title: How does a packet travel from one computer to another over the Internet based on OSI model
body: <p>I am familiar with the basic OSI model but I always get confused how does a packet travel from one machine to another over the Internet and what OSI layers do come into picture? For example, for the following topology:</p>
  
  <p>Machine A&lt;----->Switch&lt;---->Router&lt;---->Router&lt;---->Router&lt;---->Switch&lt;---->Machine B</p>
  
  <p>where the multiple routers are shown to represent the Internet, what happens at the OSI layer level, when Machine A send a packet (say a simple "ls" command over FTP) to Machine B.</p>
  
  <p>The above is just a suggested example, but if any one can explain with any other network topology, that is fine too. All I am looking a very basic explanation of how the packet gets transformed to different OSI layers at each nodes (Machine, Switch, Router, etc.).</p>