Digital Subscriber Line Technology

Bellcore first introduced digital subscriber line (DSL) technology in 1989 as a way to transmit video and television signals from telephone companies' central offices to end users over standard copper cable used for voice service. At that time, video-on-demand was perceived as the broadband application that would drive digital subscriber line (DSL) implementation. Asymmetric digital subscriber line (ADSL) service was proposed because of its higher speeds for downloading large video files. The main application for DSL has changed from video-on-demand to Internet access.

DSL is a dedicated, high-speed way to access the Internet or corporate files via a virtual private network (VPN). (See Chapter 5 for VPNs.) It ...

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