IT Officer Notes: TCP/IP Model

THE TCP/IP MODEL

           

     

TCP/IP Model  is combination of four layers and which are  host to network, internet, transport and application layer.TCP/IP is the most widely used protocol suite in networking today. This is due in part to the vast growth of the global Internet. TCP/IP is able to span wide areas and is very flexible. In addition, it provides cross-platform support, routing capabilities, as well as support for the Simple Network Management Protocol (SNMP), the Dynamic Host Configuration Protocol (DHCP), the Windows Internet Name Service (WINS), the Domain Name Service (DNS), and a host of other useful protocols. However, TCP/IP's rich set of features are provided at the expense of additional overhead, which may make it too cumbersome for some networks or applications.

The Application layer :

The application layer in TCP/IP is combination of session, presentation, and application layer in the OSI model. The Application Layer is responsible for the presentation that is format of the message and its encryption and decryption. This layer consist variety of higher level protocol for the purpose of performing its task efficiently and effectively.

Telnet (Remote Login) : It refers to logging on to someone else's system by preserving Transparency that is it seems to the user as he is working on his own system.

FTP (File Transfer Protocol) : It is responsible for transmitting the files from the source node to the destination node.

SMTP (Simple Mail Transfer Protocol) : It processes the mails.

DNS (Domain Naming Service) : It maps IP addresses to simple node addresses e.g., 192.192.190.25 to node 15.

RIP (Routing Important Protocol) : It is responsible for routing the packets from source to destination.

SNMP (Single Network Management Protocol) : A protocol that is used to collect management information from network devices.

The Transport Layer :

Traditionally the transport layer was represented in TCP/IP by two protocols : TCP and UDP. IP is a host-to-host protocol; means deliver a packet from one physical device to another. UDP and TCP are transport level protocols responsible for delivery of a message from one process to another process.

Transmission Control Protocol

The Transmission Control protocol (TCP) provides full transport-layer services to application. TCP is a reliable stream transport protocol. The term, in this context, means connection —oriented : A connection must be established between both ends of a transmission before either can transmit data.

User Datagram Protocol

The User Datagram protocol (UDP) is the simpler of the two standard TCP/IP transport protocols. It is a process-to-process protocol that adds only port address, checksum error control and length information to the data from the upper letter.

The Internet Layer :

The Internet Layer corresponds to Network Layer of TCP/IP model. The basic difference between Network Layer and Internet Layer is the transmission of data. The Network Layer performs both connectionless and connection Oriented services whereas Internet Layer performs only connectionless service.

The main functions of this layer are characterized below :

Logical Device Addressing : The packets follow the independent route. The packets need to address and may follow any route to reach, other end. The Internet layer adds information with the message, which fulfills the same purpose. This service is called Datagram Network Service.

Data Packaging : The Internet layer defines official packets format and protocol known as internet protocol packets.

Routing : Router is responsible for routing the packets from source to the destination. Router chooses the shortest path to transmit the packet to the destination.

The Network Layer :

 It comprises the function of Physical Layer and Data Link Layer of OSI reference model. TCP/IP model has not defined its own standard for this layer but takes the services of existing Data Link Layer and Physical Layer.
 The function performed by this layer is to change the IP datagrams to the physical address bytes frame and transmit on the line. it maps the logical domain name address to IP address and to the physical address of the node. This layer works as an abstraction layer and this model hides the functionality of the layer from users.

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