COMP247 Data Communication Assignment 1: Subnetting and Protocols

This document provides a detailed solution for COMP247 Assignment 1, focusing on data communication concepts. The assignment includes questions on subnetting, calculating host addresses, and identifying legal netmasks. It also analyzes application layer protocols such as SMTP for electronic mail and BitTorrent protocols, exploring their functionalities and the transport layer protocols they utilize. The solution further examines the transport layer protocols chosen by application designers and the application architecture employed, such as point-to-point architecture. The document references supporting arguments and research, adhering to IEEE referencing style, to provide a comprehensive understanding of the topics.

COMP247
ASSIGNMENT 1 2019
DATA COMMUNICATION

QUESTION 1: Subnetting and Network Layer
a) Equivalent Subnet masks denoted-decimal notation for the following slash-notation
address block
I. /21 – 255.255.248.0 = 21
11111111.11111111.11111 000.00000000
II. /13 – 255.248.0.0 = 13
11111111.11111 000.00000000.00000000
III. /29 – 255.255.255.248=29
11111111.11111111.11111111.11111 000
b) Number of Hosts addresses on the network
I. /19 – 192.168.0.1 – 192.168.31.254
(8190 Host) Private Internet
II. /30 – 192.168.0.1 – 192.168.0.2
(2 Host) Private Internet
III. /23 – 192.168.0.1 – 192.168.1.254
(510 Hosts) Private Internet
2) If the following slash notation are legal
I. 255.255.224.0 - /19 11111111.11111111.111 00000.00000000
(192.168.0.1 – 192.168.31.254) 8190 Host
II. 255.128.0.0 - /9 11111111.1 0000000.00000000.00000000
(192.128.0.1– 192.255.255.254) 8388606 Host
III. 255.252.255.0 Corrected illegal net mask 255.252.255.0 to 255.252.0.0
Net mask 255.252.0.0 = 14 11111111.111111 00.00000000.00000000
(192.168.0.1 – 192.171.255.254) 262142 Hosts
IV. 255.255.255.254 -/31 11111111.11111111.11111111.1111111 0
(192.168.0.1 – 192.168.0.1) 0 Hosts

Question 2: Application, Protocol and Layering
Application Chosen: Electronic Mail and Bit – Torrent
a) Application layer protocol does my chosen application use.
Electronic Mail – Simple Mail Transfer Protocol (SMTP)
Bit Torrent – File transfer protocol (FTP) and Point to point (P2P)
b) A brief summary of each protocol that is used in relation to the application protocol.
Electronic Mail
Simple Mail Transfer Protocol
This application layer protocol uses the rule of store and forward in the process of
communication between two nodes whereby it moves email across and within the network. It
is a part of the TCP/IP protocol and with this protocol one is able to send and receive
messages. It is one of the most used and common protocol of communication since it
provides a basic intermediate mode of service between the senders the email server and the
local user accessing the email [1].
The SMTP is simple integrated into the following application components
 Mail User Agent – this is a web based application program the provides the platform
for the message management, its composition and the reception facilities before
submitting to the other parties involved in the process of communication.
 Mail Submission Agent – this is a web based application program the receives the
message from the mail use agent and integrates it with the mail transfer agent to
deliver the email
 Mail Transfer Agent – this acts as a communication channel between the sender and
the email receiver. It’s also referred to as the exchange of contents
 Mail Delivery Agent – it’s the final hop of the email that give back the response for
the delivered email to the receiver mailbox
This type of communication was developed in the 70’s. This is found on the phases of the
OSI Modelling [2]. This is a build of communication protocol used to trans communicate
through devices on the network. It can also be used as a transmission network protocol to
private network.

