ITECH1102 Networking and Security: Content Analysis ePortfolio Assignment

This ePortfolio assignment for ITECH1102 Networking and Security explores key concepts from Topics 3, 5, and 7, including the application layer, the internet layer, and the physical layer. It analyzes client-server and peer-to-peer architectures, IP addressing, routing, and various physical layer transmission media. The assignment also includes problem sheets for Topics 4, 6, and 8, covering data link, transport, and cloud/mobile networking concepts. This ePortfolio provides a comprehensive overview of fundamental networking and security principles.

ITECH1102 Networking and Security
Content Analysis ePortfolio Assignment

ITECH1102 Networking and Security
Contents
PART A: Topic 3, 5, & 7................................................................................................................................3
Topic 3: Introduction to the application layer of the Internet Model......................................................3
Content analysis:.................................................................................................................................3
Client server interaction:.....................................................................................................................3
Peer to Peer architectures:..................................................................................................................3
Network protocols:..............................................................................................................................4
Topic 5: THE INTERNET LAYER.................................................................................................................4
Data Link Layer:...................................................................................................................................4
Role of Network Layer:........................................................................................................................5
IP addressing:......................................................................................................................................5
How to get the IP address?..................................................................................................................5
Components of an IP Address:.............................................................................................................5
Subnet Mask:.......................................................................................................................................5
CIDR – Classless inter-Domain routing.................................................................................................6
Internet Assigned Numbers Authority (IANA)......................................................................................6
Topic 7: The Physical Layer......................................................................................................................6
Point to Point and Multipoint circuits:.................................................................................................7
Multiplexing.........................................................................................................................................7
Digital transmission of Data.................................................................................................................7
Part B: Problem sheet, Topic 4, 6 & 8..........................................................................................................9
Topic 4: Data Link Problem sheet............................................................................................................9
Topic 6: Transport layer problem sheet.................................................................................................10
Topic 8: Cloud and mobile problem sheet.............................................................................................11
References.................................................................................................................................................13

ITECH1102 Networking and Security

ITECH1102 Networking and Security
PART A: Topic 3, 5, & 7
Topic 3: Introduction to the application layer of the Internet Model
Content analysis:
In this topic we will learn application architecture such as client/server, peer to peer, host-based and
cloud architectures. How easily the networked protocols work, the role of network protocols, the
common applications of layer protocols and how data travels through various protocols headers and
networks (Durdu, 2014).
The application layer or the user application provides us with the ability to interact with thousands of
service providers on internet and local network. Internet services may include Facebook, Google search
engine, Google maps, Ftp download sites and many others. At local level user application allows access
to network faxes, printers, shared resources and network attached storage. Prior to this data was carried
to shared manually using the hard disks (floppy disks).
Here we will discuss various categories of interactions.
Client-server interaction:
User applications are referred to as clients; they commonly include web clients, email clients or FTP
clients. These clients request for the services provided by the servers’ example web clients uses servers
to search for websites. The server waits for the requests from the clients, some needs authentication
and some do not. Here the client is the consumer and the server is the service provider. They have
totally different codes. Common web client software is chrome safari, Firefox, and commonly used web
servers software’s are IIS on windows and Apache on Linux (Durdu, 2014).
Peer to Peer architectures:
In this, each machine can act as a client as well as the server also simultaneously if required. They all
can share resources and can also access these shared resources. They do not require a particular
dedicated server; a best example for this can be the home networks which share files and printers.
Peer to Peer can work well in small networks, administrative duties are assigned to each Peer because
any Peer can act as a server. But this is not possible in case of large networks. In client-server
applications administers controls the network and its applications and client is given limited usage
according to day to day work (Durdu, 2014).

