 lines, ISDN Primary Rate Interface (PRI), and dedicated lines based on T-1/E-1 capacities for larger enterprises, and, in some cases, even T-3/E-3. The Evolution of the POP Architecture The early Internet point-of-presence (POP) architecture was quite simple, as illus- trated in Figure 8.19. Either 56Kbps or 64Kbps lines came in to access ports on a router. Out of that router, T-1/E-1 trunks led to a UNIX host. This UNIX environ- ment was, for most typical users, very difficult to navigate. Until there was an eas- ier way for users to interface-the World Wide Web-the Internet was very much the province of academicians, engineers, and computer scientists. The architecture of the Internet today is significantly different from its early days. Figure 8.20 shows some of the key components you would find in a higher- level network service provider's (NSP's) or a high-tier ISP's POP today. (Of course, a local service provider with just one POP or one node for access purposes, perhaps to a small community, looks quite different from this because it is much simpler.) First, let's look at the support for the dialup users. Today, we have to facilitate a wide range of speeds; despite our admiration of and desire for broadband access, it's not yet widely available. As of year-end 2005, only 15.7% of the world's population had any type of Internet access (www.internetworldstats.com). In the next several years, we should see more activity in terms of local loop modernization to provide broadband access to more users, using both fiber and wireless broadband alternatives T-1/E-1 Trunks Router 56/64Kbps Access Ports Figure 8.19 POP architecture in the 1980s Chapter 8 The Internet and IP Infrastructures T-3/E-3 To the Internet OC-3/OC-12 Supports Frame Relay Access Analog Access Supports 56/64Kbps Customers and BRI ATM Switch T-1/E-1 Concentrator ISDN Users Supports T-1/E-1 Customers T-3/E-3 Access Distribution Router T-1/E-1 Concentrator Access Router Ethernet Terminal Analog 28.8/33.6/ Modem Server 56Kbps Users E-mail Server Dom