Networking and Security

This document discusses the role and functionality of the data link layer, transport layer services, and cloud computing in networking and security. It covers topics such as local address resolution, network interface cards, MAC address, format frames, broadcast addressing, identification of applications, UDP and TCP services, TCP flags, TCP connection and termination, TCP flow control, and fundamental aspects of cloud computing and mobile computing.

Running head: NETWORKING AND SECURITY
Networking and security
Name of the Student
Name of the University
Author Note:

NETWORKING AND SECURITY
Table of Contents
1 Data Link Layer............................................................................................................................4
1.1 Local address resolution........................................................................................................5
1.2 Network Interface Card.........................................................................................................5
1.3 MAC Address........................................................................................................................6
1.4 Role and Function of NICs....................................................................................................6
1.5 Format Frames.......................................................................................................................7
1.6 Broadcast addressing.............................................................................................................7
2 Transport Layer............................................................................................................................8
2.1 Identification of the Applications..........................................................................................8
2.2 Transport layer services with UDP........................................................................................9
2.3 Transport Layer Services with TCP......................................................................................9
2.4 Benefits of TCP.....................................................................................................................9
2.5 TCP Flags............................................................................................................................10
2.6 TCP Connection and Termination.......................................................................................10
2.7 TCP Flow Control................................................................................................................10
3 Cloud Computing and Mobile....................................................................................................11
3.1 Fundamental aspects of Cloud computing...........................................................................11
3.2 Fed Uni cloud services.........................................................................................................12
3.3 Azure Cloud services...........................................................................................................12
3.4 Advantages and Disadvantages of cloud services...............................................................12
3.5 Virtualization Terminology.................................................................................................13
3.6 Different types of virtualization...........................................................................................13
3.7 Mobile Computing...............................................................................................................14
3.8 Elements of telephone networks..........................................................................................15
3.9 Communication of base stations..........................................................................................15

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1 Data Link Layer
This unit of the paper will be focussing on the role and functionality of the data link
layer. Different aspects and characteristic feature of this layer will be discussed in this unit of the
paper. The networking needs of this layer will be discussed in details in this section.
Data link layer is located in the second position among the other layers in the OSI model
of computer networking. When more than one system is connected in a network, the data link
layer is required (Hong et al., 2015). The foremost functionality of this layer of the OSI model is
to transfer data between connected devices in a specific area. The mode of transmission of data
can be termed as Hop to Hop communication. Connectivity is a very important aspect regarding
all the layers of the OSI model as the distance between the two connected systems may be
dynamic in nature.
The internet model is a very important aspect of the data link layer as the data which is
being spent from one system to another goes through a couple of platforms before being received
on the host. Usually the data from the networking media which is required to send to other
devices must be going through the network layers to the application layer on the receiving host.
It can be said that the data link layer is the interface between the physical networks such as the
Wi-Fi, Satellite, Fibre and cable with the network layer.
There are two sections of this layer of the OSI model which are Logical Link Layer and
the Media Access Control.
Logical link layer: This section of the data link layer is located in the uppermost section of the
data link layer; it helps in managing the flow of control of the data. It is also very much helpful

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to acknowledge any kinds of error in signals or connectivity. The protocol transactions such as
IPv4, IPX and IPv6 are allowed with the help of the logical link layer.
Media access control: This section of the data link layer is located after the logical link layer; it
helps in understanding about the access control of the media. The access control can be
categorized into two categories such as the centralized as well as the distributed. The entire
network trafficking is managed with the help of the Media access control (Lopacinski et al.,
2015). The two categories of access are the controlled access and the content based access. In the
controlled access only one station can transmit at a time and in the contention based access the
common protocols used are the CSMA/CD for Ethernet networks and CSMA/CA for the
wireless networks. Collision is a problem sometimes in this access control; this is solved with the
help of CSMA/CD. Availability of the network is maintained with the help of Carrier Sense,
multiple devices connected in a network is done with the help of Multiple Access, the detection
of collision is done by Collision Detect. CSMA/CD is useful to avoid collisions in the
networking media.
1.1 Local address resolution
Address Resolution Protocol is used to determine the MAC address of a specific machine
in the network. The ARP apache contains the MAC address and the IP address which is required
by the NIC.
1.2 Network Interface Card
This unit of the paper will be focussing on the role of the network interface card in
networking. The network interface card is defined as the type of card which are built in most of
the networking devices such as the networking scanners and routers. The quantity of the network

