyexams.com/cdn-cgi/image/f=auto,width=3840/https://cdn.savemyexams.com/uploads/2023/05/2-1-networks-common-network-devices-04.png)
Worked Example
Explain the difference between a switch and a hub regarding data forwarding capabilities.
[2]
Answer
A switch forwards data packets based on the destination MAC address and only sends data to the intended device [1]
A hub broadcasts incoming data packets to all connected devices [1]
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