TCP/IP Reference Model: Introduction
The OSI reference
model was the first communication model and was termed as general-purpose
model because of its ability to fit in any type of network but without
fitting the protocols in. Due to its inability to fit protocols, TCP/IP
reference model which is commonly known as Internet Model was developed in
year 1983 by US Military Wing called ARPANET.
In 1983 January 1,
TCP/IP was made active permanently for the commercial use. From then, TCP/IP
has made a revolution in the field of networking and telecommunication as it
was able to overcome the drawbacks of general purpose OSI
TCP/IP stands for
Transmission Control Protocol
with the help of which, protocol implementation over the network can be
The TCP/IP model
also has a layered architecture which allows easy data communication along
with the facility of integrating multiple protocols. The layout remains
similar to OSI Model but the number of layer, their functionalities and
properties got changed.
Model(TCP/IP) comprises of only four layers as compared to seven layers of
OSI Model. These four layers are generated by combining the layers of OSI
model internally so that protocols can be implemented. These layers have
fixed positions too and their positions cannot be altered.
Transport Layer, Internet Layer and Network Access Layers are the four
layers of TCP/IP Model.
Architecture And Layers
: TCP/IP Reference Model
Architecture : TCP/IP Reference
a) The Network
- The Network Access
Layer of TCP/IP reference model is also known as the Host-to-Host or
Host-to-Network layer as it is responsible for performing roles of the
Physical Layer along with the functions of Data Link Layer.
- Data in the form of
bits received in the Network Access Layer are connected in the form of data
packets to Internet Layer.
- Network Access Layer
Data Link Layer +
b) The Internet
- Internet layer is
also called Network Layer which is responsible for establishment of
connection to send or receive data packets between multiple users or nodes
or devices or networks. This layer is placed on the 2nd position
- The Internet Layer
en-routes the data packets from source to destination through the process of
routing with the help of various routing techniques and routing
- The Transport Layer performs the same
functions and have similar features as that in OSI Model. The functionality
of Transport Layer is, it provides end to end data transfer by using the
technique of connection oriented services between sender and receiver with
the help of various protocols.
- The Application
Layer resides on the top of the TCP/IP reference model as line in OSI Model.
The functionality of Application Layer of TCP/IP reference model is to
provide interface between users and the applications. In some cases
depending upon the requirements, it can perform the functions of Session
Layer(to provide sessions) and Presentation Layer(data
Application Layer =
Advantages : TCP/IP
- Use of protocols
implementation and their support.
- Each layer has its
definite structure and functionality which makes OSI model simple and easy
- Use of layered
Disadvantages : TCP/IP
- As some layers has
multiple functionalities, it is more complex than OSI Model where each layer
has separate functions and services.
- The TCP/IP reference
makes use of protocols. But, in case of replacement of any protocol,
difficulty and issue might arise.