ITECH1102 Networking and Security
Host Based architectures:
They were used in the early days of computing and still used sometimes for low powered systems.
Windows also supports this thin client system.
Cloud-Based Architectures:
They are more frequently used now as they do not require any hardware house for their support to the
infrastructure and maintenance cost is reduced.
1. IAAS (infrastructure as a service): due to virtualization no infrastructure cost, problems of the
power supply and air-conditioned rooms have solved.
2. PAAS (platform as a service): this allows building organizations own applications without the
worry of OS etc.
3. SAAS (software as a service) the user can access the internet and can customize their user
interface.
Network protocols:
Every application must follow a set of rules known as protocols, for example, web applications follow
HTTP (hypertext transfer protocol). These are useful as they establish a link between the sender and the
receiver, Specifies how the message has been structured inside etc. To reach the physical network client
data must pass all the layers. In other chapters, we will be dealing with these layers in detail.
Topic 5: THE INTERNET LAYER
ARP (address resolution protocol)
This is used to determine the MAC address of the local machine using the IP address. For Windows the
ARP commands for cache contents are ARP-a and to delete an entry arp-d <ip address>. If the
commands are successful a new entry in the Arp cache is added. These entries age out after a certain
time limit (Thubert, 2017).
Data Link Layer:
This is used to implement a communication between any two local machines on the local network. It
uses the source and the destination MAC address to address each device. Routers can also help for the
same purpose, so data is sent to them and they handle the remote delivery of network traffic. This can
be done with the help of the internet network layer (Thubert, 2017).

ITECH1102 Networking and Security
Role of Network Layer:
The role of the network layer is to deliver network traffic from one host to another which is separated
by long distances. It is basically all about IP addressing and routing.
IP addressing:
Each device on an IP network requires an IP address. It is required to uniquely identify the machine on
the internet. It is of two types:
1. IPv4
2. IPv6
IPv4 is a 32 bit long IP address, to ease the task we make 4 slots of 8 bits each.
IPv6 it is represented using hexadecimal and has 128-bit length.
How to get the IP address?
The operating system holds the IP address of that machine and it can be configured manually as well as
automatically.
In Manual or static addressing user himself enters the IP address in the Operating system. In Automatic
administration or (dynamic addressing) a DHCP (Dynamic Host Configuration Protocol) server allocates
IP settings to the machine. Further DNS servers are used to convert the IP address to names (Steven,
2015).
Components of an IP Address:
IP address consists of two parts:
 High order bits specify the IP network of the IP address. (Network bits) they are common to all
hosts of IP network.
 Low order bits specify the unique part of the IP address. (Node bits) they specify a particular
host on a network (Steven, 2015).
Subnet Mask:
This tells us how many bits of an IP address is devoted to network portion and how many to node
portion. The format of a subnet mask is:
A series of binary 1 bits (indicating the network portion) followed by the subnet mask

ITECH1102 Networking and Security
A series of binary 0 bits (indicating the node portion)
To determine the network address of an IP address replaces all the node bits of an IP address with
zeroes. When we are doing bitwise AND of the IP address with the Subnet Mask then we will get the
Network address (Steven, 2015).
CIDR – Classless inter-Domain routing
Another way of expressing the number of network bits of an IP address is to use CIDR notation.
Example: 192.168.22.56 /24
The number following the / is the number of network bits.
IP address can be Public (communicate on the internet) or Private (discarded by routers as cannot travel
the internet) . The role of routers is to move a network packet forward 1 step towards its destination.
Routers require a MAP of the internetwork to decide the route to use.
The map is called a routing table. When a packet arrives, the router determines the destination and
source of the frame and sends the packet on its way. The routing table specifies the interface on which
packets should exit and also the address of the next router’s address (Checko, 2015).
Internet Assigned Numbers Authority (IANA)
It is an overseeing body for the naming of domains. Once an organization has their domain name and
associated IP addresses their server/s can be found on the Internet. After this, the name resolutions are
handled by the DNS servers.
Topic 7: The Physical Layer
The Physical layer is the connection between computers and/or other devices on the network.
There are two types of Data:
 Digital data
 Analog data
The main characteristic of the digital format is that they store entire data in form of 0 and 1. Whereas
analog data can take an infinite number of levels and can be transmitted to digital networks using high
sampling rates. The cables we use to connect computers were developed for the transmission of digital
data. Radio devices like Wi-Fi Access points and Telephone system Microwave dishes are analog by
nature (Zou, 2015).

