Page 248 of 910 Features
553-3001-365 Standard 4.00 August 2005

Hardware watchdog timer

A hardware watchdog timer is enabled on the ITG-P 24-port and Media Card
line cards. This functionality adds further robustness to the existing exception
handler and maintenance task audits.
The hardware watchdog timer handles scenarios such as the following:
• the CPU failing
• the code running and not triggering an exception
• resetting the card and bringing it back to normal operation
The timer runs on the ITG-P 24-port and Media Card line card processors.
The card’s main processor is polled every 20 seconds. If three pollings are
missed, then the card is reset. This gives the main processor 60 seconds to
respond, covering most normal operating conditions.
A reset reason is logged and saved when a card resets. The reset reason is
displayed as a message during the start-up sequence and appears in the
SYSLOG file.
The following are examples of reset reasons:
• JAN 04 12:17:45 tXA: Info Last Reset Reason: Reboot command issued
Output after card reset using the CLI command cardReboot.
• JAN 04 12:17:45 tXA: Info Last Reset Reason: Watchdog Timer
Expired
Output after card reset due to watchdog timer expiration.
• JAN 04 12:17:45 tXA: Info Last Reset Reason: Manual reset
Output after card reset due to either the faceplate reset button press or a
power cycle to the card.
• JAN 04 12:17:45 tXA: Info Last Reset Reason: Unknown
Output after card reset due either the card F/W not supporting the reset
reason or a corruption of the reset reason code.
The last reset reason can also be displayed at any time by entering the
lastResetReason CLI command.