Cisco Model 6109 6 MHz Off-Air Reference (NTSC) Installation Guide
Operation Overview
78-4021139-01 Rev D
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Operation Overview
Introduction
The USRM is designed to be "always on" to enable mission critical applications. This
feature allows the USRM to be a part of the services delivery chain by ensuring the
software is always operating.
Assuring the always on status is accomplished with two distinct process
Assuring the always on status is accomplished with two distinct process
environments:
USRM Watchdog - a small application that ensures the application software is
operational.
USRM component set - the USRM base platform components plus the customer-
specific components (applications, resource models, and resource adaptors) are
referred to as the USRM component set or shortened to USRM.
USRM Watchdog
The watchdog provides two primary services, as follows.
It ensures the USRM is always operational.
It facilitates and implements the software upgrade process.
The watchdog is installed in the /etc/init.d directory and, as such, is automatically
activated on power-up of the server. The USRM is manually activated. The USRM
package sends the startup command line to the watchdog component when the
software is activated. The watchdog uses this information to restart the software in
the event of a reset. A reset occurs if the software crashes or the operator manually
commands a reset operation.
The watchdog software monitors the state of the USRM executable. Once activated,
The watchdog software monitors the state of the USRM executable. Once activated,
the watchdog helps ensure the software is always operational unless the software is
manually terminated by the operator. When the USRM is activated, an interface is
opened to the watchdog that allows it to monitor USRM operation. The software
sends a heartbeat signal at a periodic rate to indicate normal status. If the USRM
executable should fail, it stops sending heartbeat messages and the watchdog
restarts the software.
The watchdog monitors the operation of the operator. If the operator starts the
The watchdog monitors the operation of the operator. If the operator starts the
software, the watchdog then monitors the software and activates the software if the
software terminates for any reason other than a normal operator shutdown. When
the operator terminates the software, the watchdog passively waits for the software
to be restarted by the operator.