Cisco CISCO876-SEC-I-K9 Configuration Guide - Page 165

Concepts APPENDIX B ADSL OL-5332-01 This appendix contains conceptual information that may be useful to Internet service providers or network administrators when they configure Cisco routers. To review some typical network scenarios, see Chapter 2, "Sample Network Deployments." For information on additional details or configuration topics, see Chapter 11, "Additional Configuration Options." The following topics are included in this appendix: • ADSL • SHDSL • Network Protocols • Routing Protocol Options • PPP Authentication Protocols • TACACS+ • Network Interfaces • Dial Backup • NAT • Easy IP (Phase 1) • Easy IP (Phase 2) • QoS • Access Lists ADSL is a technology that allows both data and voice to be transmitted over the same line. It is a packet-based network technology that allows high-speed transmission over twisted-pair copper wire on the local loop ("last mile") between a network service provider (NSP) central office and the customer site, or on local loops created within either a building or a campus. The benefit of ADSL over a serial or dialup line is that it is always on and always connected, increasing bandwidth and lowering the costs compared with a dialup or leased line. ADSL technology is asymmetric in that it allows more bandwidth from an NSP central office to the customer site than from the customer site to the central office. This asymmetry, combined with always-on access (which eliminates call setup), makes ADSL ideal for Internet and intranet surfing, video on demand, and remote LAN access. Cisco 850 Series and Cisco 870 Series Access Routers Software Configuration Guide B-1