IB Computer Science SL: Networks

Different types of networks

LAN - Local Area Network

WAN - Wide Area Network

VLAN - Virtual Local Area Network

SAN - Storage Area Network

WLAN - Wireless Local Area Network

Internet

Extranet

VPN - Virtual Private Network

PAN - Personal Area Network

P2P - Peer-to-Peer

Server

Computer system that provides a service to other computer systems that are connected to the same network

Client

Computer system that requests a service from a server connected to the same network

Ethernet

Set of protocols for exchanging data

Differences between hub, switch, and router

• Hub = connection point for devices on a single network and it has a set limit of ports for wired connection via Ethernet cables

• Switch = connection point for devices on a single network. Unlike a hub, data is sent to the exact port.

• Router = joins multiple networks to efficiently exchange data between network devices so they can access the Internet.

The Internet + how it works

• Globally connected network system

• Uses TCP/IP protocol to transmit data

• Hosts web pages that make the World Wide Web

Data travels in the form of packets and they can take different routes but ultimately reach the same destination and are reassembled.

Local Area Network (LAN)

Connects computer systems that are within a limited geographical area.

• High data transfer rates

• Client-to-server relationship

• Can be wired or wireless

Wide Area Network (WAN)

Connects computer systems that are within a large geographical area.

• multiple LANs

• wired or wireless

Virtual Local Area Network (VLAN)

Collection of servers that appear to be on the same LAN but are in a different geographical location.

• 1 or more physical LANs

Storage Area Network (SAN)

Large storage devices that can connect to multiple servers easily.

• Backup servers

• Purpose-specific servers (email servers, application servers)

Wireless Local Area Network (WLAN)

Links two or more computer systems within a limited geographical area

• also called “Wifi network”

Intranet

• Private network

• Uses TCP/IP

Extranet

• Controlled private network that allows specific users from a specific LAN or WAN to access a private part of a website

• Requires authentication mechanisms

Virtual Private Network (VPN)

Clients can access a network remotely by encrypting the connection between two or more computer sites.

Advantages of VPN

• Authentication

• Encryption

• Tunneling

Personal Area Network

Connects devices that are centered around an individual’s workplace

Peer-to-peer

Each node acts as a client and server.

Similarities and differences between LAN and WLAN

Similarities

• Both act on a local level

• Both allow communication

• Both used to connect devices

• Both allow sharing of resources

Differences

• Use different transmission mediums

• LAN is safer

• LAN is faster

• WLANs offer greater flexibility

Similarities and differences between LAN and VLAN

Similarities

• Both act on a local level

• Both allow communication

• Both used to connect devices

• Both allow sharing of resources

Differences

• VLAN delivers better performance

• VLAN is safer

• VLAN offer greater flexibility

Similarities and differences between LAN and WAN

Similarities

• Both allow communication

• Both used to connect devices

• Both allow sharing of resources

Differences

• LAN is faster

• WAN costs more

• LAN easier to maintain

Similarities and differences between VPN and Extranet

Similarities

• Both use the internet

• Both inexpensive

• Both provides security

Differences

• VPN provides a secure connection for employees whereas an extranet limits access to a company network by selecting users who can access VPN is more secure

Similarities and differences between LAN and PAN

Similarities

• Used for data transmission

Differences

• LAN connects computers and devices that belong to different people, PAN suits the needs of a single person

• PAN operates on a smaller area than LAN
  PAN uses USB and Bluetooth as opposed to a hub or switch

Similarities and differences between P₂P and Client-server

Similarities

• Serves a lot of devices and users

• Can act on different scales, local and wide

Differences

• Client-server is centralised, P₂P is decentralised

• Client-server is more secure

• P₂P acts as both clients and servers

The importance of standards in the construction of networks

Provides a common international language that enables compatibility for all computer systems throughout the globe.

Protocols definition

A set of rules for data transmission. Examples:

• TCP/IP: rules for transmitting data on the internet

• HTTPS: rules for securely transmitting data between a web browser and server

• SFTP: rules for securely transferring files from client to server

Roles of protocols

• Maintains data integrity: same data that is sent, is received

• Flow control: data is sent and received at the same rate

• Prevents deadlock: two packets don’t ‘block each other’

• Prevents errors

Importance of OSI (Open Systems Interconnection) model

Provides an abstract depiction and explanation of the network communication process. 7 layers: Physical, Data link, Network, Transport, Session, Presentation, Application

The TCP / IP Model (Transmission Control Protocol / Internet Protocol)

4 layers:

1. Application - Program sends out data

2. Transmission - Data is broken down into packets

3. Network - Packets are addressed with destination and sender’s address

4. Link - Packets are converted into binary and sent

Wifi vs ethernet

• Ethernet faster, more consistent speed

• Wifi easier to install, cheaper

• Ethernet more secure

Fiber optic vs copper cabling

• Fibre is faster, more expensive, immune to interference

• Copper is susceptible to electromagnetic interference, shorter range, heavier and thicker

VPN technologies

• Encryption: when data is encoded the computer with the correct decoder is able to read and use it

• Tunneling: packets are encapsulated and transmitted between the VPN client and server

Requirements for VPN

• A LAN that is connected to the internet

• VPN routers

• VPN softwares

Benefits of a VPN

• Decreases operational costs

• Enables global communication

• Offers global networking opportunity

• Improves security

• Improves productivity

How VPN has changed traditional working patterns

VPNs make it possible to connect to a LAN that is protected from outside access through the internet. Therefore, it’s possible for workers to work anywhere and still be able to connect to the company’s internal network, hence the popularity of telecommuting, where people can work from home.

Factors that affect transmission speed

• Primary: traffic

• Secondary: time of day, distance, infrastructure

• Tertiary: environmental issues, financial factors, type of data

Lossy compression

• Removes original data

• Smaller file size

• Permanent removal = irreversible

• Used when some data can be lost (videos, images)

Lossless compression

• Uses algorithm to eliminate statistical redundancy

• Larger than lossy but smaller than normal size

• Can be reversed

• Used when no data can be lost (text, audio)

Wired communication

Unshielded Twisted Pair:

• OK security, if encrypted

• Susceptible to EMI

• Low cost

Shielded Twisted Pair:

• OK security, if encrypted

• Less susceptibility to EMI

• Same cost to UTP

• Harder to install than UTP

Fibre-optic cable:

• Very secure

• Fragile

• Very expensive

• Fastest

Wireless communication

Radio waves (WLAN / WiFi)

• Generally unsecure

• Susceptible to interference

• Free

Authentication

• One factor (something you know): password, security

• Two factor (something you know, something you have)

• Three factor (something you know, something you have, something you are)

Media Access Control (MAC) Address

• Unique identifer

Firewalls

• Can be hardware or software-based

• Analyses data packets

• Controls incoming and outgoing traffic

Physical security

• Locked doors

• Cages

• Security guards

• Secure rooms