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interface cards depends upon the networking devices such as in routers one network interface
cards are connected to the local network and one or more network interface cards to the other
networks. There is a huge connection between the network interface cards and the media access
control as most of the network interface cards have a distinguished 48 bit MAC address. The
MAC address is built into each of the interface by the developer. The source and destination of
the MAC address is very much required for the exchange of data in the data link layer. The MAC
address has two units such as the followings:
o Organization Unique Identifier: It considers the first 24 bits and,
o Unique 24 bit number which considers the last 24 bits.
1.3 MAC Address
This unit of the paper will be focussing on the ways to determine the MAC address in
different operating system such as Microsoft Windows and Linux based systems. The MAC
address can be determined from the run window in a Microsoft Windows system after entering
the command ipconfig/all. All the detailed configurations of the network settings will be
displayed on the black screen such as the status of the DHCP and auto configuration, physical
address, IPv4 address, subnet mask and the date of lease obtained. Such like the windows based
system, in a Linux based system, the MAC address can be determined with the help of the Linux
command ifconfig. The settings of the entire network are obtained by entering this command
such as the type of link encap, address of the inet adder, Bcast and RX packets. The entire details
of MAC address along with the address of IPv6 and IPv4 is obtained with the help of the
command.

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1.4 Role and Function of NICs
The foremost role of the network cards is the inspection of each of the packets available
in the network. All the data packets which are intended to the system where the NIC is installed
is checked by the network cards. The data packets for the hosts are also passed with the help of
network interface cards. The most important functionality of the network interface cards is the
filtering of the traffic, without having any effect on the performance of the host systems. Cyclic
Redundancy check operation of the network interface cards is the other essential function in the
data link layer. 32 bit CRC calculation is performed by this card which us useful to characterise
the contents of the network packet (Zheng & Jin (2018). After checking the errors the packets are
sent to their destination. After arriving on the destination address same CRC calculation is
performed on the received data. The value of the two tests are matched, if the value is same then
it can be said that the integrity of the packet is maintained. This kinds of error checking is
performed by the NIC in this layer.
1.5 Format Frames
The format of the Ethernet frame will be discussed in this unit of the paper. It contains
three units such as the IP, TCP and the HTTP, after each of the Ethernet frame a 32 bit frame
check sequence is attached.
1.6 Broadcast addressing
When the destination MAC address in the Ethernet frame is all in binary’s the frame is needed to
be processed by all the machines on the local network (Al-Jemeli & Hussin, 2015). Expressing in
decimals the broadcast address will be FF FF FF FF FF FF.

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Thus, this unit of the layers helps in understanding the different aspects of the data link
layer such as the two categories of the data link layer. The importance of the Local Address
Resolution and Network Interface Card in this layer can also be understood. The other aspects of
the data link layer such as the format frames, broadcast addressing can also be understood with
the help of this unit of the paper.
2 Transport Layer
One of the most important layers of the OSI model of networking, transport layer helps in
managing host to host communication services for the applications. Connection oriented
communication have different aspects associated with them such as the connectivity issue, flow
control, reliability and multiplexing (Sinha et al., 2017). Located in the 4th position, this layer
ensures each application is on the network and every connection based application can be
distinguished among them.
Segmentation: The breaking down of the larger volumes of data with into smaller fragments to
manage them in a better way considering their accessibility to the internet is termed as
segmentation.
Reassemble: The reassembling of the smaller fragments in the transportation layer into a
specific format send by the sending application is termed as the reassembly.
2.1 Identification of the Applications
Identification of the application is one of the most important aspect of the transport layer.
The transport layer helps in allocating a port number to each of the application of the client
which helps in identifying the application from the other applications. Port numbers are also

