SnapGear 1.7.8 - Manual (Page 39)

Failed connection
An Internet connection is considered failed if the SnapGear appliance tests the Internet
connection the specified number of times, and fails each time. The SnapGear appliance
can test the Internet connection by ensuring that the physical connection was made
correctly (i.e. an IP address was received from the ISP), and then pinging a remote host.
For some Internet connections (e.g. PPPoE ADSL) you may need to ping a remote host
to determine if the Internet connection is up or down. The SnapGear appliance will
usually detect if a PPPoE ADSL Internet connection is down.
For Internet connection types that require you to specify a static IP address or use
DHCP, the SnapGear appliance cannot usually detect if the Internet connection is down.
To ensure that the Internet connection is up, enter a host for the SnapGear appliance to
ping.
If the Internet connection fails, the SnapGear appliance will attempt to reconnect to the
Internet using the main connection for the number of specified times. After each failed
attempt, the SnapGear appliance will wait the number of seconds specified.
For PPPoE and dial-up connections, the SnapGear appliance sends an echo request and
the remote machine responds with an echo reply. The main connection is considered
down if more than three echo replies do not appear.
Warning
You currently cannot failover for an ADSL demand dial-internet connection, or for any
type of analog modem connection.
Connecting to the Internet
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