COIT20261: Network Routing and Switching Assignment Solution

This document presents a comprehensive solution to a network routing and switching assignment, addressing key concepts such as routing tables, classful and classless routing, and congestion control mechanisms. The solution includes detailed routing tables for routers R1 and R4, explanations of classful and classless routing differences, and an analysis of how routing processes occur. Furthermore, the assignment explores open-loop and closed-loop congestion control approaches, their drawbacks, and a comparison between TCP and BBR protocols. The solution provides insights into the performance and implementation of these protocols, concluding with an argument for the continued relevance of TCP. This resource is designed to aid students in understanding network routing principles and preparing for related assessments.

Questions
Question 1: (10 marks)
Answer: Routing table of router R1:
Mask Network address Next-hop address Interface
/24 200.11.60.0 ------- M1
/24 220.10.40.0 150.3.0.3 M0
/22 140.21.0.0 ------- M2
/18 161.22.0.0 150.3.0.3 M0
/18 150.32.0.0 150.32.0.1 M0
/16 150.3.0.0 150.3.0.3 M0
/16 150.3.0.0 150.3.0.1 M0
/16 150.3.0.0 150.3.0.4 M0
Default Default 150.3.0.4 M0
Routing table of router R4:
Mask Network address Next-hop address Interface
/24 220.10.40.0 -------- M1
/24 200.11.60.0 150.3.0.2 M0
/22 140.21.0.0 150.3.0.2 M0
/18 161.22.0.0 --------- M2
/18 150.32.0.0 150.3.0.1 M0
/16 150.3.0.0 150.3.0.2 M0
/16 150.3.0.0 150.3.0.4 M0
/16 150.3.0.0 150.3.0.1 M0
Default Default 150.3.0.4 M0
Question 2: (5 marks)
a) In classful routing, the routing protocols don’t release subnet mask info
with its routing updates. The router that executes a classful routing
actions in one the following ways during the receipt of route updates.
i. Just in case the router has a direct connection to the interface
which belongs to similar core network, it applies the equivalent
mask as the one which is at the interface.
ii. In case the router has no interface which belongs to similar
primary network, it applies classful mask to the route.
In classless routing, the protocols send the subnet mask within the
updates. Hence, VLSMs are permitted during the use of classless routing

protocols.
b) Mask Network address Next-hop address Interface
/24 220.11.60.0 150.3.0.2 M0
/24 220.10.40.0 150.3.0.3 M0
/22 140.21.0.0 150.3.0.2 M0
/18 150.32.0.0 ------- M1
/18 161.22.0.0 150.3.0.3 M0
/16 150.3.0.0 150.3.0.3 M0
/16 150.3.0.0 150.3.0.4 M0
/16 150.3.0.0 150.3.0.2 M0
Default Default 150.3.0.4 M0
The process of routing takes place as explained below;
We relate the 1st mask /24 on provided network address. Answer is
150.32.0.0. This address does not tie our network address.
We then relate the 2nd mask which is /22 on our given address. The
answer is 150.32.0.0. This address has not tied with agreeing address.
We then relate 3rd mask. Answer is 150.32.0.0. This answer ties our
matching network address. Therefore, upcoming node address and
interface number are dispatched to ARP table (Carthern, et al., 2015).
c) The table above can be routed as below steps;
- /24 which is the first mask is related on the case study IP address.
Answer is 150.32.48.0. We realise that the outcome does not tie with
allotted network address.
- /22 which is the second subnet mask is related on the offered
network address. Answer is 150.32.48.0. Note that this does not tie
with the agreeing allocated IP address.
- /18 which is the 3rd subnet mask is related to our case study IP
address. The output which is 150.32.0.0 ties with the case study
allocated case study network address. The consequent node interface
and address are handed over to ARP table.
Question 3: (10 marks)
1) Open-loop congestion control and closed loop congestion control
approaches are the overcrowding control mechanisms used to control
congestion in TCP/IP protocol. In an open-loop control approach, a
policy is deployed to stop congestion before it takes place. However, for
a closed-loop congestion control approach, the control is imposed after

an event of congestion has taken place. This prevents further
congestions (Seddiq, et al., 2019).
2) The above mentioned congestion controls have the following setbacks,
- This congestion control comes in effect after detection of data loss,
this is late.
- These control approaches do not support other networking protocols
apart from the TCP/IP (Butler, 2017).
3) - BBR protocol was primarily put in place to improve the performance
of the network, TCP congestion protocol are meant to restore packet
loss.
- TCP control approaches are meant to manage packet loss, on the other
hand, the BBR protocol approach confronts the real congestion.
- TCP implementation requires the explicitness of the client, whereas
BBR does not explicitly need the client for its implementation
(Cardwell, et al., 2017).
4) In our summative statement, it’s not easy for a different protocol to
overthrow the surviving accepted protocol. This supported by below
lines:
- The current hardware and software for the world computing systems
are built for TCP protocol, replacing the protocol implies the
replacement of all these computing technologies and devices. This is
very expensive.
- The TCP protocol has been working without any complains and it is
still working, therefore its displacement cannot just happen as the
toss of the coin.
References
Butler, B., 2017. How Google is speeding up the Internet. [Online]
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 2 10 2019].
Cardwell, N., Cheng, Y., Yeganeh, S. H. & Gunn, C. S., 2017. Congestion-based
congestion control. Communications of the ACM, 60(15), pp. 58-66.

Carthern, C., Wilson, . & Rivera, ., 2015. Cisco Networks: Engineers' Handbook of
Routing, Switching, and Security. 5th ed. New York City: Apress.
Seddiq, A. E., Omer, K. & Abdi, A., 2019. Studying the TCP Flow and Congestion
Control Mechanisms Impact on Internet Environment. International Journal of
Computer Science and Information Security, 16(5), p. 174.