Digi TransPort WR31 User Manual page 531

Configure legacy protocols
T1 timer
A standard LAPB timer. The default value is 1000 milliseconds (1 second). Normally it is not
necessary to change this parameter.
T200 timer
A standard LAPB re-transmit timer. The default value is 1000 milliseconds (1 second). Normally
it is not necessary to change this parameter.
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 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 0 or not specified, the inactivity timer is disabled. When the router uses a LAPB
instance over ISDN, it is useful to set this to a short period of time, for example, 120 seconds. You
can use this timer as a backup hang-up timer, thereby saving ISDN call charges. When using
LAPB on a synchronous port, you should normally set this parameter to 0.
Digi TransPort WR Routers User Guide
Configure Systems Network Architecture over IP (SNAIP)
531