[From the previous episode: A checklist will help you ask good questions when buying IoTThe Internet of Things. A broad term covering many different applications where "things" are interconnected through the internet. equipment.]
MachinesIn our context, a machine is anything that isn't human (or living). That includes electronic equipment like computers and phones. communicate over networksA collection of items like computers, printers, phones, and other electronic items that are connected together by switches and routers. A network allows the connected devices to talk to each other electronically. The internet is an example of an extremely large network. Your home network, if you have one, is an example of a small local network.. We’re going to talk more about that over time, so we’ll need some language to describe different parts of a computer network. We’ve already talked about some network elements, but let’s bring it all together. While we’ll look at more details later on, for now, let’s get baselined on what a network is and what we call the different pieces. For some of you this may be review, but just in case…
A network is a collection of electronic items – computers, phones, printers, whatever – that are connected together and can talk to each other. At one “end” or edgeThis term is slightly confusing because, in different contexts, in means slightly different things. In general, when talking about networks, it refers to that part of the network where devices (computers, printers, etc.) are connected. That's in contrast to the core, which is the middle of the network where lots of traffic gets moved around. of the network, where you sit, is a computer or a phone or a tablet or some kind of connected device. At the other end lies… well, that depends on what you’re trying to do. It might be your printer, or it might be a computer handling a web page, or it might be someone else’s computer, to which you’re sending an email. In between lie all of the wires and fibers and large-scale equipment that make up the coreThis can have more than one meaning. When discussing networks, the core is the heart of the network where much of the traffic (or at least that part that has to go a long ways to its destination) moves. This is in contrast to the edge -- the outer part of the network where devices like computers and printers get connected. When discussing computers, you can think of it as the same as a CPU. network.
We refer generically to all the data traveling through the connectionsThis refers to some kind of electrical connection. It might be through a network cable, a cable connection, a wireless connection, or a phone - just to name some options. The connection might be to the internet or to some other local device. as trafficRefers to any kind of electronic message -- email, web request, streaming video, or anything else -- that travels over a network.. Traffic that you generate and receive passes through a series of routersAn electronic box that helps steer data on a network. For instance, you may have one in your home connecting your phone and computer and other devices to each other and to the internet. The data itself has information about where it's being sent; the router uses that information to send it in the right direction. At a really basic level, you can think of a router and a switch as being the same thing. If you want to get more technical, a switch creates a local subnetwork, and the router connects multiple subnetworks (or multiple networks). and switchesA switch helps direct network traffic to the right destination. At a high level, it's very similar to a router. Technically, switches are used to create local subnetworks; routers connect subnetworks together. that direct it through the network in much the same way that trains are switched through the maze of tracks that gets them onto the right track.
Every time you send an email, and every time you click on a URL in your browser, you’re creating network traffic. In fact, there’s a lot of traffic that goes on that you might not even be aware of. The bottom line is that your computer (or phone or whatever) takes your instructions (clicking “send” on an email or clicking a link on a web page) and turns them into traffic that (hopefully) ends up accomplishing what you wanted.
- When you send an email, it ends up on someone else’s computer or phone. In the figure, you can see a blue email leaving your computer and arriving at a phone via the blue path.
- When your browser requests a web page, it sends that request a web serverA server whose purpose is to receive requests for web pages and then send those pages out to the requestor.. As we’ve seen, a serverA computer with a dedicated purpose. Older familiar examples are print servers (a computer that controls local printing) and file servers (a computer used for storing files centrally). More modern examples are web servers (the computers that handle your web requests when you use your browser) or application servers (computers dedicated to handling the computing needs of a specific application). Servers are often powerful, expensive machines since they have to handle a heavy load. is simply a powerful computer with a specific purpose – in this case, to serve up responses to web page requests. You request a page (red envelope and arrows), and the server returns the page to you (purple envelope and arrows).
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