Cisco Model 6109 6 MHz Off-Air Reference (NTSC) Guide De Montage

 

78-4021139-01 Rev D 

15 

 

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 

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. 

 

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 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 

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.