40-400-00001, Rev. A
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However, some terminals are designed to report link failures to their Call Control
Layer, which may then attempt to recover. If their recovery procedure is not satisfied
before various timers expire, they may clear (or dump) any active calls.
Some terminals do not attempt to recover from data link failures, but simply termi-
nate operation. These devices must be momentarily disconnected from the Simula-
tor, then reconnected to initialize them. Other terminals may have a reboot function
hidden in an Administration menu.
If a terminal is operated when simulation is halted, the device may store (queue) the
Call Control packets in its memory until simulation is resumed and its link controllers
have restarted. All stored Call Control Messages are then sent in rapid succession
to the Simulator.
Other terminals may respond to a Layer 3 failure by refusing to operate. These, too,
must be reinitialized or rebooted.
Note: ISDN-BRI devices are not normally designed to be stopped and started at
Layer 2 or 3. Consequently, not all terminals will operate in a predictable manner
after simulation is resumed. When in doubt, press RESTART, then reinitialize the
devices.
Various test conditions and configurations can cause frequent line errors and low-
level protocol violations. When using a real ISDN-BRI line, the Central Office
accumulates these errors and discontinues service after a predetermined limit is
exceeded. The Simulator attempts to continue service even though there are errors.
After testing with a particular configuration known to cause errors, it is good practice
to RESTART the Simulator and reinitialize any connected equipment before com-
mencing the next test.
Restart
Press the RESTART key to reinitialize Simulator interfaces, to clear all calls and
data link controllers, and to load new provisioning settings. When the STATUS LED
on the front panel illuminates a solid green, the Simulator is ready.
If any devices are attached via an NT-1 to the U interface, allow time for the U-
SYNC light to turn a solid green. After synchronization, reinitialize any attached
devices, either by removing and re-attaching them (power-up initialization), or by
restarting the controlling application program.