IB Computer Science HL - Topic 3 - Networks

Flashcards on topics 3.1.1 - 3.1.16

Define network

A group of nodes that are linked together through a transmission media to allow for communication and the sharing of resources.

Name 4 features of a LAN

• Small geographical area

• Uses MAC addressing and switching for routing

• Uses private infrastructure

• Uses ethernet: wireless and UTP cables

Name 4 features of a WAN

• Large geographical area

• Uses IP addressing for routing

• Uses public infrastructure

• Can be wired or wireless: fibre optic or satellite/radio

Name 2 features of a VLAN

• All devices appear to be on same LAN despite geographical distribution.

• Software implemented and creates a virtual partition on hardware

What is a SAN

A secure, high-speed data transfer network that provides access to consolidated block level centralised storage.

What is a WLAN

Same as a LAN but the permissions allow for users to be mobile with devices as they are not restricted by cables

What is the internet

Decentralised global network which uses the TCIP/IP protocols to transmit data via various types of media.

What is the intranet

A collection of private networks used within an organisation

What is the extranet

Controlled private network allowing businesses to gain information without granting access to the organisations entire network

What does a VPN do

Uses the internet to allow remote access to a private LAN whilst encrypting the connection to thwart eavesdroppers.

How does a VPN work

Transmits data through a secure pathway (tunnelling) and anomalies ones IP address

What is a PAN

A network covering a very small area

Name three examples of a PAN(2 wireless and 1 wired)

USB, Blutooth and Wi-Fi

What are standards

Rules for data transmission which help with interoperability on network devices, and transmission with integrity and minimum latency

Why do we need standards

Without them, manufacturers of networks have no common grounds on building their systems.

What is tunnelling

Transmission of data through a secure pathway using packet encapsulation.

Name 4 components of a VPN

• VPN software (client application)

• VPN router

• VPN server

• Internet

Define protocol

Set of rules that determine communication across a network.

What do protocols define

The format and order of messages exchanged and the action taken on transmission of a message.

Payload definition

Data that is going to be sent

Define packet

A small unit of data used in network communication, they have a certain size

Name 5 functions of protocols

• Ensure data integrity

• Flow control

• Congestion control

• Deadlock

• Error checking

Explain how protocols are necessary in ensuring data integrity

They manage the overall completeness, accuracy and consistency of data.

Explain how protocols are necessary in flow control

Makes sure that the sender is transmitting data at a rate at which the receiver can digest

Explain how protocols are necessary in congestion control

When a node carries too much data, network service quality can deteriorate, resulting in queuing delay, data packet loss and the loss of new connections. Protocols help to prevent this by using congestion control algorithms which take network capacity into account.

What does the term deadlock refer too?

When 2 nodes or processes are trying to access the same node simultaneously causing neither to be able to proceed

Explain how protocols are necessary in Deadlock

The relevant protocol stops both and re-queues them so that they can happen sequentially letting traffic flow.

What is error checking in a network

A method which detects noise or other impairments introduced to data during transmission

Explain how protocols are necessary in error checking

By making use of parity bits, bits at the end of a packet that are calculated to be either a 1 or 0.

Name 2 primary concepts which slow data transmission

Network traffic and Number of users

Why does more traffic = slow data transmission

More traffic = lower bandwidth available per user on network so slower upload download speeds.

Bandwidth

Total amount of data per second

Name 3 secondary causes of slow data transmission

Time of day, Distance, Infrastructure

How does infrastructure slow data transmission

If a network is not set up in a way that lets it develop, quality can be affected

Name 3 tertiary causes of slow data transmission on a network

• Environmental issues (like temperature, interference, etc.),

• Infrastructure limitations due to financial reasons (cheaper equipment)

• The type of data being transmitted (large files)

How does the type of cabeling affect transmission on a network

Some types are subject to more or less resistance (copper vs fibre optic) or interference (WiFi)

Name 4 broadband WAN connections

DSL, Fibre Optic, 3G,4G

What is lossy compression usually used to compress

Multimedia such as audio, image and video

What is lossless compression usually used to compress

Text data files and images

Negatives of lossy

Irreversible and reduces quality

Negatives of lossless

The file is not as small as in lossy

Why is compression used ?

Reduces the time of transmission and optimises storage space.

What are the 4 types of media comparison points

Security, reliability, cost and speed

How good is the security of UTP

ok if encrypted

How reliable are UTP cables

Suseptible to electrical magnetic interferance

How much do UTPs cost

<£1 per metre

How fast are UTP cables

100Mbps-1Gbps

How good is the security of Fibre Optic

Very secure, difficult to break in

How good is the security of Radiowaves(WLAN/WiFi)

Very insecure unless encrypted

How reliable are Fibre optic cables

Generally quite fragile

How reliable are Radiowaves(WLAN/WiFi)

Very susceptible to interference

How much do Fibre Optic cables cost

£2-£8 per unit

How much do radiowaves cost

Technically free but have to pay for service provider

How fast are Fibre optic cables

5-100 Gbps

How fast are radiowaves

5-200 Mbps

1st step of packet switching

A payload is split into smaller data packets (packetization)

2nd step of packet switching

The data packet is assembled with a header and tail, containing the IP addresses, sequence number and checksum

3rd step of packet switching

The packets are sent through multiple and optimal routes the the receiver

4th step of packet switching

Receiver re-orders the packet using the sequence number

5th step of packet switching

Receiver checks for lost and corrupted packets using the checksum

6th step of packet switching

The receiver requests a resend for corrupted or missing packets.

What does the header of a packet contain(packet switching)

IP address of sender/receiver nodes(or MAC if it is an internal network)

What does the tail of a packet contain(packet switching)

Sequence number for reordering packets at the receiver node and the checksum.

WAP

Allows for users to connect to a wireless network

Router

Maps out routes for data to follow, allowing transmission in a network

NIC

Holds the MAC address to identify nodes on a network

Name 3 pieces of hardware needed for a wireless network

WAP, Wireless router and a Wireless Network Interface card

Name 2 pieces of software needed for a wireless network

Software protocol stack and Network OS (specific for data transmission)

Name positives of a wireless network (5)

• Flexible position of nodes(extended range/availability)

• Easy to set up and maintain

• Easy to add/remove nodes

• Cheaper as there is no cabling

• BYOD- bring your own device (companies don’t have to pay for infrastructure)

Name negatives of a wireless network (3)

• Less secure so subject to interception

• Slower data transmission than wired (As there is a lower bandwidth and channel interference)

• Limited range-easily worsened by obstacles

Name characteristics of a wireless network (5)

• No cabling

• Uses radio waves as transmission media

• Limited range

• Needs specialist hardware/software to set up

• Encryption is main mode of security

Give examples of types of wireless networks

• WiFi- Radiowaves

• WiMax- Microwaves(Longer range)

• LTE Networks/ Mobile networks

• 4G- fast internet access

• 5G- Internet of things

What are the two security methods for wireless networks

Encryption and Authentication

What are the two encryption algorithms

WEP and WPA2

What is WPA2

WiFi protected access, encryption algorithm which makes data very secure as it has a longer encryption key

What is authentications role in Wireless network security

Used to gain access to the network, by verifying the user.

+/- of encryption

• If one gains access to the private key then the algorithm isn’t effective

• Longer keys = more secure

• Encryption is reversible

+/- of Authentication

• Secure access

• Username+ Password can be shared/Stolen