The toggle-interface is a combined commit and event script that pings between two GRE endpoints and toggles the GRE interface status.
This script uses RPM to monitor each GRE interface. The ping probes run and check if the SA and DA pair can be pinged. If not, an error is sent to the syslog daemon. Based on the event log configuration, the toggle-interface.slax file is called. The GRE interface is set to disable. The probe runs again and if the SA+DA pair are reachable, toggle-interface.slax file is called to delete the disable parameter.
See the document toggle-interface