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Why do we need to use a protocol in data communication ?

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• As we saw in the last webpage:
  • Bus protocols contains a rigid set of steps that communicating devices must perform to complete a data transfer operation (buses are always use to perform data transfer)

  • These steps are pre-planned, i.e., specified a priori.
    (You can find analogies of bus protocols in archaic practices like a visit from a foreign head of state. The protocol dictates that the foreign head of state must be received in a certain manner. One of the steps in the reception is the "inspection of the guards").

• Important fact:

  The pre-planned steps must be followed rigidly to ensure success !!!

• Let me illustrate this important fact using a mundane task of "frying an egg".

  The steps to successfully fry an egg consist of:

  1. Turning on the stove
  2. Putting a pan on the stove
  3. Poor oil in the pan
  4. Break the egg and put it in the pan
  5. Wait until the egg is cooked
  6. Remove the egg and turn off the stove
  7. (As any examplary student would do it, we ignore the dish washing step... :-))

  To fry an egg successfully, the steps must be followed in the specified order !!!

  E.g., you cannot put the egg in, fry it and then poor the oil (yes, human knows that (we have common sense !!!), but try telling that to a computer... you have to spell it out to machines... it's worst than teaching kindergarten kids...)