Topic 3 - Networks

cable

copper wire and fibre. allow for connections between computers in a LAN

data integrity

the accuracy of data after input, transmission, storage and processing

microwave transmission

a wireless system that uses microwaves for high-volume, long-distance, point-to-point communication

modem

electronic equipment that converts computer digital signals into audio signals, and vice versa

network

computer systems that are interconnected and can share resources and data

packet switching step one

Packet switching entails data being separated into specially formatted units (packets). Each packet contains data and information such as packet number. Each packet contains the (IP) address of both the sender and recipient in order to identify them.

Packet switching step two

Packets are routed from source to destination using (different) network switches and routers. Using IP addresses, network switches and routers determine how best to transfer the packet on the path to its destination;

packet switching step three

Packets are reassembled at the destination (using packet numbers);

packet switching step four

Missing packets should be retransmitted;

WAN

WAN includes a large number of devices connected together that covers a large area (national/international). Nodes connected to WANs often make use of connections through public networks (such as the telephone system). They are generally expensive to implement because of their size and the specialllized hardware required to connecter different networks together. largest WAN is the Internet

Server

A computer system or a software application that provides a service to the other computer systems connected to the same network.

Client

A computer system or a software application that requests a service from a server connected to the same network.

Router

(computer science) a device that forwards data packets between computer networks \n \n Router devices will be bundled with a switch as sold as a "wi-fi router".

LAN

Local Area Network \n \n A computer network where all the connected computers are within a limited geographical area. Connection between the computers may be through cables and/or microwave transmissions(WLAN)

WLAN

Wireless Local Area Network \n \n Is a less secure, more convenient LAN.

VLAN

A Virtual Local Area Network. Software can be used to separate physical LAN's. Say 5 room are connected to one router. They are in the same physical LAN. Software can be used so that each of the rooms is still connected to one router, but each room thinks that they are in a different Network that the others. This would create 5 Virtual LANs on one Physical LAN

SAN

Storage Area Network \n \n Created when servers are connected to large storage devices. Firebase, and other cloud platforms, are examples.

PAN

Personal Area Network \n \n Is used to refer to the set of devices that are used in near proximity. You usually create a PAN by connecting your phone to your computer and perhaps your iPad/tablet.

P2P network

A locally managed, uncentralized, network in which each node can communicate directly with every other node in the network. \n \n Since there is no central server these networks are more reliable as all computers on the network would have to be unavailable for the network to not be operational.

VPN

A Virtual Private Network allows clients that are not within a LAN to connect to it. \n \n This can be used to improve security for a LAN while still allowing the client to have access to some essential information.

MAC address

A Media Access Control address is a hardware address that uniquely identifies each node on a network.

MAC address filtering

Method of limiting wireless network access based on the physical, hard-wired address of the wireless NIC of a computing device.

OSI Model Layers

Application, 

Presentation, 

Session, 

Transport, 

Network, 

Data Link, 

Physical

Importance of standards

Standards ensure compatibility between nodes on the network through the use of common techniques, protocols, and languages.

Technologies required to provide a VPN

Client VPN software

VPN-aware routers and firewalls

VPN appliance/server to handle VPN trafficEncryption protocol like IPSec of SSL

Evaluate the use of a VPN

Allows for enhanced security of data by using encryption which prevents unauthorized access 

Allows remote access to data and resources from any location. These resources are normally only accessibly from local networks, creating an sense that the user is using the network on site, even though they are in a far away location.

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packet

A unit of data made into a single unit that travels along a given network path. As packets travel through networks they are kept as a unit, i.e. they are not broken apart. It contains a set amount of data, a fixed structure (or identify elements of the structure other than data), and specific details for transmission e.g. address of sender and receiver, error codes.

Necessity of protocols

Protocols define the rules that govern network communication (for example, packet format, type and size, what happens when an error occurs, and which part of the network is supposed to handle the error and how);

Causes of network speed difference

Malicious attacks can lead to decreased speeds.

The type of connection might lead to slow or fast speeds. E.g. wireless dial-up connections are slower than wired fixed fiber optics.

Hardware malfunction can lead to considerable slow down if modem-router configuration is not correct or updated.

During peak hours, there is more network traffic than at other times of the day.

Need of compression of data

To save on transfer times as it reduces the number of bits needed to represent data, when compared to the original amount of data. 

Compressing data involves modifying/restructuring files, so that they take up less space, which results in cost savings in cloud storage

To take up less bandwidth because data compression reduces the size of files to be transmitted over a network

Fibre optic cable

material that allows for fast transmission speeds, high security, highly reliable transmission over long distances and massive bandwidth.

Wireless speeds

Less reliable and secure than fiber optic. Provides lower bandwidths than fiber optics and allows for slower transmission speeds. More convenient as it removed the need for cables. 

Advantages of Wireless networks

Allows users to use their own devices and carry them freely. 

Ability to access the network from multiple locations on the site. 

No cables are used, which reduces cost, possible tripping, and maintenance if they break. 

Number of connections are not limited to cable ports, so greater number of users can connect at any given

Disadvantages of wireless networks

Slower connection speeds

Possible interference from obstacles, like walls

Less secure than wired connections as data can be intercepted

Components of a wireless network

Wireless router

Wireless NIC Card

Wireless access point:

Wireless repeaters

Wireless router

enables wireless network packet forwarding and routing. It is a hardware device that is connected to multiple channgels for different networks. It acts as a processing unit for information packets and uses a protocol to determine which information packets are to be routed to certain parts of the network.

Wireless NIC card

Allows the computer to communicate with the router. They can communicate with the network router to receive information packets. They determine the infrastructure of a LAN and allow all of the computers to connect to the network.

Wireless access points

Allows wi-fi devices to connect to a wireless network.

Wireless repeaters

Expands the reach of the network.

Encryption

calculations/algorithms that transform plain text into a form that is non-readable to unauthorized parties (authorized recipient of an encrypted text uses a key and the algorithm to decrypt the data/ to transform it to the original plain text version)

MAC Address

Wireless network adapters have a unique label called a MAC address. Routers uses these addresses to identify/authenticate computers (routers include an option to whitelist or blacklist certain devices based on MAC addresses, so access could be restricted to any device which is not in the whitelist)

MAC address advantage

It is hard to fake a MAC address

Allows ability to tract users in a network

MAC address disadvantages

the whitelist should be amended any time a new device is purchased / when access to guests should be granted.

Also useless against hackers who use programs that intercept data passing through networks and report the MAC address of any device communicating on the network;