That's right, everybody! This week it's hardcore, hard-wired hardware!*
So you've got a bunch of computers to network and they're ready to go. How do you go about actually connecting them? You've got three options:
- You don't physically connect them, relying on a wireless signal. This can be convenient, but you're using radio waves. And, well:
"Radio is bad. I mean, it's necessary. I'm not saying we don't all use it. I do. I've got WiFi here. I've got it wrapped up in a WPA encryption with a passphrase from hell that I got from GRC.com/passwords. So I'm as secure as I can be. But several times during the history of this podcast we've talked about vulnerabilities in, for example, Intel's WiFi drivers. There was one not even that long ago where it was found that down in the actual packet processing, way down at the bottom, the first place the packets go when it comes hot in off the aerial, off the radio antenna, had an overflow. So before encryption and decryption, before authentication, before anything else, it was possible to simply broadcast a malformed, deliberately malicious bit of radio noise and take over a machine." - Steve Gibson (Security Now Episode 158)
(There will be more about wireless networking in 5 posts.) - You use cables of some kind to connect your devices. This is more secure and often more reliable, sometimes cheaper, and often a higher-performance option than wireless.
- You give up and kick it old school.
For the purposes of this blog post, we're going to assume that option 3 is not an option, and, realistically, in today's marvelously high-tech world, it's really not.
Unlike my two blog posts previous, I'm going to diverge a bit from the order the book uses and talk about cables first, because in my humble opinion, it makes more sense to do it that way.
There are two main types of cable:
Copper Wire: This can be anything from Coaxial cable, (yep, the exact same stuff you get cable TV through) Unshielded Twisted Pair, (which is some of the most evil stuff on the planet, but more on that later) and Shielded Twisted Pair. These all have their sub-types, but those are the basics. - Fiber Optic: The "good stuff" as it were, fiber optic cable sends data as light rather than electricity. As you would expect, fiber optic cable is very fast, but it's also expensive.
These cables carry data in one of two ways: analog or digital.
Analog Data: Analog data is kind expressed as a wave. The human voice is an analog signal, and if you compare it to one of those horrific automated talking phone systems, you'll immediately grasp one of the major benefits of analog - it's able to carry a lot more data than digital over a similar medium. However, it's extremely vulnerable to noise. Noise is anything that interferes with the signal in this case. For a perfect example of noise, just put something on the radio and drive past a hospital. When the signal cuts out and is replaced by static, you are experiencing noise.
- Digital Data: Digital data is sent as a series of pulses. It has the advantage of being more noise resistant, because either there's light/voltage or there isn't.And there you have it; the basics of the physical parts of a network.
And there you have it. The hardware end of network connections.
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