Network Routing and Switching Assignment COIT20261 Term 2, 2019

This document presents a comprehensive solution to a Network Routing and Switching assignment (COIT20261) from Term 2, 2019. The assignment covers crucial aspects of network routing, including the creation and interpretation of routing tables for routers R1 and R4, detailing the mask, network address, next-hop address, and interface configurations. It delves into the packet forwarding process within routers, explaining how destination IP addresses are used to make routing decisions, and how packets are encapsulated and decapsulated at different layers. Furthermore, the solution explores TCP congestion control mechanisms, contrasting the traditional methods with Google's BBR algorithm. It discusses the impact of shallow and deep buffers on network performance, as well as the challenges involved in adopting new protocols like BBR as a global standard. The document includes references to support the analysis, providing a complete understanding of the subject matter.

COIT20261 Network Routing and Switching Term 2, 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 R1:
Mask Network address Next-hop address Interface
255.255.0.0 150.3.0.0 150.3.0.4 Loopback
255.255.25
5.0
200.11.60.0 150.3.0.2 M0
255.255.25
2.0
140.21.0.0 150.3.0.2 M0
255.255.19
2.0
150.32.0.0 150.3.0.1 M0
255.255.25
5.0
220.10.40.0 150.3.0.3 M0
255.255.19
2.0
161.22.0.0 150.3.0.3 M0
Routing table of router R4:
Mask Network address Next-hop address Interface
255.255.0.0 150.3.0.0 150.3.0.1 Loopback
255.255.25
5.0
200.11.60.0 150.3.0.2 M0
255.255.25 140.21.0.0 150.3.0.2 M0
5 max
5 max

COIT20261 Network Routing and Switching Term 2, 2019
Assignment item —Written Assessment-2
2.0
255.255.25
5.0
220.10.40.0 150.3.0.3 M0
255.255.19
2.0
161.22.0.0 150.3.0.3 M0
255.255.19
2.0
150.32.0.0 150.3.0.1 M0
Question 2: (5 marks)
a) The router is designed to route the data packet reaching to it with the
help of switching mechanism. Firstly the header of the received data
packet is de-encapsulated for exposing the third layer of the data
packets. The packet is examined for getting the destination IP and a
checking is done on routing table for getting the presence of IP address.
If the destination IP is present in the routing table it is forwarded to that
address and in case the address is not found the packet is sent to the next
hop router. The next hop router performs the same mechanism and this
process continues until the data packet is sent to its final destination IP.
During forwarding the data packet the third layer data packets are
encapsulated in layer 2 frame and sent to exit interface of router.
1 max
b) Packet arrives at R3 having destination address of 200.11.60.120 the
forwarding process of the router is given below:
The packet gets forwarded to interface labelled M0 and it reaches
the loopback address of 150.3.0.0/16 and from there it is forwarded
to router R2. The router determines the path for delivering packet
to IP 200.1160.120 and forwards it to the m1 interface havin
network address if 200.11.60.0/24 by estimating header index. The
outgoing interface is selected from the header index and the data
packet is forwarded to the destination node.
2 max
c) In case a packet having IP address as destination 150.32.203.10 arrives
at Router R3 an examination is made on the header index and such that
an outgoing interface is selected such that the data packet is forwarded.
The m0 interface is selected on finding the address of the header for
forwarding it to the next hop router. This step is continued until the
destination address is found for the data packet.
2 max
Question 3: (10 marks)
1) Congestion control that are used in TCP are achieved with the
application of different algorithm for increasing the efficiency of a
network. The throughput can be improved with the use of RENO and
1 max

COIT20261 Network Routing and Switching Term 2, 2019
Assignment item —Written Assessment-2
CUBIC algorithm and this is achieved by eliminating bottleneck
condition such that the congestion can be avoided. The availability of
the bandwidth and RRT (Round Trip Delay) in the network
communication channel is analysed before sending the data packets.
Moreover deep or shallow buffers can also be applied such that the
congestion can be controlled. The virtualization of the network path
helps in identification of the best path available for the BBR and
increasing the rate of delivery for the data packets in the network.
2) An abnormal result can be obtained with the use of shallow buffer
because it can reduce the rate of sending the data packet in the network
for multiplicatively and since it is dynamic in nature it can never be fully
utilized (Butler 2019). On the other hand the application of deep buffer
increases delay in sending the data packet with filling repeatedly the
buffer with last mile route and generating an unnecessary queue.
2 max
3) The current TCP congestion controls differs from the newer BBR
protocol in multiple ways. The TCP congestion control is works with the
network models by analysing the available routes in the network and the
congestion in the available route. Google’s BBR algorithm uses the data
traffic flowing in the network for analysis and optimizes them before
sending such that it does not creates a clog on the route (Butler 2019). It
selects the fastest path for sending the data packet. The RRT and
throughput of the path is analysed for finding the time needed to send
the packet and optimized the packet such that it can be sent at a speed
that is manageable for the current network.
3 max
4) From the evaluation of the network world article it has been analysed
that multiple difficulty are faced while acceptance of new protocol and
keeping it as a global standard for the TCP/IP. The first step is to
standardize the protocol and management of compatibility between the
protocol and testing with IETF (Tools.ietf.org. 2019). The transmission
can be speeded up with the use of TCP protocol and different algorithm
and it acts as a long term procedure such that the standardization process
can be improved and application of packet timing. It also helps in using
different routes such that congestion can be figured and best
methodology can be selected.
4 max
Total marks awarded 25 (max)

COIT20261 Network Routing and Switching Term 2, 2019
Assignment item —Written Assessment-2
Less late penalties
Less plagiarism penalties
Total marks earned
Markers comments:
References
Butler, B. (2019). How Google is speeding up the Internet . [online]
Network World. Available at:
https://www.networkworld.com/article/3218084/how-google-is-
speeding-up-the-internet.html?
cid=nww_nlt_networkworld_daily_news_alert_2017-08-22
[Accessed 15 Sep. 2019].
Tools.ietf.org. (2019). BBR Congestion Control. [online] Available
at: https://tools.ietf.org/id/draft-cardwell-iccrg-bbr-congestion-
control-00.html [Accessed 15 Sep. 2019].