3com 3031 Instruccion De Instalación

automatically when the master link is disconnected without any dial-up delay 
(excluding the route convergence time). 

Dialer Listen configures a group of destination IP addresses on the master link, so 
that it can monitor and track the master interface when the system adds/deletes 
monitored routes to/from the routing table. Dialer Listen monitors the routes in 
the following procedure:

■

Dialer Listen registers the monitored segment (IP address range) configured by 
a user to the system;

■

The system listens to the refreshed route to the monitored segment. When a 
route is deleted, Dialer Listen checks if there is still a valid route to the 
monitored segment; 

■

If there is at least one route to the monitored segment and the route starts 
from some other interface on which Dialer Listen has not been enabled, the 
master link is considered as connected;

■

If there is no valid route left, the master link is cut and unavailable. In this case, 
Dialer Listen notifies the routing protocol at once and triggers dial-up to 
activate the standby link; 

■

After the standby link is enabled, DCC link carries the communication data. 
During the idle-timeout, the system automatically checks if the master link is 
resumed; 

■

If the master link is still unavailable, reset the idle-timeout timer and check the 
master link status repeatedly.

■

If the master is connected, cut the standby link after a specified delay. 

Dialer Listen configuration tasks include:

■

Enabling/Disabling Dialer Listen

■

Configuring the destination network to be monitored

■

Configuring the delay for disconnecting the standby interface

Preparation for configuring Dialer Listen:

1 Specify master and standby interfaces. Specify an interface of a router as master 

interface or standby interface. You can specify multiple interfaces of several 
routers. 

2 Specify the segment (interface IP address of network) to be monitored, for 

example, the IP address of an interface on a remote router. 

Before enabling Dialer Listen, make sure the circular DCC has been successfully 
configured in the standby interface. The following command enables the Dialer 
Listen on the standby interface and monitors the routes defined in corresponding 
Dialer Listen group.