IB Computer Science HL Paper 1 Topic 3

Network

* A group of computers and other computing hardware devices linked together through communication channels to enable communication between users

Bus topology

Computer network in which a bus (cable) connects all devices together through a common cable

Check digit

Extra digit added to numerical data that is used to check data integrity after input, transmission, storage and processing

Data packet

* Portion of a message that is transmitted through a network
* Contains data such as check digits and destination address

Handshaking

Exchange of predetermined signals to signify that a connection has been established between two systems

Protocol

* International rules that ensure the safe transfer of data between systems

Hub

* Network connection point for devices
* Data arriving at a hub is copied and sent to all the devices on the network

What does TCP / IP stand for?

Transmission Control Protocol / Internet Protocol

TCP / IP

* Standard communications protocol used to connect hosts on the Internet

Server

* A computer system that serves as a central repository of data and programs and is shared by clients
* Role is to await and fulfill requests from client programs

Client

* A piece of computer hardware or software that accesses a service made available by a server

Network Types

* Local Area Network (LAN)
* Wireless Local Area Network (WLAN)
* Virtual Local Area Network (VLAN)
* Wide Area Network (WAN)
* Storage Area Network (SAN)
* Internet
* Extranet
* Virtual Private Network (VPN)
* Personal Area Network (PAN)
* Peer-To-Peer (P2P)

Local Area Network (LAN)

* Computer network where all the connected computers are within a limited geographical area (e.g school, office, home)
* Connection may be through cables and / or microwave transmission

Virtual Local Area Network (VLAN)

* A logical group of network devices that appear to be on the same LAN despite their geographical distribution
* Allows a group of network devices to communicate in a simulated environment as if they exist in a single LAN

Pros of VLAN

* Scalability
* Security
* Ease of network management
* Can quickly adapt to changes in network requirements and relocation of workstations and server nodes

Wireless Local Area Network (WLAN)

* A wireless distribution method for two or more devices that use high-frequency radio waves, and often includes an Internet access point
* Allows users to move around the coverage area while maintaining an Internet connection

Wide Area Network (WAN)

* Computer network where all the connected computers are in a larger geographic are than served by a LAN or MAN (metropolitan area network)
* Internet is a WAN

Peer-To-Peer (P2P)

* A network model in which some computers or hardware devices exchange files (e.g. BitTorrent)
* No central server - equal client system
* Supports file sharing or collaborative work

Virtual Private Network (VPN)

* Uses the Internet to allow people to access the network remotely
* Provides a secure connection by encrypting the network (IPSEC protocol) - of hacked data will not be understood
* Uses tunneling protocols - allows the data to be hidden while travelling across the Internet

Extranet

* A controlled private network
* Allows people to gain information about a specific company without granting access to the entire network
* The specific LAN or WAN is the extranet, and can only be accessed by people with the required credentials e.g usernames / passwords

Personal Area Network (PAN)

* A network that interconnects devices centred around an individuals workspace - a LAN that only supports one person
* Covers a very short range

Pros and cons of wireless networks

Proa

* Ease of use for mobile users, as they can work in many different locations
* Less time, space and cost due to lack of need for cables

Cons

* Security issues, as wireless transmissions are easily intercepted

Voice Over IP (VoIP)

* Audio and video stream transmitted over the Internet, broadband internet connection needed
* Can be integrated in an office desk computer

Layers in the seven layer Open Systems Interconnection (OSI) model

* Application
* Presentation
* Session
* Transport
* Network
* Data Link
* Physical

Advantages of using layers in communication

* Easy to manage
* Greater understanding of each layer
* Common language for each layer
* Makes protocol design easier

Layers in TCP / IP protocol model

* Network access
* Internet
* Transport
* Application

Benefits that protocols provide

* Data integrity - information has not been changed / corrupted
* Source integrity - identity of the sender is validated
* Error checking / correction

Bandwidth

* The theoretical speed of data in a medium
* Depends on the signalling technique used and the physical properties of the medium

Throughput

* The actual transfer rate of data
* Affected by:
* Bandwidth of the network
* Distance
* Amount of users