Operation Manual

58 NetWAYS/ISDN – Glossary
Glossary
ADSL (Asymmetric Digital Subscriber Line)
ADSL is a communication technology that permits Internet
access with high bandwidth over ordinary telephone cables.
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. Other telecommunication services and
dial-up connections to other subscribers are not possible
over ADSL. This technology is marketed by telecom providers
under various brand names, such as Deutsche Telekom AG’s
“T-DSL”.
ISDN and ADSL can be carried over the same telephone ca-
ble using different frequency bands.
AH (Authentication Header)
A security protocol in the IPsec suite. AH ensures the authen-
ticity of a packet’s source and the integrity of its contents. AH
does not provide encryption of the data payload, however.
AOCD
AOCD, or Advice of Charge During Call, is an ISDN feature.
When this feature has been activated for the ISDN line,
charge information is transmitted over the D channel as
charges are incurred during a connection according to the
European standard AOCD. For more information about AOCD,
consult your ISDN provider.
AO/DI
AO/DI stands for Always On/Dynamic ISDN. This procedure
uses the ISDN D channel for connections with the Internet.
Data packets are communicated in the D channel using the
X.25 protocol. The connection is permanently active. The ca-
pacity of the D channel is sufficient for the transmission of
smaller amounts of data and no connection costs are
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