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Why is packet-switching superior to circuit-switched networks?

I'm completely new to computer science and networking, so an easy-to-understand response would be very appreciated!

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Is that one of the questions on your homework assignment? – Dustin G. Sep 17 '11 at 22:56
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Hey, just in case you forgot: You've already asked this before: rate-limiting network scheduler v.s. STFQ network scheduler: what's the difference? — please don't do that. If your question doesn't get an answer you should maybe read How to Ask before and do your homework, then come back to us. – slhck Sep 18 '11 at 1:38
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closed as not a real question by slhck, Gareth, studiohack♦ Nov 23 '11 at 0:17

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Packet switched vs circuit switched is sort of like the postal services vs the phone company (pre-digital era).

With both postal and phone services you address things to your intended recipient. For the phone call you do this once at setup when you dial, whereas with a written postal conversation you put the address on ever letter.

With telephone conversation you know a lot about the properties of the call - once it's connected you're assured a pair of wires that takes some route between you and the person you called.

When you send a letter though you don't really know how it gets there and more specifically you don't know how busy all of the sorting offices it passes through are.

In some respects the circuit switched setup can be advantageous, if what you seek truly is guaranteed end to end channels. However in computing applications what you typically want isn't a fixed, "pipe", but a "bursty" variable service and you don't really care that everything you send goes via the same route to get there.

When you set up a "call" though it requires every intermediate node to know something about the "call" since future messages won't be coming with an address, but a call ID instead. In a computer that requires a chunk of memory. If you want to do it for millions of "calls" that can be quite a lot of memory, to remember the call ID, source, destination and next hops. With packet switched the intermediate nodes don't need to be aware of the fact that they're actually carrying a conversation, all they do is look at the destination, for each packet they receive and make a destination (usually) solely based upon that.

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Yep, and generally packet switching is faster, since the packet can be sent before the circuit is established, vs waiting for the other end to respond with a "go ahead" signal. Plus, if an intermediate node fails (or is simply too busy), the packet can be rerouted around it, whereas with circuit switching the call would have to be broken and re-established. These are reasons why even most long distance "land line" phone calls are now packet switched. – DanH Sep 18 '11 at 1:58
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