Configure X.25 parameters
Digi TransPort User Guide 524
RR Timer x milliseconds
A standard LAPB Receiver Ready timer. The default value is 10,000 milliseconds (10 seconds)
and it should not normally be necessary to change this.
T1 Timer x milliseconds
A standard LAPB timer. The default value is 1000 milliseconds (1 second) and under normal
circumstances, it should not be necessary to change it.
T200 Timer x milliseconds
The standard LAPB re-transmit timer. The default value is 1000 milliseconds (1 second) and
under normal circumstances, it should not be necessary to change it.
X.25 Window Size
The X.25 window size. The value range is from 1 to 7 with the default being 7.
Disconnect link if there has been no X.25 activity for x seconds
The length of time, in seconds, before the link is disconnected if there has been no X.25
activity. If this parameter is 0 or not specified, then the inactivity timer is disabled.
Disconnect link if there has been no activity for x seconds
The length of time, in seconds, before the link is disconnected if there has been no activity. If
this parameter is zero or not specified, then the inactivity timer is disabled. It is useful to set
this to a short period of time, for example, 120 seconds, when a LAPB instance is being used
over ISDN for example with TPAD. Should the POS device fail to instruct TPAD to hang up then
this timer can be used as a backup hang-up timer thus saving ISDN call charges. When LAPB is
being used on a synchronous port, this parameter should normally be set to 0.
Send X.25 Restart packet on receipt of SABM frame
This parameter can be set to No or Immediate.
• When set to Immediate, the LAPB instance sends an X.25 restart packet immediately on
receipt of an SABM (Set Asynchronous Balanced Mode) frame.
• If the parameter is set to No, no X.25 restart is sent.
ISDN Parameters
Allow this unit to answer calls
If enabled, this instance of LAPB answers incoming ISDN calls.
Only accept calls from calling number ending with
The filter for the ISDN Multiple Subscriber Numbering facility. It is blank by default. When set
to an appropriate value with Allow this unit to answer calls enabled, the router answers
incoming calls only to ISDN numbers where the trailing digits match the MSN value. For
example, setting the MSN parameter to 123 prevents the router from answering any calls to
numbers that do not end in 123.
Only accept calls with sub-address ending with
The filter for the ISDN sub-addressing facility. It is blank by default but when set to an
appropriate value, with Allow this unit to answer calls enabled, the router answers
incoming ISDN calls only where the trailing digits of the sub address called match the Sub-
address value. For example, setting the Sub-address to 123 prevents the router from
answering any calls where the sub-address called does not end in 123.
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