Fast up/down checking

By default, LibreNMS sends an ICMP ping to a device before the poll. This ping tests the up state or the down state. The check uses the poller frequency, usually 5 minutes. A down device therefore takes up to 5 minutes to appear.

Some users need a faster report of a device without a ping response. The ping.php script runs the ping checks as fast as possible. It does not increase the SNMP load of 1-minute polling on your devices.

Warning

Fast Ping checks need a device down alert rule. The Alert Rules Collection holds one.

Setting the ping check to 1 minute

To run the fast pings with the dispatcher service:

poller/rrdtool

lnms config:set schedule_type.ping dispatcher
lnms config:set service_ping_frequency 60
systemctl restart librenms.service

With cron:

/etc/cron.d/librenms

*    *    * * *   librenms    /opt/librenms/ping.php >> /dev/null 2>&1

Note

With distributed pollers, limit a poller to a group. Add -g to the cron entry. You can also run ping.php on only one node.

Device dependencies

The ping.php script obeys the device dependencies. For technical reasons, the main poller does not. This script does not disable the ICMP check of the poller. A child device can therefore appear as down before its parent.

Settings

ping.php uses almost the same settings as the poller fping. There is one difference: it uses retries in place of count. ping.php measures only the up state and the down state. It does not measure the loss or the average response time. It stops the ping of a device after the first response.

poller/ping

lnms config:set fping_options.retries 2
lnms config:set fping_options.timeout 500
lnms config:set fping_options.interval 500