The Internet has become the primary source of information for individuals and businesses. In addition, businesses have come to rely on the Internet as a source of customers as well as a medium for facilitating sales. A greater understanding of the Internet or networks in general requires an understanding of how data is transferred using packets.
Packing Up the Data
The data in a network transmission is packed up at the source end by the layers of the specific network protocol in use on the network. Regardless of the specifics, the general process is the same. The application packs the data along with some header information into an "envelope" and passes it to each layer in the protocol "stack." The final layer is the physical layer, where the packet is put on the wire.
Transferring the Data
Once the data is on the wire (or in the air in the case of wireless networks), it typically passes through a network hub or switch. A hub broadcasts the packet to all other computers attached to it without looking at the packet information. A switch examines the header information, which includes source and destination addresses, and sends the packet directly to the destination computer or to a router if the packet is destined for a computer on a different network.
Unpacking the Data
At the destination computer, the packing process is reversed in that each envelope is opened as it passes up the protocol stack. Each layer determines whether the packet is valid and, if so, it passes it to the next higher level. When it gets to the top level, typically the application level, the last envelope is unpacked and formatted and displayed for the user.
Tags: destination computer, header information, protocol stack