Specifications

106 Chapter 4. Configuring Special Features

check whether the DSL link has been restored. This time period between checks is called the retry period

(default, 30 minutes).

When the retry period expires, the router determines if the DSL link has been restored. To do so, it first

determines if the DSL link status signal has been up for the minimum stability period. If it has, then the router

stops the data traffic going through the backup V.90 modem, and checks whether the DSL link can be used

instead.

If you have specified one or more ping addresses, the router pings those addresses via the DSL link. If the DSL

link fails the ping test, the router once again switches data traffic to the backup port until the retry period expires

again.

However, if the DSL link passes the ping test, the DSL link is assumed to be restored and it is used for data traffic

until another failure is detected. The serial port reverts to being the console port.

The default retry period is 30 minutes. To change the retry period, enter this command:

system backup retry <minutes>

Specifying Modem Parameters

You need to provide the router with modem parameters so it can effectively use the V.90 modem connected to the

console port. A default modem setup is provided. To see the default settings, enter:

system defaultmodem

system list

To change the modem settings from the defaults, specify which setting you want to change and the new string. To

do so, use this command:

For example, the following command changes the string for the init setting:

system modem init ATS0=0Q0V1&C2&D3&K1X4&H1&I0S12=20

The string for the dial setting can be either ATDT for tone dialing or ATDP for pulse dialing. The default is tone

dialing. For example, the following command selects pulse dialing:

system modem dial ATDP

Specifying the Dialup Parameters

To use the V.90 modem to connect to the ISP, the router requires a remote entry defining the connection

parameters. For example, the following commands define a new remote entry named backup:

remote add backup

# Defines the connection as asynchronous and using the PPP protocol

remote setprefer async backup

remote setprotocol ppp backup

# Specifies the phone number to be used when dialing out. The phone

# number begins with 9 (to get an outside line), a comma (for a 2-second