PACKET SWITCH NETWORKS

When you try to imagine what the Internet is and how it operates, it is natural to think of the telephone system. After .111, they" are hoth electronic, they both let you open a connection and transfer information, and the Internet is primarily composed of dedicated telephone lines. Unfortunately, this is the wrong picture, and causes
Many misunderstandings about the Internet operate. The telephone network is what is known as a circuit network. When you make a call, you get a piece of the net work dedicated to you. Even if you aren't using it (for example, if you are put on hold), your piece of the network is unavailable to others wishing to do real work. This leads to underutilization of a very expensive resource, the net- work.
A hetter model for the Internet, which may not instill confidence in you, is the u.s. Postal Service. The Postal Service is a packet switched network. You have no dedicated piece of the network. What you want to send is mixed together with everyone else's stuff, put in a pipe, transferred to another Post Office, and sorted out again. Although the technologies are completely different, the Postal Service is a surprisingly accurate analogy; we'll continue to u.