ZyXEL Communications 2602H Series User Manual

Prestige 2602H/HW Series User’s Guide

Introduction to DSL

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DSL (Digital Subscriber Line) technology enhances the data capacity of the existing twisted-
pair wire that runs between the local telephone company switching offices and most homes 
and offices. While the wire itself can handle higher frequencies, the telephone switching 
equipment is designed to cut off signals above 4,000 Hz to filter noise off the voice line, but 
now everybody is searching for ways to get more bandwidth to improve access to the Web - 
hence DSL technologies. 

There are actually seven types of DSL service, ranging in speeds from 16 Kbits/sec to 52 
Mbits/sec. The services are either symmetrical (traffic flows at the same speed in both 
directions), or asymmetrical (the downstream capacity is higher than the upstream capacity). 
Asymmetrical services (ADSL) are suitable for Internet users because more information is 
usually downloaded than uploaded. For example, a simple button click in a web browser can 
start an extended download that includes graphics and text.

Prestige

Computer

Notebook Computer

Server

Switch

Router

Telephone

DSLAM

Trunking Gateway

Firewall

 Wireless Signal