SIT202: Network Security Problem Solving Report - Semester 1

This report provides comprehensive solutions to a computer networks assignment, addressing key concepts and practical applications. The report begins by defining bit rate and calculating it based on signal levels and bandwidth. It then explores channel capacity using the Shannon-Hartley theorem and analyzes multiplexing techniques, including their role in securing signals and demultiplexing processes. Packet switching, including virtual circuit and datagram approaches, is discussed, along with the analysis of data transmission through network switches. The report also covers error detection using Hamming distance and examines the communication between Alice and Bob via routers. Furthermore, it compares various network access methods like TDMA, CSMA/CA, and polling. Finally, the report identifies wireless technologies and evaluates the truthfulness of statements related to cellular systems, including CDMA and handoff processes. References to relevant sources are also provided.

Running Head: Internetworking 0
Internetworking
Task
Student name

Network Security 1
Table of Contents
Answer 1......................................................................................................................................................1
1.1............................................................................................................................................................1
1.2............................................................................................................................................................1
1.3............................................................................................................................................................1
1.4............................................................................................................................................................1
Answer 2......................................................................................................................................................1
2.1............................................................................................................................................................1
2.2............................................................................................................................................................2
2.3............................................................................................................................................................2
Answer -3....................................................................................................................................................2
3.1............................................................................................................................................................2
3.2............................................................................................................................................................2
Answer-4.....................................................................................................................................................3
4.1............................................................................................................................................................3
4.2............................................................................................................................................................3
4.3............................................................................................................................................................3
References...................................................................................................................................................4

Network Security 2
Answer 1
1.1
Rate of data transfer in a second is known as bit rate. It is based on the medium as well. It is
used for the channel capacity, such as bps, Mbps, and others.
1.2
We can calculate the bit rate using this formula, which is:
signal per level * bandwidth = bit rate
So, according to provides data,
Bitrate = 8*3 = 24
1.3
We can calculate the channel
C = B log2(1+SNR)
SNRdB = 6 dB
Therefore,
SNR= 10 log10(S/R)  SNR = 4
C = 3*106 x 1og2(1+4) ≈ 8 Mbps.
C= 2 Mbps
1.4
A channel is used for transfer the data using a medium. We can provide actual transfer rate of
that medium using data rate. It is a speed of data transfer in a medium between two
workstations (Tanenbaum).
Answer 2.
2.1
Multiplexing: it is a way to combine analog or digital signal into one signal and transfer it over a
shared medium. It is necessary to secure the signal with a high level of frequency and it is also
secure the signal from distortion, attenuation, and noise

Network Security 3
When analog or digital signals combined in a single signal and transfer it with a career
frequency then this process is known as multiplexing. It has used to secure the signal from
various transmission impairments, such as attenuation, distortion, and noise (Kenneth C.
Mansfield and Antonakos).
In addition, demultiplexing is reverse process of multiplexing in which combined signals are
separated at the end of workstation.
2.2
1. Packet switching can further be divided into two subcategories – virtual circuit approach and
the datagram approach.
2. Circuit switching takes places at the physical layer.
3. In packet switching the resources need to be reversed during the setup phases.
2.3
Host A has three options, which are 3,0,1. Therefore, it chose to switch 1 port 1 for outgoing so VCI is b.
after that switch 2 accept it on port 3 as b and transfer that packet from port 2. Therefore, VCI value is e.
now, switch 3 accept it on port 0 and used port 1 for packet transfer. Therefore, VCI at port 1 of switch 3
is h.
Answer -3
3.1
4+1 =5 total length will be 5 bits and only one bit will be add based on the parity in the data word.
Moreover, hamming distance will be 1 and it can correct only 1 bit error from the transfer data .
3.2
Alice and bob communicate with the help of three frames and two routers. They should have specific
link and ip address for the communication. This is the physical links of three frames.
Link-1 has L6 and L2
Link-2 has L4 and L2
Link-3 has L5 and L1

Network Security 4
Router will provide IP address to all the devices at the source and destination (Forouzan).
Answer-4
4.1
Are there packet
collisions
Is carrier sensing
required
Is the number of the
stations fixed
TDMA NO Yes yes
Polling No Yes No
Slotted-ALOHA Yes No Yes
CSMA/CA Yes Yes yes
4.2
These are the wireless technologies in between given choices, which are Bluetooth, 802.11n, ADSL only (
Thakur ).
4.3
True or false
In AMPS, CDMA has been used for
channelization
False
Handoff is used in a cellular system to support
continuous transmission for a mobile station
True
In CDMA-based cellular systems, the
frequency-reuse factor can be 1.
False
CSMA/CD is used for wireless LAN as it can
avoid the hidden node problem (Cowley)
False

Network Security 5
References
Thakur , Dinesh. Bluetooth - What is Bluetooth? . 2018. 4 December 2018.
<http://ecomputernotes.com/computernetworkingnotes/communication-networks/bluetooth>.
Cowley, John . Communications and Networking. 2. kingswinford: Springer Science & Business Media,
2012.
Forouzan, A. Behrouz. Data communications & networking . 8th. New Delhi: Tata McGraw-Hill
Education, 2007.
Kenneth C. Mansfield, Jr and James L Antonakos. Computer Networking for LANS to WANS: Hardware,
Software and Security. 1. Bostan: Cengage Learning, 2009.
Tanenbaum, Andrew S. Computer networks. Harlow, Essex: Pearson, 2014.