Wired & wireless networks, protocols and layers

Two methods of connection

• wired

• Wireless

Wired

• A wired network is a network where physical cables are used to join devices together and transmit data

• Require a network interface card to connect to a network

What is the most common cable on a LAN

• ethernet cable

Ethernet

• wired networking standard to carry electric signals through devices

• common in most offices and homes to connect devices such a desktop computers & servers

• twisted pair cables to allow duplex communication

Advantages of ethernet

• fast data transfer

• Better physical security

• High range (up to 100m), less susceptible to interference

Disadvantages of ethernet

• Can't move easily, location is limited by physical cable

• Need more cables to add a new device

• Cables can be trip hazards, need routing along walls, under floors

Wireless network

a network where connections are made using radio waves to transmit data through the air

Types of wireless network

• WiFi

• Bluetooth

Advantages of wired network (for example at an airport)

• Fast connection/speed / high bandwidth / consistent bandwidth e.g. reduce delays at check in / by example for airport

• Secure / unlikely to have unauthorised access/hacked / data transmissions are likely to be safe e.g. so that data about passengers/staff/aeroplanes is not intercepted / by example for airport •

Little interference / little chance of data loss / reliable e.g. flight status is received without delay / by example for airport

• Long range transmission e.g. airport has a large floor area/terminals / by example for airport

reasons for using wireless network

• Staff do not need to be in one-place / movement of staff / can work whilst moving to another part of the airport / can be accessed from any location (in range)

• Staff can be more responsive to customers/requests

• Allows a larger number of connections/devices / more scalable without the disruption/cost of installing more cables

• Some devices do not allow physical/wired connection / allow wider range of type of device (or by example such as vehicles/mobile devices/aeroplanes)

• Easier to add/connect more devices

• Do not need to find/use a physical connection/wire / can allow you to connect in a place where there isn't a cable/connection

• For use as a backup if the wired connection fails

disadvanages of wireless network

• slower data transfer than wired networks, so will cause delays e.g. when checking passengers’ data

• less secure than wired, so people’s personal data could be exposed, hacked and stolen

• Range - Relies on signal strength to the WAP, signals can be obstructed (up to 90m). If obstructed, could cause significant delays in loading data

WiFi

• Wireless fidelity (Wi-Fi) is a common standard for wireless networks

• Wi-Fi is common in most homes and offices to connect devices such as laptops, tablets & smart phones

• Using Wi-Fi, devices communicate with a wireless access point (WAP), which can be a standalone device or built into a router or switch 

Advantages of WiFi

• Easy to move around, location is only limited by range

• Less expensive to set up and add new devices

• Most devices are manufactured with a built in Wi-Fi adapter

Disadvantages of WiFi

• Slower data transfer than ethernet

• Less secure than ethernet

• Relies on signal strength to the WAP, signals can be obstructed (up to 90m)

Bluetooth

• Bluetooth is another common standard for wireless networks

• Bluetooth is common in most homes and offices to connect devices such as headphones, controllers, keyboards & mice

• Bluetooth is used typically for a direct connection between two devices 

Advantages of bluetooth

• ideal for personal devices

• Very low power consumption

Disadvantages of bluetooth

• very slow transfer speeds

• Data can be intercepted by anyone in range

• Very short range (10cm)

Encryption

Process of scrambling data into an unreadable format so that if attackers will not be able to understand it if intercepted during transmission

encryption of wireless data

The original data (known as plaintext) is converted to scrambled ciphertext using an encryption key. Only at the correct destination will the encryption key be used to convert the ciphertext back into plaintext to be understood by the receiving computer.

Encryption of wired data

• Wired networks are encrypted in a very similar way to a wireless network, using a master key to encrypt data and the same key to decrypt data

• Encryption on a wired network differs slightly as it is often left to individual applications to decidehow encryption is used, for example HTTPS

Two types of network address

• IP

• MAC

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)

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

Format of a MAC address

• (usually presented in) hexadecimal / denary / binary

• 6 groups of numbers / 12 (hex) numbers, each group has paired/2-digit (hex) numbers / 8 bit binary number

• 48 bits long

• Separated by colons/hyphens

• (The first half/part) contains the manufacturer ID / (first half/part) identifies the manufacturer

• (The second half/part) contains the serial number / (second half/part) identifies the device