Layer 2 and Layer 3 Networks Concept

http://www.accuwebhosting.com/Articles/Layer_2_Vs._Layer_3_Networks.html

http://computer.howstuffworks.com/lan-switch15.htm

http://blog.globalknowledge.com/technology/layers-and-numbers/ <====

https://www.youtube.com/watch?v=p3E5OukyocE <====

https://www.youtube.com/watch?v=O_rsqVtaloI

https://www.youtube.com/watch?v=kdFOCleUkVE