WANs III: The ULTIMATE WAN (aka, the Internet)!

The Internet (GREATLY Simplified)!

As promised, now we want to consider the most extensive WAN ever created–the Internet!  Begun as a public project, the Internet is not actually a single monolithic network, but rather a collection of INTER-Connected NETworks (notice the way the terms break out).  If you think about all of the logistics involved with integrating the various components, geographies, devices, and access methods, it’s a wonder that it even works at all!  When I started in the networking business back in 1998, the hierarchy was much simpler, with large backbone carriers (AT&T, UUNET/Verizon, etc.), and regional providers, with smaller Internet Service Providers connecting to smaller customers. Needless to say, a lot has happened with the public Internet, with many more developments on the horizon.

In the “old days” there were very limited ways to access the Internet, most often through dedicated access, or through dial-up.  Today there are many ways to get to Internet resources, including cellular (typically 3G), 4G, DSL, cable, and so forth.  For the purpose of simplicity, we will narrow the types of access to the four most common types, as follows:

1. Dedicated Internet Access: Probably still the “gold standard”of Internet access, dedicated access uses private-line connectivity of some type between the customer location and the provider’s Point of Presence (POP).  If you remember our discussion about private lines, this involved a telecommunications circuit, usually terminated by a CSU/DSU and can have speeds from T1/E1 up to insanely huge optical connections.

2. Dial-Up: Archaic by today’s standards, dial-up networking once ruled the information world, with big names like America Online, CompuServe, and Earthlink once considered the “heavyweights.”  An analog device called a modem (modulator-demodulator) turned digital information into analog tones from transmission over standard phone lines, usually at very slow speeds.  Originally it was terribly slow (I remember 2400 bps being the top speed), but newer techniques helped promised 56 Kbps speeds.  Dial-up was eclipsed by the introduction of broadband technologies (considered next), and is difficult to find today.

3. Cable: If you have ever had cable television, you know first-hand the amount of information that is possible to squeeze through that fairly narrow coaxial cable it is known for.  Hundreds of channels with specialized content is available at the click of a remote-control button.  In many ways, delivering Internet access across this connection is similar to just adding another “channel” of sorts into the lineup.  Boasting great speeds, it is a popular option where available.

4. Digital Subscriber Line: For years it was possible only to transmit voice conversations across analog telephone lines, including dial-up networking (which used audio tones for transmission).  Of the number of possible frequencies to transmit across an analog line, a fairly narrow amount is used for voice, leaving the rest open for, yes, you guessed it, transmitting data.  The benefit of this is being able to support voice calls and data transmission at the same time.

While this covers Internet access, there is much more to say about how the Internet communicates, which we will look at next time!

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