Mahlatse Iven Somela

Unique Number: 640309

Student Number: 60232811
ICT1532: Assignment 1
SECTION A
1. Transmission Control Protocol (TCP) works with the Internet Protocol (IP). The sending of
packets of data from one computer to the other is its main role. TCP and IP, together, are the two
protocols that rule the internet. In the Request for Comment (RFC) standards document number
793, Transmission Control Protocol is defined by the Internet Engineering Task Force (IETF).

Data sent over TCP connections are divided into independently numbered segments. Each segment
contains the source destination and data section which is put into a header. The transmission control
protocol is the one responsible for reordering the segments in the right sequence as it arrives in the
receiving end. TCP is responsible for keeping track of these segments while the IP handles the actual
delivery of the data. It includes built-in error checking that ensures each requested segment is
received. TCP also includes error checking, which ensures each packet is delivered as requested. The
transfer of data such as files and webpages over the internet makes use of TCP. Controlling the
reliable transfer of data is the main function of TCP.

2. SMTP
 It is a push protocol, i.e., the sending mail server pushes the data onto the receiving mail
server by initiating a TCP connection.
 SMTP uses a persistent connection.
 By default, SMTP uses port 25.
 It requires binary multimedia data to be encoded in 7-bit ASCII.
 It places all the objects into a single message.

HTTP
 It is a pull protocol, i.e., a client pulls the information available on a server by initiating a TCP
connection.
 HTTP can use both a persistent and non-persistent connection.
 By default, HTTP uses port 80.
 It does not require binary multimedia data to be encoded in 7-bit ASCII.
 It places each object in its own HTTP message.

3. (a) Address Resolution Protocol (ARP)

The address resolution protocol (ARP) is a protocol used by the Internet Protocol (IP) [RFC826],
specifically IPv4, to map IP network addresses to the hardware addresses used by a data link
protocol.

Open Rubric
DNS
Domain Name System (or Service or Server), an Internet service that translates domain names into
IP addresses

(b) IPv4 address is a 32-bit number that uniquely identifies a network interface on a
machine.

MAC address
A media access control address is a unique identifier assigned to a network interface controller for
use as a network address in communications within a network segment

MAC ADDRESS IPv4

MAC Address stands for Media Access IP Address stands for Internet Protocol Address.
Control Address.

MAC Address is a six byte hexadecimal IP Address is either four byte (IPv4) or six byte
address. IPv6 address

(c) The Internet Checksum is a checksum used in (nearly?) every IP packet crossing
the Internet or any IP-based network, therefore the speed of the calculation is very important;
oftentimes it is performed in hardware.

A cyclic redundancy check (CRC) is an error-detecting code commonly used in

digital networks and storage devices to detect accidental changes to raw data.

 CRC is more thorough as opposed to Checksum in checking for errors and reporting.
 Checksum is the older of the two programs.
 CRC has a more complex computation as opposed to checksum.
 Checksum mainly detects single-bit changes in data while CRC can check and detect double-
digit errors.
 CRC can detect more errors than checksum due to its more complex function.
 A checksum is mainly employed in data validation when implementing software.
 A CRC is mainly used for data evaluation in analogue data transmission.

4. (a) IEEE 802 local area networks, the data link layer is described in more detail with media
access control (MAC) and logical link control (LLC) sublayers; this means that the IEEE 802.3 LLC
protocol can be used with all of the IEEE 802 MAC layers, such as Ethernet, Token Ring, IEEE 802.11.

(b) In the IEEE 802 reference model of computer networking, the logical link control (LLC) data
communication protocol layer is the upper sublayer of the data link layer (layer 2) of the seven-
layer OSI model. The LLC sublayer acts as an interface between the media access control (MAC)
sublayer and the network layer.

(c) The wired Local Area Network (WDLAN) is based on IEEE 802.3 (Ethernet) standard with carrier
sense medium access with collision detection (CSMA/CD) MAC protocol, as access method.. In this
research work the performance analysis of wired and wireless communication networks was carried
out using some performance metrics, such as throughput, Packet Delay, Bit Error Rate (BER) and
Signal to Noise Ratio (SNR) as a basis for comparison.

