192
6620-3201
LCN:
The unit supports up to eight logical X.25/TPAD 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
fi
rst LCN that will be assigned for outgoing X.25 CALLs. The default
is 1027.
For incoming calls, the unit accepts the LCN speci
fi
ed by the caller.
LCN direction:
This parameter determines whether the X.25 LCN used for outgoing TPAD calls is incremented or
decremented from the starting value when multiple TPAD instances share one layer 2 (LAPB or
LAPD), connection. The default is “DOWN” and LCN’s are decremented, i.e. if the
fi
rst 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.
Direct Sync:
This parameter is used to turn direct synchronous mode on or off. When set to On, TPAD transactions
are transmitted without any “outer” protocol such as X.25, i.e. they are placed directly in a
synchronous frame.
Response timeout (s):
This is the length of time in seconds that the unit will wait for a response to a TPAD transaction
request before clearing the TPAD call.
Excessive transaction time (s):
Setting this parameter to a non-zero value causes the unit to generate an “Excessive Transaction
Time” event (code 56) each time a TPAD transaction takes longer that the speci
fi
ed number of
seconds. This could be used in conjunction with an appropriate
Event Handler
con
fi
guration to
generate email alert messages or SNMP traps when TPAD transactions take longer than expected.
See “LOGCODES.TXT” for a complete list of events.
SLA Tran Time (ms):
When the total transaction time exceeds the value (in ms) set in this parameter, the
NB SLA
exceptions
statistic on the
Statistics
>
TPAD
page is incremented. This statistic can be viewed on
the CLI interface by entering the
at\mibs=tpad.x.stats
command.
TID timeout (s):
This speci
fi
es the time in seconds before the Terminal ID is considered inactive.
Restart delay (ms):
When the Restarts parameter is set to “On”, the Restart delay value determines how long (in
milliseconds) that the unit will wait before issuing a Restart packet. The default value is 2000 giving a
delay of 2 seconds.
Restarts:
The Restarts parameter is only used in D-channel X.25 mode, i.e. when the speci
fi
ed TPAD
instance has been bound to a LAPD instance.
It is normally possible to make X.28 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”.
