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INFT12-230 Assignment 2 Result Overview
1 GENERAL POINTS
OSI Layer 6 applies to your assignments: always present your work well. This means
proper sentences, justify text, use headings and tables where appropriate, etc. Easy
to read means easier to get your point across to the reader.
Proof-read written questions for spelling and grammar. 60% of the class had at least
some spelling or grammar problem. You can always ask someone else to proof-read
for you if you have a friend who wouldn't mind.
Out of university we want to produce thinkers. IT is an ever-changing field, and in
almost every job you'll be required to learn something yourself and to come to your
own conclusions. I want to see in your answers your thinking, your own opinion and
thought process. Justify your answers based on your own knowledge - you'll be able
to put a lot more emphasis behind it if you yourself believe it.
Included below are some sample answers from various students. These are answers
I feel show the quality of work I would expect from every question in any submitted
work.
2 SAMPLE ANSWERS
[Henry's comments: gets the point across to the reader by backing up the answer, not just
giving it]
d) [2 marks] How many collision domains exist in your network? How many broadcast
domains?
As indicated in the picture, there are 6 collision domains which exist in the network, and 2
broadcast domains.
[Henry's comments: uses pictures to illustrate the situation, where visuals are useful in
explaining distance]
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INFT12-230 Assignment 2 Result Overview
1) CAT5 cable will be used in my network. I will use 3 long cables that are 10m
each. These cables are to connect PC0, PC1 and PC2 with the switch. Two more cables, 1m
each, are used to connect the switch with the router (ADSL MODEM) and with the access
point, which are in close proximity to each other (see the illustration below).
[Henry's comments: justifies the features "ADSL2" and "USB port" with opinions which show
thought has been put into it. This applies regardless of whether they are perfectly accurate or
not]
2.1.1 DLINK DSL-502T USB/ETHERNET ADSL & ADSL2
MODEM/ROUTER
This ADSL modem was selected as it has ADSL2 and ADSL2+ expansion capability. With the
rise of higher bandwidth broadband services, it is worth thinking ahead and purchasing an
ADSL modem with support for future technologies. It has a RJ45 cable port which we require
to connect to our switch. It also has USB port, which is not useful for our final network design,
but may be useful for bug testing and troubleshooting should the internet connection not work.
Another feature is NAT, which is important as we are using private IP addressing for our client
PCs.
[Henry's comments: gives a clear example to help explain a difficult question. When you have
trouble formulating an answer, the use of an example is a good strategy]
2.1.2 f)
Network Address Translation (NAT) is a means of allowing multiple private computers to
connect to the internet via a single public IP address. NAT is also known as IP masquerading.
The way it works is: when the router receives a packet destined for the internet from a private
computer (on the internal LAN), it records the source address and source port in a table , and
replaces the packets source address with its own public IP, and then transmits the packet
(request) onto the internet. When the request is sent back from a server on the internet, the
router looks up its table for the person who requested this particular request on the specified
port in the packet. Once it finds the private computer that requested the packet, the router
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INFT12-230 Assignment 2 Result Overview
replaces the destination address in the packet with the private computers private IP address
and also replaces the destination port to be the one listed in the table as the packet left the
network.
This would be useful for our situation as when we connect to the internet we would only be
allocated a single IP address. Therefore, by using NAT we can support multiple computers on
a private LAN behind a router using a single public IP address. See below for an example.
Figure 1: NAT Example
Step Operation
1 Computer “Ben” sends out a request for www.google.com leaving on
port 1500.
2 The router receives the packet, removes the source IP from the packet
and replaces it with its own public IP address. The router then stores
the original source port and original IP from the packet into a table so
it can remember who requested it.
3 The router then sends the packet out onto the internet.
4 The google server on the internet replies with some data (ie a website)
to the router. Google's packets have the routers IP as the destination,
and the original port (1500) set at the destination port.
5 The router receives the data from the google server on port 1500, then
looks up the record in its table for who requested the page. Once it
finds the private computer who requested it, based on the port/ip
listed in the table, it replaces the packets destination IP with the
private IP of Ben, and keeps the destination port (1500) intact. The
router then forwards the packet onto Ben.
6 Ben now receives the final packet which was addressed to it on port
1500.
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INFT12-230 Assignment 2 Result Overview
[Henry's Comments: lists the things which are important, outlines several alternatives, makes
selection and backs up the choice with reasons]
Switch ___________________________________________________________
There are few points need to consider before purchasing a switch:
10/100/1000 Mbps Ethernet connection
Automatic connection detection for cable & network type
Half/Full Duplex
Cat6 copper cabling
Net Gear GS105/ 5 port
10/100/100 Mbps Ethernet
Automatically adjusts for
straight-through or crossover
Full-duplex connections
Cat6 copper cables for use
AUD $148.50
SMC 5-port Gigabit Switch
10/100/100 Mbps Ethernet
Cat6 copper cables for use
AUD $170.50
D-Link DGS-1005D/ 5 port
10/100/1000 Mbps Ethernet
Automatic cable-type detection
Cat6 copper cables for use
AUD $166.10
Compares the result of above devices, Net Gear GS105 is the best recommend for
switch use. It has support up to Gigabit Ethernet. Therefore, the range of use would
be more flexible. Also can detect and adjusts for cables connection, full duplex, and
Cat6 cables can be use. Then it would save lots of time on setting up a network. As
well as can apply with better quality of cables.
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