protocol

Protocol

A protocol is a program return as per mutually accepted standard that two computers use to communicate with each other. Computers use protocols ( protocol programs) to format consistently their masages so that others computers can understand them , acknowledge the receipt off messages indicate that they are finished sending a message and so on. In the network when one computer requests for the service of another, it is called a client. In order to establish the needed connectivity, watch the client machine and the server machine must have a common protocol programs. This is illustrated in  figure.

In short a protocol age and agreed upon format for transmitting data between two devices. The protocol determines the following

1. In the type of error checking to be used

2:- data compression method, if any

3:- how the sending device will indicate that it has finished sending a message

4:- how the receiving device will indicate that it has received a message

There are a variety of standard protocol from which programmers can choose. Each has particular advantage and disadvantage; for example, some aur simple than others, Samar Mor reliable, and some are faster.

From a user's point of view the only interesting aspect about protocols is that your computer or device must support the right ones if you want to communicate with other computers. The protocol can be implemented either and Hardware or in software.

Some standard protocols used in networks are list below:

1. Simple mail transfer protocol ( SMTP )

2. Post office protocol version 3 ( POP3 )

3. Point to point/ protocol serial line interface protocol (POP/SLIP) 

4. Transmission control protocol / internet protocol ( TCP/IP )

5. Hypertext transfer protocol(HTTP)

6.. file transfer protocol(FTP) 

7. Internet mail access protocol (IMAP)

8. Internet relay chat (IRC)

9. Network news transfer protocol (NNTP)

10.Telnet

11.Gopher

12. Lightweight directory access protocol

Simple mail transfer protocol

Simple mail transfer protocol used for sending email messages between servers. Most email system that send mail over the internet use SMTP to send message from one server to another; the message can then be retrieved with an email client using either pop or IMAP.

In in addition SMTP h generally used to send message from a mail client to a mail server. This age by you need to specify both the pop aur IMAP server and the SMTP server when you configure your Email application.

Post office protocol

Post office protocol is a protocol used to retrieve email from a mail server. Most email applications (e- client ) use the pop protocol all through some can use the Newer protocol such as IMAP ( internet message access protocol ). There are two burgeons of pop. The first called pop 2. Became a standard in the mid 80's and require SMTP to send message. The new verson, POP3 ,can be used with or without SMTP.

TCP /IP on the internet

TCP/IP Rajitha widely accepted protocols used in the networks. It is a protocol Suite that consists of several protocols including two primary protocols, transmission control protocol and internet protocol. The TCP/ IP protocol( protocol program ) video picture works asynnchronously to handle multiple message traffic simultaneously from multiple sources to multiple destination as shown in figure .TCP(TCP Protocol program) handles Data integerity. It

 makes Source data Gates to the destination without errors. TCP is also responsible for the assembling and assembling data. It divides large message into smaller packets of at the most 15 KB size. Each of this packet is called a segment.TCP numbers gauge segments and hands over to the IP. IP protocol (protocol program) that controls how data moves around on the network. After TCP divides the message into segments IP levels them with source and destination. These packets are now called IP datagrams. IP also takes care of sending the datagrams by tererminding the route. These datagram may hope serveral network before reaching ka destination.

. At the destination IP verify the label and passes them to the TCP. tcp (at the destination) checks if all the segments have been received. If any of the segments are missing it informs this to the source TCP and request the segment to be sent again. A page called retry. After verification the TCP assembles the message from the data segments and supplies to the destination program.

Packet switching (Routing) 

Routing (Packet Switching ) refers to the job of transferring the data packets ( IP datagrams ) to an appropriate computer . Special computer that the routing is called router. We have already seen that internet is a network of networks. So when a packet of data (IP datagram) starts from a computer, it is submitted to the router of the network to which the computer belongs to. The router verify the IP address of the destination. The destination network may not be directly reached. The router finds the next network to which the datagram must be submitted and does it. Similarly the datagram passes server routers and finally reach the final destination network. Every router.use routing levels and routing algorithms to accomplish the job. The routing algorithm will choose the next network to which the datagram may be routed depending upon the data traffic and the shortest route. Datagrams of the same message mein travel through different route to reach the final destination. For example suppose a computer even in network a wants to connect communicate with a computer C2 in network Fas shown in figure.

 vahan a message has to be sent from a to air the message is assembled into IP datagrams some datagrams may travel in topic C1 AC DFC 2 whereas some main travel through C1 abefc2. However C To verify if all the datagrams have reached. Then it assembles the message age supplies to the application program in C 2.

Tracing the route ( tracert command)

In Windows or Windows NT when we are connected to internet we can see the route from our computer to any internet cost. This is God by the Tracert command in command prompt. In Windows NT first open the DOS CMD prompt while running CMD command. In the DOS CMD prompt type

Tracert< domain>

For example, we can type tracert.lsu.edu

Router

A router is special computer that manage the traffic from network to network. The router determines the path of travel for a datagram TCP/ IP. Routers keeps track of the next computer to which the datagram has to hop. Day use routing tables and routing algorithm to do routing. In Windows NT, we can see the IP addresses of the router in our network by running the theWINIPCFG.EXE program. When we run the program click more info and then select PP adaptor in the dropdown list. In the middle of the dialogue box the IP addresses of the router is show the field default gateway. This is the IP address of the router to which your computer will send a TCP IP datagram when it is address to a computer that is not on your Local Network.

Hypertext transfer protocol ( HTTP )

Hypertext transfer protocol is the underlying protocol used by the world wide web http defines how message are formatted and transmitted, and what action web server and browsers take in response to various commands. For example, when you enter a URL in your browser, this is actually sends an HTTP commands to the web server directing 82 paige and transmit the requested web page. The other main standard that controls how the world wide web works is HTML, which covers how web pages are formatted and displayed. HTTP is called a a state less protocol because each command is executed independently, without any knowledge of the commands that came before it. This is the main reason that it is difficult to to experiment websites that rekt intelligently to user input. This is salt coming off http is being address in a number of new technologies, including active x, Java , JavaScript and cookies. 

File transfer protocol ( FTP) 

  File transfer protocol or FTP,  is a protocol used to upload file from a work station to a FTP server aur Download file from a FTP server to a workstation.    It is the fact that file get transferred from one device to another in order for the file to be available on the internet. when FTP ferred from one device to another in order for the files to be available on the internet. When ftp appears in a u r l ate means that the user is connecting to a server and not a web server and that some form of file transfer is going to take place. Most app service require the user to log on the server in order to transfer files.

In the contrast, hypertext transfer protocol or  http, protocol used to transfer file from a web server onto a browser in order to view a web page that is on the internet. Unlike FTP, where and entire files are transferred from one device to another and copied in memory,HTTP age one way system age files are transported only from the server on to the work station's browser. When http appears in a URL that means that the user is connecting to a web server and not a file server. Transferred what not downloaded therefore not copied in the memory of the receiving device.