holddown (PfR)
To configure the Performance Routing (PfR) prefix route dampening timer to set the minimum period of time for which a new exit must be used before an alternate exit can be selected, use the holddown command in PfR master controller configuration mode. To return the prefix route dampening timer to the default value, use the no form of this command.
holddown timer
no holddown
Syntax Description
timer |
The prefix route dampening time period, in seconds. The range is from 90 to 65535. With CSCtr26978, the default time period changed from 300 to 90. |
Command Default
With CSCtr26978, the default value of 300 seconds changed to 90 seconds for the prefix route dampening time period if this command is not configured or if the no form of this command is entered.
Command Modes
PfR master controller configuration (config-pfr-mc)
Command History
Release |
Modification |
---|---|
15.1(2)T |
This command was introduced. |
15.0(1)S |
This command was integrated into Cisco IOS Release 15.0(1)S. |
Cisco IOS XE Release 3.3 |
This command was integrated into Cisco IOS XE Release 3.3S. |
15.2(3)T |
This command was modified. With CSCtr26978, the default timer value changed. |
15.2(2)S |
This command was modified. With CSCtr26978, the default timer value changed. |
Cisco IOS XE Release 3.6 |
This command was modified. With CSCtr26978, the default timer value changed. |
Usage Guidelines
The holddown command is entered on a master controller. This command is used to configure the prefix route dampening timer to set the minimum period of time for which a new exit must be used before an alternate exit can be selected. The master controller puts a prefix in a hold-down state during an exit change to isolate the prefix during the transition period to prevent the prefix from flapping because of rapid state changes. PfR does not implement policy changes while a prefix is in the hold-down state. A prefix will remain in a hold-down state for the default or configured time period. When the hold-down timer expires, PfR will select the best exit based on performance and policy configuration. However, an immediate route change will be triggered if the current exit for a prefix becomes unreachable.
Configuring a new timer value will immediately replace the existing value if the new value is less than the amount of the time remaining. If the new value is greater than the amount of the time remaining, the new timer value will be used when the existing timer is reset.
Examples
The following example shows the commands used to set the prefix route dampening timer to 120 seconds:
Router(config)# pfr master
Router(config-pfr-mc)# holddown 120