Different layers of internet

Relevance of OSI layer in Internet

Primary Source: Classnotes

Secondary Source: http://compnetworking.about.com/cs/designosimodel/a/osimodel.htm

http://compnetworking.about.com/cs/designosimodel/g/bldef_osi.htm

http://www.sis.pitt.edu/~icucart/networking_basics/7layersofOSI.htm

Figure 1: 7 layers of OSI Model

Anyone can design new applications to operate over the internet. Good applications can then adopted widely while bad ones are ignored. The phenomenon is a part of internet's 'hourglass architecture'.

Figure 2: Hourglass Architecture of Internet

Figure 3: OS vs. Hourglass structure of Internet

The hourglass portrays two important design insights. First, is the notion that the network can be carved into conceptual layers. The exact number of layers varies depending on who is drawing the hourglass and why. One basic way to understand the network layer is through understanding of the fact that it  has 3 layers. At the bottom we have the 'physical layer'. The physical layer consists of the basic networking hardware transmission technologies of a network. It consists of the basic hardware stuffs. The physical layer defines the means of transmitting raw bits rather than logical data packets over a physical link connecting network nodes.

At the top is the 'application layer', representing the tasks people might want to perform on the network. Sometimes, above that, we might think of the 'content layer', containing actual information exchanged among the network's users, and above that the 'social layer', where new behaviors and interactions among people are enabled by the technologies underneath.

By dividing the network into layers and envisioning some boundaries among them, the path is clear to a division of labor among people working to improve the overall network. Those who are making or creating the information/data are at the top of the society.

On the proprietary networks of the 1980 s, in contrast, such divisions among layers were not as important because the networks sought to offer a one stop solution to their customers, at the cost of having to design everything by themselves.