Networking Component (Month 4) Flashcards
Definition of a network
2 or more devices which are connected to allow the exchange of data.
Why have a network
Allows users on the network to share local resources.
Allows the user to be able to send and receive data (e.g emails, files etc)
Can save shared data for multiple users to access.
Network Categories
Personal Area Network (PAN) - communicate over short distances. E.g Bluetooth headset to computer.
Local Area Network (LAN) - network confined to a small geographical area such as an office or home network. Typically makes use of Ethernet connections.
Campus Area Network (CAN) - larger that LAN and typically confined to a group of buildings such as university campus.
Metropolitan Area Network (MAN) - larger than CAN. Typically confined to a city. Offices in the same city.
Wide Area Network (WAN) - multiple networks connected to allow the exchange of data over large geographical area.
Virtual Private Network (VPN) - a computer network which some links are carried out by open connection. Creates a secure tunnel and encrypts your data.
Two Network Models
Peer to Peer - networks which have a small number of workstations and devices. Allow data to be shared together and peripherals. Undertakes the role of server, administrator and share its resources.
Client-Server - designed for larger networking needs and provide centralised administration. Provided by one or more servers and manages all devices connected to the network.
Network Components
Node - any device on the network which is transmitting and receiving data. This could be a computer, printer.
Host - the node which is the beginning or end point of communication.
Media - the physical path connecting the nodes. Typically the copper cables, fibre optic cables or wireless access point.
Data - the information carried by the media. Data transmits along a cable, typically done using electrical signals
Networking devices
Hubs
Bridges
Switches
Repeaters
Routers
Gateways
Modems
Firewalls
Hubs
Provide very basic connectivity for devices in a network.
Once a common place for ethernet networks however data is sent to every other node.
Data that is sent to one port is then sent to all ports.
All computers are in the same collision domain.
E.g is talking to one person the 5 people start talking to you.
Bridges
Introduced to allow more than one collision domain.
Connects 2 hubs (e.g left and right) then learns which side the which computer is on which network.
Reduce collision domain by having 2.
Increases reliability but still have collision domains.
Switches
Connects computers within a network.
Improved network performance compared to hubs.
Creates a logical temporary switch between 2 ports between 2 ports.
Allows multiple ports to send data at the same time without a collision.
Repeaters
Used to boost a signal and repeat it, also cleaning the signal.
Needed when the signal needs to travel over longer distances.
E.g 2 people are far away and can’t hear each other, place a person in the middle to transfer the data so they can hear.
Routers
Device which moves packets between networks or different subnets.
Will not track individual computers but track networks or subnets.
Not just physical but also divided into logical networks.
A subnet is separated by IP addresses.
All IP addresses are different.
Direct or route the traffic through the network
Identifies packets of data, determines best path for it to be transferred.
Gateways
Works with routers and default gateways . Grouped together as one.
Is typically a device but could be a system or software.
Responsible for converting data between incompatible networks. Acts as an entry point to the network.
Operates as a layer of 5.
A device that connects in protocol to another and converts packets to the correct protocol
Modems
Combination of modulator and demodulator that converts data to and from digital format.
4 types:
Dial up - public switched telephone network
Cable - hybrid fibre coaxial, coaxial cable infrastructure
DSL - digital subscriber line referred to as broadband.
Fibre - uses fibre optic network known as optical network terminal
Firewalls
Provides protection for both computers and networks.
Keeps malicious and unwanted traffic from entering or leaving the network.
Can be network based or host based.
Network and host based firewalls
Network-Based - provide protection to entire network. One firewall between outside world, internet and the internal network. Filter traffic based on set of rules. Combination of hardware and software.
Host-Based - individual firewalls like those found in many servers. There are software security suites which offer software-based firewalls
Stateless and Stateful Firewalls
Stateless - filters traffic based on the contents of packet such as source and destination. Known as packet filtering. Either blocks or allows the packet.
Stateful - more advanced and examines all traffic in session. Aware of communication paths and monitors traffic to analyse the conversation end to end.
Cables
Coaxial
Twisted pair
Plenum
Fibre-Optic
Coaxial cables
Used in earlier networks
Used on satellite tv’s
Still used for for cable modems
10Base2
10Base5
Types:
RG-6, RG-8, RG-58, RG-59
Connectors:
Bayonet Neill-Concelman, F-Type
Twisted Pair Cable
Physical cable much thinner than coaxial, greater resistance.
Electrical signal passes down the cable.
Have a maximum length of 100 metres
Used as Ethernet cables
Fibre Optic Cable
Contains one or more optical fibres
Can be glass or plastic fibres
Used to carry light signals
Data transfers through light signals
Types:
LC, FC, SC, MT-RJ, ST
Wireless Standards & Technologies
Becoming popular due to simple to install and gives flexibility.
Connect multiple devices to one access point.
Has 3 main categories:
Omni-directional (360), semi-directional (Cone shape), highly-directional (Narrow beam)
Types of signals:
Scattering (bounces of multiple objects)
Reflection (bounces off one object) Differential (hits the edge of an object)
WI-FI Signals
802.11 - 1 or 2 Mbps
802.11a - 54Mbps
802.11b - 11Mbps
802.11g - 54Mbps
802.11n - 600Mbps
802.11ac - 1.3-3.5Gbps
802.11ax - 10Gbps
802.11be - 40Gbps
Wireless Encryption
Wired Equivalent Privacy (WEP) - old encryption method. Very weak, easily hackable.
Wi-Fi Protected Access (WPA) - increased encryption. Each client receives a new key. Personal and enterprise mode.
Wi-Fi Protected Access 2 (WPA2) - mandatorily uses WPA but optional TKIP. Strengthens wireless communication.
Wi-Fi protected Access 3 (WPA3) - 192bit key-based encryption. Use password based and password authenticated key to improve security. Backwards compatibility reduces security
Physical Topologies
Bus - slow speeds with single point of failure.
Star - devices connected to central switch. Use Ethernet cables. You can add others to it.
Ring - devices link to a cable that forms a circle. Many connect.
Mesh - each device has a direct connection to each other.
Hybrid - combines 2 or more topologies connected together.
