Lancom 821 ADSL/ISDN Manual page 10

LANCOM 821 ADSL/ISDN – LANCOM 1621 ADSL/ISDN – LANCOM 1711 VPN
Chapter 1: Introduction
Ideal for Internet surfers
The ADSL version of DSL was designed for applications in which the user
receives high volumes of data but only transmits relatively small volumes. A
typical example for this would be access to the world wide web (www). Only
a few commands (mouse clicks) are required to initiate the download of very
large volumes of data such as graphics, texts, audio or video files. The user
typically only sends very small amounts of data across the Internet connec-
tion.
With an ADSL connection, a user can download at up to 8 Mbps ("down-
stream") and upload at up to 800 Kbps ("upstream"). These maximum rates
can be reduced as required by the ADSL provider. A typical access plan might
specify, for example, 768 Kbps download and 128 Kbps upload speed.
All services via a single cable—thanks to the splitter
With ADSL, all traditional telephony applications (telephone, fax, answering
machine, PBX) can still be used without restrictions. So-called splitters make
this possible. Splitters are devices that separate the telephone line's "voice
frequencies" from the "data frequencies" and ensure that the signals are for-
warded to the appropriate networks. Voice signals are passed on to the exist-
ing telephone network, while data signals are forwarded to their destinations
(i.e. Internet providers) via high-bandwidth network connections.
A splitter is also used at the subscriber end to permit ADSL modems/routers
and conventional telephone equipment to be used at the same time.
Internet
In some models (like in the picture above) the ADSL modem is integrated
directly in the router (e.g. LANCOM 821 ADSL/ISDN and LANCOM 1621 ADSL/
10
Telephone
network
Switching node
DSL access
multiplexer
ADSL provider
Splitter
Splitter
Router with integrated
ADSL modem
Telephone
Subscriber