Scribd
Upload
63 views7 pages

Tcp/Ip: - Application Layer

The document discusses TCP/IP and the OSI network models. It describes the layers of each model from the physical layer up to the application layer. The TCP/IP model has 4 layers: network access, internet, transport, and application. The OSI model has 7 layers: physical, data link, network, transport, session, presentation, and application. It provides details on the responsibilities and common protocols of each layer for both the TCP/IP and OSI models.

Uploaded by

Malik Ali
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as DOCX, PDF, TXT or read online on Scribd
63 views7 pages

Tcp/Ip: - Application Layer

The document discusses TCP/IP and the OSI network models. It describes the layers of each model from the physical layer up to the application layer. The TCP/IP model has 4 layers: network access, internet, transport, and application. The OSI model has 7 layers: physical, data link, network, transport, session, presentation, and application. It provides details on the responsibilities and common protocols of each layer for both the TCP/IP and OSI models.

Uploaded by

Malik Ali
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as DOCX, PDF, TXT or read online on Scribd
You are on page 1/ 7

TCP/IP (Transmission Control Protocol/Internet Protocol)

TCP/IP, or the Transmission Control Protocol/Internet Protocol, is a suite of


communication protocols used to interconnect network devices on the internet.
TCP/IP can also be used as a communications protocol in a private network
(an intranet or an extranet).

Layer 1. Application Layer


Application layer is the top most layer of four layer TCP/IP model. Application layer is present on the
top of the Transport layer. Application layer defines TCP/IP application protocols and how host
programs interface with Transport layer services to use the network.

 Application layer includes all the higher-level protocols like DNS (Domain Naming
System), HTTP (Hypertext Transfer Protocol), Telnet, SSH, FTP (File Transfer Protocol),
TFTP (Trivial File Transfer Protocol), SNMP (Simple Network Management
Protocol), SMTP (Simple Mail Transfer Protocol) , DHCP (Dynamic Host Configuration
Protocol), X Windows, RDP (Remote Desktop Protocol) etc.

Layer 2. Transport Layer


Transport Layer is the third layer of the four layer TCP/IP model. The position of the Transport
layer is between Application layer and Internet layer. 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.

 The main protocols included at Transport layer are TCP (Transmission Control Protocol)

Layer
Layer.3 Internet Layer
Internet Layer is the second layer of the four layer TCP/IP model. The position of Internet
layer is between Network Access Layer and Transport layer. 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.

 Packet switching network depends upon a connectionless internetwork layer. This layer is known
as Internet layer
 The main protocols included at Internet layer are IP (Internet Protocol), ICMP (Internet Control
Message Protocol), ARP (Address Resolution Protocol), RARP (Reverse Address Resolution
Protocol) and IGMP (Internet Group Management Protocol).

Layer 4. 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.

 The protocols included in Network Access Layer are Ethernet, Token Ring, FDDI, X.25, Frame

Relay etc.

OSI(Open Systems Interconnection) Model Layer


In 1977 the International Standards Organization (ISO) proposed the Open Systems Interconnection
(OSI) network model. The Open Systems Interconnection (OSI) model breaks down the problems
involved in moving data from one computer to another computer. Open Systems Interconnection (OSI)
model categorizes these hundreds of problems to Seven Layers.
Seven Layers of Open Systems Interconnection (OSI) Model

Layer 1. Physical Layer


The first layer of the seven layers of Open Systems Interconnection (OSI) network model is called the
Physical layer. Physical circuits are created on the physical layer of Open Systems Interconnection
(OSI) model. Physical layers describe the electrical or optical signals used for communication. Physical
layer of the Open Systems Interconnection (OSI) model is only concerned with the physical
characteristics of electrical or optical signaling techniques which includes the voltage of the electrical

current used to transport the signal, the media type (Twisted Pair, Coaxial Cable, Optical Fiber etc).

Layer 2. Datalink Layer


The second layer of the seven layers of Open Systems Interconnection (OSI) network model is called
the Datalink layer. The Data Link layer resides above the Physical layer and below the Network layer.
Datalink layer is responsible for providing end-to-end validity of the data being transmitted. The Data
Link Layer is logically divided into two sublayers, The Media Access Control (MAC) Sublayer and the
Logical Link Control (LLC) Sublayer.

 The Logical Link Control sublayer is responsible for synchronizing frames, error checking, and
flow control.

Layer 3. Network Layer


The third layer of the seven layers of Open Systems Interconnection (OSI) network model is the
Network layer. The Network layer of the OSI model is responsible for managing logical
addressing information in the packets and the delivery of those packets to the correct destination.
Routers, which are special computers used to build the network, direct the data packet generated by

Network Layer using information stored in a table known as routing table. The routing table is a list of
available destinations that are stored in memory on the routers. The network layer is responsible for
working with logical addresses.

Layer 4. Transport Layer


The fourth layer of the seven layers of Open Systems Interconnection (OSI) network mode is the
Transport layer. The Transport layer handles transport functions such as reliable or unreliable delivery

of the data to the destination. On the sending computer, the transport layer is responsible for breaking
the data into smaller packets, so that if any packet is lost during transmission, the missing packets will
be sent again. Missing packets are determined by acknowledgments (ACKs) from the remote device,
when the remote device receives the packets. At the receiving system, the transport layer will be
responsible for opening all of the packets and reconstructing the original message.

Layer 5. Session Layer

The position of Session Layer of the Seven Layered Open Systems Interconnection (OSI) model is
between Transport Layer and the Presentation Layer. Session layer is the fifth layer of seven layered
Open Systems Interconnection (OSI) Model. The session layer is responsible for establishing,
managing, and terminating connections between applications at each end of the communication.

Layer 6. Presentation Layer


The position of Presentation Layer in seven layered Open Systems Interconnection (OSI) model is
just below the Application Layer. When the presentation layer receives data from the application layer,
to be sent over the network, it makes sure that the data is in the proper format. If it is not, the
presentation layer converts the data to the proper format. On the other side of communication, when the
presentation layer receives network data from the session layer, it makes sure that the data is in the
proper format and once again converts it if it is not.
Formatting functions at the presentation layer may include compression, encryption, and ensuring that
the character code set (ASCII, Unicode, EBCDIC (Extended Binary Coded Decimal Interchange Code,
which is used in IBM servers) etc) can be interpreted on the other side.

Layer 7. Application Layer


The Application Layer the seventh layer in OSI network model. Application Layer is the top-

most layer of the seven layered Open Systems Interconnection (OSI) network model. Real
traffic data will be often generated from the Application Layer. This may be a web request
generated from HTTP protocol, a command from telnet protocol, a file download request from
FTP protocol etc.
TCP/IP model, Comparison and Difference between TCP/IP and OSI
models
_______________THE END____________________

You might also like