Speed Chan. Speed 64Kbps 64Kbps 64Kbps 1.544Mbps 1.544Mbps 2.048Mbps (DS-1) 6.312Mbps 6.312Mbps 8.448Mbps (DS-2) 44.7Mbps 32.06Mbps 34.368Mbps (DS-3) Appendix Table 5-4 Digital Subscriber Line Standards Digital Upstream Downstream Subscriber Top Data Top Data Line Service Voice Comments 800Kbps 7Mbps Offered to residential (Asymmetric customers. Uses one pair of wires. ADSL2 1Mbps 8Mbps Most common stan- dard worldwide for Internet access. ADSL2plus 1Mbps 24Mbps Supports video on demand on short cable runs. ADSL2- Reach 1Mbps 8Mbps Increases reach of extended ADSL2+. SHDSL 5.6Mbps 5.6Mbps Single or two pair. Two pair speeds higher than single pair. 1.5Mbps 13Mbps (Very-High- 2.3Mbps 52Mbps Bit-Rate DSL) VDSL2- 30Mbps 55Mbps Voice Requires short cable 12MHz length; TV/data/ voice. VDSL2- 100Mbps 100Mbps Requires short cable 30MHz length; TV/data/ voice. This page intentionally left blank The Internet In this chapter: Introduction The Growth of the Internet The Structure of the Internet Security Threats from Internal, External, and International Sources Privacy Video Streamed from the Internet to the Front Room Electronic Commerce Online Community Forums Network Neutrality The Digital Divide: Bandwidth, Skills, and Computers Intranets and Extranets Summary The Internet INTRODUCTION he Internet is a set of complex interconnected networks that was developed in the United States, and then spread around the world and evolved into what we SO com- monly use today-thus, the term "Internet," which is an abbreviated version of the word "internetwork." High-speed, terabit (1,000-gigabit) routers connect these net- works to one another and transmit packets over the Internet backbone. The backbone carries the greatest concentration of Internet traffic. However, the edges of the networks that make up the Internet are critical. Edge routers direct traffic to their destinations, are responsible for security, and must be compatible with many different protocols. As traffic on the Internet increases, capacity will continue to grow,