COIT20261 : Network Routing and Switching Assignment

This report is on "network routing and switching". This assessment task requires you to demonstrate your knowledge of routing concepts by completing a number of exercise questions. We will discuss here fragmentation in IPv4. An IPdatagram5,400 bytes long with no options arrives at a router, which determines that the next destination has an MTU of 1,500 bytes. We will also discuss here network diagram, assume that all the networks shown are aware of each other and have fully updated routing tables. In this report, the questions will be marked on correctness, logic, and clarity, and addressing all parts of the question.

COIT20261 Network Routing and Switching (Term 1, 2018)
Assignment item —Written Assessment-2
Due date:
11:45pm AEST, Friday, Week 10
ASSESSMEN
T
Weighting: 25% 2
Objectives
This assessment task requires you to demonstrate your knowledge of routing concepts by
completing a number of exercise questions.
The questions are designed to help you to achieve the unit learning outcomes as listed in the
unit profile.
Instructions
You must do this assignment on your own – it is not a group assignment.
Thesequestions will require more time and effort than the first assignment so plan ahead and
start as early as possible. Question #3 may require additional research and analysisto
complete.
Type all your answers in the ‘Template for Your Answers’ Section of this document and
upload only that template. You can do that by copying the Template section into a new Word
document for uploading. Answers that are not typed into the “Template for Your Answers”
section may not be marked, or may be returned to you for re-typing and re-submission – late
penalties will apply.
Where instructed, you must show the steps you took to arrive at your answers. Write
your answers in your own words to avoid potential plagiarism and copyright violations.
You must submit the Answer section as a Word file (.doc or .docx). Do not submit PDF’s
or any other type of file without express permission from the Unit Coordinator.
Plagiarism Procedures can be found in the CQUniversity Policies section of the Unit Profile.
Assessment Requirements and Marking Criteria
There are 3 main questions each with sub-questions and the requirements are stated for each
one. You must answer all questions and their sub-questions. Marks are indicated in the
Answer Template.
The questions will be marked on correctness,logic and clarity, and addressing all parts of the
question.
The Assignment Questions begin on the next page.
REMEMBER, USE THE ANSWER TEMPLATE FOR ALL YOUR ANSWERS

COIT20261 Network Routing and Switching (Term 1, 2018)
Assignment item —Written Assessment-2
Question 1 – Routing (10 marks)
Given the following network diagram, assume that all the networks shown are aware of each
other and have fully updated routing tables. Answer the questions that follow.
The questions (1 mark each except q.8):
1. From the point of view of router R4, what is the next-hop address for a packet
addressed to host 161.22.0.15/18?
2. From the point of view of router R1, which of its interfaces would it choose for a
packet being sent to network 161.22.0.0/18?
3. A host with an IP address of 200.11.60.36/24 has just sent a packet to a host with
address 150.32.0.240/18. How many hops is required between source and
destination?
4. A packet originating from network 220.10.40.0/24 arrives at router R1, however, R1
determines that the destination network is not in its routing table. What does R1 do
with the packet?
5. A packet arrives at router R2 with a destination address of 140.21.0.10/22. Which
interface port does R2 forward the packet out of?
6. A packet at router R3 has a destination address of 220.10.40.5/24. What next-hop
address would R3 use for this packet?

COIT20261 Network Routing and Switching (Term 1, 2018)
Assignment item —Written Assessment-2
7. A packet is waiting at router R4 for forwarding. If the next-hop was a “direct
delivery”, which of these three networksis the destination network? 150.3.0.0/16, or
150.32.0.0/18, or 220.10.40.0/24?
8. Complete the information in the routing table for router R2 as shown in the Answer
Template for networks 150.3.0.0/16, 150.32.0.0/18, and the Default network. Show
the masks in longest mask order using CIDR format (3 marks).
Question 2 – Fragmentation in IPv4 (5 marks)
An IPdatagram5,400 bytes long with no options arrives at a router, which determines that the
next destination has an MTU of 1,500 bytes.Use the Answer Template to complete the
following questions, showing your calculations and reasoning.
a) Assuming that the router decides to fragment the packet into 4 fragments, determinea
correct size for each fragment, and identify the starting byte and ending byte of each
fragment(2.5 marks).
b) Calculate the fragmentation offset for each fragment(1.5 marks).
c) State whether the total number of bytes from all 4 fragments leaving the router will be
greater than the initial datagram size that arrived, or less than the initial datagram size,
and the reason(1 mark).
Question 3 – Congestion controls in TCP (10 marks)
This question affords you the opportunity to extend your thinking about congestion controls
in TCP beyond the textbook to observe what a real-world technology company, Google, is
doing in this space.
First, read this Network World article that reports on Google’s approach to improving
congestion controls in TCP:
https://www.networkworld.com/article/3218084/lan-wan/how-google-is-speeding-up-the-
internet.html?
idg_eid=f32fc7aec843db7ef67d0a4f08e3322d&email_SHA1_lc=&cid=nww_nlt_networkworld_daily_
news_alert_2017-08-22&utm_source=Sailthru&utm_medium=email&utm_campaign=NWW
%20Daily%20AM%20Alert%202017-08-22&utm_term=networkworld_daily_news_alert
You should also read the following more technical paper about it: https://tools.ietf.org/id/draft-
cardwell-iccrg-bbr-congestion-control-00.html
After reading both articles, answer the following questions:
1. Write a brief summary of the congestion controls currently available in TCP as
covered in this Unit (1 mark)
2. Identify and explain two problems with current congestion controls in TCP that are
pointed out in the articles (2 marks)

