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Internet Service Providers

Every Tier 1 and Tier 2 provider leases connections to the Internet to companies called Internet service providers (ISPs). ISPs essentially sit along the edges of the Tier 1 and Tier 2 Internet and tap into the flow. You can, in turn, lease some of the connections from the ISP and thus get on the Internet.

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NOTE Microsoft calls the connections ISPs make to the Internet access points, which I think is a very bad name. You’d think we’d be able to come up with new terms for things! Instead, some folks in this industry continue rebranding things with the same phrases or catchwords, only serving to confuse already bewildered consumers.

ISPs come in all sizes. Comcast, the huge cable television provider, has multiple, huge-capacity connections into the Internet, enabling its millions of customers to connect from their local machines and surf the Web. Contrast Comcast with Unísono, an ISP in San Miguel de Allende, Mexico (Figure 25-4). Billed as the “Best Internet Service in San Miguel,” it services only a small (but delightful) community and the busy tourist crowd.

Figure 25-4 Unísono homepage

Connection Concepts

Connecting to an ISP requires two things to work perfectly: hardware for connectivity, such as a modem and a working cable line; and software, such as protocols to govern the connections and the data flow (all configured in Windows) and applications to take advantage of the various TCP/IP services. Once you have a contract with an ISP to grant you access to the Internet, the ISP gives you TCP/IP configuration numbers and data so you can set up your software to connect directly to a router at the ISP that becomes your gateway to the Internet. The router to which you connect at the ISP, by the way, is often referred to as the default gateway. Once you configure your software correctly, you can connect to the ISP and get to the greater Internet. Figure 25-5 shows a standard PCto-ISP-to-Internet connection. Note that various protocols and other software manage the connectivity between your PC and the default gateway.

Figure 25-5 Simplified Internet connectivity

Essentials

Connecting to the Internet

PCs commonly connect to an ISP by using one of seven technologies that fit into four categories: dial-up, both analog and ISDN; dedicated, such as DSL, cable, and LAN; wireless; and satellite. Analog dial-up is the slowest of the bunch and requires a telephone line and a special networking device called a modem. ISDN uses digital dial-up and has much greater speed. All the others use a regular Ethernet NIC like you played with in Chapter 23, “Local Area Networking.” Satellite is the odd one out here; it may use either a modem or a NIC, depending on the particular configuration you have, although most folks will use a NIC. Let’s take a look at all these various connection options.

Dial-up

A dial-up connection to the Internet requires two pieces to work: hardware to dial the ISP, such as a modem or ISDN terminal adapter; and software to govern the connection, such as Microsoft’s Dial-up Networking (DUN). Let’s look at the hardware first, and then we’ll explore software configuration.

Modems

At some point in the early days of computing, some bright guy or gal noticed a colleague talking on a telephone, glanced down at a PC, and then put two and two together: why not use telephone lines for data communication? The basic problem with this idea is that traditional telephone lines use analog signals, while computers use digital signals (Figure 25-6). Creating a dial-up network required equipment that could turn digital data into an analog signal to send it over the telephone line, and then turn it back into digital data when it reached the other end of the connection. A device called a modem solved this dilemma.

Figure 25-6 Analog signals used by a telephone line versus digital signals used by the computer

Modems enable computers to talk to each other via standard commercial telephone lines by converting