Protocols and layers - Intro

Join two computers with a perfect cable, and they still cannot make sense of a single thing the other sends. The wire carries every bit faithfully. What it cannot carry is the meaning: where a message starts, who it is for, and what each bit stands for.

The last chapter built the network. This chapter, Protocols and layers, is about what turns those bits into a conversation.

If protocols are new to you, start with What a protocol is. It gives you the definition first, then what each protocol on the list is for. A common slip is describing protocols when the question asks you to define one. So that definition is the sentence to learn whole. If you already know what a protocol is, go straight to The four-layer TCP/IP model. It stacks those protocols and follows one message down through the layers and back up. Some boards ask for the four layer names, while others need only the idea of layers. A very common slip is giving the names from a different model, so that video shows the four names to use. A few of the videos further down are set by only some boards. The list is the same for everyone, so check your own specification for the ones you need. IP addresses and MAC addresses explains why every device carries two addresses, and how each one is written. Standards is about why devices from different makers work together. Encryption across a network covers what happens to your data on its way, and what encryption cannot do. If it's the sums you're after, go to Transmission rate, file size and time. The thing to keep straight there is that file sizes are in bytes and network speeds are in bits. So a perfect cable is never enough on its own. Two machines understand each other only when both follow the same agreed rules, and those rules are what this chapter is about. Every video here can be found by searching its name or its code. The quickest place to do that is the scholafly.com website, which indexes every video in every subject.

Next in the chapter is What a protocol is. Hopefully that's next in your feed, but if not, search for ScholaFly C S oh eight, oh one.

Every other video is on scholafly.com too, easy to search by video code or by keyword. Whatever you're revising, go there and have a look, or, watch the next video.