COIT20261: Written Assessment 2 on Network Routing and Switching

This document presents a comprehensive solution to a network routing and switching assignment (COIT20261, Term 3, 2019), addressing key concepts such as routing tables, packet fragmentation, and Software-Defined Networking (SDN). The solution includes detailed routing tables for routers R3 and R4, calculations for packet fragmentation, including fragment size and offset, and a discussion on the features and benefits of SDN, including OpenFlow. The assignment explores how SDN addresses current networking challenges and its impact on network agility, centralized management, and vendor neutrality. It also highlights the advantages of OpenFlow in network virtualization and custom service introduction. The solution incorporates proper referencing and adheres to the assignment's marking criteria, providing a thorough understanding of the topics covered.

COIT20261 Network Routing and Switching Term 3, 2019
Assignment item —Written Assessment-2
ANSWER TEMPLATE ASSIGNMENT TWO
Type your answers in the spaces provided
Marking criteria: Your answers will be marked based on technical correctness,
completeness, clarity, originality and relevance. Proper use of referencing conventions
must be followed, and marks may be deducted for failure to comply. For discussion or
research-based questions, if you decide to include a graphic (e.g., a screenshot or a
diagram) in support of your answer, the graphic must be relevant to your discussion, be
appropriately referenced, have sufficient resolution to show all its details clearly and be
of a reasonable size for normal reader viewing, with all or any text within the graphic
being legible and readable. Originality means the work is done solely by you and is
expressed in your own words. An answer is unacceptable if it is composed mostly of
quoted material from other sources and may in some cases receive no marks as a result.
First Name:_________________________ Last Name:____________________________
Student ID: __________________________
Questions Mark
allocated
Mark
earned
Question 1: (10 marks) 5 each
table
Answer: Routing table of router R3:
Mask Network address Next-hop address Interface
/24 230.10.50.0 ………... m1
/24 133.0.10.0 180.0.0.4 m2
/21 210.20.40.0 180.0.0.4 m2
/18 170.16.64.0 180.20.0.30 m0
/16 130.24.0.0 180.20.0.30 m0
/8 180.0.10.0 180.0.10.10 m1
/0 0.0.0.0 180.0.10.10 m1
Routing table of router R4:
Mask Network address Next-hop address Interface
/24 133.0.10.0 ………... m1
/24 230.10.50.0 180.0.0.10 m0
/21 210.20.40.0 ………... m0
/18 170.16.64.0 180.20.0.30 m0
/16 130.24.0.0 180.20.0.30 m0
/8 180.0.10.0 180.0.10.10 m1
/0 0.0.0.0 180.0.10.10 m1
5 max
5 max

COIT20261 Network Routing and Switching Term 3, 2019
Assignment item —Written Assessment-2
Question 2: (5 marks)
a) Packet size = 5500 bytes including header, MTU = 1500 bytes, total
packets = 4
Assuming header = 20 bytes,
Size of data in Packet = (5500 – 20) = 5480 bytes
Fragment 1 size = 1500 including header or data bytes = (1500-20) =
1480, Therefore starting byte = 0, ending byte = 1479
Fragment 2 size = 1500 including header or data bytes = (1500-20) =
1480, Therefore starting byte = 1480, ending byte = 2959
Fragment 3 size = 1500 including header or data bytes = (1500-20) =
1480, Therefore starting byte = 2960, ending byte = 4439
Therefore, data bytes of fragments 4 = (5480 – 4440) bytes = 1040 bytes
Therefore total size of fragment 4 = (1040 + 20) bytes = 1060 bytes
Therefore total size of all 4 fragments = (1500 + 1500 + 1500 + 1060) =
5560 bytes
The total size of all fragments exceeds the size of the original datagram
by 60 bytes.
2.5 max
b) Fragment offset = (1500 – 20)/8 = 185,
For the last fragment = (1060-20)/8 = 130
Therefore, fragment offset of first fragment = 0
Fragment offset of second fragment = 185
Fragment offset of third fragment = (185 + 185) = 370
Fragment offset of fourth fragment = (370 + 130) = 500
1.5 max
c) The combined size of the above four fragments is greater than the
original message datagram that arrived. This is because four separate
headers are required for the four fragments instead of one in the original
datagram. Since the size of these headers are 20 bytes each, the total
size of four fragments exceeds that of the original datagram by 60 bytes.
1 max