ITECH1102 Networking and Security
Point to Point and Multipoint circuits:
Point to point circuits is a direct connection between two devices. Such media is not shared with any
other device. The multipoint circuits are shared to the media with multiple devices.
Systems can also be classified according to the data flow in them as:
1. Simplex systems that can send data only in one direction.
2. A half-duplex system which allowed data flow in both directions. But it only is in one direction
at any one time.
3. Full duplex: it allows data flow in both directions at the same time (Mrabito, 2015).
Multiplexing
This is used to divide the communication channel so information can be sent at a time. It can be of
various types:
1. Time Division Multiplexing (TDM): In this different stations can be transmitted at different times.
This reduces waste in the channel bandwidth.
2. Frequency division multiplexing (FDM): through this different channels can be transmitted on a
different frequency. Eg. AM radio
3. Wavelength Division Multiplexing (WDM): due to this multiple lights of different wavelength can
be sent at the same time, like an optical fiber cable (Zou, 2015).
Digital transmission of Data
This occurs between a sender and a receiver like using the network card in Ethernet network. Ethernet
uses an encoding method called Manchester encoding. This method is self-clocking. Encoding is nothing
but the way in which binary 0 and 1 bits are represented. Transmission can take place through different
media like twisted pair, coaxial, optical cable, infrared and satellite microwave (Zou, 2015).
Twisted Pair: It consists of two insulated copper wires arranged in a regular spiral pattern, commonly
used in buildings or telephone networks and in LAN connections. They are cheap, easy to work with,
have low data range and short range.
Coaxial Cable: It consists of two conductors, inner and outer where outer conductor is braided shield
whereas inner conductor is solid metal. Both are separated by insulating material and have a diameter
of 1-2.5 cm. It has superior frequency and limited attenuation (Mrabito, 2015).

ITECH1102 Networking and Security
Optical Fiber: It has three parts: core, cladding, jacket. It uses total internal reflection to transmit light
and can transmit a variety of lights like LED, LID etc. It has greater capacity, smaller size and light
weight, lower attenuation and greater repeater spacing. It is basically used in main switches of LAN,
long-haul trunks, metropolitan trunks etc.
Terrestrial Microwave: It is used for long-haul telecommunications and is an alternative to coaxial
cables, such as in mountainous areas where laying cable is difficult as it requires fewer repeaters and
uses a parabolic dish to focus a narrow beam onto a receiver antenna. It uses 1-40GHz frequencies.
Satellite Microwave: This acts as the relay station; the satellite receives on one frequency, amplifies or
repeats the signal and transmits on another frequency. Commonly used in television, long distance
telephone private business networks etc.
Infrared: It modulates noncoherent infrared light, and is blocked by walls. Mostly, it is used in TV
remotes and IRD ports (Stadelmeier, 2016).

ITECH1102 Networking and Security
Part B: Problem sheet, Topic 4, 6 & 8
Topic 4: Data Link Problem sheet
Q5.The LLC is sometimes described as providing a multiplexed service to upper layer protocols.
Describe what this statement means and try to give an example of this in action.
Answer: LLC stands for logical link control. It is the upper sublayer of the data link layer (which is itself
layer 2 of the Reference model). The role of LLC is basically to provide multiplexing protocols which are
transmitted over MAC layer and to decode them while receiving. It also provides flow and error control.
The LLC sublayer is responsible for providing an interface between the MAC layer and the network layer.
The LLC header tells the data link layer what to do after the packet is received. Example the Ether type in
the Ethernet II framing is used to multiplex different types of protocols on top of the Ethernet Mac
header which can be seen as LLC identifier (Mrabito, 2015).
Q7. Describe why routers require at least 2 network cards.
Answer: There is multiple interfaces in the router, it routes between the network and the host.
Therefore it needs to have minimum two IP addresses one for the incoming interface and other for the
outgoing interface and it functions in deciding where the package will next go (Sarkar, 2016).
Q19. Describe when entries are added and removed from the ARP cache.
Answer: An ARP stands for address resolution protocol and it allows the machine to communicate with
another interface even if they are not in the same environment. ARP entries can be added manually by
using the following command (Checko, 2015):
arp –t ib
Also, ARP cache entries can be deleted using the command:
$ arp –t ib –d IP Address
But as we are talking about the cache, it is more difficult and expensive to delete data here, therefore it
is automatically removed when a new entry enters the ARP cache (Sarkar, 2016).
Q20. As a Data Link frame moves through an internetwork the Ethernet frame header is modified at
each step. Describe why this must happen at each router.

