Introduction to Networks (non-technical)

Rather than post my typical notes from a CCNA course, I figured I'd post a non-technical description of how networks "work".  I'm going to preface this by saying this is "allegory" of TCI/IP layer 3.  This is not intended to be definitive.  

So...

You have built a company.  It's a great company.  But no one can ever find your physical location.  You live on a drab, grey, boring street.  Did I mention grey? I meant every single building is nothing but grey concrete, and the streets are bleached grey.  It is grey as far as the eye can see.

So, being the great business leader you are, you go out and buy a bucket of purple paint.  Now, purple paint is the greatest thing since sliced bread.  And because it's the greatest thing since sliced bread, it costs an arm and a leg.  To get the shade of purple you want, you buy one can of paint.  It covers the outside of the door well, but nothing else.

So, from the outside your door looks purple.  But that paint is so darn expensive, you only paint the outside.  The inside of the door is still brown.

So, a customer comes to visit.

You tell him to drive down the grey street until you see a purple door.  He find your location in minutes.  It's easy.

Back in your office, you have a discussion, and he thinks he is going to buy from you.  But he needs to talk to a few people to determine how much he wants to buy.  And he forgot how to get out of the building.

"Oh, just go out the purple door", you tell your customer.

The man spends 45 minutes wandering your halls, and finally finds you.   He curses you out, cancelling all potential business.  You are at a complete loss.  The customer can't find the purple door.

The one thing you forgot is that doors have two sides.  One side that is visible from the street, and one side that is only visible from the inside of the building.  You painted your street door purple.  It's easy to find.  But your exit door on your building?  Still just as brown as it ever was.  So telling someone to go find a purple door is an exercise in futility.

You have to name the door based off which side  you happen to be looking at.

Even though both talk about the same thing, it's a matter of which side of the door you are on.  And you have to have your discussion based on which side of the door you can see.