BinTec X4000, Руководство пользователя

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X4000 User’s Guide 207
Settings Specific to WAN Partners
8
Short Description
AO/DI uses X.25 data packet transmission in the D-channel (X.31) to set up a
PPP connection (PPP over X.25). 9600 bps are available for data transmission
in the D-channel (D-channel Mode). If more bandwidth is needed, one or two B-
channels are dynamically added (Dynamic ISDN). Data transmission in this
case is only in the B-channel or B-channels, i.e. the B-channels remain
reserved for bandwidth-intensive applications (B-channel Mode).
AO/DI offers the following advantages:
■
three full communication channels, which can be independent if required
■
permanent connection to the Internet at low-cost
■
transparent bandwidth control
■
in D-Channel Mode
– high reliability and guaranteed throughput times
– volume-oriented charges independent of distance
■
in B-Channel Mode:
– time-dependent connection charges only for bandwidth-intensive
applications
How Does AO/DI Work?
AO/DI is implemented in X4000 via a special PPP interface. As soon as the
interface is configured and ready for operation, the initial PPP connection is set
up via X.31 (X.25 in the D-channel). This involves carrying out authentication of
the PPP connection partner and assigning a dynamic IP address and DNS
addresses, if applicable (AO/DI Client Mode).
The use of the B-channels is controlled by the data throughput or by application-
dependent bandwidth management (Bandwidth on Demand, BOD for IP-based
applications). Both Bandwidth on Demand and BOD for IP-based applications
uses the Bandwidth Allocation Control Protocol (BACP/BAP to RFC 2125) in
order to agree with the remote terminal on the circumstances under which B-
channels are to be added or dropped. The use of BACP/BAP is agreed during
the initial connection setup. As the D-channel connection is normally no longer