ITECH1102 Networking and Security
Answer: to carry the data from source to another we use routers, when routers receive any packet as in
case of the Ethernet MAC address it first removes it layer 2 header information and looks for the layer 3
where the IP address for source and destination are present then it fixes that interface mac address to it
and sends forward to the destination (Tate, 218).
Topic 6: Transport layer problem sheet
Q5.How many bits are used in a UDP header to store the destination port number? Explain how you
arrived at this number.
Answer: UDP is a datagram-oriented transport layer protocol, and the UDP message is called as user
datagram. Each user datagram consists of two parts: UDP header and the UDP data area. Each UDP
header is further divided into four 16 bit fields namely the source port, destination port, length, and
checksum. Therefore the destination port number has 16 bits and is used for DE multiplexing among the
various processes waiting to receive them in the destination computer.
Q.8. It is commonplace for two tabs on a browser to be concurrently connected to the same web
server. Discuss how the data meant for one browser tab is never mixed up with that of the other tab.
Answer: Every tab or page is made on a different port number of the computer and when the browser
sends HTTP requests, which is further sent to web servers and it responds to it and returns back to the
requesting web browsers. As each tab sends its individual and unique request to the server they never
get mixed up. Also, the server does not know anything about the tabs it just responds to that unique
id/request (Tate, 2018).
Q.14. Describe the 3-way handshake process. Your description should make it clear the Flags that are
exchanged at each step and the meaning of each of those flags.
Answer: The 3-way handshake process starts with the TCP segment with the SYN control bit set. Here
SYN stands for Synchronize. So TCP allows one side connection establishment, and the other side
responds to it. As the other host receives this request from A it returns TCP segment with SYN =1 and
ACK =1 where ACK stands for acknowledgment. Again when the host A receives the returned message it
sends back the acknowledgment message with SYN =0 and ACK =1. In this way, a # way handshake is set
up between the two computers with the flags as SYN, SYN-ACK, and ACK (Checko, 2015).
Q.15. Describe how flow control is achieved in a TCP connection.
Answer: When we need to send the data to the network the following process takes place:

ITECH1102 Networking and Security
The sender application writes data to the socket that is the TCP layer from which it goes to the network
layer with an IP address, this network layer will further transmit the data to the destination by the help
of the TCP layer of the receiver with the exact copy of the data sent that means the serial of the packets
does not change if some of the packets are received prior to the information they wait for the complete
stream of bytes to occur. From the receiver buffer, the packets are read by the destination application.
Flow control ensures that no more packets are stored at a time in the TCP buffer as it has a limit and
won’t be able to handle them, resulting in the loss of information (Sharma, 2016).
Topic 8: Cloud and mobile problem sheet
Q5. Describe the differences between type 1 and type 2 Virtualization.
Answer:
Type 1 hypervisors run directly on the system server hardware. They are called as Native, or bare metal
or embedded. They are more efficient, provide high performance, easily available and has more security.
It also has better hardware resources like CPU, memory etc. It is served as small or thin layer hypervisor
hence offering more efficiency. Example: VMware ESXi, Citrix Xen Server, Microsoft Hyper-V, Oracle VM
Server on X86 etc.
Type 2 hypervisors run on host operating system, this could easily be bought and installed on a server.
But they offer low and slow performance, less efficient, lower availability and security. Example:
VMware Workstation, VMware Player, Microsoft Virtual PC, Oracle Virtual Box etc. (Mrabito, 2015)
Q.8. The switching technologies used for mobile communications has changed throughout the mobile
phone technologies 1G through to 4G. Describe the changes that have occurred.
Answer:
The evolution of mobile technologies from 1G to 4G has undergone significant changes and
advancement in the technologies. As the first generation, mobile communication provided only the
basic facility of calling or voice transferring, a 2nd generation came up with both voice and data services.
Further with the evolution 3rd generation had greater technologies with internet access, video, and
multimedia applications, this was a boom for the society but still with the increase in demands there
came the fourth generation which provided mobile ultra-broadband internet access and much faster
data transmission rates with LTE services. Also, this made the faster transfer of information and better
connectivity all around the world (Checko, 2015).

