ISYS1000 Lecture Notes - Lecture 4: Telstra, Unified Communications, Wimax
29 May 2018
School
Department
Course
Professor
Module 4 – Telecouicatio &
Networkig
LEARNING OUTCOMES
4.1 What is a computer network
4.2 Network fundamentals
4.3 The internet and the world-wide web
4.4 Network applications
4.1 WHAT IS A COMPUTER NETWORK
A computer network is a system that connects computers and other devices (e.g. printers)
via communications media so that data and information can be transmitted.
Bandwidth refers to the transmission capacity of a network, i.e., how fast/much a network
can carry.
Broadband refers to the network transmission capacities ranging between 1 megabits/sec
to around 20 megabits/sec. It is represented by such technologies as ADSL and/or DSL,
which still use existing analogue (copper) telephone lines. These are significantly higher than
the 1st generation internet modem connectivity of (max) 56kb/sec. Fibre optic broadband is
significantly faster than DSL broadband.
NETWORK TYPES CONCEPTUALISED BY SIZE
Personal area networks (PANs)
Local area networks (LANs)
Metropolitan area networks (MANs)
Wide area networks (WANs)
The internet
Local area network (LANs)
Connects two or more devices in a limited geographical region, usually within the same
building, so that each device on the network can communicate with every other device.
find more resources at oneclass.com
find more resources at oneclass.com
Wide area networks (WANs)
Required when organisations have to transmit/receive data beyond the confines of a LAN. It
typically connects multiple LANs. It is generally provided by carriers such as telephone
companies. WANs have large capacity and typically combine multiple channels (e.g. fibre
optic cables, microwave and satellite). They also contain routers: i.e. a communications
processor that routes messages from a LAN to the internet, or across several connected
LANs (via internet protocols).
4.2 NETWORK FUNDAMENTALS
TYPES OF SIGNALS USED FOR NETWORK TRANSMISSION
Analogue
All souds ae aalogue, tasittig soud alog aes ad easued usig to
parameters:
Amplitude: is volume; the higher the waves/amplitude the louder the sound
Frequency: is pitch; the more closely packed the waves, the higher the pitch
Digital
Discrete pulses that are either on or off representing a series of bits (1s and 0s). Sound
oeted ito iay fo, that a e itepeted y oputes. All ICTs speak iay.
Modems
Convert digital signals to analogue (modulation) and vice versa (demodulation) – hence the
ae od-de. Thee ae thee types of odes: Dial-up modem, cable modem, digital
subscriber line (DSL) modem.
COMMUNICATIONS MEDIA AND CHANNELS
Communications channels are comprised of 2 types of media:
Cable
Twisted-pair wire, cable, or fibre optic cable.
Broadcast
Microwave, satellite, radio or infrared.
NETWORK PROTOCOLS
Deies o a etok ae efeed to as the odes. Nodes adhee to a oo set of
protocols that enable them to communicate with one another.
There are two major protocols in computer networks:
Ethernet
The most common LAN protocol.
Transmission Control Protocol/Internet Protocol
TCP/IP is the protocol of the internet. It uses packet switching technology, a transmission
technology that breaks blocks of text into packets. Each packet carries information that will
help it reach its destination.
1. “edes IP addess
2. Iteded eeies IP addess
3. Number of packets in message
4. The number of each packet
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
A computer network is a system that connects computers and other devices (e. g. printers) via communications media so that data and information can be transmitted. Bandwidth refers to the transmission capacity of a network, i. e. , how fast/much a network can carry. Broadband refers to the network transmission capacities ranging between 1 megabits/sec to around 20 megabits/sec. It is represented by such technologies as adsl and/or dsl, which still use existing analogue (copper) telephone lines. These are significantly higher than the 1st generation internet modem connectivity of (max) 56kb/sec. Fibre optic broadband is significantly faster than dsl broadband. Connects two or more devices in a limited geographical region, usually within the same building, so that each device on the network can communicate with every other device. Required when organisations have to transmit/receive data beyond the confines of a lan. It is generally provided by carriers such as telephone companies.
