What is a Network Router? Routing Terms

COIT20261 Network Routing and Switching Term 3, 2019
Assignment item —Written Assessment-2
ANSWER TEMPLATE ASSIGNMENT TWO
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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
/24 230.10.50.24 .... m1
/24 133.0.10.12 180.0.0.4 m2
/21 210.20.40.2 180.0.0.4 m2
/18 170.16.64.0 180.20.0.30 m0
/16 130.24.10.16 180.20.0.30 m0
/0 0.0.0.0 180.0.10.10 m1
Routing table of router R4:
Mask Network address Next-hop address Interface
/24 230.10.50.24 180.0.0.10 m0
/24 133.0.10.12 .... m1
/21 210.20.40.2 .... m0
/18 170.16.64.0 180.20.0.30 m0
/16 130.24.10.16 180.20.0.30 m0
/0 0.0.0.0 180.0.10.10 m1
5 max
5 max
Question 2: (5 marks)

COIT20261 Network Routing and Switching Term 3, 2019
Assignment item —Written Assessment-2
a) IP datagram packet size= 5,500 bytes containing header, MTU=1500,
number of packets=4.
Let us assume the header= 20 bytes.
Size of data included in original packet= (5500-20) = 5480.
Size of first 3 fragments from original packet= size of MTU= 1500.
Size of last fragment= 5500-(1500+1500+1500) = 1000.
Size of Fragment 1= 1500 including the header=
(1500-20) = 1480. Hence the starting byte= 0 and the ending byte=
1479.
Size of Fragment 2= 1500 including the header= (1500-20) = 1480.
Hence, the starting byte= 1480 and the ending byte= 2959.
Size of Fragment 3= 1500 including the header= (1500-20) 1480.
Hence, the starting byte= 2960 and the ending byte= 4439.
Therefore, data part of Fragment 4= (5480-4440) = 1040.
Full fragment size of last packet= 1040+20= 1060. Hence, the starting
byte= 4440 and the ending byte= 5479.
2.5 max
b) Fragment offset= (1500-20)/8= 185.
Fragment offset for the last fragment= (1060-20)/8= 130.
Fragment offset for Fragment 1= 0.
Fragment offset for Fragment 2= 185.
Fragment offset for Fragment 3= (185+185) = 370.
Fragment offset for Fragment 4= (370+130) = 500.
1.5 max
c) Total size of the 4 fragments= (1500+1500+1500+1060) = 5560. Here it
is visible that the total size of the four fragments is larger than the
original sized datagram. On the contrary, in the initial size of the
datagram there is only one size of header included that is 20 bytes.
However, in all of the fragments 20 bytes of the header is also included
that is standing out to be 80 bytes in total. On the contrary, one of the 20
bytes is already included in the original datagram. This leads to the fact
that one header of 20 bytes gets cancelled out by one of the fragments,
and hence three other header size of 20 bytes is getting added to 5500
amounting up to 5560.
1 max

COIT20261 Network Routing and Switching Term 3, 2019
Assignment item —Written Assessment-2
Question 3: (10 marks)
a) Software-Defined Networking refers to the physically existing
separation belonging to the control plane in regards to the respective
network coming from that of the forwarding place as well as where the
controls meant for the control plane has the real time existence in
reference to the several existing devices (Tang et al., 2016). This
commonly refers to a rising architecture, which is specifically dynamic,
operable as well as cost-efficient. The salient features of the SDN
architecture within the field of networking are,
 Directly programmable- the control over the network has the
inclusion of a feature that allows to be directly programmable
because of the reason that it has to be specifically decoupled
from all of the functions in particular.
 Agile- abstraction of the control from the forwarding provisions
all the administrators with the allowance to adjust the traffic flow
across the network in a dynamic method for meeting the needs in
regards to changing (Bera, Misra & Vasilakos, 2017).
 Centrally managed- the network expertise that is centralized
completely based upon the software related to SDN controllers
that maintains a particular globalized view in relation to the
entire network. This specifically takes the form of the
applications as well as the policy engines in the form of a local
and a single switch.
 Configured with programs- SDN provisions the network
managers with the allowance to configure, secure, manage as
well as optimize the network and the relative resources in a quick
manner with the help of a dynamic as well as an automated SDN
program (Haque & Abu-Ghazaleh, 2016). This can be written
by them itself because of the fact that all such programs have no
dependency upon the software related to proprietary.
 Based upon open-standards as well as the vendor-neutral- during
the implementation with the help of open standards, the SDN
simplifies the design of the network as well as the relative
operations in accordance to the instructions placed forward by
the SDN controllers keeping aside the devices and the protocols
that are vendor-specific.
3 max