(d) Wireless local area networks (WLANs) based on the 802.11 family of standards are already used
by many operators for offloading cellular networks and embracing capacity expansion into license-
exempt spectrum bands. WLAN provides better data speeds at lower rates. In a wireless network
various multiple access technologies such as wireless LAN and UMTS are used because cellular
networks like UMTS provide various voice and data services and WLAN provides high speed.

(e) -High Capacity Load Balancing

-The Ability to Measure Performance
-Ability to communicate with both 2.4 GHz devices and 5 GHz devices
5. There are many benefits and it represents one of the core concepts of networking.
From the practical perspective, understanding the OSI model and in which layer a specific protocol is
placed makes troubleshooting of simple and complex network related issues easier.

With the OSI layered model, troubleshooting can be a well-structured task which helps reduce the
troubleshooting time and increase operational efficiency. In networking (mainly in production
environments) every second counts.

6.
 Select strong passwords, consisting of at least eight characters and
containing a mixture of alphabetic (upper- and lowercase), numeric, and
special characters.
 Never give out your password to anyone, even if that person claims to be
from IT
 Do not visit unauthorized websites
SECTION B

1. (a) Mesh Topology

Star Topology

Ring Topology
Bus Topology

Hub – and – spoke Topology

(b) Advantages of a ring topology

 All data flows in one direction, reducing the chance of packet collisions.
 A network server is not needed to control network connectivity between each workstation.
 Data can transfer between workstations at high speeds.
 Additional workstations can be added without impacting performance of the network.

Disadvantages of a ring topology

 All data being transferred over the network must pass through each workstation on the
network, which can make it slower than a star topology.
 The entire network will be impacted if one workstation shuts down.
 The hardware needed to connect each workstation to the network is more expensive than
Ethernet cards and hubs/switches.
The advantages of a star network are:

 it is very reliable – if one cable or device fails then all the others will continue to
work
 it is high-performing as no data collisions can occur

The disadvantages of a star network are:

 it is expensive to install as this type of network uses the most cable (network cable is
expensive)
 extra hardware is required (hubs or switches) which adds to cost
 if a hub or switch fails, all the devices connected to it will have no network
connection

The advantages of a bus network are:

 it is easy to install
 it is cheap to install, as it doesn't require much cable

The disadvantages of a bus network are:

 if the main cable fails or gets damaged the whole network will fail
 as more workstations are connected the performance of the network will become slower
because of data collisions
 every workstation on the network "sees" all of the data on the network – this is a security
risk

Advantages of a mesh topology network are:

 messages can be received more quickly if the route to the intended recipient is short
 messages should always get through as they have many possible routes on which to travel
 multiple connections mean (in theory) that no node should be isolated
 multiple connections mean each node can transmit to and receive from more than one node
at the same time
 new nodes can be added without interruption or interfering with other nodes

Disadvantages of a mesh topology network are:

 full mesh networks can be impractical to set up because of the high number of connections
needed
 many connections require a lot of maintenance
Advantages of hub-and-spoke network are:

 Encouraged the rapid growth in the airline business

 Efficient use of scarce transportation resources.

Disadvantages of hub-and-spoke network are:

 Congestion and delays at hub airports

 Discontinuous use of airport facilities
 Airport dependency

2. (a) The Open Systems Interconnection (OSI) model is a reference tool for understanding data
communications between any two networked systems. It divides the communications processes into
seven layers.

Each layer both performs specific functions to support the layers above it and offers services to the
layers below it. The three lowest layers focus on passing traffic through the network to an end
system. The top four layers come into play in the end system to complete the process.

(b)
(c)
Application -Application services
-Service advertisement
Presentation -Data formatting
-Encryption
Session -Setting up a session
-Maintaining a session
-Tearing down a session
Transport -TCP/UDP
-Windowing
-Buffering
Network -Logical addressing
-Switching
-Route discovery and selection
-Connection services
-Bandwidth usage
-Multiplexing strategy
Data link MAC – Physical addressing
-Logical topology
-Method of transmitting on the media

LLC - Connection services

-Synchronizing transmission
Physical -Physical topology
-Synchronizing bits
-Bandwidth usage
-Multiplexing strategy
-Wiring standards for connection and
jacks
-How bits are represented on the
medium
 RESULTS
Total = 59.5 / 70 (85%)