Nortel BCM 3.7 Manual page 735

Table 213 Permanent WAN Connections settings (Continued)
Attribute Description
Down Poll Allows you to set the polling interval on the Primary WAN Link, in seconds, when the primary
Interval WAN link is down, and the backup (dial-up) WAN link is operational.
A short interval provides faster recovery.
Switch Over Allows you to define the interval, in seconds, that Net Link Manager waits before switching back
Delay to the primary WAN link when it becomes available. This delay is to let the router at the other end
of the primary link recognize that the primary link has come up and allows for necessary routing
table updates. The default value is 30 seconds.
Backup Dial-up Allows you to select which dial up interface to use for WAN backup.
Interface
You must configure a backup interface before you can select it. When you are configuring the
backup interface, make sure you include "backup" in the interface name. Only interfaces that
contain the word backup in their name appear on this list. For information about how to create an
ISDN backup interface, refer to
Fast Backup Allows you enable or disable the Fast Backup Switch Over feature.
Switch Over
When Fast Backup Switch Over is enabled, Business Communications Manager uses the Link
Status of the WAN interface to reduce the amount of time it takes to switch over to the Backup
WAN Link, when the Primary WAN Link is down.
When Fast Backup Switch Over is Disabled, Business Communications Manager retries
contacting the next hop router if there is no response from the previous attempt. If there is no
response after several retries, Business Communications Manager switches over to the Backup
WAN Link.
When Fast Backup Switch Over is Enabled, Business Communications Manager checks the Link
Status of the WAN interface when there is no response from the next hop router. If the Link
Status is Down, Business Communications Manager immediately switches over to the Backup
WAN link. If the link status is Up, Business Communications Manager attempts to contact the
next hop router again. If there is no response after several retries, Business Communications
Manager switches over to the Backup WAN Link.
Note: PPP active/WAN link switch over delay issue: If you enable Fast Backup Switch Over
on a WAN link that is using PPP protocol, change the setting for LCP Keep Alive Interval to 3.
This reduces the time it takes for Business Communications Manager to determine that the WAN
link is not functioning to 30 seconds (3 seconds X 10 intervals). If you leave the LCP Keep Alive
Interval at its default value, the Business Communications Manager takes 100 seconds (10
seconds X 10 intervals) to determine that the WAN link is not functioning.
Note: If Business Communications Manager receives a response from the next hop router on any
attempt, it does not switch over to the Backup WAN Link.
The default setting is Disabled.
Note: The Fast Backup Switch Over feature does not affect how Business Communications
Manager switches from the Backup WAN Link to the Primary WAN Link.
7 Press the Tab key to save the settings.
Selecting a permanent WAN link as the primary WAN connection
"Creating an ISDN dial up interface" on page 695.
Programming Operations Guide
735