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allocated to the server daemons running on the network. Server daemon can be identified with
the help of the port number and the combination of the IP addressing. The different type of
sessions are also distinguished with the help of the server daemon. The combination of the port
number and host IP address is known as Socket. There is a specific protocol used in writing the
sockets such as 192.168.22.33:47658. The port numbers starting from 0 to 1023 is for the server
daemons which is also known as well-known ports. The port numbers above 1023 are
dynamically selected by the user applications (Papastergiou et al., 2017). Each application has
different source port numbers, which is useful in the identification of the sessions and also the
applications. Specific port numbers are used by the server daemons. The user applications know
how to address the requests to the server applications.
2.2 Transport layer services with UDP
The arrival of the packets is done safely with the use of the UDP communications. UDP
transport protocol is helpful in streaming high quality video. Basic transport services are
provided by User Datagram Protocol for the networking applications (Hares, 2015). The specific
format of UDP are as followings:
o Header is the source and destination of the port number.
o The length of the UDP file is in bytes and a check sum.
UDP is a type of stateless protocol as it treats each request as an independent transaction which
is not related to any of the requests.
2.3 Transport Layer Services with TCP
The format of the transmission control protocol are as followings:

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o Sequence number: It helps in tracking the progress of the data transfer in connection
phase.
o Acknowledgement number: Confirms the delivery of the data.
o Flags: Confirms the function done by TCP segment.
o Size of the window: Direct flow control between the source and destination.
2.4 Benefits of TCP
o It provides reliability of the transfer of data.
o Secured connectivity between the sender and receiver.
o Useful acknowledgements in receiving data throughout the session.
o Detection of lost segments
2.5 TCP Flags
The different categories of TCP flags are as followings:
o SYN: Synchronise sequence numbers.
o ACK: acknowledge segments.
o FIN: Close a connection.
o RST: Aborts connectivity.
o PSH: Sends data in the first place.
o URG: Helps in prioritising packet.

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2.6 TCP Connection and Termination
The connections are set up with the help of the handshake protocol. The handshake
protocol manages both the ends of the connection before data transfer takes place with the help
of the Initial Sequence Number. A different ISN is created in the opposite direction. The SYN
and ACK flags are set. Then in the final step the client acknowledges the server’s response, and
the stage is set for reliable transfer of data.
2.7 TCP Flow Control
The slow receivers need the TCP flow control. The window size field implements the
flow of control of the TCP protocol. The value of TCP is the maximum number of bytes’ senders
can receive without acknowledgement. The flow can be delayed by the receiver in the TCP flow
control which is known as sliding windows flow control.
Thus from this unit of the paper, the different aspects of the transport layer can be
understood which includes the identification of the application and the protocols associated with
the transfer of data from the sender and the receiver (Chen et al., 2015). The detailed
functionality of the handshake protocol can be identified in this unit. The different aspects of
TCP such as the benefits, flags, flow control, connection and termination are understood with the
help of this paper.
3 Cloud Computing and Mobile
This unit of the paper will be discussing on cloud computing and mobile computing
services.

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3.1 Fundamental aspects of Cloud computing
The process of managing, storing and processing data on the cloud servers is termed as
cloud computing. The resources used in the cloud computers are developed by the third party.
There are different types of cloud computing services available, which can be used to store large
chunks of data in a secured way such as the followings:
o Microsoft’s One Drive.
o Google Drive
o Apple’s iCloud
o Dropbox.
The type of cloud services depends upon the storage of the files, synchronization of the file
systems with the local devices, user defined shared devices, specific accessibility to the files and
access from other locations.
3.2 Fed Uni cloud services
The Fed Uni services runs mainly on the cloud and local servers. The local servers which
are mostly used all over the world are managed with the help of the Fed Uni cloud services.
There are around 85 servers hosted in the Fed Uni Camp which runs on the VMware
virtualization software, this software is installed in Microsoft Windows Operating systems as
well as Linux based system. The amount of the guest servers increases with time in this category
of the cloud services. The cloud services are very much useful in managing the data (Marinescu,
2017). The cloud services used by Fed Uni is the Amazon Cloud Services which falls in the
category of SaaS. The most important part of using this kinds of cloud service is that it is useful

