INTERNET PACKETS AND SNAIL MAIL

My sister-in-law asked me the other day what Internet packets are and how they work. My quick answer was that they're little packaged snippets of information and very well, thank you.

My sister-in-law said a bad word and then told me exactly what she thought of my answer and what I could do with it. I finally calmed her down by promising to give her a more useful explanation by way of an analogy. Here's how our conversation went:

"First of all, you need to understand that all information on the Internet, whether it's e-mail, pictures, text or whatever is divided into packets and that's how it's sent."

"Thanks, that still doesn't explain what packets are," she snarled.

"All right then, remember when people actually used to write letters, put them into envelopes, and expect Canada Post to deliver them within a reasonable period of time?" I asked.

"What's that got to do with anything?"

"Well, suppose you wanted to send someone in Toronto a copy of Beautiful British Columbia magazine using Canada Post."

"I don't know anybody in Toronto."

"Just suppose, okay? Well, lets say Canada Post says that it's not efficient to send entire magazines all at once so it wants them sent one page at a time each in its own envelope. Also, they'll only accept the envelopes one at a time but they'll start them on their way as soon as they take them."

"That's stupid."

"It's just an analogy, work with me on this. So each envelope has the person's address on it and your return address. You realize that the person at the other end won't know what order to put the pages in (I know they're numbered, pretend they aren't) or how many pages there are in total (20, okay?) so you number the envelopes: 1 of 20, 2 of 20, etc.

"Now you line up at the post office (it doesn't matter which one, for this they're all the same) and you start giving them the envelopes as they're ready for them.

"The envelopes go into different trucks, planes, trains, etc. as they're processed. The trucks, planes, and trains all take different routes and at every stop the envelopes are read to see what the final destination is and put on a vehicle that's headed closer to that address.

"Now, it's likely that the ones that travel by air will arrive faster than some of the ones that travel by truck or train. This is where it's important that the envelopes are numbered so that the person in Toronto knows how many to expect and what order to put them in.

"Yes, I know you don’t know anybody in Toronto. Anyway, true to Canada Post form some of the envelopes get lost and some get there really, really, slowly. So, the person in Toronto phones you (enough about who you don't know, okay?) and tells you what pages they're missing. Because you're smart and thinking of all the things that can go wrong with this process you've made copies of all the pages so you send the missing ones again. Sometimes you have to do this a few times until you know that all the pages have arrived.

"Okay I'm getting to the point. See in a very oversimplified way packets are like the envelopes. Each packet contains one part of the total information being sent and it shows (among many other things) who the sender is, who the addressee is, how many packets there are in total, and which packet number this is.

"The different routes the envelopes take are like the Internet where no two packets necessarily take the same route to their destination and they don't arrive at the same time or in order.

"You still don't get it? Okay, do you know anybody in Montreal?…"

Peter Kast
Information Technology Officer