Data Transfer Over The Internet
“The internet could be a very positive step towards education, organisation and participation in a meaningful society.” ~Noam Chomsky
What follows is a very qualitative, non technical discussion about how data is transmitted between computers across the Internet through TCP/IP. A very basic rule of data (files, e-mails, web pages et-cetera) transmission across the Internet, and actually a distinctive feature of the TCP/IP protocols used to move data, is that data is never transmitted “as such”. Instead, it is subdivided in so-called “packets” before transmission. The number of the packets depends on the size of the data. For simplicity, let us think about the transmission of a text file. The bigger the file, the more packets will be needed to “represent” the file.
Each packet contains the following information: the source of the data (sender), the destination of the data (receiver), information on the source file and on the position of the packet in this file (say packet 3 of 123 from file X). With this information, once all the packets for a file have reached the intended destination, they can be used by TCP/IP to rebuild the original file.
We could summarize the journey of a file such as an e-mail message or a web page, from computer A to computer B, as follows.
File in computer A –> Subdivided in packets by TCP/IP –> Packets travel, individually, to destination –> TCP/IP “remounts” the packets to re-create the original file in computer B –>File in computer B
Internet Protocol Suite
While using Internet, the most common protocols are :
• Transmission Control Protocol (TCP)
• Internet Protocol (IP)
Usually they are collectively known as the TCP/IP protocol.
The information which we send through the Internet is broken into packets by TCP using the technique of ‘Packet Switching’ .
These packets are wrapped by a wrapper which contains the sender’s address, the receiver’s address and a sequence number.
The IP is responsible for sending these packets to the right address by assigning them a sequence number.
First, the packets are sent to a local Internet Service Provider (ISP).
From here the packets travel through multiple levels of networks, computers and communication lines before reaching the destination.
The packets are sent from different routes so as to maintain speed.
If a packet could not reach the destination from a route then it’s route is changed with the help of routers. As the name implies, routers allow packets to find the best route between two computers that do not belong to the same network. Data are generally relayed through several such routers before they reach their final destination.
When the information packets reach the destination device, the TCP, with the help of packet Switching, again assembles the packets into a single message.
All data transfers across the Internet work on this principle. It helps networks manage traffic — if one pathway becomes clogged with traffic, packets can go through a different route.
That’s not the case with traffic across IP networks. If one connection should fail, data can travel across an alternate route. This works for individual networks and the Internet as a whole. For instance, even if a packet doesn’t make it to the destination, the machine receiving the data can determine which packet is missing by referencing the other packets. It can send a message to the machine sending the data to send it again, creating redundancy. This all happens in the span of just a few milliseconds.
This is enough for today I think I give some interesting facts. We meets soon with interesting about internet