TCP/IP and Layers

TCP/IP Model

TCP/IP (Transmission Control Protocol/Internet Protocol)

 is the basic communication language or protocol of the Internet. It can also be used as a communications protocol in a private network (either an intranet or an extranet).

TCP/IP consist of a group of protocol which responsible of data communication parts. The protocols may not know how other protocols work like as long they can still sending and receiving data.

When you are set up with direct access to the Internet, your computer is provided with a copy of the TCP/IP program just as every other computer that you may send messages to or get information from also has a copy of TCP/IP.

TCP/IP become a flexibel data communication protocol. TCP/IP protocol can be applied easily in every kind of komputer and network interface, because most of protocol’s content is not specific to computers or other specified network devices.

In order for TCP/IP to run on specified network interface,you just need to change the protocol which related to the network interface.

The Function of TCP/IP

The main design goal of TCP/IP was to build an interconnection of networks,

referred to as an internetwork, or internet, that provided universal

communication services over heterogeneous physical networks. The clear

benefit of such an internetwork is the enabling of communication between hosts

on different networks, perhaps separated by a large geographical area.

The TCP/IP Layers

By dividing the communication software into layers, the protocol stack allows for

division of labor, ease of implementation and code testing, and the ability to

develop alternative layer implementations. In this regard, a layer provides a service

for the layer directly above it and makes use of services provided by the layer

directly below it.

For example: the IP layer provides the ability to transfer data

from one host to another without any guarantee to reliable delivery or duplicate

suppression. Transport protocols such as TCP make use of this service to

provide applications with reliable, in-order, data stream delivery.

In the TCP/IP model there are 4 layer:

1)Application layer

The application layer is provided by the program that

uses TCP/IP for communication. An application is a

user process cooperating with another process usually

on a different host.

The protocols on each application layer provide services to softwares that run in the computer, application layer does not provide the software but just providing them services that can be used by the softwares that run in the computer.

example mozilla firefox that run in our computers provide us the http protocol to access a website.

Few protocol that operate in this layer are : HTTP,FTP,POP3,SMTP,etc.

2)Transport layer

The transport layer provides the end-to-end data transfer by delivering data from an application to its remote peer. Multiple applications can be supported

simultaneously. Its function is to provide services which will be used by application layer.

This layer contain 2 main protocol, there are:

Transmission Control Protocol (TCP) and

User Datagram Protocol (UDP).

The most-used transport layer protocol is the Transmission Control Protocol (TCP),

which provides connection-oriented reliable data delivery, duplicate data suppression, congestion control, and flow control.

example : HTTP software ask TCP to guarante the delivering progress to the destinated user, if interruption ocurs during the transfer so HTTP will not do anything, but TCP will resend the lost data and make sure the data was sended to the destinated user.

3)Internetwork layer

The internetwork layer provides the “virtual network” image of an internet

(this layer shields the higher levels from the physical network architecture below it).

And add function of ip addresing,routing and best path determination.

example internetwork layer protocols are IP, ICMP, IGMP, ARP, and RARP.

4)Network interface layer

Also called the link layer or the data-link layer, is the interface to the actual

network hardware. This interface may or may not provide reliable delivery, and may be packet or stream oriented. In fact, TCP/IP does not specify any protocol here, but can use almost any network interface.

Examples are IEEE 802.2, X.25 (which is reliable in itself), ATM, FDDI, etc.