Packet Switching for Not Yet Techies

Packet switching is a type of network that has proven efficient and effective - the Internet itself is such a network. The other kind of network is circuit-switched, which is like the regular telephone lines. When you call your mother (you do every week, don't you?) there's a dedicated line transmitting your conversation. In packet switching, all data is broken up into small electronic units of data and sent off to the find their way around the network the best way they can.

This packet switching allows the network to be shared by many more users at the same time. Each unit of data contains a header containing its origin and destination. As it travels through the network, the hardware involved reads the destination code and sends the data toward its goal.

Once all the units reach their destination, they must be re-assembled in order. They don't go the same way through the network and therefore arrive at different times.

You want to move your house from New York City to Los Angeles. You take it apart and code every piece of wire, every brick and every pipe with a special code that signifies where that piece fits into the house. You hire several hundred thousand movers to haul one piece of your house in their car. They speed away but some encounter traffic problems. Some prefer to drive through the Upper Midwest, some via St Louis and some want to visit Elvis's house in Memphis. Some linger over their coffee at truck stops and some drive straight through. Some get detoured and some are slowed by farmers driving tractors at 5 miles an hour.

But eventually all reach your new home site in Los Angeles, and a builder there, knowing how you coded each piece of the house, puts it back together in perfect order. And if a few bricks are out of order, you don't really notice if the house looks right.

Another kind of packet switching network is X.25, a commercial wide area network protocol. This type actually supports virtual circuits, which is a dedicated line through the network. You can even set up a PVC / permanent virtual circuit between two parties. This capability makes sense since X.25 is for businesses.

These are the packet switching basics.

Next: PAN Personal Area Network