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ISDN TA/V
17.2 V.42bis Data-Compression Characteristics
Only used on links which are using the LAPM error-correction protocol,
V.42bis data compression can increase the throughput rate of data by up
to 300%. The
"H
command setting determines whether V.42bis data
compression is used or not.
"H0
V.42bis compression is disabled.
"H1
V.42bis compression is only actioned on transmitted data.
"H2
V.42bis compression is only actioned on received data.
"H3
V.42bis compression is actioned on both the transmitted
and received data.
It should be noted that data which has already been compressed (by a
software program for example) may experience a slight decrease in
throughput speed when V.42bis data compression is enabled. This slowdown
will however be hardly noticeable; it is therefore recommended that this
compression technique is always enabled.
17.3 Flow-Control Characteristics (XON/XOFF)
Defined using the
\Q
and
\G
commands. The type of flow control you should
use on a given communication link is normally dictated by the requirements
of the service you’re connecting to, and whichever of the two methods your
ISDN TA/V is configured to use must also be configured into the operational
settings of your communication software program.
\Q0
ISDN TA/V to DTE flow control is disabled.
\Q1
Enables bidirectional software flow control, governed by
XON/XOFF characters from the ISDN TA/V or the DTE.
An XOFF character stops the flow of data. XON restarts it.
\Q2
Enables unidirectional hardware flow control from the ISDN
TA/V to the DTE. The CTS signal being dropped stops data
flow, and CTS on restarts it.