TCP/IP means Transmission Control Protocol and Internet Protocol. It is the network model used in the current Internet architecture as well. Protocols are set of rules which govern every possible communication over a network.
These protocols describe the movement of data between the source and destination or the internet. They also offer simple naming and addressing schemes.
Protocols
and networks in the TCP/IP model:
Overview of
TCP/IP reference model:
TCP/IP that is
Transmission Control Protocol and Internet Protocol was developed by Department
of Defense’s Project Research Agency (ARPA, later DARPA) as a part of a
research project of network interconnection to connect remote machines.
The features
that stood out during the research, which led to making the TCP/IP reference
model were:
Support for a
flexible architecture. Adding more machines to a network was easy.
The network was
robust, and connections remained intact until the source and destination
machines were functioning.
Different
Layers of TCP/IP Reference Model
Below we have
discussed the 4 layers that form the TCP/IP reference model:
Layer 1:
Host-to-network Layer
·
Lowest
layer of the all.
·
Protocol
is used to connect to the host, so that the packets can be sent over it.
·
Varies
from host to host and network to network.
Layer 2:
Internet layer
·
Selection
of a packet switching network which is based on a connectionless internetwork
layer is called an internet layer.
·
It
is the layer which holds the whole architecture together.
·
It
helps the packet to travel independently to the destination.
·
Order
in which packets are received is different from the way they are sent.
·
IP
(Internet Protocol) is used in this layer.
·
The
various functions performed by the Internet Layer are:
o
Delivering
IP packets
o
Performing
routing
o
Avoiding
congestion
Layer 3:
Transport Layer
·
It
decides if data transmission should be on parallel path or single path.
·
The
applications can read and write to the transport layer.
·
Transport
layer adds header information to the data.
·
Transport
layer breaks the message (data) into small units so that they are handled more
efficiently by the network layer.
·
Transport
layer also arrange the packets to be sent, in sequence.
Layer 4:
Application Layer
The TCP/IP
specifications described a lot of applications that were at the top of the
protocol stack. Some of them were TELNET, FTP, SMTP, DNS etc.
1.
TELNET
is a two-way communication protocol which allows connecting to a remote machine
and run applications on it.
2.
FTP
(File Transfer Protocol) is a protocol, that allows File transfer amongst
computer users connected over a network. It is reliable, simple and efficient.
3.
SMTP
(Simple Mail Transport Protocol) is a protocol, which is used to transport
electronic mail between a source and destination, directed via a route.
4.
DNS
(Domain Name Server) resolves an IP address into a textual address for Hosts
connected over a network.
5.
It
allows peer entities to carry conversation.
6.
It
defines two end-to-end protocols: TCP and UDP
a.
TCP
(Transmission Control Protocol): It is a reliable connection-oriented protocol
which handles byte-stream from source to destination without error and flow
control.
b.
UDP
(User-Datagram Protocol): It is an unreliable connection-less protocol that do
not want TCPs, sequencing and flow control. Eg: One-shot request-reply kind of
service.
Merits of
TCP/IP model
1.
It
operated independently.
2.
It
is scalable.
3.
Client/server
architecture.
4.
Supports
a number of routing protocols.
5.
Can
be used to establish a connection between two computers.
Demerits of
TCP/IP
1.
In
this, the transport layer does not guarantee delivery of packets.
2.
The
model cannot be used in any other application.
3.
Replacing
protocol is not easy.
4. It has not clearly separated its services, interfaces and protocols.
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