SIT202 Computer Networks Assignment: Solution and Network Analysis

This document presents a comprehensive solution to the SIT202 Computer Networks assignment. It addresses various aspects of computer networks, including the invalidity of half-duplex configurations, the benefits of replacing hubs with switches, and congestion control mechanisms like the Leaky Bucket and Token Bucket algorithms. The solution also explores Network Address Translation (NAT) and its associated problems, compares distance vector and link state routing protocols, and discusses the advantages of DHCP for IP address management. Furthermore, it delves into the Address Resolution Protocol (ARP), including its function and the calculation of network parameters. Finally, it includes a detailed analysis of network configurations and routing scenarios, providing a thorough understanding of the concepts discussed.

Running head: SIT202 COMPUTER NETWORKS
Computer Networks
Name of the Student
Name of the University
Author’s Note

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Table of Content
Answer to Question 1:.........................................................................................................2
Answer to Question 2:.........................................................................................................2
Answer to Question 3:.........................................................................................................5
Answer to Question 4:.........................................................................................................7
Bibliography......................................................................................................................12

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Answer to Question 1:
a. The solution proposed by the junior team member of configuring some of the network switch
with half duplex can solve the current situation of running out of buffer is invalid. This is
because the half duplex connection uses a single pair of cable for transmission of data and thus
the speed of transmission is much slow compared to the full duplex connection. This would thus
does not solve the problem of running out of buffer and increase the congestion in the network.
b. i. The replacement of the hubs with switch can resolve the issue of buffer overflow and the
Ethernet switches can be used for bridging Ethernet frames.
ii. This would be an upgrade of the network because the hubs are obsolete and in the hubs the
same data packets are broadcasted to the connected host and thus it increases the congestion in
the network. The deployment of the switch reduces the congestion in the network and the ports
that are not in use can be disabled for reducing the amount of traffic generated from the system.
Answer to Question 2:
a. The mechanism that is implemented for the high layer protocol for creation of a reliable
delivery and policy and determine their use for removal of the congestion in the network are as
follows:
 Application of Leaky Bucket algorithm and
 Application of Token bucket algorithm

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Figure 1: Congestion control
Leaky bucket algorithm- it would create a time span of 9 second for the transmission of the data
packet and maintain the flow of data

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Figure 2: Leaky bucket algorithm
Token Bucket Algorithm
It allows bursty data and to be transferred in the network and a token is generated and for each of
the clock tick and for transmission of the data packet the token is required to be removed from
the bucket.
ii. The two figures illustrating the exchange of the data packets over time that is used for
demonstrating the use of timers used by the higher layer protocols and reliable delivery for
influencing the congestion is given below:

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Figure 3: Exchange of the data packets over time (Timers are set incorrectly)
Figure 4: Exchange of the data packets over time (Timers are set correctly)
b. The Network Address Translation (NAT) is the procedure where a system gadget, more often
than not a firewall, allots an open deliver to a PC (or gathering of PCs) inside a private system.
The fundamental utilization of NAT is to restrain the quantity of open IP tends to an association
or organization must use, for both economy and security purposes. The two problems caused by
the approach are as follows:

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The most widely recognized type of system interpretation includes an extensive private
system utilizing addresses in a private range (10.0.0.0 to 10.255.255.255, 172.16.0.0 to
172.31.255.255, or 192.168.0 0 to 192.168.255.255). The private tending to plot functions
admirably for PCs that lone need to get to assets inside the system, similar to workstations
requiring access to document servers and printers. Switches inside the private system can course
activity between private locations with no inconvenience. Notwithstanding, to get to assets
outside the system, similar to the Internet, these PCs need to have an open address with the end
goal for reactions to their solicitations to come back to them. This is the place NAT becomes
possibly the most important factor.
It requires special access for the accessing the outside network and a special access is
required for accessing the external IP address using the network address translation. A firewall
can act as the intermediary and can be used for controlling the session in both direction.
Answer to Question 3:
a. i. The distance vector routing and the linked state routing is used in a network depending on
the type of the network. The two routing protocols differs from each other and in case of the
distance vector routing the routing table of the router is shared with the neighboring router such
that the neighboring router have all the information of the neighbor. In case of the linked state
routing protocol the routing table is shared with all the routers connected in the network such that
for sending a data packet the shortest path is chosen. The distance vector routing can be easily
applied in the network because it is easy to implement and EIGRP, RIP protocol is used for
configuring the router with distance vector router while the link state routing uses the OSPF and
ISIS protocol for configuration. The distance vector routing and slow for adoption of change in
the network because the addition of a new router required configuration of the old router and the

