Lindy IPower Switch 4 DIN S Pro User Manual page 20

Configuration
Enable watchdog: Enables the watchdog function for this Output Port.
W atchdog type: Here you can choose between the monitoring by ICMP pings or TCP
pings.
· ICMP Pings: The classic ping (ICMP echo request). It can be used to check the ac-
cessibility of network devices (for example, a server).
· TCP Pings: W ith TCP pings, you can check if a TCP port on the target device would
accept a TCP connect. Therefore a non-blocked TCP port should be selected. A
good choice would be port 80 for http or port 25 for SMTP.
TCP port: Enter the TCP port to be monitored. W hen using ICMP pings this is not
needed.
Hostname: The name or IP address of the monitored network device.
Ping interval: Select the frequency (in seconds) at which the ping packet is sent to
each network device to check its operating status.
Ping retries: After this number of consecutive unanswered ping requests the device is
considered inactive.
W atchdog mode: W hen Reset port when host down is enabled, the Output Port is
turned off and switched back on after the time set in Reset Duration. In mode Switch
off once when host down the Output Port remains disabled.
At the default setting (Infinite wait for booting host after reset) the watchdog monitors
the connected device. W hen there is no longer a reply after a set time, the watchdog
performs the specified action, usually a reset of the Output Port. Now the watchdog
waits until the monitored device reports again on the network. This may take several
minutes depending on the boot duration of the device. Only when the device is access-
ible from network again, the watchdog is re-armed. If the option Repeat reset on boot-
ing host after x ping timeout is enabled, this mechanism is bypassed. Now the watch-
dog is re-activated after N Ping intervals (input field ping timeouts).
When enabling the IP master-slave mode, the port is switched depending on the avail-
ability of a remote device. Depending on the configuration, the port is switched on
when the terminal is reachable, or vice versa.
The option Repeat reset on booting host after x ping timeout has the following pit-
fall: If a server, that is connected to the monitored Port is in need for a long boot pro-
cess (e.g. it is doing a file system check), the server would probably exceed the trip-
ping time of the watchdog. The server would be switched off and on again, and the file
system check is restarted. This would be repeated endlessly.
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