User`s guide

278
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.
On the backup interface 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.
Enable X.25 Restart Packets
It is normally possible to make X.25 CALLs immediately following the initial SABM-UA
exchange. In some cases however, the X.25 network may require an X.25 Restart before it
will accept X.25 CALLs. The correct mode to select depends upon the particular X.25 service
to which you subscribe. The default value is “On”. This means that the unit WILL issue X.25
Restart packets. To prevent the unit from issuing Restart packets set this parameter to
“Off”.
Restart delay
When the Restarts parameter is “On” the Restart Delay value determines the length of time
in milliseconds that the unit will wait before issuing a Restart packet. The default value is
2000 giving a delay of 2 seconds.
IP Settings
Remote IP address
This field indicates the destination host that will answer the XOT, TCP, SSL, UDP call.
Remote IP Address when using the backup interface