OSI and TCP/IP Models: A Comparative Analysis of Network Architectures

Desklib provides past papers and solved assignments for students. This report compares OSI and TCP/IP network models.

Ans. 1.
For characterizing and standardizing the communication functions in telecommunication, a
conceptual model is introduced known as open system interconnection model commonly known
as the OSI model. It ensures the interoperability of the communication systems with common
standard protocols. There are seven layers in this model, given as:
1. Application layer
2. Presentation or control layer
3. Session layer
4. Transport layer
5. Network layer
6. Data link layer
7. The physical layer (Bahl, 2018)
TCP/IP protocol suite (The Internet Model): TCP/IP acronym is used for a set of network
protocols that compose a combined suite and ensures the network connectivity to the wide area
network and the bodies that govern the internet all over. There are four layers in the TCP/IP
model as first three layers of the OSI model combined to only one layer in TCP/IP. These layers
are:
1. Application layer
2. Transport layer
3. Internet layer
4. Network access layer (Data link + Physical Layer) (Yadav, 2018)
Ans. 2
TCP/IP internet model was developed prior to the OSI reference model. Therefore, the TCP/IP
layers do not match exactly to OSI model layers. In the TCP/IP layer, the first application layer

is the combination of the first three layers in the OSI model, that is, the application layer,
presentation layer, and session layer. Also, the host to network layer commonly known as
network access layer in TCP/IP model is the combination of last two layers of OSI model, that is,
data link layer and physical access layer. Hence, the OSI model is the extension of the TCP/IP
model (Kashif, 2018).
Ans. 3
In TCP/IP protocol suite, the application layer is the user support layer because it allows the
interoperability of software systems which are unrelated to each other and the remaining three
layers that are transport layer, internet layer, and network access layer are the network support
layers as these deals with electrical specification, transportation, physical connection and
reliability (gayathritc, 2011).
Ans. 4
Data encapsulation is defined as putting headers and trailers around some data. For TCP/IP and
OSI layer, the data from the higher level layer is encapsulated by just lower level layer by adding
some headers or trailers around the data. In TCP/IP, the term segment, packet and frame are
being used at different layers which refers to a whole data packet, but in OSI model, a different
term is used known as a protocol data unit (PDU) (cicnavi, 2011).
Ans. 5
The second layer of OSI model is known as data link layer which is responsible for encoding the
bits into packets before transmission and at the destination it decodes the packets back to data
bits. It is divided into two sublayers: the media access layer (MAC) which controls the network
gain access of the system and permits the data to be transmitted and other one is logical to link
control (LLC) layer which performs error checking, synchronization of packets and ensures
reliable flow of data (Anonymous, 2018).
Ans. 6
The network layer is responsible for sending the packets from one node to another node through
routing protocols. This layer not at all ensures the delivery of packets to the destination, or in the

same order in which the data is transmitted. The main function of this layer is to deliver the
packet across multiple networks by providing connection services. It is responsible for the host
(source) to host (destination) delivery.
But the transport layer which is built upon a network layer provides the quality of delivery
service by providing error control, flow control, sequence control. In contrast to the network
layer, this layer is responsible for the process (source) to process (destination) delivery (Myréen,
2016).
Ans. 7
The errors between the source node and destination node can be detected by the data link layer.
But in case, if there is any error exist at the source or destination node (input port and output
port), the data link layer is unable to detect. Hence, the mechanism for the transport layer is
needed to detect the errors at the system nodes (TheRequiemEmpire, 2018).
Ans. 8
The network layer is the third layer from the bottom of the OSI reference model which is
responsible for delivering packets from source to destination across multiple network links
through its routing protocols using the best delivery path. It also assembles the packets into
messages for higher level layers and converts the logical level address into a physical address. It
breaks the larger packet information into smaller packet units for delivery (gayathritc, 2011).
Ans. 9
The transport layer is responsible for end-to-end communication of different nodes over a
network. Through its layered architecture of transfer protocols, the error detection, quality
transmission, and reliability is offered by this layer to the users. It breaks the messages from the
upper layer into segments and transfers them to the network layer. The opposite action will be
performed at the destination side by this layer. Flow control, traffic control, data integrity,
multiplexing and same order transferring data are ensured by this layer (Corenetworks, n.d.).
Ans. 10

