3. Introduction
Like OSI network model, TCP/IP also has a
network model.
The TCP/IP model is not same as OSI model. OSI is
a seven-layered standard, but TCP/IP is a four
layered standard. The OSI model has been very
influential in the growth and development of TCP/IP
standard, and that is why much OSI terminology is
applied to TCP/IP. The following figure compares the
TCP/IP and OSI network models.
As we can see from the above figure, presentation
and session layers are not there in TCP/IP model.
Also note that the Network Access Layer in TCP/IP
model combines the functions of Datalink Layer and
Physical Layer.
4. Layer 4. Application Layer
Application layer is the top most
layer of four layer TCP/IP model.
Application layer defines TCP/IP
application protocols and how
host programs interface with
Transport layer services to use
the network.
5. 1. DNS (Domain Naming System)
2. HTTP (Hypertext Transfer
Protocol)
3. FTP (File Transfer Protocol)
4. TFTP (Trivial File Transfer
Protocol)
5. SNMP (Simple Network
Management Protocol)
6. SMTP (Simple Mail Transfer
Protocol)
7. DHCP (Dynamic Host
Configuration Protocol)
8. RDP (Remote Desktop Protocol)
4
6. Layer 3. Transport Layer
Transport Layer is the third layer of
the four layer TCP/IP model . The
purpose of Transport layer is to permit
devices on the source and destination
hosts to carry on a conversation.
Transport layer defines the level of
service and status of the connection
used when transporting data.
8. Layer 2. Internet Layer
Internet Layer is the second layer of the
four layer TCP/IP model . Internet layer
pack data into data packets known as IP
datagrams, which contain source and
destination address (logical address or IP
address) information that is used to
forward the datagrams between hosts and
across networks. The Internet layer is also
responsible for routing of IP datagrams.
9. 1. IP (Internet Protocol)
2. ICMP (Internet Control Message
Protocol)
3. ARP (Address Resolution Protocol)
4. RARP (Reverse Address Resolution
Protocol)
5. IGMP (Internet Group
Management Protocol)
2
10. Layer 1. Network Access Layer
Network Access Layer is the first layer of
the four layer TCP/IP model. Network
Access Layer defines details of how data is
physically sent through the network,
including how bits are electrically or
optically signaled by hardware devices that
interface directly with a network medium,
such as coaxial cable, optical fiber, or
twisted pair copper wire.
13. FTP
In active mode, the client starts listening for
incoming data connections from the server
on port M. It sends the FTP command PORT
M to inform the server on which port it is
listening. The server then initiates a data
channel to the client from its port 20, the FTP
server data port.
14. HTTP
Hypertext Transfer Protocol (HTTP) is the
protocol that enables the connection
between a web server and a client. Hypertext
Transfer Protocol (HTTP) is an application
layer protocol for distributing information in
the World Wide Web (WWW). Hypertext
Transfer Protocol (HTTP) is based on the
client–server architecture.
15. TCP
Transmission Control Protocol (TCP - RFC
793) is considered as a reliable protocol.
Transmission Control Protocol (TCP) is
responsible for breaking up the message
(Data from application layer) into TCP
Segments and reassembling them at the
receiving side.
16. IP
The Internet Protocol (IP) is the principal
communications protocol in the Internet
protocol suite for relaying datagrams across
network boundaries. Its routing function
enables internetworking, and essentially
establishes the Internet.
17. CSMA/CD
Carrier-sense multiple access with collision
detection (CSMA/CD) is a media access
control method used most notably in early
Ethernet technology for local area
networking. It uses a carrier-sensing scheme
in which a transmitting station detects
collisions by sensing transmissions from
other stations while transmitting a frame.
