Techie Tip of the Week – Networking basics (TCP/IP)

Ever noticed those blinking lights  continuously blinking on the back of your computer? Ever wondered why they’re blinking, or what’s going on?

This week, we’ll talk about two of the basic protocols of Networking — the Transmission Control Protocol over the Internet Protocol (TCP/IP).

First off, a protocol is a set of rules that define how computers and other devices communicate with one another — the “language” that computers use to “speak with each other. The TCP/IP are the set of protocols that allow the Internet to work.

Basically, here’s what happens:

  1. The destination’s application (web browser, email application, etc.) communicates to the network software in its computer’s OS, which in turn makes a connection to the computer that houses the desired item (email, movie, web page, etc.).
  2. Assuming the sending computer approves the sending of the information, the sending computer’s Transmission Control Protocol (“TCP”) takes the information to be sent and chops it up into little pieces (“packets”).
  3. These Internet Protocol (“IP”) packets are given address information, and, using the IP, they sent off to their destination.
  4. Each packet then “hops” from computer to computer (“node” to “node”), asking each node if they are at the final destination yet. If so, they wait for the other packets to arrive; if not, they hop to the next node until they finally reach their destination.
  5. Once all of the packets make it to the destination, they are reassembled back into the original item using the destination’s TCP.

This is similar to how moving a houseful of items works.

Let’s say you’re moving all of your belongings from one house in one city to another house in a different city. You would most likely take all of your possessions and put them into many different boxes. Then, after applying a label with your new address on it, you’d take each box to the shipping company. The shipping company then takes the package, and sends it off with all the other packages going to the same region. You never know exactly which direction the package may go – there might be a tornado in the northern part of the country, so the package might go the southern route; there might be a hurricane in the southern route, so the package may go the northern route. But each package continues on its way until it reaches the destination. And, until all of the packages arrive, you won’t have all of your items. But once you do, you could reassemble your entire houseful of possessions in your new place.

Graphical representation of how TCP/IP works

Next week, we’ll talk about some of the tools people use to track and “sniff” these IP packets as they’re traveling across the Internet.

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