Guralp Systems CMG-DCM build <10,000 User Manual
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Acquisition Modules and Platinum Firmware
Networking Configuration
User description: If you are configuring a number of watchdogs give each of
them memorable names.
Enable: Should normally be ticked but can be left clear if you only want to
use the associated PPP connection occasionally.
Delete: Deletes the instance when the form is submitted.
Daemon startup delay: If the PPP connection relies on a modem link for its
transport, there may be a significant delay between instructing the PPP link to
start and the connection being established. So that the watchdog does not
falsely detect a failed link during this period, it can be instructed to sit idle for
a number of seconds before it begins to test the link. The length of the
required delay should be entered into the field.
Test command: Once the start-up delay time has elapsed, the watchdog
periodically tests the connection. To ensure that there is a valid end-to-end
connection where, for example, a multi-hop link is in use, the exact method of
testing is user-configurable: any valid command can be entered into the field
and its exit status is taken to represent the link status (zero for link up,
non-zero for down). The most common method used is to use the ping
command to verify ICMP connectivity to the ultimate remote host, but you are
free to use the command or script of your choice here, so long as it returns a
non-zero exit status on link failure.
Time between tests: Determines how often the configured test is applied. It
can be set high to conserve bandwidth or set low to improve failure response
times. It can also be used to keep a sparsely-used link alive where a
“disconnect-on-inactivity” feature would otherwise interrupt it.
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Issue E - February 2014