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neighbor information is required to be added. The link state routing can be applied in the
network but more memory and processing power is required for it. It reduces the problem
associated with the distance vector routing and adopt the change in the network efficiently. Thus
for the scenario where the links are growing up and down the link state routing is required to be
applied for the management of the network.
ii. For a smaller network the distance vector routing is ideal and because it does not require much
computational power or memory of the router to process the request and can be applied easily in
the router. It helps in faster convergence and adds less load in the network because the
broadcasting of the router table is limited to the next node and there is no need to pass the
routing table to the whole network. No extra traffic is created in the network and reduces the risk
of congestion.
b. i. The DHCP can be used for addition of the IP address automatically to the nodes connected
in the network. The DHCPv4 is used for allocation of the IPv4 address in the network but there
is limit of 4.3 Billion IP address and DHCPv6 can also be used for allocation of the IPv6 address
in the network and reduce the limit of accommodation of the nodes connected in the network.
300 trillion address can be provided to the nodes and it is a simplistic asset for management of
the network resources. The two advantage of the DHCP feature is that it helps in IP address
management and it also helps to maintain a centralized network.
ii. The DHCP is useful for implementation of DHCpv6 on the server and it can be used for
allocation of IPv6 address to the nodes connected in the network. A dual stack network can be
configured with the implementation of the DHCPv6 on the server. The network that uses the
IPv6 can thus communicate with the old devices for transferring of the data packets in the
network.

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Answer to Question 4:
a. The ARP Address resolution protocol is used as a crucial component in the IP networking for
any of the operating system. The ARP is used for linking the Ethernet address with the hardware
address and without the ARP the communication cannot be done between the nodes connected in
the network. The ARP entries are used for collection of the ARP cache and is created during
resolving the hostname. The cache entries remains in the system until the entry timeouts and
issuing bad entries can cause problem for establishment of the internet connection and loading of
the webpage.
b. i.
PC A
Address: 92.168.75.14 01011100.10101000.01 001011.00001110
Netmask: 255.255.192.0 = 18 11111111.11111111.11 000000.00000000
Wildcard: 0.0.63.255 00000000.00000000.00 111111.11111111
=>
Network: 92.168.64.0/18 01011100.10101000.01 000000.00000000 (Class A)
Broadcast: 92.168.127.255 01011100.10101000.01 111111.11111111
HostMin: 92.168.64.1 01011100.10101000.01 000000.00000001
HostMax: 92.168.127.254 01011100.10101000.01 111111.11111110
Hosts/Net: 16382

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PC B
Address: 192.168.58.43 11000000.10101000.0 0111010.00101011
Netmask: 255.255.128.0 = 17 11111111.11111111.1 0000000.00000000
Wildcard: 0.0.127.255 00000000.00000000.0 1111111.11111111
=>
Network: 192.168.0.0/17 11000000.10101000.0 0000000.00000000 (Class C)

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Broadcast: 192.168.127.255 11000000.10101000.0 1111111.11111111
HostMin: 192.168.0.1 11000000.10101000.0 0000000.00000001
HostMax: 192.168.127.254 11000000.10101000.0 1111111.11111110
Hosts/Net: 32766 (Private Internet)
Both the PCs A and B are connected in different network

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ii. If both the PCs are configured with a default gateway of 192.168.127.254 then PC A will be
able to ping PC B and vice versa. An Echo request is sent to PC B from PC A and the PC A uses
the ARP table of the router to find the Ethernet or the MAC address of the PC and respond to the
request for receiving the Echo and broadcast the Ethernet address in the network. The Ethernet
address of PC B is thus added to the ARP table and it receives a reply from the PC B.
c. i. After completion of RIP configuration on two routers and configuring a loopback address in
the router it is found that the R3 ping 172.16.1.1 path would be taken by the router for generating
five echo request and five echo response.

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