ITECH1102 Networking and Security
Q9. Describe the roles of the following elements of the mobile phone network:
1. Cell
2. Base station
3. Mobile switching center
Cell: It is the geographical area covered by the cellular telephones or the wireless equipment. Depending
on the terrain and the transmission power the area under the cell can range from one mile to twenty
miles of diameter. It has a number of RF channels and covers a limited number of subscribers.
Base station: as the name suggests it acts as the transceiver for a number of wireless devices, it has the
information of wide area connected through networks and work as a hub for transmitting and receiving
information from various places.
Mobile switching center (MCS): it is a centerpiece of network switching and functions as a call set up,
release and routing. it is so made so that the base stations can report to it and it further reports to PSTN.
All calls from cell phones or other devices pass through the MSC (Castells, 2015).
Q 10. Describe the roles of the Base station and the Mobile switching center as a mobile phone moves
from one cell to another.
When a user or mobile phone subscriber moves from one cell to another, the cell site automatically
switches to the stronger and the closest frequency and signal to keep the link. The cellular network is
the part of the base station which further acts as the part of the main switching center which ultimately
works for the PSTN. Base stations provide direct communications with the mobile phones whereas MSC
coordinates the actions of the base stations and acts as a switch in it (Agrawal, 2015).

ITECH1102 Networking and Security
References
 Agrawal, D. P., & Zeng, Q. A. (2015). Introduction to wireless and mobile systems. Cengage
learning.
 Castells, M. (2015). Networks of outrage and hope: Social movements in the Internet age. John
Wiley & Sons.
 Checko, A., Christiansen, H. L., Yan, Y., Scolari, L., Kardaras, G., Berger, M. S., & Dittmann, L.
(2015). Cloud RAN for mobile networks—A technology overview. IEEE Communications surveys
& tutorials, 17(1), 405-426.
 Durdu, S., Iskar, M., Revenu, C., Schieber, N., Kunze, A., Bork, P., ... & Gilmour, D. (2014). Luminal
signalling links cell communication to tissue architecture during
organogenesis. Nature, 515(7525), 120.
 Morabito, R., Kjällman, J., & Komu, M. (2015, March). Hypervisors vs. lightweight virtualization:
a performance comparison. In Cloud Engineering (IC2E), 2015 IEEE International Conference
on (pp. 386-393). IEEE.
 Sarkar, S. K., Basavaraju, T. G., & Puttamadappa, C. (2016). Ad hoc mobile wireless networks:
principles, protocols, and applications. CRC Press.
 Sharma, V. N., Stuck, B. W., Hu, C. T., Chou, Y. C., & Chu, W. (2016). U.S. Patent No. 9,323,708.
Washington, DC: U.S. Patent and Trademark Office.
 Stadelmeier, L., Loghin, N., Robert, J., & Atungsiri, S. A. (2016). U.S. Patent No. 9,236,927.
Washington, DC: U.S. Patent and Trademark Office.
 Stevens, M., Bauer, S. M., & Kingsley, P. (2015). U.S. Patent No. 9,137,135. Washington, DC: U.S.
Patent and Trademark Office.
 Tate, J., Beck, P., Ibarra, H. H., Kumaravel, S., & Miklas, L. (2018). Introduction to storage area
networks. IBM Redbooks.
 Thubert, P., Levy-Abegnoli, E., & Ribiere, V. J. (2017). U.S. Patent No. 9,654,502. Washington,
DC: U.S. Patent and Trademark Office.
 Zou, Y., Zhu, J., Wang, X., & Leung, V. C. (2015). Improving physical-layer security in wireless
communications using diversity techniques. IEEE Network, 29(1), 42-48.