Prestige 681 SDSL Router
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What is DSL?
What is DSL?
DSL (Digital Subscriber Line) 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).
As data rates increase, the carrying distance decreases. That means that users who are beyond a certain
distance from the telephone company’s central office may not be able to obtain the higher speeds (
see Table
3-2
for
SDSL Maximum Transmission Distances ). A SDSL connection is a point-to-point dedicated circuit,
meaning that the link is always up and there is no dialing required.
SDSL
SDSL (Symmetrical Digital Subscriber Line) is a symmetrical, bi-directional DSL service that operates on
one twisted-pair wire. It can provide data rates up to 2.3 Mbits/sec. Unlike traditional HDSL systems, which
use two twisted pair, SDSL reduces equipment and lease-line costs by providing the same service using
only one twisted pair and one modem at each end. SDSL is symmetric, which means you get the same
amount of bandwidth to and from the Internet. SDSL provides speeds up to 12 times faster than an ISDN
line and up to 50 times that of an analog modem connection at a fraction of the price of traditional dedicated
access services.
The "always-on" digital connection provides the stability and consistent high bandwidth so crucial to
today's online business community, allowing applications such as video conferencing, distance learning and
high-powered Web browsing to perform with peak efficiency.
SDSL allows Webmasters to set-up a web
server, mail server and any other Internet service with increased bandwidth yet no additional charges.
Because SDSL is symmetric, it is ideal for businesses, especially if you host a web site. It provides you with
the high bandwidth required for uploading and downloading large data files and graphics. SDSL also gives
you the bandwidth you need to retrieve information from Internet POPs, Internet servers and private data
networks.
These are the main characteristics of SDSL:
•
Continuous
Connection
SDSL users are never disconnected. There is no wait for dialup, where
ISDN and regular analog modems often take half a minute to establish a
connection.
•
Dedicated
Bandwidth
You select the line speed and it is “symmetric,” i.e., the same bandwidth in
both directions.
