Voice Over IP

ARCHITECTURE OF AN INTERNET

Today, the Internet is a complex collage of regional and national networks that are interconnected together with routers. The communications links used by the ISPs are leased lines from the telephone system, usually DS1 or DS3 lines, and increasingly SONET lines. Other lines are provided by competitive access providers (CAPs), and still others are provided by private carriers, such as private microwave, and satellite operators.

Figure 2-1. Internet overview

The Internet connections and the many ISPs are impossible to depict in one illustration, but Figure 2-1 provides an accurate view of the basic structure of the ...