User`s guide

281
X.25 Settings
Default X.25 packet size
This parameter determines the default X.25 packet size. This may be set to “16”, “32”,
“64”, “128”, “256”, “512” or “1024”, but the actual values permitted will normally be
constrained by your service provider.
Answer incoming calls from NUA
This is the NUA that the unit responds to for incoming X.25 calls.
Only answer calls with CUG
The PAD will only answer calls with this Call User Group (CUG) specified.
Use X.25 Call Macro macroname to an ATD command
This parameter specifies the name of an X.25 call macro that is used when an ATD
command is received by the unit. The ATD command is ignored, and a PAD CALL command
using the macro replaces it. The purpose of this feature is to allow non-PAD terminals to use
an X.25 PAD network connection. X.25 call macros are set up in the Configuration -
Network > Legacy Protocols > X.25 > Call Macros web page, or by using the macro
text command.
Use NUA
This NUA will be used as the calling NUA when an outgoing X.25 call is made.
LCN
The unit supports up to eight logical X.25 channels. In practice, the operational limit is
determined by the particular service to which you subscribe (usually 4).
Each logical channel must be assigned a valid Logical Channel Number (LCN). The LCN
parameter is the value of the first LCN that will be assigned for outgoing X.25 CALLs. The
default is 1027.
For incoming calls, the unit accepts the LCN specified by the caller.
LCN Direction
This parameter determines whether the LCN used for outgoing X.25 calls is incremented or
decremented from the starting value when multiple X.25 instances share one layer 2 (LAPB
or LAPD), connection. The default is “Down” and LCNs are decremented, i.e. if the first CALL
uses 1024, the next will use 1023, etc. Setting the parameter to “Up” will cause the LCN to
be incremented from the start value.
NUI/NUA selection
If both an NUI and an NUA are included in the call string, this parameter allows the unit to
filter one of these out of the X.25 call request. This can be extremely useful in backup
scenarios. Consider the following example; the unit is configured to do online authorisations
via the ISDN D channel and to fall back to B-channel (if the D-channel host did not respond
for any reason). Using this parameter in conjunction with the backup equivalent, it is
possible to configure the unit to use the supplied NUA to connect over D-channel and the
supplied NUI to connect over B channel (for backup).
On the backup interface LCN
The LCN parameter is used to set the first LCN that will be used for the backup interface.
On the backup interface LCN Direction
This parameter determines whether the LCN used for the backup X.25 interface is
incremented or decremented from the starting value when multiple X.25 instances share a
single layer 2 connection.