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to manage each unit of the services. Contents can be added, edited, deleted in this service, the
backend services of the servers are managed by the cloud service providers.
3.3 Azure Cloud services
There are different types of servers used by the Fed Uni. Those different categories of
server provide services to the followings departments.
o Workstation Management.
o Identity Management.
3.4 Advantages and Disadvantages of cloud services
The advantage of the cloud service are as followings:
o Enhanced services can be deployed to the data which are already stored in the cloud
services.
o The infinite resources can be managed in an effective manner with the help of the cloud
computing services.
o The technical errors of the staffs can be avoided with the application of the cloud based
services.
The disadvantages of using the cloud services are as followings:
o High initial cost is required to buy packages in the cloud services.
o The CPU power memory, disk, capacity, backup status are the essential parameters
responsible for the high cost of the cloud based services.

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3.5 Virtualization Terminology
The virtualization process is done on the host system; this process requires the use of the
virtual operating system termed as the guests. The products of the virtualization run directly on
the hardware is termed as the type 1 virtualization systems and the virtualization technique which
run on the operating systems such as Mac, Linux and Windows are termed as the type 2
virtualization. The virtual box setup is an example of the type 2 virtualization and the type 1
virtualization is offered by the cloud service providers.
3.6 Different types of virtualization
Type 2 virtualization Type 1 virtualization
It relies on the operating system of the hosts. It depends on the virtualization layer or the
hypervisor.
It runs as an application. It is a lean virtualization-centric kernel.
The microprocessor architecture consists of
the CPU, Memory, NIC and Disk.
The microprocessor architecture of this
category of virtualization is the Disk, NIC,
Memory and CPU.
Table 1: Different aspects of virtualization architectures
(Source: Created by the author)

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3.7 Mobile Computing
The technologies used in the mobile computing has evolved over the years as it started
from the 1st generation wireless technologies to the 4th generation wireless mobile technology
(Bettini et al., 2015). The descriptions of the different types of wireless technologies are stated in
the following unit of the paper.
Generations Specifications
1st generation technology Circuit switching was used in this technology,
FDMA access systems, it only provided the
voice technology, analog bandwidths were
used in this wireless technology with a carrier
frequency of 30 kHz.
2nd generation technology Circuit switching was used along with the
packet data. The access system used was
TDMA and CDMA with facilities like MMS
and SMS. The bandwidth of this technology
was around 25 MHz with a carrier frequency
of about 200 kHz.
3rd generation technology Packet data are used in this generation. The
access system used in this generation was
CDMA. The bandwidth offered by this
generation is around 25 MHz with a carrier
frequency of 5 MHz
4th generation technology Packet switching was introduced in this
generation. The access system used in this
category is CDMA. The data speed of this
generation is much higher than the previous
generations with a carrier frequency of MHz
The bandwidth of this technology is around
MHz.
Table 2: Different aspects of wireless technologies
(Source: Created by the author)

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3.8 Elements of telephone networks
The mobile coverage area is divided into smaller areas 30kms apart. Each 30kms requires
a base station or a radio frequency transmitter or receiver. The transition of the mobile phone
which moves from one cell to another is done with the help of mobile switching centre. Each
mobile device use one frequency which comes from the base station control communications
(Kang, Kim & Kim, 2015). The signal coming from the base station to the mobile station
weakens as it moves away from the base stations, in this particular circumstances Rx/Tx radio
frequencies are required which redirects the mobile devices towards the next base stations.
3.9 Communication of base stations
The method of communication with the base station is different for each generations of
the wireless technologies. The three methods of communication are as followings:
o CDMA: In this technique the chipping code is combined with the bits for the
transmission of the data. The data obtained from multiple devices are also combined and
send as one transmission (Chen & Zhao, 2014).
o TDMA: Time Division Multiple Access is used in the shared medium networks as it
allows multiple user to share same frequency channel.
o FDMA: Frequency Division Multiple Access have channels of equal bandwidth which is
used by the multiple users to send data through single communication channel such as co-
axial cables.
Thus, from this unit of the paper the different specifications of the wireless technologies
which evolved through the years can be understood along with that the methods of
communications used in the mobile technologies can also be understood. This unit of the paper

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help in understanding the two types of virtualization and the fundamental aspects of the different
types of cloud computing services.

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