From Zenitel Wiki
IP stations software version: 01.05.
The hardware watchdog is implemented in the IP station's system microprocessor. Once started, the hardware watchdog requires tick updates from software to prevent it from executing a hardware reset. Hardware watchdog timeout is 10 seconds.
Software process watchdog
The software process watchdog (ipst_cmd_srv) is started at the end of the IP station's boot process, before the application processes are started. It starts the hardware watchdog, and then waits for alive signals from the software application processes. As long as these signals are received, it will update the hardware watchdog. If the signals stop, the hardware watchdog is not updated, and will eventually time out.
The maximum allowed alive signal interval from the software application processes is defined by the hardware watchdog timeout (10 seconds).
Software application watchdog
There are two software application processes that send alive signals to the software process watchdog:
* ipstweb * ipstd
ipstweb: ipstweb sends alive signal at intervals of 1 second.
ipstd: The alive signal from ipstd depends on basic system functionality to work. This ensures that most of the functions in ipstd is operating. If these stop working, the alive signal will stop. Also, if certain critical system-level functions fail to execute, the ipstd application will intentionally exit and the alive signal will stop. The alive signal interval time is 1 second.
Recovery from a failure situation
When an alive signal is not received from one of the software applications within specified time, the software process watchdog (ipst_cmd_srv) will stop updating the hardware watchdog. The hardware watchdog will then time out, and restart the IP station. The restart takes about 20 to 30 seconds.
No information is recorded locally about the watchdog reset. It will appear in the AlphaCom exchange as if the station was powered down and powered back up.