Task 6: networks (AIT)

Computer network

Set of computers connected tog for the purpose of sharing resources

e.g., connection to internet, files

Advantages of networking

Sharing devices (e.g., printers) saves money

Software licences are cheaper than buying several single licenses (e.g., site license)

Easily share files between users

Easy to backup data as all data is stored on the file server

Quick/easy/free comm between users worldwide (e.g., zoom)

Disadvantages of networking

Network cabling and file servers for LAN can be expensive

Complicated to manage - requires people with specific skills (e.g., network admin)

Single point of failure results in network that doesn’t function properly (e.g., file server breaks down -> files become inaccessible)

Security - viruses can spread to other computers throughout a network

Tranamission media

Movement of data by up/download

For this data to move, it needs to go through the air or cables

Wired - fibre optic, copper (UTP, ethernet)

Wireless - wifi, bluetooth, mobile data

Fibre optic

Optical fibre cabling has long strands of glass inside a cable

Data travels inside the strands of glass as pulses of light

Fibre optic pros/cons

+fastest

+no interference from other cables

-expensive

UTP

Unshielded twisted pair (copper cable)

Very commonly used in networks

Ethernet cables are UTP, but can transfer data very quickly (won’t bottleneck a fibre connection)

Cat6 (latest ethernet)

UTP pros/cons

+much cheaper than fibre optic

-not as fast as fibre optic

WiFi

Uses radio waves

Used for portable devices

Device requires a wireless adaptor to receive wireless transmission (built into portable devices, desktops need separate receiver)

WiFi pros/cons

+secured with WPA2 (wifi protected access)

+don’t need wires

+easy to connect to

-range of ~20m (can be extended with WAPs of extenders)

-security risks - can be hacked

-prone to interference (microwave, walls, other signals)

Bluetooth

Used for short distances ~10m

Used to connect two devices tog (e.g., portable speaker, car stereo to phone)

Bluetooth pros/cons

+doesn’t require an established network/data/isp

-very short range

-slow wireless connection

Mobile data

5G - latest, more than 1Gb/s

‘G’ stands for generation of mobile tech, installed in phones and on cellular networks

Transmit data between device and cell tower

Mobile data pros/cons

-requires phone plan and data

Transmission rates

Speed of transmission

Measured with Mbps (megabits per second)

NOT MBps (megabytes for second)

Wireless impacts on transmission rate

Range - closer will transmit faster

Concrete walls - stops/slows connection

Interference - from other electrical devices

More clients online - greatly reduces speed

Wired impacts on transmission rates

Other clients on cable - speed greatly reduced by more clients online

Twisted pair - slight interference from other wires

Server

Type of computer that manages network resources

Checks user name and passwords so only authorised users can access the network

e.g., web (where websites are stored), print (manages 1< printers), file (store/retrieve files), mail (allows emails to be sent to/from)

Modem

Brings internet connection into the network

Creates connection to internet

Converts analogue signals to digital signals

Router

Connects multiple networks together (LAN to internet)

Distributes internet connection by performing ‘traffic directing’ functions (chooses best route for data to travel)

Take info that arrives to modem, decipher and deliver it to the devices on network

Provides internet connections to all devices within home network

NIC

Network interface card

Required to connect to network or communicate with another device

Desktops may need wireless adaptors for wireless internet connections (wifi)

Switch

Connects devices tog on a computer network (wired connection)

Serves as a controller, enabling networked devices to talk to each other differently

WAP

Wireless access point provides wireless network connection to devices

Uses wifi to transmit data

Additional WAPs can be used to extend wifi ranges around a larger area

Wifi can be transmitted at 2 frequencies - 2.4GHz large range, slow speeds, 5GHz less range, fast speeds

Home routers

Functionality of a router, modem, switch and WAP built into it

Communication protocols

For a network to work correctly, it needs to have rules (protocols) to make the system work

Set of rules for communication between network devices

e.g., TCP/IP, HTTP, HTTPS

Data packet

When data has to be transmitted, it’s broken down into smaller pieces of data before transmission (packets)

Reassembled to the original data chunk once destination is reached

Includes source and destination IP and number of the packets (sequence number to put them in order)

TCP/IP

Set of rules that governs comms among all computers on the internet

Combination of TCP and IP protocols

Defines how computers should be connected over the internet and how data is transmitted between them

Completes error checking to ensure packets aren’t missing

Allows the internet to be scalable and reliable

Transmission control protocol (TCP)

Means for creating packets, putting them back tog in the correct order and checking to make sure that no packets get lost in transmission

Internet protocol (IP)

Routes packets to their destination

Every computer has its own unique IP address

When a packet is sent, it may go through a number of routers before arriving at its destination

HyperText Transfer Protocol (HTTPS)

Used by the World Wide Web

Defines what actions web servers and browsers should take in response to various commands

HyperText Transfer Protocol Secure (HTTPS)

Takes care of secure communication between a web server and browser

Data that passes is encrypted by secure socket layer (SSL)

Handles any personal/sensitive info sent through the site

Encryption

Data that travels between a website and device is encrypted

Can’t be read by intruders

Web server will authenticate to see if the digital certificate public/private key matches

Communication standards

State the expected characteristics for that type of comm

802.3 = Ethernet

802.11 = Wireless (Wifi)

LABEL ON LAN DIAGRAM

802.11

Comm over the air, through radio waves, between wireless devices

Comm in different frequency ranges

Operates at the physical and data link layer

Current - wifi 6, 802.11ax, 14Gbps

802.3

Different categories of ethernet that offer different connection speeds

Operates at physical and data link layer

Ethernet prone to electromagnetic interference

Current - CAT6, gigabit ethernet

Network topologies

Structure for the network

Way the nodes are connected

Star

Has a central point (normally switch)

Connections from switch to other devices

Uses ethernet cables to connect nodes

Star pros

Improves performances - passes through fewer nodes

Centralised management of devices

Easy to connect new devices

Failure at one node doesn’t affect the rest of the network

Star cons

If central point fails, entire network is useless

Central computer could be comm bottleneck

Expensive to set up

Wireless

Like a star but devices are connected wirelessly

Wireless pros

Easier to set up than other topologies

Easier to connect to

Wireless cons

Needs wireless adaptor on device and WAP

Desktops may require additional NIC or wireless adaptor

Client server

Central computer is server

All other computers connected to it are clients

Central server provides all the resources for client computers (e.g., internet, file saving and printing)

Client server pros

Offers greater security than p2p because of central server

Client server cons

More expensive to set up than p2p as server hardware and software is expensive

Peer to Peer (P2P)

Don’t have central server to manage network resources

Resources are distributed between the various peers that make up the network

P2P pros

Cheap and easy to configure

P2P cons

Less secure than client server because there’s no central server to manage security

Network security

Needs to be secured against attack to work correctly

e.g., firewalls, passwords, physical

Firewalls

Monitors incoming and outgoing network traffic of a system

Filters traffic based on pre defined security rules

Can be configured to suit needs

Can be soft/hardware

Passwords

Access code to get into a network, computer or device

Used to authenticate the user

Prevents unwanted users from accessing the network

Good password is complex - upper, lower, numbers, symbols

Don’t use passwords related to life, don’t share, change regularly

Physical security

Used to prevent anyone from getting into the building and physically tampering with network hardware

e.g., locks, physically attached, biometric security, video surveillance