An IP address assigned to the system when connected through another network is known as
Logical address.
Each system has its own NIC (Network Interface Card) through which it gets connected to
another system via any cable. This NIC address is known as the physical address of the system.
As many applications can run on one system. So, for differentiating, each application run with its
port number on the system. This port number is known as the port address of the system (Prasad,
2014).
Ans. 11
Application layer provides some standard internet services and network applications that anyone
can use. The protocols provided by these layers are:
 Standard TCP/IP (transfer control protocol/internet protocol) such as File transfer
protocol (FTP) and telnet commands.
 UNIX r commands
 Domain name system (DNS)
 Network Information Service (NIS)
 Router Discovery Server Protocol (RDSP)
 Simple Network Management Protocol (SNMP) (C. Ibe, 2017)
Ans. 12
The primary advantage of a combination of the three layers in TCP/IP model over OSI model is
fewer layers in the queue. During transmission and reception, the packets have to be passed
through different levels in the model which introduces additional latency for transmitting the
information and also requires more memory. So, the advantage of combining those three layers
into one layer in TCP/IP is one fewer layer in the queue, high latency as compared and less
storage memory. Although it has many drawbacks also (Sukosd, 2018).

References
Bahl, M. (2018). OSI Model Layers — “Explained” – Madhav Bahl – Medium. Retrieved from
https://medium.com/@madhavbahl10/osi-model-layers-explained-ee1d43058c1f
Yadav, V. (2018). Learning the TCP/IP Protocol Suite – codeburst. Retrieved from
https://codeburst.io/learning-tcp-ip-protocol-suite-6947b601ea11
kashif, e. (2018). How do the layers of the internet model correlate to the layers of the OSI
model?. Retrieved from https://www.question.com/how-do-the-layers-of-the-internet-model-
correlate-81815.html
gayathritc. (2011). network support layers and the user support layers. Retrieved from
https://www.classle.net/submission/network-support-layers-and-user-support-layers
cicnavi. (2011). Data Encapsulation in the OSI Model - Utilize Windows. Retrieved from
https://www.utilizewindows.com/data-encapsulation-in-the-osi-model/
Anonymous. (2018). What Are The Responsibilities Of Data Link Layer? - Blurtit. Retrieved
from https://technology.blurtit.com/118940/what-are-the-responsibilities-of-data-link-layer
Myréen, J. (2016). Transportation Layer vs Network Layer. Retrieved from
https://serverfault.com/questions/818068/transportation-layer-vs-network-layer/818218
TheRequiemEmpire. (2018). If the data link layer can detect errors between hops , why do we
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http://answers.wikia.com/wiki/If_the_data_link_layer_can_detect_errors_between_hops_,_why_
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gayathritc. (2011). responsibilities of Network Layer. Retrieved from
https://www.classle.net/submission/responsibilities-network-layer
Sukosd, A. (2018). What are some advantages and disadvantages of combining the session,
presentation, and application layers in the OSI model into one single application layer in the
Internet model?. Retrieved from https://www.quora.com/What-are-some-advantages-and-

disadvantages-of-combining-the-session-presentation-and-application-layers-in-the-OSI-model-
into-one-single-application-layer-in-the-Internet-model
Corenetworkz, (n.d.). Role of Transport Layer - Responsibilities and Protocols. Retrieved from
https://www.corenetworkz.com/2007/06/what-is-role-of-transport-layer-in-osi.html
Prasad, V. (2014). What is the difference between port address, logical address and physical
address?. Retrieved from https://2it414vkp.wordpress.com/2014/01/27/what-is-the-difference-
between-port-address-logical-address-and-physical-address/
C. Ibe, O. (2017). Application Layer Services. Retrieved from
https://onlinelibrary.wiley.com/doi/10.1002/9781119436294.ch10