Wired and wireless networks, protocols and layers

Wired and Wireless Networks

Modes of Connection

Wired:

Ethernet
Fibre optic cables

Wireless:

Wi-Fi
Bluetooth

Wired Connections

Computers can be connected to networks using lots of different types of wires to transmit data.

The most common type of cable in LANs are:

Ethernet - uses wires to carry electrical signals between devices and is common in most offices and classrooms.

Fibre optic cables use beams of light instead of electrical signals and are used for high speed connections

Advantages of Ethernet

Speed: Ethernet is capable of high-speed data transfer, making it ideal for transferring large amounts of data quickly.
Reliability: Ethernet is a reliable technology that is less prone to interference and signal loss than wireless networks.
Security: Ethernet is generally considered more secure than wireless networks because you need physical access to the cables to get into the network.
Compatibility: Ethernet is widely supported by a variety of devices and operating systems, making it easy to integrate into existing networks.

Disadvantages of Ethernet

Ethernet networks require physical cables to be connected – this makes it much harder to change or move around.

Cables can also be trip hazards, so should always be routed along walls, under floors or through the ceiling where possible.

Wireless Connections

Wi-fi Connections

Wireless connections use radio waves to transmit

data through the air.

The most common type of wireless used in LANs is Wi-Fi. Devices communicate with a wireless access point (WAP) – which can be a standalone device or built into a router or switch. Many people have one of these as the centre of their home network and many schools and offices have Wi-Fi access as well as wired Ethernet.

Advantages

Ease of movement - portable
Doesn't need extra cabling

Disadvantages

Vulnerable to hacking as radio waves can be intercepted
Transfer speeds over Wi-fi are typically slower than Ethernet
Walls or other obstructions will reduce the signal speed

Bluetooth Connections

Wireless connections use radio waves to transmit

data through the air.

Bluetooth is also a popular wireless connection method though it has a much shorter range than Wi-fi.

Advantages

Ideal for personal devices such as headphone
Uses less power
No cables

Disadvantages

Can be intercepted by anyone in range
Bluetooth only works over a very short range and transfer speeds over Bluetooth are very slow

Encryption

What is Encryption?

Encryption is the process of scrambling a message so that it cannot be understood by anyone but its intended recipient. This is done by converting the original message or data into an unreadable format, known as ciphertext, using a mathematical algorithm and a secret key. So that if the data is intercepted it has no meaning. To decrypt the message, the process is reversed. Wi-Fi network anyone can join and sniff out packets of data from other users.

When you are using a secure site for example Apple, encryption is applied to keep your details safe: The encryption method used is called 'SSL' (Secure Socket Layer).

A tiny padlock appears in your browser window, usually on the left hand side of the address bar and the website address starts with HTTPS://

IP Addressing and MAC addressing

IP Stands for internet protocol
Used to uniquely identify a computer within that network
IP addresses are dynamic - they can change. If you connect a device to one network it will be given an IP address. If you move a different network then the IP address will change

IP addressing - IPv4

Stands for Internet Protocol version 4
It is written as 4 blocks of denary number between 0 and 255, separated by full stops.
E.g. 192.164.0.1
It provides over 4 billion unique addresses - which sounds a lot - but there are are over 8 billion people on the planet and every phone, laptop, smart plug , computer and router needs its own address

IP addressing - IPv6

Due to the shortage of IPv4 addresses, IPv6 is now used as well, though some older devices don't support the new format.
To solve this problem, new devices have both IPv4 and an IPv6 address so that they can work on any network
IPv6 addresses are represented using 8 blocks of 4 hexadecimal digits, separated by colons
E.g. 4164:3122:6C6F:8665:6C62:6365:2043:4B3B
When displayed, an IPv6 address will often miss leading zeroes, so ... :6365:0001:2043: … might appear as … :6365:1:2043: …
This gives us 3.4x1038 unique addresses – which means that we are very unlikely to run out of IP addresses in the near future.

MAC addressing

MAC stands for Media Access Control
Written as 12 hexadecimal digits, usually grouped in pairs.
Every MAC address is completely unique
E.g. E0-26-D4-6C-A7-44
MAC addresses are static - they can never change. No matter which network you are on, your MAC address will stay the same.

Standards

Standards provide rules that make sure different manufacturers and providers create products that work together – both hardware and software.

Examples of standards

IEEE 802.11 Wi-Fi
IEEE 802.15.1 Bluetooth
IEEE 802.3 Ethernet
IEEE 802.1 IP Addressing
RFC 1035 Domain Names / DNS

Protocols

A protocol is a set of rules designed to ensure everyone involved is on the same page - e.g fire alarm protocols
Networks which control the communication between devices on a network.

TCP ( Transmission Control Protocol)

Breaks up messages sent over the Internet into small chunks called packets
Reassembles the packets at the other end
Detects errors
Resends lost messages

IP protocol

Routes the individual packets across the network using IP addresses

HTTP - Hyper Text Transfer Protocol

Used by web browsers to access websites and communicates with webs servers.

HTTPS - HTTP Secure

A more secure version of HTTP. Encrypts all information sent and received.

FTP - File Transfer Protocol

Used to access, edit and move files between devices on a network, e.g. to access files on a server from a client computer.

POP3 - Post Office Protocol- version 3

Used to retrieve emails from a server. The server holds the email until you download it, at which point it is deleted from the server

IMAP - Internet Message Access Protocol

Used to retrieve emails from a server. The server holds the email until you delete it - you only download a copy. Used by most web-based email clients.

SMTP - Simple Mail Transfer Protocol

Used to send emails. Also used to transfer emails between servers.

Layers

Computer networking is detailed, there are lots of different things going on, to make it simple the concept of layers is used

The concept of layers

Layers - divsion of networking functionality

The concept of layers involves breaking the stages of networking down into smaller, more manageable stages, or layers

The hardware/software involved in that stage of networking will only be responsible for it's particular tasks

Benefits of layers

Layers are self contained, meaning developers can create hardware / software to do one networking task
Layers can be changed/edited without affecting other layers, as they self are contained

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