In the last article, we saw the mode of data transfer in a TCP/IP network (can be an intranet or Internet). To complete the series, today we take a look at the way this data is processed by the receiving system.
Protocols such as TCP/IP determine how computers communicate with each other over networks such as the Internet. These protocols work in concert with each other, and are layered on top of one another in what is commonly referred to as a protocol stack. Each layer of the protocol is designed to accomplish a specific purpose on both the sending and receiving computers. The TCP stack combines the application, presentation, and the session layers into a single layer also called the application layer. The exact way of data transfer can be very well explained via a simple diagram. But I am not very good at drawing so I better stick to text description.
- The TCP application layer formats the data being sent so that the layer below it, the transport layer, can send the data. The TCP application layer performs the equivalent actions that the top three layers of OSI perform: the application, presentation, and session layers.
- The next layer down is the transport layer, which is responsible for transferring the data, and ensures that the data sent and the data received are in fact the same data-in other words, that there have been no errors introduced during the sending of the data. TCP divides the data it gets from the application layer into segments. It attaches a header to each segment. The header contains information that will be used on the receiving end to ensure that the data hasn't been altered en route, and that the segments can be properly recombined into their original form.
- The third layer prepares the data for delivery by putting them into IP datagrams, and determining the proper Internet address for those datagrams. The IP protocol works in the Internet layer, also called the network layer. It puts an IP wrapper with a header onto each segment. The IP header includes information such as the IP address of the sending and receiving computers, and the length of the datagram, and the sequence order of the datagram. The sequence order is added because the datagram could conceivably exceed the size allowed for network packets, and so would need to be broken into smaller packets. Including the sequence order will allow them to be
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