Tags: standard layers
How can my home computer in Hawaii talk to my friend’s computer in Holland?
The short answer is standards. By using the same standards rules on both of those computers, you and your friend (and just about everyone) can talk across the Internet.
Okay, so who uses these standards?
Well, since they are set by different organizations, they cover different parts of the communication process. Let’s take a generic look at that process.
When you start sending data, your computer uses a set of rules or protocols. The first rules, we’ll call them Data Formatting, are up to the software you and your friend use in your computers. For example, you may save your file as a PDF (Portable Data Format), and, if your friend has software to read a PDF, it will appear on their screen just as you sent it. If your friend’s computer is missing the right software to read a PDF, they will see gibberish (if anything) instead.
Some of these standards get set by users accepting the software like Microsoft’s Word while other standards are set by The Internet Engineering Task Force (IETF). Each Working Group is made up of lots of different people who are interested in working on that group’s application standards.
Inside your computer, the formatted data reaches other software that comes with the computer. That software, based on the standards set by another IETF Working Group, makes sure the two computers talk with each other in a way that gets the data to its destination without errors and in the right order. We’ll call that the Session Handling part of the process. At this step, a communication header gets added to the data that holds the Session Handling information.
|Routing Header||Session Header||Data|
Since you and your friend are probably on different networks, there needs to be some rules for getting the data from one network, through another network, to the destination network. That involves addressing, checking for errors, setting how important the data is to be treated, logical addressing, and routing. Those rules come from a separate IETF Working Group. That group adds another header that carries the information about the Routing part of the process.
|Ethernet Header||Routing Header||Session Header||Data|
Before your computer send the data out the local network cabling on the first leg of the journey toward your friend’s computer, it passes the data to the network software in your computer. That software decides which path to take and rules to use. These standards come from industry groups who work on the Local Signaling part of the process. The most commonly used choices come from the Institute of Electrical and Electronics Engineers (IEEE) who set the standards for Ethernet and wireless communications. Yes, they also add a header to carry their information.