title: Network: Does router breaks end-to-end principle?
body: <p>Here is the part of <code>end-to-end principle</code> from Wikipedia</p>
  
  <blockquote>
    <p>End-to-end connectivity is a property of the Internet that allows all
    nodes of the network to send packets to all other nodes of the
    network, without requiring intermediate network elements to further
    interpret them.</p>
  </blockquote>
  
  <p>But you should notice that routers (intermediate device) always among end nodes. So, as <code>end-to-end principle</code> above, not only <code>NAT</code>, but normally network with break <code>end-to-end principle</code> too.</p>
  
  <p>Does it true ? If not, please explain for me why, normally network with router doesn't break end-to-end principle.</p>
  
  <p>Thanks :)</p>