Operation Manual

Internet Connections
34 NetWAYS/ISDN – 3 Remote Access with NetWAYS/ISDN
3.4 Internet Connections
For connections to the Internet, NetWAYS/ISDN also sup-
ports the economical AO/DI service and high-speed ADSL ac-
cess. AO/DI allows you to maintain a permanent, economical
connection to the Internet over the ISDN D channel. ADSL
permits Internet access at significantly higher data speeds.
IP masquerading and Short-Hold Mode provide additional
security on connections to the Internet.
AO/DI
The AO/DI (Always On/Dynamic ISDN) technique uses the
ISDN D channel for a permanent connection to the Internet.
Data packets are transmitted over the D channel using the
X.25 protocol. In this way the NetWAYS/ISDN computer is
constantly connected to the Internet (Always On). The capac-
ity of the D channel is sufficient for the transmission of
smaller amounts of data, and no connection costs are in-
curred. When the amount of data to be transmitted requires
more bandwidth, one or more B channels are automatically
connected as well (Dynamic ISDN).
AO/DI saves connection charges in Internet communication
involving lower volumes of data, since no connection costs
are incurred as long as no B channel is used.
AO/DI can only be used if it is supported by both the Internet
Service Provider and the ISDN provider.
ADSL
ADSL (Asymmetric Digital Subscriber Line) is a communica-
tion technology that permits Internet access with high band-
width over ordinary telephone cables. ISDN and ADSL use
different frequency bands for simultaneous operation over
the same wire.
Data communication takes place at up to 6 Mbit/s down-
stream (that is, from the Internet to the user) and up to
640 kbit/s upstream. Dial-up connections to other subscrib-
ers are not possible over ADSL.
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