COIT20261 Network Routing and Switching (Term 1, 2018)
Assignment item —Written Assessment-2
3. Summarize in your own words the difference(s) between the current TCP congestion
controls and Google’s new BBR protocol (3 marks)
4. The Network World article points out that it is difficult to get a new protocol accepted
as a global standard for TCP/IP. Why do you think this is the case? Give carefully
thought out reasons for your answer. (4 marks)
Important: for every direct quotation you use from these two sources or any other source, you
must immediately, after the quote, provideyourownexplanation of the quotation (for example,
explain why are you quoting it, how does it help answer the question, how does it support what you
are saying?) – marks will be deducted for failure to do so. In addition, correct referencing
conventions must be used throughout your work using the Harvard referencing convention. Your
answers will be marked on clarity, logic, relevance, use of own words and fully addressing all parts of
each question.
Remember that quotations alone will not be accepted as your explanation of the questions.
Quotations can support your explanations, but you must still provide the explanations yourself.
Best way forward is to keep direct quotations to a minimum, and use your own words.

COIT20261 Network Routing and Switching (Term 1, 2018)
Assignment item —Written Assessment-2
TEMPLATE FOR YOUR ANSWERS
Type your answers in this section in the spaces provided. Spaces
can expand as you type.
First Name:_________________________ Last Name:____________________________
Student ID: __________________________
Question Number Mark
allocated
Marks
earned
Question 1: (10 marks)
1.
2.
3.
4.
5.
6.
7.
8.
150.3.0.3
M2
2 hops required
Packet gets dropped by router.
M0
150.3.0.3/16
150.30.0.16
q.8 Routing table of router R2:
Prefix Network address Next-hop address Interface
255.2
55.25
5.0
220.10.40.0 150.3.0.3 M0
255.2
55.25
5.0
200.11.60.0 200.21.60.1 M1
255.2
55.25
2.0
140.21.0.0 140.21.0.1 M2
255.2
55.19
2.0
161.22.0.0 150.3.0.3 M0
255.2
55.19
2.0
150.32.0.0 150.3.0.1 M0
255.2 150.3.0.0 150.3.0.2 loopback
1-7 1
mark
each, q.8
3 marks

COIT20261 Network Routing and Switching (Term 1, 2018)
Assignment item —Written Assessment-2
55.0.0
Question 2: (5 marks)
a) IP datagram = 5400 bytes
MTU = 1500 bytes
IP header = 20 bytes
Therefore, 5400 -20 = 5380
MTU of 1500 bytes, 1500 -20 = 1480 bytes of data is transmitted for each
of the data packets
Ceiling (5380 /1480) = 4 packets are required
1st packet: 20 bytes: IP header, 1480 bytes: Data ==
Correct size: 20+1480 = 1500 bytes, starting byte :1 , ending bytes : 1480
2nd packet: 20 bytes: IP header, 1480 bytes: Data ==
Correct Size: 20 +148 = 1500 bytes, starting bytes : 1481, ending bytes :
2960
3rd packet: 20 bytes: IP Header, 1480 bytes: data ==
Correct Size: 20+1480 = 1500 bytes, starting bytes:2961, ending bytes:
4440
4th packet: 20 bytes: IP Header, 1345 bytes: Data ==
Correct size: 20 +1345 = 1365 bytes, starting bytes: 4441, ending bytes:
5805
2.5
b) For the 1st packet:
Offset Value = 0
For the 2nd packet:
Offset Value = 185
For the 3rd packet:
Offset Value = 370
For the 4th packet:
1.5

COIT20261 Network Routing and Switching (Term 1, 2018)
Assignment item —Written Assessment-2
Offset Value = 555
c) To send any data packet in any network, the IP header file consumed 20
bytes data. However, it becomes similar for all kinds of header files
provided in data packets. Due to which the next datagram size is reduced t
20 bytes, for 1500 bytes packet, 1481 is become the starting byte because
of the header file length=20 bytes.
Hence, the total bytes count depending on 4 fragments leaving from
router becomes greater from initial size of previous datagram that is
already available.
1
Question 3: (10 marks)
1. The congestion control techniques used in TCP while any unit covers
BBR algorithm such as RENO and CUBIC. Apart from that, it assists to
raise more network throughput and the bottleneck reduction together with
congestion issues present in the network. In addition to this, it also helps
to calculate delivery rate connection based on maximum bandwidth as
well as minimum sort of round-trip delay.
For doing the congestion control, shallow as well as deep buffer
techniques are used while BBR produces the network path model to evade
the congestion of network.
1
2. Shallow Buffers: the shallow buffer technique used of loss based
congestion control results become terrible as it also overreacts because of
its multiplicity of sending rate; data packets get decreased.
Deep Buffers: the deep buffers technique enhances the delay occurrence
with the help of recurring filling of buffers based on last mile link as well
as the creation of needled queue in a network.
2
3. The TCP protocol organized in a network model depending on available
network paths to do proper response based on actual congestion. In
addition to this, the Google created algorithm reduces the sharing speed of
data packets with the help of different algorithm and routes operate traffic
in any types of congestion routes. Therefore, round trip traffic and
throughput for multiple routes are estimated as well as the time
consumption of data in a network get to known. In addition to this, traffic
send in high speed will be handled with the help of any network.
3
4. There are various difficulties available in Network World article that
generates barrier for the new protocol used in Global Standard of TCP/IP.
IETF is used to test the compatibility of BBR algorithm and different
protocols to get these standardized. However, the RENO and CUBIC
protocols mainly follow same types of principle while BBR mainly uses
the packet timing technique and other figures to identify any types of
congestion available in route.
4

COIT20261 Network Routing and Switching (Term 1, 2018)
Assignment item —Written Assessment-2
Total marks awarded 25 (max)
Less late penalties if applicable
Less plagiarism penalties if applicable
Total marks earned
Markers comments: