# Can I learn Networking?September 3, 2004 11:29 AM   Subscribe

Though I'm pretty computer savvy, my lack-of-knowledge about networking keeps tripping me up. Where can I learn about IP addresses, routers, http, etc.? I don't have a specific problem at the moment; I'm just looking for general information that might help someone who tinkers around with web-development and who occasionally needs to get machines to play nice with each other.
posted by grumblebee to Computers & Internet (7 answers total) 1 user marked this as a favorite

posted by cmonkey at 11:44 AM on September 3, 2004

Computer Networks, a Top-Down Approach Featuring the Internet, is a good introductory book on networks.
posted by chunking express at 11:52 AM on September 3, 2004

There's a ton of flash-based tutorials here, which I found useful.
posted by punilux at 12:04 PM on September 3, 2004

Sticking with O'Reilly, oreillynet.com has a Networking as a 2nd Language column that introduces some key concepts. Start here.
posted by ar0n at 12:21 PM on September 3, 2004

Thanks all for your help. I will probably look into all of those suggestions. I've already started with the "2nd Language" articles.

In the first article, the writer states:

A common phrase today is that we live in a digital age. The term "digital" means that a device uses bursts of electricity in discrete values. That is, a burst may be sent out over the wire of five volts. This one discrete burst would represent a bit set to one. A low voltage burst of zero represents a bit set to zero. A bit belongs to a binary number system whose values consist of 0s and 1s. The binary system has only those two digits. Hence the name binary digits or simply, bits. [Emphasis added.]

Is that a typo? Can there be such a thing as a "burst" of zero volts? I know you don't need to go down this deep to understand the rudaments of networking, but I'm curious: how DO computers represtent the bit we call 0 -- by NO electricity or by a particular voltage of electricity? Is there a constant stream of "garbage" electricity being sent, but within that lie the zero and one signals? Or is it simply on off on on off?
posted by grumblebee at 3:05 PM on September 3, 2004

Yes, one of the ways of representing a zero is with zero volts.
There is indeed "garbage" electricity. It is called noise. One of the advantages of discrete systems is that they "only" have to discern if a signal is closer to the representation of '1' or of '0'. The noise usually should be well below this decision threshold.
Regarding the zero volt "burst", take into account that the bits are discrete no only in their value (amplitude) but also in their duration. A system must decide if the signal it received during the period when a bit was expected resembles more a '0' or a '1. If no signal was sent it will be interpreted as a zero.
I guess this describes in general terms what goes on inside a computer. At high bit rates and/or long distances more elaborate representations are used, Ethernet for example uses Manchester encoding .
posted by golo at 3:48 PM on September 3, 2004

W Richard Stevens' books on network programming and protocols are pretty highly thought of. They go more into the innards of the protocols than you're likely to want, but you can skim those parts.

Re the 0 volts: there's a difference between not doing anything to a line, and forcing a line to be at 0 volts. The sender of data is alternately forcing the wire to be at 0V or 5V above ground (or 0 and 3.3V, or -9 and +9, or whatever's appropriate in the situation). If the wire were left unconnected --- with circuitry "listening" to it but no one talking --- it might drift to 0, or +5, or halfway in between, or bounce around erratically in response to minuscule amounts of external noise, depending on the details of the circuit.

Hmm. Here's an analogy (which isn't very good: don't take it TOO far). Consider an old TV set, one that doesn't automatically go blue when it loses the signal. The difference between a TV screen showing black and a TV set showing the snow of a dead channel is kind of like the difference between "0 volts" and "nothing".
posted by hattifattener at 10:36 PM on September 3, 2004

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