COIT20261 Network Routing and Switching Term 3, 2019
Assignment item —Written Assessment-2
Question 3: (10 marks)
a) The features of SDN that help meet current networking challenges are:
 Network can be programmed directly
 Network agility
 Centralized Management
 Programmatically Configurable
 Vendor Neutral and Open Standards
The network controls can be programmed directly as they are decoupled
from the functions of forwarding data in switches and other network
equipment.
The abstracting of network controls from the functions of forwarding
data enables administrators in adjusting the variable network-wide
traffic flow dynamically.
Logical centralization of the network intelligence is performed by SDN
controllers to maintain a global view (Cerroni et al. 2017). This reflects
to applications as one logical switch.
Being programmatically configurable, SDNs help managers in
configuring, managing, optimizing and securing network resources at a
rapid rate through automation.
The open standard implementations simplify the design and operations
of SDN networks as SDN controllers provide the instruction rather than
through different vendor specific protocols and devices.
3 max
b) “SDN allows network devices such as switches and routers to be
responsible only for forwarding data packets, and frees them from
making control decisions, e.g., packet forwarding rules”
In SDNs the traffic is directed by controllers as per the forwarding
policies of the network, thus it reduces the need for manually
configuring the different network devices (Karakus and Durresi 2017).
SDNs take the control plane out of networking equipment and runs them
as software instead, these centralized SDN controllers facilitate
managing of the automated network making it easy to integrate as also
administer business applications (Scott-Hayward 2017). The switches
therefore only execute forwarding functions and is directly
programmable.
4 max
c) SDNs based on OpenFlow makes it more flexible to use and operate the
network (Sgambelluri et al. 2019). The governing software can be
3 max

COIT20261 Network Routing and Switching Term 3, 2019
Assignment item —Written Assessment-2
provided by the all enterprises and service providers. It helps in quickly
introducing custom services. Operating expenses can significantly be
reduced (May et al. 2017). OpenFlow also helps in network
virtualization thus providing seamless integrating of networks with
available storage and computational resources. It also helps with better
alignment of networks to suitably meet the business objectives
(Machado, Granville and Schaeffer-Filho 2016). OpenFlow is used as
the standard means of conveying information regarding flow table and
network devices.
Bibliography
Cerroni, W., Buratti, C., Cerboni, S., Davoli, G., Contoli, C., Foresta, F.,
Callegati, F. and Verdone, R., 2017, July. Intent-based management and
orchestration of heterogeneous openflow/IoT SDN domains. In 2017
IEEE Conference on Network Softwarization (NetSoft) (pp. 1-9). IEEE.
Karakus, M. and Durresi, A., 2017. A survey: Control plane scalability
issues and approaches in software-defined networking (SDN). Computer
Networks, 112, pp.279-293.
Machado, C.C., Granville, L.Z. and Schaeffer-Filho, A., 2016, June.
ANSwer: Combining NFV and SDN features for network resilience
strategies. In 2016 IEEE Symposium on Computers and Communication
(ISCC) (pp. 391-396). IEEE.
May, R., El-Hassany, A., Vanbever, L. and Vechev, M., 2017, April.
Bigbug: Practical concurrency analysis for sdn. In Proceedings of the
Symposium on SDN Research (pp. 88-94). ACM.
Scott-Hayward, S., 2017. Trailing the Snail: SDN Controller Security
Evolution. arXiv preprint arXiv:1711.08406.
Sgambelluri, A., Giorgetti, A., Paolucci, F., Castoldi, P. and Cugini, F.,
2019, July. Open source implementation of OpenConfig telemetry-
enabled NETCONF agent. In 2019 21st International Conference on
Transparent Optical Networks (ICTON) (pp. 1-4). IEEE.
Total marks awarded 25 (max)
Less late penalties
Less plagiarism penalties
Total marks earned

COIT20261 Network Routing and Switching Term 3, 2019
Assignment item —Written Assessment-2
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