Data Communications Uni notes

FIT9020: Summary

FIT9020 Data Communications was a compulsory subject for students without comparable undergraduate credit. It did however turn out to be well worth the time. Some of the best parts about this subject were:

  • Tutorials
    • Learning how to use applications such as Wireshark, Kistmet, inSSIDer
    • Learning about the array of network tools included in both windows and *unix systems (netstat, tracert etc)
  • Lectures
    • Much more detailed understanding of how computer networks send and receive data
    • How network routing works

Of course the subject was not perfect, some of the points that I did not enjoy so much were:

  • Excessive time spent on physical communication
  • Heavy lectures which focused on technical details rather than discussion of concepts

I would definitely recommend this subject to anyone who wants a greater understanding of how networks and the internet work. You will get a very detailed practical knowledge base and learn how to use a number of invaluable tools for getting more information about the underlying network communications that make the internet work. Thanks to Andrew Paplinski for running a great subject with very interactive tutorials.

Links to tools:





Data Communications

FIT9020: Week 9

Data Communications 9th week moved from Wireless networks back to the standard variety and now focused on Backbone networks.

The two major topics were:

  • Switched, Routed and Gateway Backbones
  • Virtual LANs

Routed backbones operate on the 3rd network layer, allowing for cross data link protocol communications. This is not possible for the faster but simpler switch backbones. Some Gateways work on the application layer and involve more processing than routed backbones. Gateways are most often used for networks connecting to mainframes.

Example of a VLAN architecture, source: Week 9 Lecture notes

Additionally, for our assignment we must analyze the differences between the IEEE 802.11 wireless protocols, information for this can be found here:

Data Communications

FIT9020: Week 8

Data communications week 8 brought a focus on wireless communications.

In the tutorial we worked with some wireless network sniffers to get a deeper understanding of wireless networking. As I was running ubunutu on my laptop I was unable to use the software prescribed ( which is a replacement for NetStumbler.

Instead I had to use Kismet which is an Ubuntu option that was not very user friendly as it ran in the terminal (

inssider - allows analysis of wireless network traffic
inssider - allows analysis of wireless network traffic
Data Communications

FIT9020: Week 7

Another missed lecture and tutorial for Data Communications which I definitely regret as the subject is very interesting.

Week 7 focused on Local Area Networks, the reasons for them, how they work and how to implement them.

Typical Multi-building LAN

Data Communications

FIT9020: Week 6

Data Communications sixth week was a follow up on the assignment topics:

  • TCP/IP
  • ARP
  • DHCP
  • more wireshark analysis

The lecture was an audio recording which gave us a very nice overview of routing.

Three major types of routing:

  • Centralized routing
  • Static Decentralized routing
  • Dynamic Decentralized routing (adaptive routing)

Al three are used through the internet.

source - Alan's Recording: Routing and TCP example

The recording followed some example of HTTP requests travelling through a network.

Data Communications

FIT9020: Week 5

Data Communication, week 5 was unfortunately a  missed class for me due to illness. A summary of the lecture on Network and Transport layers are as follows:

  • TCP/IP!

TCP segment (source: week 5 lecture notes)
  • Review of three-way handshake conducted by TCP
  • User Datagram Protocol [UDP]
  • IP packet contents:

IP Packet (source: week 5 lecture notes)
  • Addresses and subnets
  • MAC addresses
  • Address resolution ARP
  • DNS processes

Data Communications

FIT9020: Week 4

The Data link Layer was covered in week 4 of Data communications, which was another high detail lecture [All Trains Now Depart Promptly -> Application, Transport, Network, Data Link, Physical] .

Using both Logical Link Control [LLC] and Media Access Control [MAC] the Data Link layer controls when computers transmit data, detects and correct transmission errors and identifies the beginning and end of messages.

Reminder, half duplex is one message at a time, full duplex (enabled by co-axial cables) message can pass each other.
Data Communications

FIT9020: Week 3

Data Communication’s third lecture review in more detail the Physical Layer (Application -> Transport -> Network -> DataLink -> Physical).

Analogue vs Digital

Dataflow transmissions (Simplex, Half Duplex, Full Duplex, Multiplex)

Multiplexing Division methods:

  • Frequency Division multiplexing [FDM]
  • Time Division multiplexing [TDM]
  • Statistical Time Division Multiplexing [STDM]
  • Wavelength Division Multiplexing [WDM]

Communication Medias


    • Twisted Pair Cables
    • Coaxial Cable
    • Fiberoptic
  • Wireless
    • Radio
    • Infrared
    • Microwave
    • Satellite

Interestingly, as satellites need to orbit the earth at quite a high distance to maintain stable service (ideally geostationary appx. 36,000kms) the delay due to the speed of light makes fibre optic a much faster option.

Optical fiber is number 1 in data transmission
Data Communications

FIT9020: Week 2

Data communications in week to delved deeper into the Application Layer. Looking specifically at HTTP and SMTP and Application architectures.

The Application Layer can be further segmented into User Interface, Business Logic, Data Access and Data Storage. Clients and servers where defined and three basic architectures:

  • Host base architectures (server heavy)
  • Client-based architectures (client heavy)
  • Client-server architectures (shared)

Client Server architectures are the latest in the application architecture evolution and has give rise to the need for some middleware softwares. Middleware acts as a translator between different varieties of software. Some examples include:

  • Distributed Computing Environment (DCE)
  • Common Object Request Broker Architecture (CORBA)
  • Open Database Connectivity (ODBC)

The client server architecture is still evolving and segmentation of the application layer onto multiple tiers is now being enable by faster connection speeds. This allows for better load balancing and greater extendibility/scalability of services.

Wireshark open source network protocol analyzer
Data Communications

FIT9020: Week 1

Started off the subject with a two hour lecture which was mostly housekeeping. The second half of the lecture was quite interesting though with the focus on previewing the topics we would be covering this semester.

Amoung the topics to be covered:

  • Application Layer
  • Transport Layer
  • Network Layer
  • Data Link Layer
  • Physical Layer
source: Lecture 1
  1. Concepts of networking
  2. Technologies in use today
  3. Management of networking technologies

Five Layer model of internet networking

  • Physicals – Hubs, switchers, routers,cables satelites etc. [Ethernet]
  • DataLink Layer – Controls physical layer, formats transmission etc. [Ethernet]
  • Network and Transfer protocols – [TCP/IP]
  • Application Layer – [Web Browsers and web pages]

Also covered was the important of standards and the evolution of data comms/networks