What Is a Protocol

What Is a Protocol

Now that we've got a bit of a feel for what the Internet is, let's think about another important buzzword in computer networking: protocol. What is a protocol? What does a protocol do?

A Human Analogy

It is perhaps easiest to understand the concept of a computer network protocol by first considering some human analogies, since we humans carry out protocols all of the time. Think what you do when you want to ask someone for the time of day. A typical exchange is shown in the following figure. Human protocol (or good manners, at least) dictates that one first offer a greeting (the first "Hi" in the following figure) to begin communication with someone else. The typical response to a "Hi" is a returned "Hi" message. Absolutely, one then takes a friendly "Hi" response as an indication that one can proceed and ask for the time of day. A different response to the initial "Hi" (such as "Don't bother me!" or ''I don't speak English", or some unprintable reply) might indicate an unwillingness or inability to communicate. In this case, the human protocol would be not to ask for the time of day. Sometimes one gets no response at all to a question, in which case one typically gives up asking that person for the time. Note that in our human protocol, there are particular messages we send, and particular actions we take in response to the received reply messages or other events (such as no reply within some given amount of time). Clearly, transmitted and received messages, and actions taken when these messages are sent or received or other events take place, play a central role in a human protocol. If people run different protocols (for example, if one person has manners but the other does not, or if one understands the idea of time and the other does not) the protocols do not interoperate and no useful work can be completed. The same is true in networking - it takes two (or more) communicating entities running the same protocol in order to complete a task.

A human protocol and a computer network protocol

Let's consider a second human analogy. Assume you're in a college class (a computer networking class, for instance!). The teacher is droning on about protocols and you're confused. The teacher stops to ask, "Are there any questions?" (a message that is transmitted to, and received by, all students who are not sleeping). You raise your hand (transmitting an implicit message to the teacher). Your teacher recognizes you with a smile, saying "Yes . . ." (a transmitted message encouraging you to ask your question - teachers love to be asked questions), and you then ask your question (that is, transmit your message to your teacher). Your teacher hears your question (receives your question message) and answers (transmits a reply to you). Once again, we see that the transmission and receipt of messages, and a set of conventional actions taken when these messages are sent and received, are at the heart of this question-and-answer protocol.


computer networking, protocol, communicating entities

Copy Right

The contents available on this website are copyrighted by TechPlus unless otherwise indicated. All rights are reserved by TechPlus, and content may not be reproduced, published, or transferred in any form or by any means, except with the prior written permission of TechPlus.