Specifications

104 Chapter 4. Configuring Special Features
¥ Minimum retry period before DSL link restoration is attempted
¥ Specify the modem parameters.
¥ Specify the ISP phone number and other dialup parameters.
Enabling Dial Backup
To enable the Dial Backup option, enter the command:
system backup enable
The option can be disabled using the command:
system backup disable
Setting DSL Link Conditions
The router can determine that the DSL link has failed at either of these levels:
¥ No DSL link status signal
If the signal remains down for a minimum time (the stability period), the DSL link is assumed to be
physically disconnected and down.
¥ IP addresses do not reply to ÒpingsÓ
You have the option to provide the router with one or more addresses to ping. (These could be the addresses
that are vital to your application.) The router pings these addresses at the interval you specify (default, every 5
seconds). It compares a specified number of samples (default, 6) against the specified minimum success rate
(default, 50%). If the success rate is less than the minimum, the DSL link is assumed to be down.
Stability Period
As listed above, DSL link failure is indicated if the DSL link status signal remains down for a minimum time.
This minimum time is the stability period that guards against frequent switching back and forth between the DSL
link and the backup port.
The default stability period is three minutes. To change the stability period, use this command:
system backup stability <minutes>
The minimum stability period is one minute.
Addresses to Ping
If you specify one or more addresses, the router pings those addresses to determine if the DSL link is up. You may
request that the router ping any or all of these:
¥ One or more specific IP addresses (four decimals separated by periods)
¥ Your gateway address (GW)
¥ Your domain name server address (DNS).