VACETS Regular Technical Column

The VACETS Technical Column is contributed by various members , especially those of the VACETS Technical Affairs Committe. Articles are posted regulary on [email protected] forum. Please send questions, comments and suggestions to [email protected]

August 29, 1996

Asynchronous Transfer Mode (ATM) - An analogy.

Recently a friend of mine came up with the following great story about ATM that I would like to share with all of you:

Each day each branch of the post office receives many thousand of letters and packages from its customers going to other branches of the post office around the country. One day an engineer working for the post office realized that it is not efficient to pack the mail truck because of the different sizes and shapes of the letters and packages. The engineer came up with a great solution (he thinks so) and proposes it to the Postmaster. The conversation goes like this:

The Engineer: "I propose for us to open all of the letters and packages and shred them so that they all consist of smaller pieces of the same size. That way they can be packed neatly and efficiently in each of the mail truck. Since more can be packed in each truck, we will need less truck thus saving lots of money".

The Postmaster asks: "How are we going to know how to put the shredded pieces together before delivering the mails to the customers?"

The Engineer: "As we shred the letters, we will attach a small note to each piece with an indexing scheme to mark its destination, and its sequence so that we can put it back together at the far end. This way we can even send each piece a different route, they still can be found and delivered to the right destination".

The Postmaster: "What happens if a few pieces of shreds got lost in transit?"

The Engineer: "For the letter or package that we cannot put together in one piece, we just trash it, the customer will send it again. After all we only promise to do best effort delivery".

The Postmaster: "What happens if it is a piece of registered or certified mail?"

The Engineer: "For those, we can mark them with a special blue pen, make a copy of it then deliver it as usual. If we cannot put a blue letter together at the far end then we will try to send the copy again. This way we can justify the new class of service and can charge more for it"

The Postmaster: "What about other kinds of specialty mails such as express mails, special delivery, or second or third class mails, etc."

The Engineer: "This is the beauty of my method, we can mark each type of mails with a different color pen, and handle it differently. For example, with express mails, we mark them in red before shredding them then put them on the trucks first. For 3rd class mails, we mark them in black, and only put them on the trucks if we have room, etc."

The Postmaster: "Who is going to be doing the shredding and glueing back the letters?"

The Engineer: "Since we save so much money by improving the efficiency of the trucks, we can either hire more people, outsourcing the jobs, or send out a Request For Proposal (RFP) for someone to build us a machine to do that"

The Postmaster: "Do you know of anybody who has done something like this before?"

The Engineer: "Yes, the telecommunications industries and the computing industries has been trying to standardize this methodology for several years, except that they call it "Asynchronous Transfer Mode" or ATM.

Nguyen Tien Luc, Ph.D.

[email protected]

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Copyright © 1996 by VACETS and Nguyen T. Luc

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