Bit Torrent
File transfer Protocol
In this protocol, files and other information are able to be shared between the client computer
and the server on the computer network. This is enable by the action of uploading and
downloading of files from a computer to a server. On a security feature, the file transfer
protocol uses the clear text sign in protocol to form the username and the password which
allows users to connect anonymously if the server allows [3]. The protection is encrypted on
both ends to offer secure file transfer.
The protocol runs in both passive and active mode which determines the basic flow of file
transfer and how the communication is established.
In Active Mode – the client listens the channel of the incoming data from the server and then
initiates data exchange. At this point it informs the server that it’s listening, the server then
initiates the communication and transfer of files.
Data transfer can also be done in 3 other modes.
Streaming mode – packets are sent in continuous manner. Data is not divided into records and
all the process of transfer is done at the TCP [4].
Block mode – the protocol initially divides the data into several blocks and then forwards it to
the TCP for transportation.
Compressed mode – data packet are minutely compressed into simpler version of algorithms
c) Transport Layer protocol does each of you application layer protocol use?
User Datagram Protocol (UDP), Datagram congestion control protocol (DCCP)
d) For each why do you think the transport layer Protocol was chosen by the
application designer?
This is a protocol for network applications whose connectivity is a bit challenging such as
voice connectivity and video communication in which it suffers major loss which in turn
affects the quality of the message being conveyed. The protocol on the other hand is used in
different application where there is loss of data transmission where the application is set and
configures the directly correct and arrange the massive loss of packet data in the network.
This network application protocol enables process to process and it considers the
connectionless because the circuit is established before the data transfer is initiated.

Unlike TCP some of calculation such as checksum is not mandatory in UDP. There is no
error control nor flow control that is provided hence depending on the IP and ICMP. On the
other hand UDP uses the simple request response communication. In some instance the size
of data is less and hence giving lesser concern about flow and error control.
Some other services that uses the UDP include:
 Voice Over IP
 Trivial File Transfer Protocol
 Domain Name system
In real time media the appropriate protocol to be used it the transmission control protocol
reason being so that it’s a secure mode of transmission and communication between devices.
TCP is a connection oriented protocol whereas UDP is a connectionless protocol. Network
elongates a private network across a public network and enables users to share and receive
information and data across a given shared or public networks as if their communication
devices were directly linked to the private network.
It was simply developed to allow remote user access to offices to securely access software
applications among others.
Communication between computers on a network is done through protocol suites such as
TCP/IP protocol suite [5]. A protocol suit consist of a layered architecture where each layer
depicts some functionality which can be carried out by a protocol.
TCP/IP is normally considered to be a four layer system. The four layers are as follows:
 Application layer
 Transport layer
 Network layer
 Data link layer /network interface layer.
e) Choose one of your application; which application architecture does your protocol use?
Point to Point Architecture Protocol
f) Provide an explanation for the above chose.
This is a network application layer that is used to distribute files across a given
communication channel. It simply uses the point to point network architecture where many
peers act like client and servers at the same time. This type of protocol uses the data link
layer protocol of communication over synchronous and asynchronous circuits, where the

dominant one is supressed over the latter such as serial line internet protocol and also
telephone company mandated standards.
The basic requirement of the point to point protocol circuit is that it provides the duplex mode
of communication. This is an instance where there both ends of communication, the sender
and the receiver are able to transmit and receive signal at relatively the same time.

References
[1] Green, Heather, Chohen Brian , Bharambe, Ashwani, “Data communication and
Incentive build robustness and respectability in BitTorrent,” Bit-Torrent , 16 Fubruary
2015. [Online]. Available:
http://www.businessweek.com/technology/content/sep2005/tc20050927_3006_tc024.ht .
[Accessed 03 April 2019].
[2] William, Steve W & Michael P,E, Competitive Advantage: Creating and Sustaining
Superioir Performance on Making Better Communication, New York: Free Press, 2017.
[3] Anagnostakis, Dimitrios & Ritchie, James & Lim, T & Craig, Conor & Speedie, Jamie.,
The Environment of Communication Media, EL Paso, Texas: Queens Publication, 2015.
[4] E. F. Harrison, Communication Media and Networking Protocols, Houston: Hougton
Miffin, 2017.
[5] P. Michael, Competitive Strategy: Techniques for analysing Network Protocols,
Englewood Cliffs.: NJ: Prentice-Hall, 2016.