File sharing - you can easily share data between different interconnected devices Resource sharing - using network-connected output devices like printers, or can share the same software within the network Higher storage - can store files in network-connected storage mediums.

Network that connects devices within a small geographical area Only private ownership Transmission medium: twisted pair cable, coaxial cable or Wi-Fi Higher data transfer rate Lesser congestion

Network that connects devices within a larger geographical area Private or public ownership Transmission medium: PSTN or satellite link Lower data transfer rate Higher congestion

A client that solely runs on the resources provided by the server and has no local storage Only provides input and receives output; processing done by server Smaller purchase cost: expensive, demanding hardware is not required Improved security: cannot run unauthorized, harmful software

An independent client that does not require the server to run Thick client processes most of the application Can function even if no server is connected (works offline) No lag related to network problems

Centralized backup Files & resources centralized in server: prevents illegal resource usage Improved security: files are stored on central server which would be regularly scanned for malware

Lesser initial setup cost Lesser network traffic: each peer can simultaneously receive data from different sources Can work even if a device goes down, but Client-server model can’t work if server goes down

Single line (bus) connecting all devices with terminators at each end. Other computers can read the data being sent from one to another computer. Unsuitable for heavy traffic since collisions occur.

Consists of a central server (‘Switch’) and all other computers connected with a dedicated connection to each, hence server can send packets to different devices simultaneously and bidirectionally. No collisions possible.

Network setup where every device (node) is directly interconnected to the each of the other devices (nodes) It is commonly used for wireless networks (such as the Internet), via the mesh connection of routers

2.1. Networks including the Internet Flashcards by Dorky

Networking devices

Interconnected devices that allow a fast means of data transmission within the network.

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Networking benefits

File sharing - you can easily share data between
different interconnected devices
Resource sharing - using network-connected output
devices like printers, or can share the same software
within the network
Higher storage - can store files in network-connected
storage mediums.

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LAN

Network that connects
devices within a small
geographical area
Only private ownership
Transmission medium:
twisted pair cable, coaxial
cable or Wi-Fi
Higher data transfer rate
Lesser congestion

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WAN

Network that connects
devices within a larger
geographical area
Private or public ownership
Transmission medium: PSTN
or satellite link
Lower data transfer rate
Higher congestion

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Client-server Model

Server based network: dedicated server provides an
application (administration of users, security and
resources) for the client computer to utilize

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Client-server Applications

Printer: manages print jobs from client computers
File Sharing: the client accesses software and user’s
data files stored on the server
Proxy server
Email server: for sending, receiving & storing emails
Database server: manages DBMS
Domain controller server
Management of user accounts (IDs & passwords)
Client sends login request to server which
processes and grants request if user ID &
password recognized

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Thin Clients

A client that solely runs on
the resources provided by
the server and has no local
storage
Only provides input and
receives output; processing
done by server
Smaller purchase cost:
expensive, demanding
hardware is not required
Improved security: cannot
run unauthorized, harmful
software

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Thick Clients

An independent client that
does not require the server
to run
Thick client processes most
of the application
Can function even if no
server is connected (works
offline)
No lag related to network
problems

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Peer-to-peer network model (P2P)

Decentralised network where each connected
computer stores data and operates independently as
a ‘peer’, and can act as both a client & server.
Applications: Internet and Ad hoc networks

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Client-server

Centralized backup
Files & resources centralized
in server: prevents illegal
resource usage
Improved security: files are
stored on central server
which would be regularly
scanned for malware

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Peer-to-peer

Lesser initial setup cost
Lesser network traffic: each
peer can simultaneously
receive data from different
sources
Can work even if a device
goes down, but Client-server
model can’t work if server
goes down

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Network Topologies

Bus
Star
Mesh
Hybrid

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Bus

Single line (bus) connecting all devices with
terminators at each end.
Other computers can read the data being sent
from one to another computer.
Unsuitable for heavy traffic since collisions occur.

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Star

Consists of a central server (‘Switch’) and all other
computers connected with a dedicated connection
to each, hence server can send packets to
different devices simultaneously and bidirectionally.
No collisions possible.

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Mesh

Network setup where every device (node) is
directly interconnected to the each of the other
devices (nodes)
It is commonly used for wireless networks (such as
the Internet), via the mesh connection of routers

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Hybrid

Combination of two or more topologies.
E.g. when there is a connection between 2 or
more LANs of different topologies

Wired Networks

Use (copper (twisted-pair cable or
coaxial cable) or fibre-optic) cables connected to an
Ethernet port on the network router

Copper Cable

Benefits:
Less expensive and
easier to
install FlexibleEasier to
make terminations

Drawbacks:
Doesn’t perform well
with small
charges. Affected by
electromagnetism

Fiber-Optic
Cables

Benefits:
Greater
bandwidthImproved
security Lightweight:
easy to installLess
signal boosting
required; used in long
distance comm.

Drawbacks:
Needs expensive
optical transmitters
and receivers.

Wireless Networks

Use radio waves (including WiFi),
microwaves, satellites to connect devices to networks
without cables.

Benefits:

Drawbacks:

Radio
waves

Benefits:
Can travel over large
distances since they
have largest range of
wavelengthRelatively
inexpensive.Used for TV
signals & mobile phone
comms.

Drawbacks:
Low frequency so
transmits less data at
one time.Affected by
radio stations with
similar frequency

Microwaves

Benefits:
Larger bandwidth, can
transfer more data at a
time

Drawbacks:
Emitting towers
expensive to
build Physical obstacles
can interfere

Satellites

Benefits:
Cheap with long
distanceUsed for
Satellite phones,
satellite radio broadcast

Drawbacks:
Easy to
interfere
Expensive set
up

Ethernet

* Most common wired medium of transmission, that can be used to transfer data between LANs or WANs * Usually used in bus topology; since all data travelled on a single wire there is a possibility of data corruption by the “collision” of signals * This collision is prevented by the CSMA/CD (Carrier Sense Multiple Access Collision Detection) method: Before transmitting, device checks if channel is busy * If busy, device calculates a random wait time and waits that time, after which it begins transmission * Then during transmission, the device listens for other devices also beginning transmission * If collision, transmission is aborted and both devices wait different random times, then tried again

Bit Streaming

* Sequence of digital signals (bits) transferred over a communication path at high speeds * Requires a fast broadband connection and some form of buffers (short-term memory) * Bits arrive in the same order they are sent * Bit rate: number of bits transmitted per second

Real-time bit streaming

* Event captured live via video camera that is connected to a computer * Video signal converted to an encoded streaming video signal * Encoded video signal uploaded from computer to a dedicated streaming server via cables or high-speed wireless internet connection * Server then sends live images to all users requesting it as a real-time video * Cannot be paused, fastforwarded, etc.

On-demand bit streaming

* Existing digital files converted to encoded bit-streaming format for broadcasting on the internet by uploading to a dedicated server * A link for encoded video is placed on website and the user clicks on link to view encoded streaming video * The data is streamed to a buffer in user’s computer and the buffer stops the video from being paused as the bits are streamed * As the buffer is emptied, it’s filled again thus providing continuous viewing * Can be paused, fastforwarded, etc.